Health Implications of Milk Containing beta-Casein with the A(2) Genetic Variant

摘要

Milk from dairy cows has long provided a high quality source of protein and selected micronutrients such as calcium to most populations. Recently, a relationship between disease risk and consumption of a specific bovine ss-casein fraction either A(1) or A(2) genetic variants has been identified. Populations, which consume milk containing high levels of ss-casein A(2) variant, have a lower incidence of cardiovascular disease and type 1 diabetes. Furthermore, consumption of milk with the A(2) variant may be associated with less severe symptoms of autism and schizophrenia. The mechanism of action focuses on ss-casein A(1) and related forms preferentially that are able to produce a bioactive opioid peptide, ss-casomorphin-7 (ss-CM-7) during digestion. Infants may absorb ss-CM-7 due to an immature gastrointestinal tract. Adults, on the other hand, appear to reap the biological activity locally on the intestinal brush boarder. ss-CM-7 can potentially affect numerous opioid receptors in the nervous, endocrine, and immune systems. Whether there is a definite health benefit to milk containing the A(2) genetic variant is unknown and requires further investigation.