A2 Milk: Breakthrough of Science or Marketing?

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


August 10, 2018

In This Article

What Are the Clinical Implications of Drinking A1 Milk?

For years, the dominant argument for A1's risks to humans appears to have been built primarily from animal study data and causal associations showing higher rates of chronic disease in countries primarily reliant on A1 milk.[1] Researchers have used both to establish a link between A1 milk consumption and an elevated risk for gastrointestinal impairment[4]; type 1 diabetes[5]; coronary heart disease[1]; and, perhaps further afield, autism and schizophrenia.[6]

Many of these studies have been knocked for being funded by the A2 Milk Company, the main producer of this product. However, an independent 2014 study that noted the existing link between A1 milk and human health was "scanty" nonetheless reported that inflammatory markers significantly spiked in mice consuming A1 milk.[7]

Some have hypothesized that lactose-intolerant individuals may be negatively responding, at least in part, to the presence of A1. This theory was first supported by relatively small clinical studies linking A1 milk to softer stools, worsening gastrointestinal symptoms, decreased cognitive function, and markers of inflammation in self-reported lactose-intolerant participants.[3,8,9] These findings were reconfirmed in a 2017 randomized, crossover trial of 600 Chinese adults in which participants reported moderate though significant improvements in gastrointestinal symptoms, such as abdominal pain and bloating, up to 12 hours after consuming A2 milk, in comparison with A1.[10]

Among critics, these results have not moved the needle considerably from where it was over a decade ago, when a 2006 critical review[1] found "no convincing or even probable evidence" of A1's harmful effects in humans. The author went so far as to attribute any such theories to the profit motive rather than scientific evidence, writing, "The A1/A2 milk hypothesis was ingenious. If the scientific evidence had worked out it would have required huge adjustments in the world's dairy industries."

In a turnaround befitting the tit-for-tat nature of this debate, the author was later found to have been a consultant for a New Zealand dairy company, who presumably had some interest in maintaining the dominance of so-called "conventional milk."[11]


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