• Journal of Dairy Science and Biotechnology
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• v.26 no.1
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• pp.11-19
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• 2008

Milk from dairy cows has long provided a high quality source of protein and selected micronutrients as calcuim to most populations. Recently, a relationship between disease risk and consumption of specific bovine ${\beta}$-casein fraction either A1 or A2 genetic variants has identified. Populations, which consume milk contain high containing high levels of ${\beta}$-casein A2 variants, have a lower incidence of cardiovascular disease and type 1 diabetes. Furthermore, consumption of milk with the A2 variants may be associated with less severe symptoms of autism and schizophrenia. The mechanism of action focuses on ${\beta}$-casein A1 and related forms preferentially that are able to produce a bioactive opioid peptide, ${\beta}$-casomorphin-7(${\beta}$-CM-7) during digestion. Infants may absorb ${\beta}$-CM-7 due to an immature gastrointestinal tract. Adult, on the other hand, appear to reap the biological activity locally on the intestinal brush boarder. ${\beta}$-CM-7 can potentially affect numerous opioid receptors in the nervous, endocrine, and immune system. Whether there is a definite health benefit to milk containing the A2 genetic variant is unknown and requires further investigation.

• Journal of Dairy Science and Biotechnology
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• v.42 no.2
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• pp.23-34
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• 2024

Milk, which is often referred to as a healthy beverage, is the first food encountered at birth. During digestion, A1-type milk often leads to digestive disorders due to increased levels of 𝛽-casomorphin-7. It also tends to induce inflammatory responses in the gut immune system by altering the gut microbiota and triggering conditions such as diabetes and respiratory hypersensitivity. In contrast, A2-type milk is gaining attention because of fewer associated problems than A1 milk and its unique functional benefits. However, information on the efficacy of A2 milk relies primarily on limited clinical and animal trial data, and substantiating its efficacy and functional superiority remains a challenge. Therefore, various studies, including research on the distinctive efficacy and functions of A2 milk compared with conventional A1 milk and investigations into the mechanisms underlying its effects on human health following consumption, are necessary in the future.