When milk is separated into curds and whey, these two products represent the two main types of protein found in milk. The curds, which can be made into cheese, are rich in casein, a type of amino acid. There are four types of caseins, and the ratio of each present in milk will depend on the breed of cow, its particular genetics and diet.
Features
Casein is a type of amino acid usually associated with milk, cheese and other dairy products. In fact, according to professors at Cornell University, more than 80 percent of the protein content of milk is casein. The chemical structure of casein, which has a high phosphate content relative to other proteins, allows milk to contain more calcium than it otherwise could. Casein curdles in acidic environments, a feature that is the basis for manufacturing cheese.
Function
The unique features of casein proteins provide a particular benefit sought by bodybuilders: a slow-release protein. Bodybuilders seek to constantly remain in an anabolic state so they do not lose muscle mass. Because casein digestion occurs slowly and steadily, it acts like a time-released protein supplement that peaks hours after consumption. This slow-acting digestion is likely due to the fact that casein coagulates in the acidic environment of the stomach.
Benefits
An additional benefit of casein being explored by scientific research is the reduction of blood pressure. A study published in the American Journal of Hypertension in 2007 confirmed that a casein-derived peptide can significantly reduce blood pressure in prehypertensive people. In the study, subjects consumed 3.8 grams of the peptide daily for four weeks and experienced an average reduction in diastolic pressure of 10.7 mm Hg and an average reduction in systolic pressure of 6.9 mm Hg.
Significance
Ongoing research is exploring the use of dairy-based drinks for individuals with phenylketonuria. Milk that is rich in a 6-casein, a type of casein found in milk, can be used to derive a protein source that does not contain phenylalanine, a type of amino acid to which some people are allergic. This unique feature is possible because 6-casein includes a carbohydrate attached to the amino acid chain. In the process of making cheese, the amino acid chain is split to form glycomacropeptide, which is safe for people with phenylketonuria. A 2010 study found blood phenylalanine levels in test subjects declined as much as 30 percent to 80 percent when consuming glycomacropeptide drink.
Potential
Another direction of study with respect to casein is its effects on autism. At least one study has attempted to gauge the benefits of a gluten and casein-free diet on autistic children. Though the study did not yield statistically significant results, there was anecdotal evidence from some of the parents that the restricted diet did produce noticeable benefits for their children.
References
- Cornell University: Milk Protein
- Muscle and Strength Website: Protein Supplements
- Americaan Journal of Physiology: Digestion Rate of Protein
- American Journal of Hypertension: Bovine casein hydrolysate reduces blood pressure
- North American Journal of Medical Sciences: Therapeutic dairy-based drink for phenylketonuria
- Journal of Austism and Developmental Disorders: The gluten-free, casein-free diet in autism
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