Whey protein

Containers of whey protein being sold at a health food store.

Whey protein is a mixture of globular proteins isolated from whey, the liquid material created as a by-product of cheese production. Some preclinical studies in rodents have suggested that whey protein may influence glutathione production and possess anti-inflammatory or anti-cancer properties; however, human data are lacking.^[1][2] The effects of whey protein on human health are of great interest and this protein mixture is being investigated as a way of reducing disease risk, or as a supplementary treatment for several diseases.^[3] Whey protein is commonly marketed and ingested as a dietary supplement, and various health claims have been attributed to it in the alternative medicine community.^[4] Although whey proteins are responsible for some milk allergies, the major allergens in milk are the caseins.^[5][6]

Production

Whey is left over when milk coagulates, and contains everything that is soluble from milk. It is a 5 percent solution of lactose in water, with some minerals and lactalbumin.^[7] It is removed after cheese is processed. The fat is removed and then is processed for human foods ^[7]. Processing can be by simple drying, or the protein content can be increased by removing lipids and other non-protein materials.^[8] For example, spray drying after membrane filtration separates the proteins from whey. ^[9]

Whey protein can be denatured by heat. High heat (such as the sustained high temperatures above 72 degrees Celsius associated with the pasteurization process) denatures whey proteins. While native whey protein does not aggregate upon renneting or acidification of milk, denaturing the whey protein triggers hydrophobic interactions with other proteins, and the formation of a protein gel.^[8] Heat-denatured whey can still cause allergies in some people.^[10]

The price of whey is 25-40% less of other dairy products but because of the production problems in the cheese industry whey has not been used as often as it could be.^[11]

Composition

Whey protein is the collection of globular proteins isolated from whey, a by-product of cheese manufactured from cow's milk. It is typically a mixture of beta-lactoglobulin (~65%), alpha-lactalbumin (~25%), and serum albumin (~8%), which are soluble in their native forms, independent of pH. The protein fraction in whey (approximately 10% of the total dry solids within whey) comprises four major protein fractions and six minor protein fractions. The major protein fractions in whey are beta-lactoglobulin, alpha-lactalbumin, bovine serum albumin and immunoglobulins.^[12]

Major forms

Whey protein typically comes in three major forms: concentrate, isolate, and hydrolysate.

• Concentrates contain a low level of fat and cholesterol but, in general, have higher levels of bioactive compounds, and carbohydrates in the form of lactose — they are 29%-89% protein by weight.
• Isolates are processed to remove the fat, and lactose, but are usually lower in bioactive compounds as well — they are 90%+ protein by weight. Both of these types are mild to slightly milky in taste.
• Hydrolysates are predigested, partially hydrolyzed whey proteins that, as a consequence, are more easily absorbed, but their cost is generally higher.^[8] Highly-hydrolysed whey may be less allergenic than other forms of whey.^[10] They are very bitter in taste.

Health effects

The use of whey proteins, as a source of amino acids and its effect on reducing the risks of diseases such as heart disease and cancer, is the focus of ongoing research.^[3] Whey is a source of branched chain amino acids (BCAAs) which are used to fuel working muscles and stimulate protein synthesis.^[13] Whey contains high amounts of BCAAs.^[14]. In particular, leucine plays a key role in initiating the transcription pathway that fires up protein synthesis.^[15] When leucine is ingested in high amount, such as with whey protein supplementation, there is greater stimulation of protein synthesis, which may speed recovery and adaptation to stress (exercise).^[16]

Whey protein contains the amino acid cysteine which can be used to make glutathione. However, this amino acid is not essential for the synthesis of glutathione and some studies have suggested that the amount of cysteine in the diet may have little effect on glutathione synthesis.^[17] However, another study suggested that large amounts of whey protein can increase cellular glutathione levels.^[18] Glutathione is an antioxidant that defends the body against free radical damage and some toxins, and studies in animals have suggested that milk proteins might reduce the risk of cancer.^[19]

References

External links

• Whey protein resources, National Dairy Council
• Whey Protein Healthnotes, University of California, San Diego