Whey protein



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 possess anti-inflammatory or anti-cancer properties. The effects of whey protein on human health are of great interest and are currently being investigated as a way of reducing disease risk, as well as a possible supplementary treatment for several diseases.

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. Although whey proteins are responsible for some milk allergies, the major allergens in milk are the caseins.

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

Whey can be denatured by heat. High heat (such as the sustained high temperatures above 72 °C 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. Heat-denatured whey can still cause allergies in some people.

Composition
Whey protein is the collection of globular proteins isolated from whey, a by-product of cheese manufactured from cow's milk. The protein in cow's milk is 20% whey protein and 80% casein protein, whereas the protein in human milk is 60% whey and 40% casein. The protein fraction in whey constitutes approximately 10% of the total dry solids in whey. This protein is typically a mixture of beta-lactoglobulin (~65%), alpha-lactalbumin (~25%), bovine serum albumin (~8%)(see also serum albumin), and immunoglobulins. These are soluble in their native forms, independent of pH.

Being a by-product of the cheese making process, and likelihood of animal rennet use, whey protein as well as casein products may not be suitable for consumption by lacto-vegetarians or observers of kosher dietary laws. There are, however, specialty producers of vegetarian-approved whey protein products produced using non-animal "rennet" (enzymes). These products are often also labeled as kosher and halal approved.

Major forms
Whey protein typically comes in three major forms: concentrate (WPC), isolate (WPI), and hydrolysate (WPH).
 * Concentrates have typically a low (but still significant) level of fat and cholesterol but, in general, compared to the other forms of whey protein, 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 bioactivated compounds as well — they are 90%+ protein by weight. Like whey protein concentrates, whey protein isolates are mild to slightly milky in taste.
 * Hydrolysates are whey proteins that are predigested and partially hydrolyzed for the purpose of easier metabolizing, but their cost is generally higher. Highly hydrolysed whey may be less allergenic than other forms of whey.

Whey protein and muscle building
The effects of whey protein supplementation on muscle growth in response to resistance training are debatable. One study demonstrated some increase in lean body mass and strength in men supplementing whey protein vs. no supplementation, while another study found greater increases in strength in a group supplementing whey compared to another group supplementing casein, which could be evidence of whey protein's superior amino acid profile. However, other research exists that show little to no benefit of whey protein supplementation. The authors of one study concluded that "young adults who supplement with protein during a structured resistance training program experience minimal beneficial effects in lean tissue mass and strength,", although it did not control for other sources of protein in the participant's diets. The timing of protein supplement ingestion may not have any significant effects on strength, power, or body-composition. A study of elderly men found supplementation with whey protein after exercise improved muscle protein synthesis.

Health effects
The use of whey protein as a source of amino acids and its effect on reducing the risks of diseases such as heart disease, cancer and diabetes is the focus of ongoing research. Whey is an abundant source of branched-chain amino acids (BCAAs), which are used to stimulate protein synthesis. In particular, leucine plays a key role in initiating the transcription of protein synthesis. When leucine is ingested in high amounts, such as with whey protein supplementation, there is greater stimulation of protein synthesis, which may speed recovery and adaptation to stress (exercise).

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. However, another study suggested that large amounts of whey protein can increase cellular glutathione levels. 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.

Aflatoxin, an extremely potent carcinogen and major cause of mitochondria damage (thereby having the potential to negatively affect all bodily processes including skeletal muscles), has been shown to be inhibited by whey protein and ginseng extract. However, the amount of aflatoxin within whey protein itself, was shown to be reflected by the amount in the unprocessed milk used to make it.

Digestive issues
Some people experience severe digestive issues following consumption of whey protein powder. These may include gas, bloating, cramps, tiredness, weakness, fatigue, headaches, and irritability. One of the possible causes is lactose intolerance after they ingest whey concentrate. Undigested protein in the colon will undergo bacterial fermentation which leads to the production of, among other things, gas and fatty acids.