Bell Stacey J, Grochoski Gregory T, Clarke Andrew J
Research and Development, Ideasphere, Inc., 56 Amherst Road, Belmont, MA, 02478, USA.
Crit Rev Food Sci Nutr. 2006;46(1):93-100. doi: 10.1080/10408390591001144.
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 A1 or A2 genetic variants has been identified. Populations, which consume milk containing high levels of ss-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 ss-casein A1 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 A2 genetic variant is unknown and requires further investigation.
长期以来，奶牛产的奶一直是大多数人优质蛋白质和特定微量营养素（如钙）的来源。最近，人们发现疾病风险与食用特定的牛β-酪蛋白组分（A1或A2基因变体）之间存在关联。食用含有高水平β-酪蛋白A2变体牛奶的人群，心血管疾病和1型糖尿病的发病率较低。此外，食用含有A2变体的牛奶可能与自闭症和精神分裂症症状较轻有关。作用机制主要集中在β-酪蛋白A1及相关形式上，它们在消化过程中能够产生一种生物活性阿片肽——β-酪蛋白吗啡-7（β-CM-7）。由于胃肠道不成熟，婴儿可能会吸收β-CM-7。另一方面，成年人似乎在肠道刷状缘局部获得这种生物活性。β-CM-7可能会影响神经、内分泌和免疫系统中的众多阿片受体。含有A2基因变体的牛奶是否确实对健康有益尚不清楚，需要进一步研究。
