Just The Facts: Whey Protein!
Whey Protein (aka lactalbumin) is the supplemental protein source of choice for many fitness enthusiasts.
Whey Protein Composition
- Bovine serum albumin (BSA)
- Immunoglobulins (IgG1, IgG2, secretory IgA and IgM)
- Smaller components: iron binding proteins (lactoferrin, lactoferricin), calcium, potassium, sodium, phosphorous, Vitamins A, C, B1, B2, B3, B5, B12, folic acid and biotin.
- Balanced source of essential amino acids and peptides
- High protein efficiency ratio: One study showed that milk protein elicits greater increase in branched chain amino acid concentrations in peripheral tissues as compared to soy. 1
- Excellent source of sulfur amino acids (methionine and cysteine): Cysteine is the rate limiting amino acid for the synthesis of the antioxidant, glutathione.
- Excellent source of branched-chain amino acids (leucine, isoleucine, valine): Leucine is a both a key signal molecule for initiation and an important substrate for new protein synthesis. 2
- Excellent source of glutamine
- Crosses stomach quickly and rapidly absorbed in the intestine (vs. casein which exits the stomach much slower). 3
* Ratings as of article's date of publication
Whey & Fat
Calcium (a minimal component of whey protein) decreases accumulation of body fat and accelerates weight and fat loss. The proposed mechanism is thought to be that parathyroid hormone and 1,25-(OH)2-D respond to low calcium diets and promote fat storage. High calcium diets inhibit these hormones and thus inhibit fat storage and promote increased fat breakdown and energy partitioning from fat to lean. 4, 5
Whey & The Digestive Tract
Lactose (found in whey but not whey concentrate) is broken down into galacto-oligosaccharides that are used by intestinal bacteria leading to better functioning of the digestive tract. 6
Whey & Free Radical Production
Glutathione: Powerful antioxidant used in detoxification. Glutathione levels have been shown to decrease with exercise. 7 The rate limiting amino acid for the synthesis of glutathione is cysteine.
- Whey protein increases glutathione levels far more than casein, specifically in heart and liver tissues. 8
- Kent and colleagues looked at whether enzymatically hydrolyzed whey protein isolate (WPI) could increase intracellular GSH concentrations and protect against cell death secondary to free radicals in a human prostate epithelial cell line. They found that treating these cells with WPI increased intracellular GSH by 64% and protected the cells against oxidant-induced cell death compared with control cells receiving no hydrolyzed WPI ( P <0.05).
- Interestingly, they found a similar increase in GSH with N -acetylcysteine, which donates cysteine and thereby raises intracellular GSH levels. In contrast, treating the cell line with hydrolyzed sodium caseinate, a cysteine-poor protein source, did not significantly elevate intracellular GSH. 9
- BOTTOM LINE: Whey protein can increase GSH synthesis and protect against oxidant-induced cell death. Lactoferrin and lactoferricin (two minor whey proteins) function as antioxidants via their iron binding capacity, which inhibits bacterial growth and oxidative reactions. 10
The body is highly sensitive to insulin after exercise and shuttles carbohydrates and proteins into muscle cells instead of fat cells. This sensitivity declines post-workout until ~2 hours at which point it reaches baseline.
Furthermore, the anabolic effects of insulin are synergistic with amino acids.11 Given the rapid absorption of whey, it is the ideal choice for post-workout to take advantage of the insulin-amino acid synergistic effect.
- Minimal risk of food allergies (same risk as with soy, casein, or egg-based proteins)
- Questionable risk Insulin-dependent diabetes mellitus (IDDM) in children: BSA (bovine serum albumin) thought to be a possible trigger for IDDM. Some studies have found increased levels of anti-BSA antibodies in sera from children developing IDDM.12 However, other studies have shown no increases in anti-BSA in IDDM children. 13 Thus the exact role of BSA in IDDM development remains unclear.
- Kidney damage. Research does not support the idea of kidney damage. 14 However, some researchers warn against excessive protein intake (>2g/kg of body weight per day).
- Increased risk of dehydration with excess protein intake. 15
- Possible risk for calcium loss. Very large amounts of protein intake results in increased acid production. Calcium is released from bone as a buffer for the increased acid load.16
- Fouillet H, Mariotti F, Gaudichon C, Bos C, Tome D. Peripheral and splanchnic metabolism of dietary nitrogen are differently affected by the protein source in humans as assessed by compartmental modeling. J Nutr. 2002; 132: 125-33.
- Anthony JC, Anthony TG, Kimball SR and Jefferson LS. Signaling pathways involved in translational control of protein synthesis in skeletal muscle by leucine. J Nutr. 2001 ; 131: 856S?860S.
- Boirie Y, Dangin M, Gachon P, Vasson MP, Maubois JL, Beaufrere B. Slow and fast dietary proteins differently modulate postprandial protein accretion. Proc Nat Acad Sci. 1997; 94: 14930-14935.
- Zemel MD, Shi H, Greer B, DiRienzo D, Zemel PC. Regulation of adiposity by dietary calcium. FASEB J. 2000; 14: 1132-1138.
- Zemel MB . Mechanisms of dairy modulation of adiposity. J Nutr. 2003; 133: 252S-256S.
- Shah NP. Effects of milk-derived bioactives: an overview. Br J Nutr. 2000; 84: S3-S10.
- Kanter MM. Free radicals, exercise, and antioxidant supplementation. Int J Sport Nutr. 1994; 4: 205-220.
- Bounous G, Batist G, Gold P. Immunoenhancing property of dietary whey protein in mice; role of glutathione. Clin Invest Med. 1989; 12: 154-161.
- Kent KD, Harper WJ, Bomser JA. Effect of whey protein isolate on intracellular glutathione and oxidant-induced cell death in human prostate epithelial cells. Toxicology in vitro 2003; 17(1): 27-33.
- Dillar CJ, Walzem RL, German JB. Whey components: Millenia of Evolution create functionalities for mammalian nutrition. Crit Rev Food Sci Nutr. 2002 (in press).
- May ME, Buse MG. Effects of branched-chain amino acids on protein turnover. Diabetes Metab Rev. 1989; 5: 227-245.
- Karjalainene J, Martin JM, Knip M et al. A bovine albumin peptide trigger of insulin-dependent diabetes mellitus. N Engl J Med 1992; 327: 302-307.
- Pardini VC, Vieira JG, Miranda W et al. Antibodies to bovine serum albumin in Brazilian children and young adults with IDDM. Diabetes Care 1996; 19: 126-129.
- Ivarsson SA, Mansson MU, Jakobsson IL. IgG antibodies to bovine serum albumin not increased in children with IDDM. Diabetes 1995; 44: 1349-1350.
- Lemon PW. Is increased dietary protein necessary or beneficial for individuals with a physically active lifestyle? Nutr Rev . 1996; 54: S169-S175.
- Barzel US , Massey LK. Excess dietary protein can adversely affect bone. J Nutr. 1998; 128: 1051-1053.
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