Whey protein is available as a powdered supplement, and is often consumed by athletes as a source of easily digestible protein. As well as the ability to facilitate increased protein needs of athletes, whey protein has some interesting modulatory effects on the immune system because of the protein and amino acids it contains. Commercially available whey protein is manufactured from bovine milk by separation from the casein, followed by freeze drying. The whey protein fraction of bovine milk contains a number of proteins that are thought to have specialised nutritional functions in humans, including α-lactalbumin (α-LA), β-lactalbumin (β-LA), glycomacropeptide (GMP), lactoferrin, immunoglobulin and bovine serum albumin. Research has identified a number of specific nutritional uses for a number of these proteins. However, of particular interest is the ability of some of these proteins to prime the innate immune system.
Neutrophils are the first white blood cells to enter tissue inflammation where they destroy pathogens. Neutrophils can also counterbalance the pro-inflammatory effects of tumour necrosis factor-α (TNF-α) and interleukin-1 (IL-1) by the release of antagonist chemicals such as IL-1Ra. The α-LA and β-LA components of bovine whey protein enhances chemotaxis, phagocytocis, oxidative burst and degranulation in neutrophils as well as stimulates the release of IL-1Ra in a dose dependent manner in vitro. The main protein in the whey protein is β-LA1, and research shows that it is able to stimulate γ-interferon (IFNγ) production by different lymphocytes. Production of IFN-γ is necessary for viral and bacterial control as well as tumour suppression. Whey is also a good source of the sulphur amino acid cysteine and disulfide linked cystine, which are both able to increase glutathione levels in cells.
Chronic stress is known to decrease the responsiveness of the immune system because stress causes the release of corticosteroids that have immunosuppressive effects. Individuals with stressful lifestyles or athletes under hard training can be particular susceptible to infections because of the decreased immune responsiveness to pathogens. Whey protein has shown very useful properties that make it worth considering as a supplement to boost immunity. Whey protein is particularly suited to athletes during intense training because as well as immunomodulatory effects it also provides an easily digestible and absorbable form of high quality animal protein that is low in both fat and carbohydrate. Whey protein is also high in leucine, which may prevent the breakdown of muscle tissue during intense exercise by sparing skeletal muscle leucine. A good quality whey protein isolate that has undergone ion-exchange or cross-flow microfiltration is recommended for optimal immune system function.
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