A2 Milk: Breakthrough of Science or Marketing?

John Watson; Reviewed by: Anya Romanowski, MS, RD


August 10, 2018

In This Article

Shoppers in the United States are about to encounter something new in the dairy aisle. A2 milk, a substitute for conventional milk successfully launched in New Zealand two decades ago, is hoping to win over American consumers with an expansive pitch of health claims.

Advocates of A2 milk don't just see it as the next almond or soy milk. Instead, they're positioning it as an alternative to one of Western society's foundational food sources, which they believe has had an outsized role in causing maladies ranging from simple indigestion to cardiovascular disease, autism, and schizophrenia.

These claims have been met in equal measure by critics who have identified A2 milk as something more conventional—a hype-driven product building a profitable foundation on limited science.[1]

Medscape reviewed the data to get a clearer picture of this often murky debate.

What Is A2 Milk, and Why Is It Important?

Beta-casein is the major source of protein in milk. Around 8000 years ago, however, the characteristics of beta-casein began to change, with a lone mutation occurring at one of the 209 amino acids in its genetic profile. Breeding practices and random acts of history made A1-producing cows the norm in Europe and, subsequently, the majority of the Western world.[1,2]

The difference is potentially important because digesting A1, but not A2, beta-casein can cause the release of the opioid beta-casomorphin (BCM-7) in the small intestine. BCM-7 has been linked to impaired gastrointestinal function, such as decreased intestinal contractions and suppressed lymphocyte proliferation.[2,3]


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