含A2基因型β-酪蛋白的牛乳对健康的影响

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 β-casein fraction either A1 or A2 genetic variants has been identified. Populations, which consume milk containing high levels of β-casein A2 variant, have a lower incidence of cardiovascular disease and type 1 diabetes.

 Furthermore, consumption of milk with the A2 variant may be associated with less severe symptoms of autism and schizophrenia. The mechanism of action focuses on β-casein A1 and related forms preferentially that are able to produce a bioactive opioid peptide, β-casomorphin-7 (β-CM-7) during digestion. Infants may absorb β-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. β-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 A2 genetic variant is unknown and requires further investigation.