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Whey is one of the two major classes of protein in milk. (The other is casein, the “curds” of “curds and whey.”) Proteins are made of amino acids, and whey contains high levels of the amino acid cysteine. This is the basis for many of its proposed uses. It also contains branched chain amino acids ( BCAAs). However, while there is no question that whey is a highly digestible and rich protein source, there is no meaningful supporting evidence that it provides any specific health benefits.
When milk is converted into cheese, whey is the liquid that is left behind. There is no specific dietary requirement for whey, as the amino acids it contains are present in a wide variety of other foods, as well.
A typical dose of whey protein is 20-30 g per day.
There are no well-documented medicinal uses of whey protein.
There is some evidence that whey can raise levels of glutathione. Glutathione is an antioxidant that the body manufactures to defend itself against free radicals. In certain diseases, glutathione levels may fall to below-normal levels. These conditions include cataracts, HIV, liver disease, diabetes, and various types of cancer.1 This reduction of glutathione might in turn contribute to the symptoms or progression of the disease. To solve this problem, glutathione supplements have been recommended, but glutathione is essentially not absorbed at all when it is taken by mouth.2 Whey protein may be a better solution. The body uses cysteine to make glutathione, and whey is rich in cysteine. Meaningful preliminary evidence suggests that whey can raise glutathione levels in people with cancer, hepatitis, or HIV.3-8
However, while these are promising findings, one essential piece of evidence is lacking: there is no evidence as yet that this rise in glutathione produces any meaningful health benefits.
Whey protein has also been proposed as a bodybuilding aid, based partly on its high content of BCAAs. However, there is no more than minimal evidence that whey protein helps accelerate muscle mass development.9-11 Furthermore, there is little evidence that whey protein is more effective for this purpose than any other protein. For example, one small double-blind study found evidence that both casein and whey protein were more effective than placebo at promoting muscle growth after exercise, but whey was no more effective than the far less expensive casein.12 However, a single small study did find ergogenic benefits with whey as compared to casein.32
One study looked at whether whey protein could help women with HIV build muscle mass.13 Participants were divided into three groups: those who undertook a course of resistance exercise (weight lifting), those who took whey, and those who did both. Resistance exercise alone was just as effective as resistance exercise plus whey, while whey alone was not effective.
Whey contains alpha-lactalbumin, a protein that in turn contains high levels of the amino acid tryptophan. Tryptophan is the body’s precursor to serotonin, and is thought to affect mental function. In a small double-blind study, use of alpha-lactalbumin in the evening improved morning alertness, perhaps by enhancing sleep quality.14 Another small double-blind study found weak evidence that alpha-lactalbumin improved mental function in people sensitive to stress.15 A third study failed to find that alpha-lactalbumin significantly improved memory in women experiencing premenstrual symptoms.16
Infant formula based on pre-digested (hydrolyzed) whey protein is somewhat less allergenic than standard infant formula; this might reduce symptoms of colic28 and possibly decrease the risk that the infant will later develop allergies.29,30
As a constituent of milk, whey protein is presumed to be a safe substance. People with allergies to milk, however, are likely to be allergic to whey as well (even partially hydrolyzed forms of whey).31
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5. Micke P, Beeh KM, Buhl R, et al. Effects of long-term supplementation with whey proteins on plasma glutathione levels of HIV-infected patients. Eur J Nutr. 2002;41:12-18.
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9. Burke DG, Chilibeck PD, Davidson KS, et al. The effect of whey protein supplementation with and without creatine monohydrate combined with resistance training on lean tissue mass and muscle strength. Int J Sport Nutr Exerc Metab. 2001;11:349-364.
10. Borsheim E, Aarsland A, Wolfe RR, et al. Effect of an amino acid, protein, and carbohydrate mixture on net muscle protein balance after resistance exercise. Int J Sport Nutr Exerc Metab. 2004;14:255-271.
11. Chromiak JA, Smedley B, Carpenter W, et al. Effect of a 10-week strength training program and recovery drink on body composition, muscular strength and endurance, and anaerobic power and capacity. Nutrition. 2004;20:420-427.
12. Tipton KD, Elliott TA, Cree MG, et al. Ingestion of casein and whey proteins result in muscle anabolism after resistance exercise. Med Sci Sports Exerc. 2004;36:2073-2081.
13. Agin D, Gallagher D, Wang J, et al. Effects of whey protein and resistance exercise on body cell mass, muscle strength, and quality of life in women with HIV. AIDS. 2001;15:2431-2440.
14. Markus CR, Jonkman LM, Lammers JH, et al. Evening intake of alpha-lactalbumin increases plasma tryptophan availability and improves morning alertness and brain measures of attention. Am J Clin Nutr. 2005;81:1026-1033.
15. Markus CR, Olivier B, de Haan EH, et al. Whey protein rich in alpha-lactalbumin increases the ratio of plasma tryptophan to the sum of the other large neutral amino acids and improves cognitive performance in stress-vulnerable subjects. Am J Clin Nutr. 2002;75:1051-1056.
16. Schmitt JA, Jorissen BL, Dye L, et al. Memory function in women with premenstrual complaints and the effect of serotonergic stimulation by acute administration of an alpha-lactalbumin protein. J Psychopharmacol. 2005;19:375-384.
17. Bounous G. Whey protein concentrate (WPC) and glutathione modulation in cancer treatment. Anticancer Res. 2000;20(6C):4785-4792.
18. Bounous G, Papenburg R, Kongshavn PA, Gold P, Fleiszer D. Dietary whey protein inhibits the development of dimethylhydrazine induced malignancy. Clin Invest Med. 1988;11:213-217.
19. Hakkak R, Korourian S, Ronis MJ, Johnston JM, Badger TM. Dietary whey protein protects against azoxymethane-induced colon tumors in male rats. Cancer Epidemiol Biomarkers Prev. 2001;10:555-558.
20. Hakkak R, Korourian S, Shelnutt SR, Lensing S, Ronis MJ, Badger TM. Diets containing whey proteins or soy protein isolate protect against 7,12-dimethylbenz(a)anthracene-induced mammary tumors in female rats. Cancer Epidemiol Biomarkers Prev. 2000;9:113-117.
21. Kennedy RS, Konok GP, Bounous G, Baruchel S, Lee TD. The use of a whey protein concentrate in the treatment of patients with metastatic carcinoma: a phase I-II clinical study. Anticancer Res. 1995;15(6B):2643-2649.
22. McIntosh GH, Regester GO, Le Leu RK, Royle PJ, Smithers GW. Dairy proteins protect against dimethylhydrazine-induced intestinal cancers in rats. J Nutr. 1995;125:809-816.
23. Marshall K. Therapeutic applications of whey protein. Altern Med Rev. 2004;9:136-156.
24. Rowlands JC, He L, Hakkak R, Ronis MJ, Badger TM. Soy and whey proteins downregulate DMBA-induced liver and mammary gland CYP1 expression in female rats. J Nutr. 2001;131:3281-3287.
25. Sternhagen LG, Allen JC. Growth rates of a human colon adenocarcinoma cell line are regulated by the milk protein alpha-lactalbumin. Adv Exp Med Biol. 2001;501:115-120.
26. Tsai WY, Chang WH, Chen CH, Lu FJ. Enchancing effect of patented whey protein isolate (Immunocal) on cytotoxicity of an anticancer drug. Nutr Cancer. 2000;38:200-208.
27. Tsuda H, Sekine K, Ushida Y, et al. Milk and dairy products in cancer prevention: focus on bovine lactoferrin. Mutat Res. 2000;462:227-233.
28. Lucassen PL, Assendelft WJ, Gubbels JW, et al. Infantile colic: crying time reduction with a whey hydrolysate: a double-blind, randomized, placebo-controlled trial. Pediatrics. 2000;106:1349-1354.
29. Chandra RK. Five-year follow-up of high-risk infants with family history of allergy who were exclusively breast-fed or fed partial whey hydrolysate, soy, and conventional cow's milk formulas. J Pediatr Gastroenterol Nutr. 1997;24:380-388.
30. Szajewska H, Mrukowicz JZ, Stoinska B, et al. Extensively and partially hydrolysed preterm formulas in the prevention of allergic diseases in preterm infants: a randomized, double-blind trial. Acta Paediatr. 2004;93:1159-1165.
31. Caffarelli C, Plebani A, Poiesi C, et al. Determination of allergenicity to three cow's milk hydrolysates and an amino acid-derived formula in children with cow's milk allergy. Clin Exp Allergy. 2002;32:74-79.
32. Cribb PJ, Williams AD, Carey MF, et al. The effect of whey isolate and resistance training on strength, body composition, and plasma glutamine. Int J Sport Nutr Exerc Metab. 2006;16:494-509.
Last reviewed December 2015 by EBSCO CAM Review Board Last Updated: 12/15/2015