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Recent Studies
- Whey protein is one of the most heavily researched nutritional supplements.

 
Dozens of published studies have proven its many benefits, from increased muscle strength and mass to better immune system function. The following are small selections of noteworthy studies highlighting key benefits of whey protein.
Whey Protein and Body Composition Studies

1) Whey proteins effects on body composition changes (+/-)

A preexercise Alpha-Lactalbumin-enriched whey protein meal preserves lipid oxidation and decreases adiposity in rats.

  • Increase in lean body mass through increase protein synthesis.

The composition of the preexercise food intake is known to affect substrate utilization during exercise and thus can affect long-term changes in body weight and composition. These parameters were measured in male rats exercised 2 h daily over 5 wk, either in the fasting state or 1 h after they ingested a meal enriched with glucose (Glc), whole milk protein (WMP), or -lactalbumin-enriched whey protein (CP L). Compared with fasting, the glucose meal increased glucose oxidation and decreased lipid oxidation during and after exercise.

In contrast, the WMP and CP L meals preserved lipid oxidation and increased protein oxidation, the CP L meal increasing protein oxidation more than the WMP meal. At the end of the study, body weight was larger in the WMP-, Glc-, and CP L-fed rats than in the fasted ones. This resulted from an increased fat mass in the WMP and Glc rats and to an increased lean body mass, particularly muscles, in the CP L rats.

Conclusion: That the potential of the CP L (whey protein alpha-lactalbumin rich) meal to preserve lipid oxidation and to rapidly deliver amino acids for use during exercise improved the efficiency of exercise training to decrease adiposity.

Bouthegourd, Jean-Chistophe, J., et al. A preexercise Alpha-Lactalbumin-enriched whey protein meal preserves lipid oxidation and decreases adiposity in rats. Am. J. Physiol. Endocrinol. Metab. Vol. 283, pp. E565-E572, 2002.

2) Whey protein effect on lean mass and fat loss (+/-)

Effect of a Hypocaloric Diet, Increased Protein Intake and Resistance Training on Lean Mass Gains and Fat Mass Loss in Overweight Police Officers.

  • More fat loss with whey protein than casein.

This study compared the effects of a moderate hypocaloric, high-protein diet and resistance training, using two different protein supplements, versus hypocaloric diet alone on body compositional changes in overweight police officers. A randomized, prospective 12-week study was performed comparing the changes in body composition produced by three different treatment modalities in three study groups.

One group (n = 10) was placed on a nonlipogenic, hypocaloric diet alone (80% of predicted needs). A second group (n = 14) was placed on the hypocaloric diet plus resistance exercise plus a high-protein intake (1.5 g/kg/day) using a casein protein hydrolysate. In the third group (n = 14) treatment was identical to the second, except for the use of a whey protein hydrolysate.

We found that weight loss was approximately 2.5 kg in all three groups. Mean percent body fat with diet alone decreased from a baseline of 27 ± 1.8 to 25 ± 1.3% at 12 weeks. With diet, exercise and casein the decrease was from 26 ± 1.7 to 18 ± 1.1% and with diet, exercise and whey protein the decrease was from 27 ± 1.6 to 23 ± 1.3%. The mean fat loss was 2.5 ± 0.6, 7.0 ± 2.1 and 4.2 ± 0.9 kg in the three groups, respectively. Lean mass gains in the three groups did not change for diet alone, versus gains of 4 ± 1.4 and 2 ± 0.7 kg in the casein and whey groups, respectively. Mean increase in strength for chest, shoulder and legs was 59 ± 9% for casein and 29 ± 9% for whey, a significant group difference.

This significant difference in body composition and strength is likely due to improved nitrogen retention and overall anticatabolic effects caused by the peptide components of the casein hydrolysate.

Conclusion: Whey protein is the best protein for fat loss during energy restricted diets, when combined with exercise.

Demling, Robert, H., et al. Effect of a Hypocaloric Diet, Increased Protein Intake and Resistance Training on Lean Mass Gains and Fat Mass Loss in Overweight Police Officers. Nutr. And Metabolism. Vol. 44, No. 1, 2000.

3) Whey protein and its potential toward appetite suppression (+/-)

Whey Protein Beverage Influences Satiety Hormones

  • Fructose has a lower blood glucose response compared to glucose.
  • Whey protein produced a 2-4 hour suppression of ghrelin.
  • Whey stimulate appetite suppressing hormones.

Australian researchers conducted a randomized, doubleblind crossover study in 28 obese men (20-65 years) to compare blood glucose response, response of appetite regulating hormones (ghrelin, GLP-1 and cholecystokinin) and calorie intake at a meal after consuming fructose-, glucose- or whey-based beverages.

They also wanted to observe the effect of whey when consumed in combination with fructose, a sugar that stimulates a lower blood glucose and insulin response than glucose.

On the test day, subjects were randomly assigned to consume one of four test beverages. The beverages were composed of 1% milk and water containing either: 1) 50 gm of whey, 2) 50 gm fructose, 3) 50 gm glucose, or 4) 25 gm whey + 25 gm fructose. Blood samples and appetite ratings were collected for four hours. Then a buffet lunch was offered.

Results: The fructose beverage produced significantly lower blood glucose and insulin responses than the glucose beverage. The blood glucose response to the fructose beverage was significantly greater than that of the whey or whey/fructose beverages. However, fructose produced a significantly lower insulin response compared to all of the other treatments.

Blood levels of appetite hormones were similar after drinking the fructose and the glucose beverages. The whey protein beverage produced a prolonged (2-4 hours) suppression of ghrelin. Ghrelin is a hormone that, when elevated, signals the brain to increase hunger. The satiety hormones, GLP-1 and cholecystokinin, were elevated after the whey beverage. These responses were reduced when whey was combined with fructose, but blood glucose and insulin responses were similar.

Despite differences in appetite and satiety hormones between beverages, calorie intake at the buffet meal served four hours later did not differ between beverages.

Conclusion: Whey Protein has hormonal impact on satiety.

Bowen, J. et al. Whey Protein Beverage Influences Satiety Hormones. Int. J. of Obesity. Vol. 31, pp. 1696-1703. 2007

4) Whey proteins influence on appetite and hunger controlling hormones (+/-)

Casein and whey exert different effects on plasma amino acid profiles, gastrointestinal hormone secretion and appetite.

  • 48g of whey showed lower intake of food from a buffet compared to casein.
  • A 48g preload also showed a 28% increase in amino acid concentrations
  • CCK increase by 60%, and GLP-1 increased 65%.

Protein, generally agreed to be the most satiating macronutrient, may differ in its effects on appetite depending on the protein source and variation in digestion and absorption. We investigated the effects of two milk protein types, casein and whey, on food intake and subjective ratings of hunger and fullness, and on postprandial metabolite and gastrointestinal hormone responses.

Two studies were undertaken. The first study showed that energy intake from a buffet meal ad libitum was significantly less 90 min. after a 1700kJ liquid preload containing 48g whey, compared with an equivalent casein preload. In the second study, the same whey preload led to a 28% increase in postprandial plasma amino acid concentrations over 3 h compared with casein.

Plasma cholecystokinin (CCK) was increased by 60%, glucagon like peptide (GLP-1) by 65% and glucose-dependent insulinotropic polypeptide by 36% following the whey preload compared with casein. Gastric emptying was influenced by protein type as evidenced by differing plasma paracetamol profiles with the two preloads. Greater subjective satiety followed the whey test meal.

Conclusion: These results implicate post-absorptive increases in plasma amino acids together with both CCK and GLP-1 as potential mediators of the increased satiety response to whey and emphasize the importance of considering the impact of protein type on the appetite response to a mixed meal.

Hall, W.L., et al. Casein and whey exert different effects on plasma amino acid profiles, gastrointestinal hormone secretion and appetite. British Jour. of Nutrition. Vol. 89, pp. 239-248. 2003.

5) Whey Protein and Satiety (+/-)

Whey Proteins in the Regulation of food intake and Satiety

  • Whey reduces short term food intake
  • Whey affect satiation through its complex peptides
  • Whey activates the food intake regulatory system

Whey protein has potential as a functional food component to contribute to the regulation of body weight by providing satiety signals that affect both short-term and long-term food intake regulation. Because whey is an inexpensive source of high nutritional quality protein, the utilization of whey as a physiologically functional food ingredient for weight management is of current interest. At present, the role of individual whey proteins and peptides in contributing to food intake regulation has not been fully defined. However, Whey protein reduces short-term food intake relative to placebo, carbohydrate and other proteins.

Whey protein affects satiation and satiety by the actions of: (1) whey protein fractions per se; (2) bioactive peptides; (3) amino-acids released after digestion; (4) combined action of whey protein and/or peptides and/or amino acids with other milk constituents. Whey ingestion activates many components of the food intake regulatory system. Whey protein is insulinotropic, and whey-born peptides affect the renin-angiotensin system.

Conclusion: Whey protein has potential as physiologically functional food component for persons with obesity and its co-morbidities (hypertension, type II diabetes, hyper- and dislipidemia).

Luhovyy, Bohdan, L., et al. Whey Proteins in the Regulation of Food Intake and Satiety. Journ Am. Coll. Nutr. Vol. 26, No. 6, pp. 704S-712S. 2007.

6) Whey protein and body composition changes (+/-)

Effects of supplemental protein on body composition and muscular strength in healthy athletic male adults.

  • Whey protein improves body composition.
  • Improved body composition by increase in lean mass.
  • Whey protein may decrease body fat.

This study investigated whether supplementation with whey protein combined with glutamine and branched-chain amino acids (BCAA) can enhance muscular performance and improve body composition. The diets of 16 male athletes were supplemented with 40g of whey protein alone or 40g of whey protein plus 5g of glutamine and 3g of branched chain amino acids daily for 10 weeks while engaging in resistance training. The whey protein, BCAA, glutamine group achieved significant gains in lean muscle mass and improved exercise performance (as assessed by leg-press repetition) compared to the whey protein group. However, both groups achieved significant decreases in percent body fat.

Conclusion: This study suggests that whey protein combined with BCAA and glutamine leads to improved body composition (increase lean muscle mass) and resistance exercise performance. Whey protein supplementation may help decrease body fat.

Colker, C.M. et al. Effects of Supplemental Protein on Body Composition and Muscular Strength in Healthy Athletic Male Adults. Current Therapeutic Research. Vol. 61, No. 1, pp. 19-28. 2000.

7) Reduced Waist Line. (+/-)

Whey Protein Improves Body Composition and Reduces Waist Circumference.

  • 6 months of 60g/day of whey supplementation resulted in:
  • Less Body Weight
  • Less Body Fat, especially belly fat

The purpose of this study was to investigate the effects of whey protein, compared to both soy protein and carbohydrate, on body weight and composition. In the six month study, researchers provided whey protein, soy protein or carbohydrate supplements to 90 free-living, overweight and obese (BMI > 28 and < 38) but otherwise healthy individuals.

The study participants were randomly assigned to one of three treatment groups: 1) 60 grams/day of whey protein, 2) 60 grams/day of soy protein or 3) a control group receiving 60 grams/day of carbohydrate, and were instructed to incorporate the supplement they received as part of their normal diet. Body composition and weight were measured weekly.

After six months, the researchers found that individuals who consumed whey protein weighed less, had less body fat and lost more inches around the waist compared to the carbohydrate group. The difference in body weight observed was associated with a decrease in body fat without a significant loss in lean body mass. While the body weight was not different between the whey and soy groups, the whey group lost more inches around the waist than the group consuming soy protein.

Conclusion: Consuming 60g/daily of whey protein for 6 months can lower body weight, decrease body fat and lose more inches around the waist.

Baer, David, et al. Whey protein decreases body weight and fat in supplemented overweight and obese adults. U.S. Department of Agriculture, Beltsville Human Nutrition Research Center, Beltsville, Maryland. 2006.

8) Whey protein an its potential to reduce weight gain (+/-)

A High-Whey-Protein diet reduces body weight gain and alters insulin sensitive relative to red meat in Wistar Rats.

  • Whey protein reduce body weight
  • Whey protein increases insulin sensitivity.
  • High dietary protein reduced visceral, subcutaneous and carcass fat.

A high-protein diet can reduce body weight and increase insulin sensitivity, but whether the type of dietary protein affects these outcomes is unknown. We hypothesized that feeding insulin-resistant rats a high-protein diet (32%) containing whey protein concentrate (WPC) would reduce body weight and tissue lipid levels and increase insulin sensitivity more than a diet containing red meat (RM).

Rats were fed a high-fat diet (300 g fat/kg diet) for 9 wk, then switched to a diet containing either 80 or 320 g protein/kg diet, provided by either WPC or RM, for 6 wk (n = 8). The rats were then killed after overnight food deprivation. High dietary protein reduced energy intake (P < 0.001) and visceral (P < 0.001), subcutaneous (P < 0.001), and carcass fat (P < 0.05). Increasing the dietary density of WPC, but not of RM, reduced body weight gain by 4% (P < 0.001). Dietary WPC also reduced plasma insulin concentration by 40% (P < 0.05) and increased insulin sensitivity, compared to RM (P < 0.05).

Conclusion: These findings support the conclusions that a high-protein diet reduces energy intake and adiposity and that whey protein is more effective than red meat in reducing body weight gain and increasing insulin sensitivity.

Belobrajdic, Damien P., et al. A High-Whey-Protein Diet Reduces Body Weight Gain and Alters Insulin Sensitivity Relative to Red Meat in Wistar Rats. Journal of Nutrition. Vol. 134, pp. 1454-1458. 2004.

9) Whey protein and its appetite suppressing hormone responses (+/-)

Effect of a high-protein breakfast on the postprandial ghrelin response.

Background: The most satiating macronutrient appears to be dietary protein. Few studies have investigated the effects of dietary protein on ghrelin secretion in humans.

Objective: This study was designed to investigate whether a high-protein (HP) breakfast is more satiating than a high-carbohydrate breakfast (HC) through suppression of postprandial ghrelin concentrations or through other physiologic processes.

Design: Fifteen healthy men were studied in a single-blind, crossover design. Blood samples and subjective measures of satiety were assessed frequently for 3 h after the consumption of 2 isocaloric breakfasts that differed in their protein and carbohydrate content (58.1% of energy from protein and 14.1% of energy from carbohydrate compared with19.3% of energy from protein and 47.3% of energy from carbohydrate). The gastric emptying rate was indirectly assessed with the acetaminophen absorption test.

Results: The HP breakfast decreased postprandial ghrelin secretion more than did the HC breakfast (P < 0.01). Ghrelin concentrations were correlated with glucose-dependent insulinotropic polypeptide (r = –0.65; 95% CI: –0.85, –0.29) and glucagon concentrations (r = –0.47; 95% CI: –0.75, –0.03). Compared with the HC breakfast, the HP breakfast increased glucagon (P < 0.0001) and cholecystokinin (P < 0.01), tended to increase glucose-dependent insulinotropic polypeptide (P = 0.07) and glucagon-like peptide 1 (P = 0.10), and decreased the gastric emptying rate (P < 0.0001). Appetite ratings were not significantly different between the 2 treatments, and the HP breakfast did not significantly affect ad libitum energy intake.

Conclusion: The HP breakfast decreased postprandial ghrelin concentrations more strongly over time than did the HC breakfast. High associations between ghrelin and glucose-dependent insulinotropic polypeptide and glucagon suggest that stimulation of these peptides may mediate the postprandial ghrelin response. The HP breakfast also reduced gastric emptying, probably through increased secretion of cholecystokinin and glucagon-like peptide 1.

Blom, Wendy A.M. et al. Effect of high-protein breakfast on the postprandial ghrelin response. Amer. Jour. Clin. Nutr. Vol. 83, No. 2, pp. 211-220. 2006.

Whey Protein and Increased Strength and Lean Muscle Mass Studies

1) Whey protein supplementation and increases in strength and lean muscle (+/-)

Effect of an Amino Acid, Protein, and Carbohydrate mixture on Net Muscle Protein Balance after Resistance Exercise.

  • Whey protein gives an immediate rise in the amino acid pool following resistance exercise.
  • Whey gives a second rise, in the amino acid pool, 90 minutes after ingesting, following resistance exercise.
  • Whey protein, amino acids, and carbohydrate stimulate muscle protein synthesis to a greater extent than carbohydrate alone.

This study tested the hypotheses that a mixture of whey protein, amino acids, and carbohydrates would stimulate net muscle protein synthesis to a greater extent than carbohydrate alone after resistance exercise. Eight subjects participated in two trials. In one, they ingested 77.4g of carbohydrate, 17.5g of whey protein, and 4.9g of amino acids one hour after resistance exercise.

Conclusion: In the other, 100g of carbohydrate was ingested instead. The net protein balance response to the mixture consisted of two components, one rapid immediate response, and a smaller delayed response about 90 minutes after drinking, whereas in the second trial only a small delayed response was seen.

Borsheim E, Aarsland A, Wolfe R. Effect of an Amino Acid, Protein, and Carbohydrate mixture on Net Muscle Protein Balance after Resistance Exercise. 2004. International Journal of Sport Nutrition and Exercise Metabolism, Vol. 14, pp. 255-271. 2004.

2) Whey protein and its increase in strength and lean muscle (+/-)

The effect of whey isolate on strength, body composition and plasma glutamine.

  • Whey protein, creantine, carbohydrate increase strength, lean mass, and muscle girth.
  • Whey protein, creatine and carbohydrate also showed great increases in type II muscle fiber size, compared to a carbohydrate and creatine group.

This study investigated the effects of various supplements on strength, body composition, and glutamine levels in resistance-trained men. Thirty-three resistance-trained men were matched for strength and placed into one of four groups: creatine/carbohydrate, whey protein isolate, creatine/whey isolate or carbohydrate only.

All subjects undertook the same fully supervised resistance training program three times per week and consumed 1.5 g of supplement per kg body weight per day. While all groups demonstrated increases in strength, lean mass and muscle girth, the creatine-carbohydrate, whey and creatine-whey groups all demonstrated significantly larger gains in strength and lean mass and greater increases in type II muscle fiber size. Additionally, the creatine-whey group demonstrated a greater increase in strength, lean mass, and fiber size than the whey group.

Cribb P, Williams A, Carey M. The effect of whey isolate on strength, body composition and plasma glutamine. Med Sci Sports Exercise, Vol. 34(5):S299. 2002.

3) Whey protein and its potential to increase strength and lean muscle (+/-)

Effects of resistance training and protein plus amino acid supplementation on muscle anabolism, mass, and strength.

  • 20g of whey protein and free amino acids up-regulated protein synthesis and anabolism when compared to a carbohydrate only drink.
  • Whey and amino acids were consumed 1 hour before and after resistance exercise.
  • The protein groups showed, increase in body mass, fat free mass, thigh mass, muscle strength, serum IGF-1, IGF-1 mRNA, Myosin Heavy Chain I and IIa expression and myofibrillar protein.

This study examined 10 wks of resistance training and the ingestion of supplemental protein and amino acids on muscle performance and markers of muscle anabolism. Nineteen untrained males were randomly assigned to supplement groups containing either 20 g protein (14 g whey and casein protein, 6 g free amino acids) or 20 g dextrose placebo ingested 1 h before and after exercise for a total of 40 g=d. Participants exercised 4 times=wk using 3 sets of 6–8 repetitions at 85–90% of the one repetition maximum. Data were analyzed with two-way ANOVA (p<0.05).

Conclusion: The protein supplement resulted in greater increases in total body mass, fat-free mass, thigh mass, muscle strength, serum IGF-1, IGF-1 mRNA, MHC I and IIa expression, and myofibrillar protein. Ten wks of resistance training with 20 g protein and amino acids ingested 1 h before and after exercise is more effective than carbohydrate placebo in up- regulating protein synthesis and anabolism along with regulating markers of muscle subsequent improvements in muscle performance.

Willoughby, D.S. et al. Effects of training and protein plus amino acid supplementation on muscle anabolism, mass and strength. Exercise and Biochemical Nutrition Laboratory, Baylor Univ. Waco Texas, USA. Septemer 2006.

4) Whey protein and muscle anabolism (+/-)

Ingestion of Casein and Whey Proteins Result in Muscle Anabolism after Resistance Exercise.

  • 20g Whey protein casein switch net amino acid balance to positive after ingestion.
  • Whey protein had great leucine net balance over time when compared to casein.
  • Both protein increase muscle protein net balance, however, whey was shown to be better at sustaining leucine balance over time.

Purpose: Determination of the anabolic response to exercise and nutrition is important for individuals who may benefit from increased muscle mass. Intake of free amino acids after resistance exercise stimulates net muscle protein synthesis. The response of muscle protein balance to intact protein ingestion after exercise has not been studied. This study was designed to examine the acute response of muscle protein balance to ingestion of two different intact proteins after resistance exercise.

Methods: Healthy volunteers were randomly assigned to one of three groups. Each group consumed one of three drinks: placebo (PL; N = 7), 20 g of casein (CS; N = 7), or whey proteins (WH; N = 9). Volunteers consumed the drink 1 h after the conclusion of a leg extension exercise bout. Leucine and phenylalanine concentrations were measured in femoral arteriovenous samples to determine balance across the leg.

Results: Arterial amino acid concentrations were elevated by protein ingestion, but the pattern of appearance was different for CS and WH. Net amino acid balance switched from negative to positive after ingestion of both proteins. Peak leucine net balance over time was greater for WH (347 +/- 50 nmol[middle dot]min-1[middle dot]100 mL-1 leg) than CS (133 +/- 45 nmol[middle dot]min-1[middle dot]100 mL-1 leg), but peak phenylalanine balance was similar for CS and WH. Ingestion of both CS and WH stimulated a significantly larger net phenylalanine uptake after resistance exercise, compared with the PL (PL -5 +/- 15 mg, CS 84 +/- 10 mg, WH 62 +/- 18 mg). Amino acid uptake relative to amount ingested was similar for both CS and WH (~10-15%).

Conclusion: Acute ingestion of both WH and CS after exercise resulted in similar increases in muscle protein net balance, resulting in net muscle protein synthesis despite different patterns of blood amino acid responses.

Tipton, Kevin D. et al. Ingestion of Casein and Whey Proteins Result in Muscle Anabolism after Resistance Exercise. Medicine and Science in Sports and Exercise. Vol. 36(12), pp. 2073-2081. December 2004.

5) Whey protein and lean muscle preservation (+/-)

Branched-chain Amino Acids and Arginine Supplementation Attentuates Skeletal Muscle Proteolysis induced by Moderate Exercise in Young Individuals.

  • Single dose of 2g BCCA’s and .5g Arginine
  • Attentuates proteolysis in moderate endurance activity.

This study aimed at evaluating the effect of a single oral intake of branched-chain amino acids (BCAA) with Arg on skeletal muscle protein metabolism during moderate exercise in young individuals. Eight healthy volunteers (4 males and 4 females, means ± SEM, 26 ± 1 yrs, 177.8 ± 3.7 cm, 72.6 ± 3.9 kg) were studied in a randomized double-blind placebo-controlled cross-over trial. The subjects performed 3 bouts of 20-min cycling exercise (5-min break between each bout) at 126 ± 13W corresponding to 50% of the maximal work intensity.

A single oral supplement of either a BCAA drink containing 2 g of BCAA and 0.5 g of Arg or an isocaloric placebo drink was given at 10 min of the 1st exercise bout. This amount equates to about 8 g of whey protein for 2 g of BCAA’s, and about 200 g of whey protein for .5 g of Arginine. Both arterial and venous blood samples were simultaneously taken from the radial artery and the femoral vein, respectively. Blood flow in the femoral artery was determined using the ultrasound Doppler technique.

The blood sampling and blood flow measurements were performed at rest, every 10 min during each exercise bout. Net balance of BCAA and Phe across the leg muscles were measured by the arteriovenous difference method. The BCAA ingestion resulted in increases in both the plasma BCAA concentration and BCAA uptake into the working leg. The Phe release from the leg during exercise significantly increased as compared to the basal level in the placebo trial (0.97 ± 0.28 vs. 0.23 ± 0.22 μmol/min, p < 0.05). In the BCAA trial, the cumulative Phe release from the leg during the 3rd exercise bout was significantly lower than that in the placebo trial (5.0 ± 7.4 vs. 35.9 ± 13.2 μmol/25 min, p < 0.05).

Conclusion: These results suggest that endurance exercise at moderate intensity enhances proteolysis in working muscles, and a single oral intake of 2 g of BCAA with Arg at onset of exercise effectively suppresses exercise-induced skeletal muscle proteolysis.

Matsumoto, K., et al. BCAA’s and Arginine Supplementation Attentuates Skeletal Muscel Proteolysis Induced by Moderate Exercise in Young Individuals. Int. J. Sports Med. Vol. 28, pp. 531-538, 2007.

6)Whey protein and its potential to spare lean muscle. (+/-)

Relation between glutamine, branched-chain amino acid, and protein metabolism.

  • BCAA’s and glutamine for enhance recovery.
  • BCAA’s assist in synthesis of glutamine.
  • Glutamine/ alanine decrease protein breakdown

The branched-chain amino acids (BCAA’s, valine, isoleucine and leucine) are the major nitrogen source for glutamine and alanine synthesis in muscle. Synthesis of glutamine, alanine and BCAA use activate in critical illnesses. The use of glutamine often exceeds synthesis, resulting in the lack of glutamine in blood and tissue. In illness, extreme stress, and over-training, resynthesis of BCAA from branched-chain keto acids is activated.

The BCAA released to circulation may be used for protein synthesis or synthesis of alanine and glutamine. Glutamine and/or alanine infusion has an inhibitory effect on the breakdown of body proteins and decrease BCAA catabolism. Decrease protein breakdown also was observed when glutamine synthesis was activated by ammonia infusion.

Conclusion: Some favorable effects of BCAA supply can be explained by its role in the synthesis of glutamine and some positive effect of glutamine exogenous supply can be explained by if effect on metabolism BCAA.

Hole, M. Relations between glutamine, branched chain-amino acids, and protein metabolism. Int. J. App. Basic Nutr. Sci. Vol. 18, pp. 130-133, 2002.

7) Whey proteins influence on muscular power and strength (+/-)

Effect of supplementation with a cysteine donor on muscular performance.

  • Whey protein can increase muscle power
  • Whey protein can increase intracellular glutathione

Oxidative stress contributes to muscular fatigue. GSH is the major intracellular antioxidant, the biosynthesis of which is dependent on cysteine availability. We hypothesized that supplementation with a whey-based cysteine donor [Immunocal (HMS90)] designed to augment intracellular GSH would enhance performance. Twenty healthy young adults (10 men, 10 women) were studied pre supplementation and 3 mo post supplementation with either Immunocal (20 g/day) or casein placebo. Muscular performance was assessed by whole leg isokinetic cycle testing, measuring peak power and 30-s work capacity. Lymphocyte GSH was used as a marker of tissue GSH. There were no baseline differences (age, ht, wt, %ideal wt, peak power, 30-s work capacity). Follow-up data on 18 subjects (9 Immunocal, 9 placebo) were analyzed.

Both peak power [13 ± 3.5 (SE) %, P < 0.02] and 30-s work capacity (13 ± 3.7%, P < 0.03) increased significantly in the Immunocal group, with no change (2 ± 9.0 and 1 ± 9.3%) in the placebo group. Lymphocyte GSH also increased significantly in the Immunocal group (35.5 ± 11.04%, P < 0.02), with no change in the placebo group ( 0.9 ± 9.6%).

Conclusion: The first study to demonstrate that prolonged supplementation with a product designed to augment antioxidant defenses resulted in improved volitional performance.

Lands, L.C., et al. Effect of supplementation with a cysteine donor on muscular performance. J. Appl. Physiol. Vol. 87, pp. 1381-1385, 1999.

8) Whey protein can creatine show an increase in lean muscle f0iber adaptations (+/-)

Effects of Whey Isolate, Creatine, and Resistance Training on Muscle Hypetrophy.

Purpose: Studies that have attributed gains in lean body mass to dietary supplementation during resistance exercise (RE) training have not reported these changes alongside adaptations at the cellular and subcellular levels. Therefore, the purpose of this study was to examine the effects of two popular supplements—whey protein (WP) and creatine monohydrate (CrM) (both separately and in combination)—on body composition, muscle strength, fiber-specific hypertrophy (i.e., type I, IIa, IIx), and contractile protein accrual during RE training.

Methods: In a double-blind randomized protocol, resistance-trained males were matched for strength and placed into one of four groups: creatine/carbohydrate (CrCHO), creatine/whey protein (CrWP), WP only, or carbohydrate only (CHO) (1.5 gIkgj1 body weight per day). All assessments were completed the week before and after an 11-wk structured, supervised RE program. Assessments included strength (1RM, three exercises), body composition (DEXA), and vastus lateralis muscle biopsies for determination of muscle fiber type (I, IIa, IIx), cross-sectional area(CSA), contractile protein, and creatine (Cr) content.

Results: Supplementation with CrCHO, WP, and CrWP resulted in significantly greater (P G 0.05) 1RM strength improvements (three of three assessments) and muscle hypertrophy compared with CHO. Up to 76% of the strength improvements in the squat could be attributed to hypertrophy of muscle involved in this exercise. However, the hypertrophy responses within these groups varied at the three levels assessed (i.e., changes in lean mass, fiber-specific hypertrophy, and contractile protein content).

Conclusion: Although WP and/or CrM seem to promote greater strength gains and muscle morphology during RE training, the hypertrophy responses within the groups varied. These differences in skeletal muscle morphology may have important implications for various populations and, therefore, warrant further investigation.

Cribb, P.J., et al. Effects of Whey Isolate, Creatine, and Resistance Training on Muscle Hypertrophy. Med. Sci. Sports Exerc. Vol. 39, No. 2, pp. 298-307, 2007.

9) Milk protein superior to soy protein for lean muscle gains (+/-)

Dietary Protein to Support Anabolism with Resistance Exercise in Young Men.

  • Milk protein support greater increases in lean mass compared to soy protein.
  • 12 wks of milk supplement showed greater gains in whole body lean mass and greater muscle hypertrophy.

Resistance exercise is fundamentally anabolic and as such stimulates the process of skeletal muscle protein synthesis (MPS) in an absolute sense and relative to skeletal muscle protein breakdown (MPB). However, the net effect of resistance exercise is to shift net protein balance (NPB _ MPS _ MPB) to a more positive value; however, in the absence of feeding NPB remains negative.

Feeding stimulates MPS to an extent where NPB becomes positive, for a transient time. When combined, resistance exercise and feeding synergistically interact to result in NPB being greater than with feeding alone. This feeding- and exercise-induced stimulation of NPB is what, albeit slowly, results in muscle hypertrophy. With this rudimentary knowledge we are now at the point where we can manipulate variables within the system to see what impact these interventions have on the processes of MPS, MPB, and NPB and ultimately and perhaps most importantly, muscle hypertrophy and strength.

We used established models of skeletal muscle amino acid turnover to examine how protein source (milk versus soy) acutely affects the processes of MPS and MPB after resistance exercise. Our findings revealed that even when balanced quantities of total protein and energy are consumed that milk proteins are more effective in stimulating amino acid uptake and net protein deposition in skeletal muscle after resistance exercise than are hydrolyzed soy proteins.

Importantly, the finding of increased amino acid uptake would be independent of the differences in amino acid composition of the two proteins. We propose that the improved net protein deposition with milk protein consumption is also not due to differences in amino acid composition, but is due to a different pattern of amino acid delivery associated with milk versus hydrolyzed soy proteins. If our acute findings are accurate then we hypothesized that chronically the greater net protein deposition associated with milk protein consumption post-resistance exercise would eventually lead to greater net protein accretion (i.e., muscle fiber hypertrophy), over a longer time period.

In young men completing 12 weeks of resistance training (5d/wk) we observed a tendency (P _ 0.11) for greater gains in whole body lean mass and whole as greater muscle fiber hypertrophy with consumption of milk. While strength gains were not different between the soy and milk-supplemented groups we would argue that the true significance of a greater increase in lean mass that we observed with milk consumption may be more important in groups of persons with lower initial lean mass and strength such as the elderly.

Conclusion: Milk protein is better than soy protein for greater gains in lean mass and greater muscle hypertrophy.

Phillips, Stuart, M. et al. Dietary Protein to Support Anabolism with Resistance Exercise in Young Men. Jour. of American College of Nutrition. Vol. 24, No. 2, pp- 134S-139S. 2005.

Whey protein and post-exercise recovery studies

1) Whey proteins influence on protein synthesis (+/-)

A preexercise Alpha-Lactalbumin-enriched whey protein meal preserves lipid oxidation and decreases adiposity in rats.

  • Increase in lean body mass through increase protein synthesis.

The composition of the preexercise food intake is known to affect substrate utilization during exercise and thus can affect long-term changes in body weight and composition. These parameters were measured in male rats exercised 2 h daily over 5 wk, either in the fasting state or 1 h after they ingested a meal enriched with glucose (Glc), whole milk protein (WMP), or -lactalbumin-enriched whey protein (CP L). Compared with fasting, the glucose meal increased glucose oxidation and decreased lipid oxidation during and after exercise.

In contrast, the WMP and CP L meals preserved lipid oxidation and increased protein oxidation, the CP L meal increasing protein oxidation more than the WMP meal. At the end of the study, body weight was larger in the WMP-, Glc-, and CP L-fed rats than in the fasted ones. This resulted from an increased fat mass in the WMP and Glc rats and to an increased lean body mass, particularly muscles, in the CP L rats.

Conclusion: That the potential of the CP L (whey protein alpha-lactalbumin rich) meal to preserve lipid oxidation and to rapidly deliver amino acids for use during exercise improved the efficiency of exercise training to decrease adiposity.

Bouthegourd, Jean-Chistophe, J., et al. A preexercise Alpha-Lactalbumin-enriched whey protein meal preserves lipid oxidation and decreases adiposity in rats. Am. J. Physiol. Endocrinol. Metab. Vol. 283, pp. E565-E572, 2002.

2) Whey protein better than casein for increases in lean mass and fat loss (+/-)

Effect of a Hypocaloric Diet, Increased Protein Intake and Resistance Training on Lean Mass Gains and Fat Mass Loss in Overweight Police Officers.

  • More fat loss with whey protein than casein.

This study compared the effects of a moderate hypocaloric, high-protein diet and resistance training, using two different protein supplements, versus hypocaloric diet alone on body compositional changes in overweight police officers. A randomized, prospective 12-week study was performed comparing the changes in body composition produced by three different treatment modalities in three study groups. One group (n = 10) was placed on a nonlipogenic, hypocaloric diet alone (80% of predicted needs). A second group (n = 14) was placed on the hypocaloric diet plus resistance exercise plus a high-protein intake (1.5 g/kg/day) using a casein protein hydrolysate. In the third group (n = 14) treatment was identical to the second, except for the use of a whey protein hydrolysate.

We found that weight loss was approximately 2.5 kg in all three groups. Mean percent body fat with diet alone decreased from a baseline of 27 ± 1.8 to 25 ± 1.3% at 12 weeks. With diet, exercise and casein the decrease was from 26 ± 1.7 to 18 ± 1.1% and with diet, exercise and whey protein the decrease was from 27 ± 1.6 to 23 ± 1.3%. The mean fat loss was 2.5 ± 0.6, 7.0 ± 2.1 and 4.2 ± 0.9 kg in the three groups, respectively.

Lean mass gains in the three groups did not change for diet alone, versus gains of 4 ± 1.4 and 2 ± 0.7 kg in the casein and whey groups, respectively. Mean increase in strength for chest, shoulder and legs was 59 ± 9% for casein and 29 ± 9% for whey, a significant group difference. This significant difference in body composition and strength is likely due to improved nitrogen retention and overall anticatabolic effects caused by the peptide components of the casein hydrolysate.

Conclusion: Whey protein is the best protein for fat loss during energy restricted diets, when combined with exercise.

Demling, Robert, H., et al. Effect of a Hypocaloric Diet, Increased Protein Intake and Resistance Training on Lean Mass Gains and Fat Mass Loss in Overweight Police Officers. Nutr. And Metabolism. Vol. 44, No. 1, 2000.

3) Whey proteins potential to increase lean mass and decrease body fat (+/-)

Effects of supplemental protein on body composition and muscular strength in healthy athletic male adults.

  • Whey protein improves body composition.
  • Improved body composition by increase in lean mass.
  • Whey protein may decrease body fat.

This study investigated whether supplementation with whey protein combined with glutamine and branched-chain amino acids (BCAA) can enhance muscular performance and improve body composition. The diets of 16 male athletes were supplemented with 40g of whey protein alone or 40g of whey protein plus 5g of glutamine and 3g of branched chain amino acids daily for 10 weeks while engaging in resistance training.

The whey protein, BCAA, glutamine group achieved significant gains in lean muscle mass and improved exercise performance (as assessed by leg-press repetition) compared to the whey protein group. However, both groups achieved significant decreases in percent body fat.

Conclusion: This study suggests that whey protein combined with BCAA and glutamine leads to improved body composition (increase lean muscle mass) and resistance exercise performance. Whey protein supplementation may help decrease body fat.

Colker, Carlon, M., et al. Effects of supplemental protein on body composition and muscular strength in healthy athletic male adults. Current Therapeutic Research, Vol. 61, Issue 1, pp. 19-28. 2000.

4) Whey protein stimulates protein synthesis, faster than casein (+/-)

Slow and fast dietary proteins differently modulate postprandial protein accretion

  • Whey protein induces a dramatic but short increase of plasma amino acids.
  • Protein synthesis was stimulated 68% with the whey protein meal.

The speed of absorption of dietary amino acids by the gut varies according to the type of ingested dietary protein. This could affect postprandial protein synthesis, breakdown, and deposition. To test this hypothesis, two intrinsically 13C-leucine-labeled milk proteins, casein (CAS) and whey protein (WP), of different physicochemical properties were ingested as one single meal by healthy adults.

Postprandial whole body leucine kinetics were assessed by using a dual tracer methodology. WP induced a dramatic but short increase of plasma amino acids. CAS induced a prolonged plateau of moderate hyperaminoacidemia, probably because of a slow gastric emptying. Whole body protein breakdown was inhibited by 34% after CAS ingestion but not after WP ingestion. Postprandial protein synthesis was stimulated by 68% with the WP meal and to a lesser extent (+31%) with the CAS meal. Postprandial whole body leucine oxidation over 7 h was lower with CAS (272 ± 91 µmol·kg 1) than with WP (373 ± 56 µmol·kg 1). Leucine intake was identical in both meals (380 µmol·kg 1).

Therefore, net leucine balance over the 7 h after the meal was more positive with CAS than with WP (P < 0.05, WP vs. CAS). In conclusion, the speed of protein digestion and amino acid absorption from the gut has a major effect on whole body protein anabolism after one single meal. By analogy with carbohydrate metabolism, slow and fast proteins modulate the postprandial metabolic response, a concept to be applied to wasting situations.

Conclusion: Whey protein is digested quickly and provides a quick rise in plasma amino acids.

Boire, Yves, et al. Slow and fast dietary proteins differently modulate postprandial protein accretion. Proc. Natl. Acad. Sci. Vol. 94, pp. 14930-14935, 1997.

Whey protein and slowing sarcopenia studies

1) Whey proteins potential to increase protein synthesis in the elderly (+/-)

Differential stimulation of muscle protein synthesis in elderly humans following isocaloric ingestion of amino acids or whey protein.

  • Amino acids and whey protein increase protein synthesis in the elderly.
  • Increase in lean body mass through increase protein synthesis.

This study investigated the effects of amino acids and whey protein on muscle synthesis in elderly individuals. Net muscle protein synthesis in healthy elderly individuals (65-79 years) was measured following ingestion of a whey protein supplement or an essential amino acid supplement. Both the essential amino acid and whey protein supplements stimulated muscle protein synthesis.

Conclusion: Essential amino acids and whey protein are equally effective in stimulating muscle protein synthesis in elderly individuals.

Paddon-Jones, D., et al. Differential stimulation of muscle protein synthesis in elderly humans following isocaloric ingestion of amino acids or whey protein. Experimental Gerontology. Vol. 42(2), pp. 215-219. 2005.

2) Whey protein works on the molecular level (DNA) (+/-)

Whey protein supplementation and resistance training to enhance muscle growth in young and older adults.

  • Whey protein stimulates muscle building genes.
  • 25g of whey isolate post strength training stimulates protein synthesis through translation initiation factor.

Whey protein isolate supplementation increase significantly strength after training (25% greater than control group) in young, but not in older adults. Older participants consuming the whey protein isolate demonstrated a greater phosphorylation of the translational factor p70-S6K1(DNA signaling) after 12 weeks training (2.9 fold increase), when compared to the control group. This effect was not observed in the young groups.

Following resistance training adults who took whey protein isolate showed a 17.3 fold increase in Pax7 gene (a marker of satellite activation) compared to 2.6 fold increase in the control group post training. Only a small increase in Pax7 gene expression was observed in the young groups, with a 2.6 fold increase in the protein group and 1.9 fold increase in the placebo group.

Conclusion: These findings provide molecular evidence of enhanced activation of genetic factors related to muscle growth when whey protein intake and chronic resistance training are combined in older individuals.

Farnfield MM, et al. Whey protein supplementation and resistance training to enhance muscle growth in young and older adults. Asia Pac. Jour. of Clin. Nutr. Vol 14. Supp. S69. 2005.

3) Whey protein increase net protein gain (+/-)

The rate of protein digestion affects protein gain differently during aging in humans.

  • Whey protein digests faster than casein.
  • Faster digestion gives rise to a quicker amino acid flood into muscle cells.
  • Whey protein is the preferred protein for net protein gain

In young men ingesting protein meals, slowly digested proteins (caseins: CAS) induce a higher protein gain than those that are rapidly digested (whey proteins: WP). Our aim was to assess whether or not this is true in elderly men receiving mixed meals. The effects of meals containing either CAS or two different amounts of WP (WP-iN: isonitrogenous with CAS, or WP-iL: providing the same amount of leucine as CAS) on protein metabolism (assessed by combining oral and intravenous leucine tracers) were compared in nine healthy, elderly (mean ± S.E.M. age 72 ± 1 years) and six young men (24 ± 1 years).

In both age groups, WP-iL and WP-iN were digested faster than CAS (P < 0.001, ANOVA). Proteolysis was inhibited similarly whatever the meal and age groups (P = NS). Protein synthesis was higher with WP-iN than with CAS or WP-iL (P < 0.01), regardless of age (P = NS). An age-related effect (P < 0.05) was found with postprandial leucine balance. Leucine balance was higher with CAS than with WP-iL (P < 0.01) in young men, but not in elderly subjects (P = NS).

In isonitrogenous conditions, leucine balance was higher with WP-iN than with CAS (P < 0.001) in both age groups, but the magnitude of the differences was higher in the elderly men (P = 0.05). In conclusion, during aging, protein gain was greater with WP (rapidly digested protein), and lower with CAS (slowly digested protein). This suggests that a 'fast' protein might be more beneficial than a 'slow' one to limit protein losses during aging.

Dangin, M., et al. The rate of digestion affects protein gain differently during aging in humans. The Jour. of Physiol. 2003.

4) Dietary Protein and Resistance Training Effect on Muscle Body Composition in Older Persons (+/-)

  • Adequate intake of protein combats sarcopenia.
  • Resistance training helps older people gain muscle, hypertrophy muscle, and increase whole body fat-free mass.
  • Adequate intake of protein and resistance exercise synergistically can reduce sarcopenia.

The regular performance of resistance exercises and the habitual ingestion of adequate amounts of dietary protein from high-quality sources are two important ways for older persons to slow the progression of and treat sarcopenia, the age-related loss of skeletal muscle mass and function. Resistance training can help older people gain muscle strength, hypertrophy muscle, and increase whole body fat-free mass. It can also help frail elderly people improve balance and physical functioning capabilities.

Inadequate protein intake will cause adverse metabolic and physiological accommodation responses that include the loss of fat-free mass and muscle strength and size. Findings from controlled feeding studies show that older persons retain the capacity to metabolically adjust to lower protein intakes by increasing the efficiency of nitrogen retention and amino acid utilization. However, they also suggest that the recommended dietary allowance of 0.8 g protein _ kg_1 _ d_1 might not be sufficient to prevent subtle accommodations and blunt desired changes in body composition and muscle size with resistance training.

Conclusion: Most of the limited research suggests that resistance training-induced improvements in body composition, muscle strength and size, and physical functioning are not enhanced when older people who habitually consume adequate protein (modestly above the RDA) increase their protein intake by either increasing the ingestion of higher-protein foods or consuming protein-enriched nutritional supplements.

Campbell, Wayne W. Dietary Protein and Resistance Training on Muscle and Body Composition in Older Persons. Journ. Amer. Coll. Nutr. Vol. 26, No. 6, pp. 696S-703S. 2007.

5) Resistance training and dietary protein: effects on glucose tolerance and contents of skeletal muscle insulin signaling proteins in older persons. (+/-)

  • Resistance training and moderate to high protein intake increases whole body protein.
  • Fat mass decreases with low protein and high protein intakes.
  • Resistance training improved oral glucose tolerance.

Background: Resistance training (RT) and dietary protein independently influence indexes of whole-body glucose control, though their synergistic effects have not yet been documented.

Objective: This study assessed the influence of dietary protein intake on RT-induced changes in systemic glucose tolerance and the contents of skeletal muscle insulin signaling proteins in healthy older persons.

Design: Thirty-six older men and women (age: 61 ± 1 y) performed RT (3 times/wk for 12 wk) and consumed either 0.9 g protein · kg–1 · d–1 [lower-protein (LP) group; 112% of the Recommended Dietary Allowance (RDA)] or 1.2 g protein · kg–1 · d–1 [higher-protein (HP) group; 150% of the RDA]; the HP group consumed more total, egg, and dairy proteins.

Results: After RT, body weight was unchanged; whole-body protein and water masses increased, and fat mass decreased with no significantly different responses observed between the LP and HP groups. The RT-induced improvement in oral glucose tolerance (decreased area under the curve, AUC) was not significantly different between the groups (LP: –28%; HP: –25%). The insulin (–21%) and C-peptide (–14%) AUCs decreased in the LP group but did not change significantly in the HP group. Skeletal muscle insulin receptor, insulin receptor substrate-1, and Akt contents were unchanged, and the amount of atypical protein kinase C / (aPKC / ), a protein involved with insulin signaling, increased 56% with RT, independent of protein intake.

Conclusion: These results support the hypothesis that older persons who consume adequate or moderately high amounts of dietary protein can use RT to improve body composition, oral glucose tolerance, and skeletal muscle aPKC / content without a change in body weight.

Iglay, Heidi B, et al. Resistance training and dietary protein: effects on glucose tolerance and contents of skeletal muscle insulin signaling proteins in older persons. Amer. Jour. Clin. Nutr. Vol. 85, No. 4, pp. 1005-1013. 2007.

6) Post-exercise protein intake in vital following resistance training in the elderly (+/-)

Timing of postexercise protein intake is important for muscle hypertrophy with resistance training in elderly humans.

  • Resistance training can counteract age muscle loss.
  • Protein synthesis is influence synergistically by postexercise amino acid supplementation.
  • Early intake after resistance training is important for the development of hypertrophy in skeletal muscle of elderly men.

Age-associated loss of skeletal muscle mass (sarcopenia) and strength can be partly combated by resistance training, causing a net protein synthesis. Protein synthesis is influenced synergistically by postexercise amino acid supplementation, but the importance of the timing of protein intake remains unresolved.

The study investigated the importance of immediate (P0) or delayed (P2) intake of an oral protein supplement upon muscle hypertrophy and strength over a period of resistance training in elderly males.

Thirteen men (age, 74 ± 1 years; body mass index (BMI), 25) completed a 12 week resistance training program (3 times per week) receiving oral protein in liquid form (10 g protein, 7 g carbohydrate, 3 g fat) immediately after (P0) or 2 h after (P2) each training session. Muscle hypertrophy was evaluated by magnetic resonance imaging (MRI) and from muscle biopsies and muscle strength was determined using dynamic and iso-kinetic strength measurements.

Body composition was determined from dual-energy X-ray absorptiometry (DEXA) and food records were obtained over 4 days. The plasma insulin response to protein supplementation was also determined.

In response to training, the cross-sectional area of m. quadriceps femoris (54.6 ± 0.5 to 58.3 ± 0.5 cm2) and mean fiber area (4047 ± 320 to 5019 ± 615 µm2) increased in the P0 group, whereas no significant increase was observed in P2. For P0 both dynamic and iso-kinetic strength increased, by 46 and 15 %, respectively (P < 0.05), whereas P2 only improved in dynamic strength, by 36 % (P < 0.05). No differences in glucose or insulin response were observed between protein intake at 0 and 2 h postexercise.

Conclusion: Early intake of a protein supplement after resistance training is important for the development of hypertrophy in skeletal muscle of elderly men in response to resistance training.

Esmarck, B. et al. Timing of postexercise protein intake is important for muscle hypertrophy with resistance training in elderly humans. Jour. of Physiology. Vol. 535.1, pp. 301-311. 2001.

Whey protein and bone health studies

1) Whey protein fraction and its potential benefit to bone health (+/-)

Lactoferrin- A Novel Bone Growth Factor

  • Lactoferrin promotes bone growth
  • Stimulates the proliferation of osteoblasts.
  • Lactoferrin may have a physiological role in bone growth and healing.

Lactoferrin is an iron-binding glycoprotein that belongs to the transferrin family. It is present in breast milk, in epithelial secretions, and in the secondary granules of neutrophils. In healthy subjects lactoferrin circulates at concentrations of 2–7 x 10−6 g/ml. Lactoferrin is a pleiotropic factor with potent antimicrobial and immunomodulatory activities. Recently, we have shown that lactoferrin can also promote bone growth. At physiological concentrations, lactoferrin potently stimulates the proliferation and differentiation of primary osteoblasts and also acts as a survival factor inhibiting apoptosis induced by serum withdrawal.

Lactoferrin also affects osteoclast formation and, in murine bone marrow culture, lactoferrin potently inhibits osteoclastogenesis. In vivo, local injection of lactoferrin above the hemicalvaria of adult mice results in substantial increases in the dynamic histomorphometric indices of bone formation and bone area.

The mitogenic effect of lactoferrin in osteoblast-like cells is mediated mainly through LRP1, a member of the family of low-density lipoprotein receptor-related proteins that are primarily known as endocytic receptors. Using confocal laser scanning microscopy, we demonstrated that fluorescently labeled lactoferrin is endocytosed and can be visualized in the cytoplasm of primary osteoblastic cells.

Lactoferrin also induces activation of p42/44 MAPK signaling in primary osteoblasts, but the two pathways seem to operate independently as activation of MAPK signaling, but not endocytosis, is necessary for the mitogenic effect of lactoferrin.

Conclusion: Lactoferrin may have a physiological role in bone growth and healing, and a potential therapeutic role as an anabolic factor in osteoporosis.

Naot, Dorit, et al. Lactoferrin-A Novel Bone Growth Factor. Clinical Medicine and Research. Vol. 3(2), pp. 93-101. 2005.

2) Milk protein and bone resorption suppression (+/-)

Milk basic protein promotes bone formation and suppresses bone resorption in healthy adult men.

  • Milk basic protein is in the whey protein fraction.
  • 300mg of Milk Basic Protein increase serum osteocalcin concentrations.
  • Milk Basic Protein promotes bone formation and suppresses bone resorption.

Milk contains several components effective for bone health. In the previous in vitro and in vivo studies, we have shown that milk whey protein, especially its basic protein fraction (milk basic protein [MBP]), promoted bone formation and suppressed bone resorption. This present study examines the effect of MBP on the biochemical markers of bone metabolism in healthy adult men.

Experimental beverages containing MBP (300 mg of MBP a day) were given to 30 normal healthy adult men for 16 days. The serum osteocalcin concentration had increased significantly after 16 days of ingesting the experimental beverage containing MBP. Urinary cross-linked N-teleopeptides of type-I collagen (NTx) excretion had decreased significantly after 16 days of ingesting MBP. The urinary NTx excretion was related to the serum osteocalcin concentration after 16 days of ingestion.

Conclusion: These results suggest that MBP promoted bone formation and suppressed bone resorption, while maintaining the balance of bone remodeling.

Toba, Y., et al. Milk basic protein promotes bone formation and suppresses bone resorption in healthy adult men. Biosci-Biotechnology-Biochemistry. Vol. 65(6), pp. 1353-1357. 2001.

3) Whey protein fraction as a potential for new bone formation (+/-)

Lactoferrin is a potent regulator of bone cell activity and increases bone formation in vivo.

  • Lactoferrin increased osteoblast differentiation.
  • New bone formation.

Lactoferrin is an iron-binding glycoprotein present in epithelial secretions, such as milk, and in the secondary granules of neutrophils. We found it to be present in fractions of milk protein that stimulated osteoblast growth, so assessed its effects on bone cell function.

Lactoferrin produced large, dose-related increases in thymidine incorporation in primary or cell-line cultures of human or rat osteoblast-like cells, at physiological concentrations (1-100 µg/ mL). Maximal stimulation was 5-fold above control. Lactoferrin also increased osteoblast differentiation, and reduced osteoblast apoptosis by up to 50-70%. Similarly lactoferrin stimulated proliferation of primary chondrocytes. Purified, recombinant, human or bovine lactoferrins had similar potencies.

In mouse bone-marrow cultures, osteoclastogenesis was dose-dependently decreased, and was completely arrested by lactoferrin 100 µg/mL, associated with decreased expression of RANKL. In contrast, lactoferrin had no effect on bone resorption by isolated mature osteoclasts. Lactoferrin was administered over calvariae of adult mice for 5 days. New bone formation, assessed using fluorochrome labels, was increased 4-fold by a 4 mg dose of lactoferrin.

Conclusion: Lactoferrin has powerful anabolic, differentiating and anti-apoptotic effects on osteoblasts, and inhibits osteoclastogenesis. Lactoferrin is a potential therapeutic target in bone disorders such as osteoporosis and possibly an important physiological regulator of bone growth.

Cornish, Jillian. et al. Lactoferrin is a potent regulator of bone cell activity and increases bone formation in vivo. Endocrinology. 2004.

4) Whey protein and bone health (+/-)

Whey Protein Stimulates the Proliferation and Differentiation of Osteoblastic MC3T3-E1 Cells.

  • Whey protein can improve bone health.
  • The Milk Basic Protein of whey is the active protein that activates osteoblast.

We examined the effects of whey protein on osteoblastic MC3T3-E1 cells. This protein caused dose-dependent increases in [3H]thymidine incorporation and DNA content in the cells. It also increased the total protein and hydroxyproline contents in the cells. These activities were heat resistant when the protein was heated at 75°C to 90°C for 10 min.

Heat-treated whey protein was first fractionated on a Mono S column, and the active fraction (basic protein fraction) was then applied to Superose 12. The molecular weights of the active components were approximately 10,000 and 14,000 Da, as determined with gel filtration. The inner solution of an everted gut-sac incubated in a solution of intact BP (basic protein), pepsin-digested BP or pepsin/pancreatin-digested BP also stimulated the [3H]thymidine incorporation. Thus these active components can possibly permeate or be absorbed by the intestines.

Conclusion: We propose the possibility that the active component in the whey protein plays an important role in bone formation by activating osteoblasts.

Takada, Y. et al. Whey protein stimulates the proliferation and differentiation of osteoblastic MC3T3-E1 Cells. Biochem. And Biophys. Res. Comm. Vol. 223, Issue 2, pp. 445-449. 1996.

Whey protein and better immune system function studies

1) Whey protein influence on the body's most powerful ant-oxidant (glutathione) (+/-)

Whole blood and mononuclear cell glutathione response to dietary whey protein supplementation in sedentary and trained male human subjects.

  • Whey protein improves glutathione status in the body.
  • Aerobic training decreases glutathione status.
  • Whey protein mitigates this decrease in glutathione.

Glutathione is the body’s most powerful antioxidant. It protects the cells against free radical damage during exercise. The effects of a whey protein supplemented diet on glutathione concentrations were investigated over a six-week period in male subjects involved in strenuous aerobic training. Blood samples were collected prior to and following a 40 km simulated cycling trial. The aerobic training period resulted in significantly lower glutathione concentrations in whole blood, an effect that was mitigated by whey protein supplementation. A significant increase in mononuclear cell glutathione was also observed in subjects receiving the whey protein supplement following the 40 km simulated cycling trial.

Conclusion: This study demonstrated that whey protein supplementation lessens the decreases in glutathione caused by prolonged exercise.

Middleton, N., et al. Whole blood and mononuclear cell glutathione response to dietary whey protein supplementation in sedentary and trained male human subjects. Inter. J Food Sci. Nutr. Vol 55(2), pp. 131-141. 2004.

2) Potential immune modulation from whey protein (+/-)

Modulation of immune function by a modified bovine whey protein concentrate

  • Whey protein suppresses T and B lymphocyte proliferation in response to mitogens.
  • Whey protein may inhibit lymphocyte activation

The commercial preparation of dairy foodstuffs generates large volumes of by-products, many of which have as yet undocumented effects on mammalian immune function. In the present report, a modified whey protein concentrate (mWPC), derived as a by-product from the commercial manufacture of cheese, was tested for its ability to modulate murine immune function in vitro. The mWPC suppressed T and B lymphocyte proliferative responses to mitogens in a dose-dependent fashion. The mWPC also suppressed alloantigen-induced lymphocyte proliferation during a mixed leucocyte reaction, but showed no suppressive effect against IL-2-sustained proliferation of mitogen-activated T cell blasts. Other indices of lymphocyte activation, such as cytokine secretion and the formation of activated (CD25+) T cell blasts, were suppressed by the mWPC, suggesting that the mode of suppression may be to inhibit the lymphocyte activation process.

Conclusion: Conclusion: Results are discussed in relation to the potential development of complex-mixture dairy products into health-modulating products.

Cross, Martin, L. et al. Modulation of immune function by a modified bovine whey protein concentrate. Immun. And Cell Biol. Vol. 77, pp. 345-350. 1999.

Whey protein and disease studies

1) Whey protein and cancer studies (+/-)

Dairy Protein Protect against Dimethylhydrazine-Induced Intstestinal Cancer in Rats.

  • Whey protein more protective against development of intestinal tumors
  • Higher intercellular glutathione concentration with whey protein.
  • Dairy proteins, particularly whey offers protection against intestinal induced tumors when compared to other protein sources.

The impact of different dietary protein sources (whey, casein, soybean, red meat) on the incidence, burden and mass index of intestinal tumors induced by dimethylhydrazine in male Sprague-Dawley rats was assessed. A purified diet (based on AIN-76A) with a fat concentration of 20 g/100 g and other proteins substituted for casein (20 g/100 g) was used. Whey and casein diets were more protective against the development of intestinal tumors than were the red meat or soybean diets, as evidenced by a reduced incidence of rats affected, fewer tumors per treatment group, and a reduced pooled area of tumors (tumor mass index) that formed. Intracellular concentration of glutathione, an antioxidant and anticarcinogenic tripeptide, measured in liver, was greatest in whey protein- and casein-fed rats and lowest in soybean-fed animals. For other tissues (spleen, colon, tumor) the differences were not significant, although the whey-fed animals had the highest concentrations of glutathione.

Conclusion: Whey is a source of precursors (cysteine-rich proteins) for glutathione synthesis and may be important in providing protection to the host by stimulating glutathione synthesis. A positive correlation was observed between mean fecal fat concentrations for rats in each treatment group and large intestinal tumor burden. Fecal fat could be involved in aiding initiation and/or promotion of carcinogenesis. Whatever the mechanism(s), dairy proteins, and whey proteins in particular, offer considerable protection to the host against dimethylhydrazine-induced tumors relative to the other protein sources examined.

McIntosh, G.H., et al. Dairy Protein Protect Against Dimethylhydrazine-Induced Intestinal Cancers in Rats. Journal of Nutrition. Vol. 125. No. 4. April 1995, pp. 809-816.

2) Whey protein and HIV studies (+/-)

Features of Whey Protein Concentrate Supplementation in Children with Rapidly Progressive HIV Infection.

  • Oral whey protein supplementation increases glutathione levels in HIV infected children.
  • Whey protein can stimulate glutathione synthesis.
  • Glutathione could potentially decrease infection in HIV infected children.

HIV infection is associated with subnormal GSH levels. An increase in glutathione levels has been observed in HIV-infected adults under oral whey protein supplementation. We studied the features associated with a whey protein concentrate supplementation in children with rapidly progressive AIDS. A prospective double-blind clinical trial was carried out for 4 months with 18 vertically HIV-infected children (1.98-6.37 years), under antiretroviral therapy, who had received whey protein, maltodextrin (placebo) or none. Erythrocyte glutathione concentration, T lymphocyte counts (CD4+ and CD8+) and occurrence of associated co-infections were evaluated.

Wilcoxon's and Fischer's Exact tests were used to assess differences between whey protein-supplemented and control (placebo and non-supplemented) groups.

Conclusion: A significant median increase of 16.14 mg/dl in erythrocyte glutathione levels was observed in the whey protein-supplemented group; the TCD4/CD8 lymphocyte ratio showed a non significant increase and lower occurrence of associated co-infections was also observed. In conclusion, whey protein concentrate supplementation can stimulate glutathione synthesis and, possibly, decrease the occurrence of associated co-infections.

Moreno, Y.F., et al. Features of Whey Protein Concentrate Supplementation in Children with Rapidly Progressive HIV Infection. Journal of Tropical Pediatrics. 2005.

3) Whey protein and CLA studies (+/-)

  • Intake of dairy fatty acids (conjugated linoleci acids) CLA has successfully treated diabetes in mice.
  • Also shown positive results in humans.
  • CLA may also help mitigate some cancers.

Compound in dairy products and whey protein concentrate targets diabetes. Fatty acids commonly found in dairy products have successfully treated diabetes in mice, according to a researcher at Penn State.

Conclusion: The compounds, known as conjugated linoleic acids (CLA), also have shown promising results in human trials, signaling a new way of potentially treating the disease without synthetic drugs. "The compounds are predominantly found in dairy products such as milk, cheese and meat, and are formed by bacteria in ruminants that take linoleic acids -- fatty acids from plants -- and convert them into conjugated linoleic acids, or CLA," said Jack Vanden Heuvel, professor of molecular toxicology in Penn State's College of Agricultural Sciences and co-director of Penn State's Center of Excellence in Nutrigenomics. Researchers first became interested in CLA when it was shown to inhibit a variety of cancers such as breast, skin and colon in mice, and further research showed effects on circulating cholesterol and inflammation. These effects are the same as the newest generation of synthetic drugs used to treat diabetes in humans.

Jack Vanden Heuvel, professor of molecular toxicology in Penn State’s College of Agriculture Sciences and co-director of Penn States Center of Excellence in Nutrigenomics.

4) Whey protein and glutathione studies (+/-)

An open-label dose-response study of lymphocyte glutathione levels in healthy men and women receiving pressurized whey protein isolate supplements.

  • Glutathione level increases are dose-dependent
  • 45g day increased glutathione by 24%
  • 15g day did not increase glutathione levels.

Background High-pressure treatment of whey protein may increase digestibility and bioavailability of cysteine. The purpose of the study was to determine whether total lymphocyte glutathione (gamma-glutamyl-cysteinyl-glycine [GSH]) levels (oxidized+reduced) can be augmented from three different doses of pressurized whey protein supplements in a dose-dependent manner over a 2-week period. Methods Eighteen healthy males and 18 healthy females were randomized into three different groups, with 31 finishing the study. Each group ingested 15, 30, or 45 g/day pressurized whey protein in the morning in bar format for 14 days. Each group was blinded to the amount of whey protein they were ingesting. Ten millilitres of blood was withdrawn before and after the 2-week period to assess blood lymphocyte levels pre and post supplementation.

Results: There was no change in body weight or reported physical activity levels pre and post supplementation. Pre-lymphocyte GSH levels were not significantly different between groups (3.7+/-0.7micromol/l). Least-squares linear regression showed that the change in lymphocyte GSH levels from pre to post supplementation was affected by the amount of whey protein ingested daily (P=0.037). The group that ingested 45 g/day pressurized whey protein augmented GSH levels the most (by approximately 24%), and the group that ingested 15 g/day did not increase lymphocyte GSH levels. Conclusions We conclude that there is a significant relationship between the dosage of supplementation and the change in lymphocyte GSH levels. Furthermore, the increase in GSH was linear with the amount of whey protein ingested. Pressurized whey protein supplementation of 45 g/day for 2 weeks can increase lymphocyte GSH by 24%.

Zavorsky, G.S. et al. An open-label dose-response study of lymphocyte glutathione levels in healthy men and women receiving pressurized whey protein isolate supplements. International Journal of Food Science and Nutrition. Vol. 58 (6), pp. 429-436, September 2007.

The biological activity of undenatured dietary whey proteins: role of glutathione.

  • Antioxidant potential of whey protein
  • Immune response is highest in dietary whey protein.
  • Whey potentiates higher levels of tissue glutathione.

Conclusion: This study compared the effects of different sources of whey protein concentrate (20 g/100 g diet) and of casein on the spleen, liver, and heart glutathione content of C3H/HeJ mice, and on the immune response of their spleen cells to sheep red blood cells. Body weight curves were similar in all dietary groups. Our data indicate that the humoral immune response is highest in mice fed a dietary whey protein concentrate exhibiting the highest solubility (undenatured conformation) and a greater relative concentration of the thermolabile bovine serum albumin and immunoglobulins. In addition, the mice fed this type of whey protein concentrate exhibit higher levels of tissue glutathione. The presence in the serum albumin fraction of glutamylcysteine groups (rare in food protein) and the specific intramolecular bond as related to the undenatured conformation of the molecule are considered to be key factors in the glutathione-promoting activity of the protein mixture.

Bounous, G. et al. The biological activity of undenatured dietary whey proteins: role of glutathione. Clinical Invest. Med. Vol. 14(4), pp. 296-309, 1991.

The biological activity of undenatured dietary whey proteins: role of glutathione.

  • Antioxidant potential of whey protein
  • Immune response is highest in dietary whey protein.
  • Whey potentiates higher levels of tissue glutathione.

Conclusion: This study compared the effects of different sources of whey protein concentrate (20 g/100 g diet) and of casein on the spleen, liver, and heart glutathione content of C3H/HeJ mice, and on the immune response of their spleen cells to sheep red blood cells. Body weight curves were similar in all dietary groups. Our data indicate that the humoral immune response is highest in mice fed a dietary whey protein concentrate exhibiting the highest solubility (undenatured conformation) and a greater relative concentration of the thermolabile bovine serum albumin and immunoglobulins. In addition, the mice fed this type of whey protein concentrate exhibit higher levels of tissue glutathione. The presence in the serum albumin fraction of glutamylcysteine groups (rare in food protein) and the specific intramolecular bond as related to the undenatured conformation of the molecule are considered to be key factors in the glutathione-promoting activity of the protein mixture.

Bounous, G. et al. The biological activity of undenatured dietary whey proteins: role of glutathione. Clinical Invest. Med. Vol. 14(4), pp. 296-309, 1991.

Whey Protein Concentrate (WPC) and glutathione modulation in cancer treatment.

  • Whey protein is a safe and effective cysteine donor.
  • Anti-carcinogenesis and anticancer activity is seen from whey protein.
  • Reports suggest an anti-tumor effect of a whey protein in urogenital cancers.

The glutathione (GSH) antioxidant system is foremost among the cellular protective mechanisms. Depletion of this small molecule is a common consequence of increased formation of reactive oxygen species during increased cellular activities. This phenomenon can occur in the lymphocytes during the development of the immune response and in the muscular cells during strenuous exercise. It is not surprising that so much research has been done, and is still being done on this small tripeptide molecule.

Whey protein concentrate has been shown to represent an effective and safe cysteine donor for GSH replenishment during GSH depletion in immune deficiency states. Cysteine is the crucial limiting amino acid for intracellular GSH synthesis.

Animal experiments showed that the concentrates of whey proteins also exhibit anti-carcinogenesis and anticancer activity. They do this via their effect on increasing GSH concentration in relevant tissues, and may have anti-tumor effect on low volume of tumor via stimulation of immunity through the GSH pathway. It is considered that oxygen radical generation is frequently a critical step in carcinogenesis, hence the effect of GSH on free radicals as well as carcinogen detoxification, could be important in inhibiting carcinogenesis induced by a number of different mechanisms.

Conclusion: Case reports are presented which strongly suggest an anti-tumor effect of a whey protein dietary supplement in some urogenital cancers. This non toxic dietary intervention, which is not based on the principles of current cancer chemotherapy, will hopefully attract the attention of laboratory and clinical oncologists.

Bounous, G. Whey Protein Concentrate (WPC) and glutathione modulation in cancer treatment. Anitcancer Research. Vol 20(6C). pp. 4785-4792, Nov.-Dec. 2000.

5) Whey protein and immunomodulation studies (+/-)

Differential effect of dietary protein type on the B-cell and T-cell immune response in mice.

  • Immune respone of whey protein (alph-lactalbumin) was higher than casein, soy or whey protein.
  • 20% whey protein in the diet of mice increased the immune response.

Conclusion: The effect of 20 g/100 g diet of lactalbumin (L), casein (C), soy (S)and wheat (W) protein on the immune responsiveness of C3H/HeN mice has been investigated by measuring the humoral immune response to the T cell-independent antigen, TNP-Ficoll. The humoral immune response of mice fed the L diet was found to be higher than that of mice fed the G, S and W diets. On the other hand, delayedtype hypersensitivity, and splenic cell mitogen responses to phytohemagglutinin and concanavalin A did not differ among mice fed the various diets. Similarly, the type of diet did not appear to influence host resistance to Salmonella typhimurium. It is postulated that the type of protein in the diet influences directly the intrinsic capacity of the B lymphocytes to respond to an immunogenic stimulus.

Bounous, G., et al. Differential effect of dietary protein type on the B-cll and T-cell immune respone in mice. Journal of Nutrition. Vol. 115(11). pp. 1403-1408. November 1985>

6) Immunomodulating effects of whey proteins and their enzymatic digests. (+/-)

Immunostimulation of murine spleen cells by materials associated with bovine milk protein fractions.

  • Whey protein (beta-lactoglobulin) showed highest immunomodulatory activity.
  • Beta-lactoglobulin had as stimulatory effect on cell prolifer and Immuglobulin M production was reduced.

Conclusion: Purified bovine milk proteins that were added to cultures of murine spleen cells significantly increased cell proliferation and production of immunoglobulin M. Casein and a whey mixture consisting of alpha-lactalbumin, bovine serum albumin, bovine gamma globulin, and beta-lactoglobulin (beta-LG) were stimulatory. Of the three beta-LG preparations that are commercially available (beta-LG containing variants A and B, purified variant A, and purified variant B), the unseparated mixture containing both the A and B variants showed the most immunomodulatory activity. Both alkaline treatment and trypsin digestion of the beta-LG preparation markedly reduced its effectiveness. Polymyxin B, while greatly diminishing the stimulatory effect of lipopolysaccharide, had no significant effect on either the enhancement of cell proliferation or the enhancement of immunoglobulin production by beta-LG. In the presence of S-(n-butyl)-homocysteine sulfoxamine, the stimulatory effect of beta-LG on cell proliferation and IgM production in vitro was markedly reduced.

Wong, K.F., et al. Immunostimulation of murine spleen cells by materials associated with bovine milk protein fractions. Journal of Dairy Science. Vol. 81(7), pp. 1825-1832. July 1998.

Immunomodulating effects of whey proteins and their enzymatic digests.

  • Microfiltered Whey Protein Isolate (WPI) increases lymphocyte proliferation.
  • No increase in lymphocyte with Ion Exchanged Whey Protein Isolate.
  • Bioactive peptides of whey protein has potent immunomodulating properties.

Conclusion: Immunomodulating properties of commercial whey protein products and their enzymatic digests (trypsin/chymotrypsin) were evaluated by measuring their effect on in vitro proliferation of lymphocytes isolated from murine spleen. The results showed that microfiltered-whey protein isolates (MF-WPI) significantly increased lymphocytes proliferation at a concentration of 100 μg mL−1. An inhibitory effect was measured for lactoferrin at the same concentration, while no effect was observed for ionic exchange-WPI, β-lactoglobulin, α-lactalbumin, and glycomacropeptide. Enzymatic digestion of protein products abrogated the inhibitory effect of lactoferrin and reduced the stimulating effect of MF-WPIs. However, fractionation by isoelectric focusing of the MF-WPI enzymatic digests led to peptide fractions that stimulated cells proliferation at much lower concentrations (0.5–500 μg mL−1) than the ones obtained for the total hydrolysates (2000 μg mL−1). The results suggest that whey proteins contain some immunomodulating peptides, which can be released by enzymatic digestion. Identification and isolation of these bioactive peptides could provide insights into the preparation of potent immunomodulating products.

Mercier, A., et al. Immunomodulating effects of whey proteins and their enzymatic digests. Int. Dairy J. Vol. 14(3), pp. 175-183. 2004.

7) Whey protein and Infant E. Coli studies (+/-)

rRNA probes used to quantify the effects of glycomacropeptide and alpha-lactalbumin supplementation on the predominant groups of intestinal bacteria of infant rhesus monkeys challenged with enteropathogenic Escherichia coli.

  • Whey protein (Alpha-lactalbumin) fed infants had no diarrhea.
  • GMP fed infants had sporadic diarrhea.
  • Supplementing infant formula with alpha-lactalbumin may be useful to resist infection caused by E. Coli.

OBJECTIVES: Certain milk factors may help to promote the growth of a host-friendly colonic microflora (e.g. bifidobacteria, lactobacilli) and explain why breast-fed infants experience fewer and milder intestinal infections than those who are formula-fed. The effects of supplementation of formula with two such milk factors were investigated in this study. MATERIALS AND METHODS: Infant rhesus macaques were breast-fed, fed control formula, or formula supplemented with glycomacropeptide (GMP) or alpha-lactalbumin (alpha-LA) from birth to 5 months of age. Blood was drawn monthly and rectal swabs were collected weekly. At 4.5 months of age, 10(8) colony-forming units of enteropathogenic E.coli O127, strain 2349/68 (EPEC) was given orally and the response to infection assessed. The bacteriology of rectal swabs pre- and post-infection was determined by culture independent fluorescence in situ hybridization.

Results: Post-challenge, breast-fed infants and infants fed alpha-LA-supplemented formula had no diarrhea, whilst those infants fed GMP-supplemented formula had intermittent diarrhea. In infants fed control formula the diarrhea was acute. CONCLUSIONS: Supplementation of infant formula with appropriate milk proteins may be useful for improving the infant's ability to resist acute infection caused by E.coli.

Bruck, W.M. et al. rRNA probes used to quantify the effects of glycomacropeptide and alpha-lactalbumin supplementation on the predominant groups of intestinal bacteria of infant rhesus monkeys challenged with enteropathogenic Escherichia coli. Vol. 37(3), pp. 273-280. September 2003.

8) Whey protein and hyper-tension studies (+/-)

Structural analysis of a new anti-hypertensive peptide (beta-lactosin B) isolate from a commercial whey product.

  • Whey peptides have Angiotensin-converting enzyme (ACE) inhibition.
  • Whey protein concentrate showed a 53% ACE reduction.
  • Whey protein exhibits anti-hypertensive effects.

Angiotensin-converting enzyme (ACE) inhibitory activities and anti-hypertensive activities in spontaneously hypertensive rats (SHR) of 12 kinds of commercial peptides of food additive grade were measured. Four peptide products derived from milk proteins showed strong anti-hypertensive activities (>-18.0 mm Hg). A sample of WE80BG derived from whey proteins showed the strongest anti-hypertensive activity (-21.2 +/- 16.9 mm Hg) with a medium level of ACE inhibitory activity (53.6%), and it was subjected to hydrophobic and gel filtration chromatography. From the low molecular weight fraction, an anti-hypertensive peptide was isolated by using reversed-phase HPLC, and it was found to be a tetrapeptide, alanine-leucine-proline-methionine (Ala-Leu-Pro-Met, ALPM), the origin of which was estimated to be beta-lactoglobulin f 142 to 145.

Results: At 8 h after oral administration of ALPM in SHR, systolic blood pressure was significantly decreased (-21.4 +/- 7.8 mm Hg), but the IC50 value (concentration of peptide needed to inhibit 50% of the ACE activity) of ALPM was not so high. We named the Ala-Leu-Pro-Met "beta-lactosin B." This peptide is the second anti-hypertensive peptide found from beta-lactoglobulin. Because WE80BG containing ALPM was also found to show the strongest anti-hypertensive activity (-24.5 +/- 10 mm Hg) at 8 h after oral administration in SHR, WE80BG would be suitable for application to the development of a new food expected to have anti-hypertensive effects.

Murakami, M., et al. Structural analysis of a new anti-hypertensive peptide (beta-lactosin B) isolate from a commercial whey product. J. Dairy Science. Vol. 87(7), pp. 1967-1974. July 2004.

Anti-hypertensive effects of a hydrolyzed whey protein isolate supplement (BioZate 1}

  • 20 gm dose of hydrolyzed whey protein isolate decrease blood pressure.
  • Lower LDL Cholesterol.
  • Increase in white blood cell count.

A double-blinded, randomized, and placebo controlled study hypothesized that a 20g dose of hydrolyzed whey protein isolate (the study used BioZate 1 brand) would reduce both systolic and diastolic blood pressure over the course of weeks. Thirty un-medicated, non-smoking, borderline hypertensive men and women were randomized to the hydrolyzed whey protein group or a control group given an un-hydrolyzed protein isolate. Individuals were instructed to take their protein dose daily with water for six weeks and maintain their normal lifestyle habits. Participants reported to a research clinic weekly for blood pressure checks, blood draws, side effect measurement, and diet assessment.

Conclusion: Results indicate a 11mmHg drop in systolic blood pressure and a 7mmHg drop in diastolic blood pressure, a drop in LDL cholesterol, and a significant change in white blood cell count, in the treatment group versus the control group. Based on these findings, hydrolyzed whey protein isolate appears to reduce both systolic and diastolic blood pressure in untreated borderline hypertensives. Early indications suggest that these peptides might inhibit angiotension converting enzyme (ACE) and thereby lower blood pressure, however further research is needed to determine the mechanism of action and to confirm these findings.

Pins, Joel J. and Keenan, Joseph M., Antihypertensive Effects of a Hydrolyzed Whey Protein Isolate Supplement (BioZate 1), Presented at the 11th International Congress on Cardiovascular Pharmacotherapy 2002.

9) Whey protein and hyper-tension studies (+/-)

The antihypertensive effect of a hydrolyzed whey protein isolate supplement (BioZate® 1): A Pilot Study

  • Participants consumed 20 g daily of a hydrolyzed whey protein isolate.
  • Hydrolyzed whey protein isolate reduced blood pressure and cholesterol.
  • Significant change in white blood cells.

Conclusion: The study involved 30 men and women, healthy, unmedicated, non-smoking, hypercholesterolemic borderline hypertensive as randomly assigned to 2 groups. Study related side effects were measured throughout the study, hypertension and ACE-inhibiting side effects, gastrointestinal dysfunction, renal function and hepatic function. Results showed a significant drop in sBP and dBP occurring after 1 week of treatment and persisted throughout the study. Compared to a regular whey protein isolate, the Biozate reduced sBP 11mm/Hg and dBP 7mm/Hg. The blood pressure effect was not gender specific. The blood pressure change was affected by initial body weight and initial blood pressure. Liver and renal functions were unchanged in both groups. White blood cell counts were significantly increase post Biozate treatment. Biozate appears to be reduce cardiovascular disease risk.

Pins, J.J., et al. The antihypertensive effect of a hydrolyzed whey protein isolate supplement (BioZate® 1): A Pilot Study. The FASEB Journal. Vol. 17(5). A1110. March 17, 2003.

10) Lactokinins: Whey protein-derived ACE inhibitory peptides (+/-)

  • Whey Protein inhibits ACE.
  • Whey may help with high blood pressure by blocking of Angiotensin-l-converting enzyme (ACE)

Angiotensin-I-converting enzyme (ACE) has been classically associated with the renin-angiotensin system which regulates peripheral blood pressure. Peptides derived from the major whey proteins, i. e. -lactalbumin ( -la) and -lactoglobulin ( -lg) in addition to bovine serum albumin (BSA), inhibit ACE. Some of these inhibitory peptides, i. e. -lactorphin ( -la f(50-53)), -lactorphin ( -lg f(102-105)), -lactotensin ( -lg f(146-149) and albutensin A (BSA f(208-216)), have other bioactivities.

The most potent lactokinin reported to date, ( -lg f(142-148)), has an ACE IC50 of 42.6 mol/l. While they do not have the inhibitory potency of synthetic drugs commonly used in the treatment of hypertension, these naturally occurring peptides may represent nutraceutical/ functional food ingredients for the prevention/treatment of high blood pressure. Studies with gastric and pancreatic proteinase digests of whey proteins indicate that enzyme specificity rather than extent of hydrolysis dictates the ACE inhibitory potency of whey hydrolysates.

Conclusion: Whey protein fractions containing lactokinin show promise to inhibit ACE and treat high blood pressure.

Fitzgerald, R.J. et al. Lactokinins: Whey protein-derived ACE inhibitory peptides. Food Vol. 43, issue 3, pp. 165-167. 1999.

11) Whey proteins potential to improve cardiovascular health (+/-)

Effect of Administration of Fermented Milk Containing Whey Protein Concentrate to Rats and Healthy Men on Serum Lipids and Blood Pressure

  • Fermented milk lowered triglyceride levels in the blood.
  • Fermented milk also lowered systolic blood pressure.
  • Fermented milk lowered the artherogenic index.

The effect of fermented milk supplemented with whey protein concentrate on the serum lipid level of rats was investigated. The serum total cholesterol level for the group fed fermented milk with both Lactobacillus casei TMC0409 and Streptococcus thermophilus TMC 1543 was significantly lower than that of the control group (P < 0.05) in rats. Furthermore, the effect of the long-term intake of this fermented milk on the serum lipid level of twenty healthy adult men was investigated. During the 8-wk study, the volunteers consumed 200 ml of fermented milk or placebo in the morning and evening. Blood samples were drawn for analysis three times, just before taking the experimental diet, and after 4 wk and 8 wk of consumption.

After 8 wk, the high density lipoprotein cholesterol level for the fermented milk group showed a significant rise after 4 wk (P < 0.05), whereas that of the placebo group showed no change even after 4 wk (P > 0.05). The triglyceride level for the fermented milk group lowered significantly after 4 wk (<0.05), whereas that of the placebo group showed no change even after 4 wk (P > 0.05). The atherogenic index [(total cholesterol – high density lipoprotein cholesterol)/high-density lipoprotein cholesterol) for the fermented milk group decreased significantly from 4.24 to 3.52 (P < 0.05). The systolic blood pressure lowered significantly by the intake of fermented milk (P < 0.05) On the other hand, such effect was not observed in the placebo group (P > 0.05).

Conclusion: These results indicate potential of the development of fermented milk with multiple therapeutic effects.

Kawase, M., et al. Effect of Administration of Fermented Milk Containing Whey Protein Concentrate to Rats and Healthy Men on Serum Lipids and Blood Pressure. Journ of Dairy Science. Vol. 83, No. 2. pp 255-263. 2000.

12) Whey proteins potential to lower cholesterol and blood pressure (+/-)

Cholesterol-lowering and blood pressure effects of immune milk

  • Hyperimmunized cows produce cardiovascular protective milk
  • A significant decrease in total cholesterol
  • A significant decrease is systolic and diastolic blood pressure.

The plasma cholesterol-lowering and blood pressure effects of a skim milk powder (immune milk) produced from dairy cows hyperimmunized with a multivalent bacterial vaccine were assessed in a double-blind crossover study of hypercholesterolemic subjects who consumed daily 90 g immune milk or a normal product. There was a significant reduction in plasma total and LDL cholesterol of 5.2% (95% CI 2.5, 7.9) and 7.4% (95% CI 4.1, 10.7), respectively, with 10 wk of immune milk consumption compared with control, but no change in HDL cholesterol or triglycerides. A significant systolic and diastolic blood pressure- lowering effect (5 and 4 mm Hg, respectively) was also demonstrated.

Conclusion: Thus, immune milk may be a useful adjunct in the dietary management of hypercholesterolemia and the mechanisms of its cholesterol-lowering and blood pressure effects warrant further study.

Sharpe, SJ. Et al. Cholesterol-lowering and blood pressure effect of immune milk. Amer. Jour. Clin. Nutr. Vol. 59, pp. 929-934. 1994.

13) Whey Protein Concentrate and inhibition of gastric mucosal ulcerative lesions. (+/-)

Efficacy of a Whey Protein Concentrate on the Inhibition of Stomac Ulcerative Lesions Caused by Ethanol Ingestion.

  • Whey protein concentrate protects gastric mucosa from ethanol damage.
  • The protective properties is due to sulfhydyl compounds, stimulators of glutathione synthesis.

The purpose of this research was to test the ability of a whey protein concentrate (WPC) to inhibit gastric mucosal ulcerative lesions caused by oral administration to rats of absolute ethanol. Acute administration (single doses) of WPC resulted in 41% inhibition of the ulcerative lesion index (ULI), and 73% inhibition was obtained with repetitive doses. In a 10-days subchronic treatment study, the inhibition was 64%, all relative to a saline treatment (negative control). Alkylation of sulfhydryl compounds by subcutaneous injection of N-ethylmaleimide essentially eliminated the WPC protection. Treating the rats with an intraperitoneal injection of butathionine sulfoximine, which inhibits glutathione synthesis, reduced WPC protection to 35% and 52% for single and double doses, respectively.

Conclusion: Taken as a whole, the results indicate that WPC does protect gastric mucosa from ethanol damage and that the protection depends on sulfhydryl compounds present in the WPC, including its capacity to stimulate glutathione synthesis.

Rosaneli, C.F., MS, et al. Efficacy of Whey Protein Concentrate on the Inhibition of Stomach Ulcerative Lesions Caused by Ethanol Ingestion. Journal of Medical Food. Vol. 5, No. 4, pp. 221-228. 2002.

14) Whey proteins potential to combat skin cancer (+/-)

Treatment of skin papillomas with topical alpha-lactabumin-oleic acid.

  • Alpha-lactalbumin-oleic acid reduce lesion volume of papilloma patients.
  • The result of treatment has a beneficial and lasting effect.

BACKGROUND: We studied the effect on skin papillomas of topical application of a complex of alpha-lactalbumin and oleic acid (often referred to as human alpha-lactalbumin made lethal to tumor cells [HAMLET]) to establish proof of the principle that alpha-lactalbumin-oleic acid kills transformed cells but not healthy, differentiated cells. METHODS: Forty patients with cutaneous papillomas that were resistant to conventional treatment were enrolled in a randomized, placebo-controlled, double-blind study, in which alpha-lactalbumin-oleic acid or saline placebo was applied daily for three weeks and the change in the volume of each lesion was recorded.

After this first phase of the study, 34 patients participated in the second phase, an open-label trial of a three-week course of alpha-lactalbumin-oleic acid. Approximately two years after the end of the open-label phase of the study, 38 of the original 40 patients were examined, and long-term follow-up data were obtained.

RESULTS: In the first phase of the study, the lesion volume was reduced by 75 percent or more in all 20 patients in the alpha-lactalbumin-oleic acid group, and in 88 of 92 papillomas; in the placebo group, a similar effect was evident in only 3 of 20 patients (15 of 74 papillomas) (P<0.001). After the patients in the initial placebo group had been treated with alpha-lactalbumin-oleic acid in the second phase of the study, a median reduction of 82 percent in lesion volume was observed. At follow-up two years after the end of the second phase, all lesions had completely resolved in 83 percent of the patients treated with alpha-lactalbumin-oleic acid, and the time to resolution was shorter in the group originally assigned to receive alpha-lactalbumin-oleic acid than among patients originally in the placebo group (2.4 vs. 9.9 months; P<0.01). No adverse reactions were reported, and there was no difference in the outcomes of treatment between immunocompetent and immunosuppressed patients.

Conclusion: Treatment with topical alpha-lactalbumin-oleic acid has a beneficial and lasting effect on skin papillomas. Copyright 2004 Massachusetts Medical Society

Gustafsson, L. et al. New England Jour of Med. Vol. 350, No. 26, pp. 2663-2672. 2004.

Whey protein's antibacterial and antiviral properties

1) Whey protein fractions potential antimicrobial activity (+/-)

Antibacterial and Antiviral Effects of Milk Proteins and Derivatives Thereof

  • Milk proteins contain many biologically active proteins.
  • Peptides found in whey protein exhibit antibacterial an antiviral activity.

Milk forms a rich source of biologically interesting components. In particular, its protein fraction is known to encompass many kinds of biological functions. In this review we focus on antibacterial and antiviral properties of milk proteins and milk protein derivatives. The latter include chemically modified proteins and enzymatically induced peptides. If such peptides are released by enzymes present within the digestive tract (e.g. trypsin or pepsin), it is likely that they play a role in the health defense system. This is especially the case when the active fragments can survive the intestinal conditions long enough to arrive at the right place to exert their beneficial function. In the first part of this paper attention is paid to the antibacterial proteins lactoferrin, lactoperoxidase, and lysozyme.

Furthermore, antibacterial peptides originating from caseins and whey proteins are described. The second part reports on studies of antiviral effects of milk proteins and derivatives thereof. Special focus is directed to the antiviral action towards the human immunodeficiency virus (HIV) and the human cytomegalovirus (HCMV). Unmodified milk proteins are generally not active against these viruses. An exception is lactoferrin, which shows significant antiviral activity against both HIV and HCMV. Several other milk proteins tested showed strong antiviral effects only after chemical modification, i.e. by making them polyanionic (for anti-HIV activity) or polycationic (for anti-HCMV activity). In a number of cases, conclusions are drawn concerning possible relationships between antibacterial / antiviral activity and molecular structure of the components described.

Conclusion: Protein, peptides, in milk, specifically whey, show promise as antibacterial and antiviral modifiers.

Floris, R., et al. Antibacterial and Antiviral Effects of Milk Proteins and Derivatives Thereof. Current Pharmaceutical Design. Vol. 9, No. 16, pp. 1257-1275(19). 2003.

2) Whey protein fractions potential antimicrobial activity (+/-)

Supplemental Dietary Whey Protein Concentrate Reduces Rotavirus-Induced Disease Symptoms in Suckling Mice

  • Rotavirus results in 500,000 child deaths annually.
  • Whey protein activates immune cell and or prevent infection.
  • Whey protein shows promise to help combat rotaviral diarrhea.

Rotavirus-induced diarrhea is a common infection that results in the death of nearly 500,000 children annually. Currently, no large-scale preventative treatments or vaccines exist. Because some whey protein concentrates (WPC) were shown to contain bioactive ingredients that may activate immune cells and/or prevent infection, the current study was conducted to assess whether the proprietary WPC IMUCARETM (WPC-IC) could protect against rotavirus. Suckling BALB/c mice were treated by gavage once daily with WPC-IC or with the control protein bovine serum albumin from the age of 9 to 17 d, and were infected with murine rotavirus at the age of 11 d.

Disease symptoms were graded as mild, moderate, or severe, and viral shedding was measured in fecal samples during the postinfection period. Severe diarrhea occurred in 63% of control mice; this was significantly reduced to 36% in WPC-IC–fed mice. Severe diarrhea occurred for a 4-d period in the control group but only for a 2-d period in the WPC-IC group. Although the mean viral load per mouse did not differ between the groups, the proportion of mice shedding high levels of the virus in the feces postinfection was significantly lower in the WPC-IC group on d 13, 16, and 17, and significantly higher on d 14. Rotavirus-specific antibody levels in serum and gut fluid did not differ between groups.

Conclusion: Prophylactic treatment with WPC-IC may reduce rotaviral disease by decreasing the prevalence of severe diarrhea and by decreasing the time period during which severe symptoms and high viral shedding occur.

Wolber, Frances M., et al. Supplemental Whey Protein Concentrate Reduces Rotavirus-Induced Disease Symptoms in Suckling Mice. J. Nutr. Vol. 135, pp. 1470-1474. 2005.

3) Whey proteins may modulate the immune response (+/-)

Effect of dietary whey protein concentrate on primary and secondary responses in immunized BALB/c mice.

  • Whey proteins modulate immune responses.
  • Mice developed antibody responses to common antigens.
  • Whey proteins enhance humoral immune responses to a range of heterologous antigens.

Proteins derived from the whey fraction of bovine milk are known to modulate immune responses. We have previously described a rennet whey protein concentrate (WPC) that can boost intestinal tract antibody responses to orally administered T-dependent antigens. In the present study, we investigated the effects of feeding WPC to mice on specific antibody responses to several orally or parenterally administered antigens, including influenza vaccine, diphtheria and tetanus toxoids, poliomyelitis vaccine, ovalbumin and cholera toxin sub-unit.

WPC-fed mice produced elevated levels of antigen-specific intestinal tract and serum antibodies against all tested antigens, compared to mice that were fed a standard chow diet. Both primary and secondary intestinal tract antibody responses were elevated by WPC feeding, while only secondary serum responses were increased in WPC-fed mice. Significant up-regulation of intestinal tract antibody was observed within 2 weeks of primary oral immunizations. A period of pre-feeding wit h WPC, prior to commencement of immunization, did not alter the kinetics or magnitude of immune enhancement.

Conclusion: These results identify bovine WPC as a potentially important dietary protein supplement, capable of enhancing humoral immune responses to a range of heterologous antigens.

Low, P.P. et al. Effect of dietary whey protein concentrate on primary and secondary responses in immunized BALB/c mice. Int. Immunopharmacology. Vol. 3, pp. 393-401. 2003.

4) Whey proteins bioactive peptides may help with caries. (+/-)

Bioactive Properties of Milk Proteins with Particular Focus on Anticariogenesis.

  • Caseinophosphopeptides and glycomacropeptides inhibit growth of cariogenic bacteria.
  • Glycomacropeptide inhibits Streptococcus mutans.
  • Glycomacropeptide has shown inhibitory activity to enamel demineralization and promotes tooth enamel remineralization.

Beyond nutrition, there is an increasing amount of data and information to demonstrate a bioactive role for dairy components in adults including a role in prevention of dental caries. Specifically, the casein fraction and hydrolysates thereof have been the focus of researchers investigating cariogenicity prevention. Tooth enamel is a polymeric substance consisting of crystalline calcium phosphate embedded in a protein matrix. Dental caries develop by acidic demineralization (calcium and phosphorus solubilization) of tooth enamel. Demineralization occurs directly (acidic food consumption) or indirectly (by fermentation products of dental plaque odontopathogenic bacteria growing on residual food particles between teeth or adhering to the plaque).

Research efforts with milk derived bioactive peptides have focused on inhibition of cariogenic, plaque-forming bacteria, inhibition of tooth enamel demineralization, and subsequent enamel remineralization. Caseinophosphopeptides (CPP) and glycomacropeptide (GMP) have been patented for use in common personal hygiene products to prevent dental caries. Research has shown CPP and GMP to be growth inhibitory to the cariogenic bacteria Streptococcus mutans and other species.

Additionally, CPP forms nanoclusters with amorphous calcium phosphate (AMP) at the tooth surface to provide a reservoir of calcium and phosphate ions to maintain a state of super saturation with respect to tooth enamel. This would buffer plaque pH, and also provide ions for tooth enamel remineralization. Glycosidic structures attached to GMP are important to numerous bioactive properties of the peptide including anticariogenicity. Like CPP, GMP has shown inhibitory activity to enamel demineralization and promotes tooth enamel remineralization.

Aimutis, William R. et al. Bioactive Properties of Milk Proteins with Particular Focus on Anticariogenesis. J. Nutr. Vol. 134, pp. 989S-995S, 2004.

Whey protein and mental health studies

1) Whey proteins potential to reduce stress (+/-)

Whey protein rich in alpha-lactalbumin increases the ration of plasma tryptophan to the sum of the other large neutral amino acids and improves cognitive performance in stress vulnerable subjects.

  • Lactalbumin rich whey protein increases serotonin activity.
  • Stressed individual were less stressed when fed Lactalbumin.

Background: Cognitive performance often declines under chronic stress exposure. The negative effect of chronic stress on performance may be mediated by reduced brain serotonin function. The uptake of the serotonin precursor tryptophan into the brain depends on nutrients that influence the availability of tryptophan by changing the ratio of plasma tryptophan to the sum of the other large neutral amino acids (Trp-LNAA ratio). In addition, a diet-induced increase in tryptophan may increase brain serotonergic activity levels and improve cognitive performance, particularly in high stress-vulnerable subjects.

Objective: We tested whether -lactalbumin, a whey protein with a high tryptophan content, would increase the plasma Trp-LNAA ratio and improve cognitive performance in high stress– vulnerable subjects.

Design: Twenty-three high stress–vulnerable subjects and 29 low stress–vulnerable subjects participated in a double-blind, placebo-controlled, crossover study. All subjects conducted a memory-scanning task after the intake of a diet enriched with either -lactalbumin ( -lactalbumin diet) or sodium caseinate (control diet). Blood samples were taken to measure the effect of dietary manipulation on the plasma Trp-LNAA ratio.

Results: A significantly greater increase in the plasma Trp-LNAA ratio after consumption of the -lactalbumin diet than after the control diet (P = 0.0001) was observed; memory scanning improved significantly only in the high stress–vulnerable subjects (P = 0.019).

Conclusion: Because an increase in the plasma Trp-LNAA ratio is considered to be an indirect indication of increased brain serotonin function, the results suggest that dietary protein rich in -lactalbumin improves cognitive performance in stress-vulnerable subjects via increased brain tryptophan and serotonin activities. Markus, CR. et al. Whey protein rich in alpha-lactalbumin increases the ration of plasma tryptophan to the sum of the other large neutral amino acids and improves cognitive performance in stress vulnerable subjects.

Amer. Journ. Of Clin. Nutr. Vol. 75, No. 6, pp. 1051-1056. 2002.

2) Alpha-lactalbumin (a whey fraction) potential to increase mental clarity (+/-)

Evening intake of -lactalbumin increases plasma tryptophan availability and improves morning alertness and brain measures of attention.

  • Evening whey protein intake increase tryptophan content by 130%
  • Reduced sleepiness and improved attention processes
  • In poor sleepers whey protein showed increase in behavioral performance.

Background: Brain serotonin function is thought to promote sleep regulation and cognitive processes, whereas sleep abnormalities and subsequent behavioral decline are often attributed to deficient brain serotonin activity. Brain uptake of the serotonin precursor tryptophan is dependent on nutrients that influence the availability of tryptophan via a change in the ratio of plasma tryptophan to the sum of the other large neutral amino acids (Trp: LNAA).

Objective: We tested whether evening consumption of -lactalbumin protein with an enriched tryptophan content of 4.8 g/100 g increases plasma Trp: LNAA and improves alertness and performance on the morning after sleep, particularly in subjects with sleep complaints.

Design: Healthy subjects with (n = 14) or without (n = 14) mild sleep complaints participated in a double-blind, placebo-controlled study. The subjects slept at the laboratory for 2 separate nights so that morning performance could be evaluated after an evening diet containing either tryptophan-rich -lactalbumin or tryptophan-low placebo protein. Evening dietary changes in plasma Trp: LNAA were measured. Behavioral (reaction time and errors) and brain measures of attention were recorded during a continuous performance task.

Results: Evening -lactalbumin intake caused a 130% increase in Trp: LNAA before bedtime (P = 0.0001) and modestly but significantly reduced sleepiness (P = 0.013) and improved brain-sustained attention processes (P = 0.002) the following morning. Only in poor sleepers was this accompanied by improved behavioral performance (P = 0.05).

Conclusion: Evening dietary increases in plasma tryptophan availability for uptake into the brain enhance sustained alertness early in the morning after an overnight sleep, most likely because of improved sleep.

Markus, C.R., et al. Evening intake of alpha-lactalbumin increases tryptophan availability and improves morning alertness and brain measures of attention. American Jour. of Clin. Nutr. Vol. 81, No. 5, pp. 1026-1033. 2005.

 
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