Dr Nick Fuller
Leading Obesity Expert at the University of Sydney and founder of Interval Weight Loss.
The latest buzz in supermarket aisles is all about ‘A2 milk’. Its arrival has sparked heated discussions, not only about whether it’s actually better for us than regular cow’s milk, but also about the fierce labelling battles between major dairy companies that have ended up in the Federal Court.
Milk is made up of different types of proteins, with caseins being the main group. Among these, beta-casein is one of the three key casein proteins, and it comes in two genetic varieties: A1 and A2. The only difference between them is a single amino acid in their structure, but that tiny variation may influence how our bodies process milk.
When milk contains the A1 protein, it produces a peptide called beta-casomorphin-7 (BCM-7). BCM-7 can affect gut function, slowing down digestion and potentially increasing inflammation in the intestinal tract in animal studies.
Most cow’s milk in Australia, New Zealand, Europe and the United States naturally contains a mix of both A1 and A2 beta-casein proteins.
The hype began when the a2 Milk Company patented a genetic test that can identify which cows produce A2 protein only. This test allows farmers to confirm whether their herds make purely A2 milk, which the company then markets under the ‘A2’ label.
In the early days, A2 milk was promoted as the ‘healthier’ alternative, with claims that A1 proteins could harm human health. However, a 2009 review by the European Food Safety Authority (EFSA) found no solid evidence supporting those claims. The EFSA concluded that A1 proteins were not linked to conditions like heart disease, type 1 diabetes or autism, the main health concerns driving the original debate.
After those findings, marketing shifted gears. Instead of focusing on disease risk, the conversation turned toward A2 milk being easier to digest, particularly for people who experience bloating or discomfort after drinking regular milk.
The first peer-reviewed human study on A2 milk involved just 41 participants, with 10 of whom reported being intolerant to regular milk. They compared how people felt after drinking milk that contained only A1 protein versus milk that contained only A2 protein.
Interestingly, participants had softer stools after consuming A1-only milk compared with A2 milk. This finding didn’t align with previous animal studies suggesting that A1 protein slows digestion and firms up stool consistency.
The researchers proposed that the softer stools might be linked to gut inflammation triggered by A1 protein, which can interfere with fluid absorption. However, no measurable difference in inflammation markers (like calprotectin levels) was found between the two groups, meaning no solid conclusions could be drawn.
A second study followed, published more recently. This time, researchers compared standard commercial milk (containing both A1 and A2 proteins) with milk containing only A2 protein. The study involved 45 participants who self-reported intolerance to cow’s milk, 23 of whom were later confirmed to be lactose-intolerant.
Since lactose is present in both A1 and A2 milk, any discomfort in lactose-intolerant individuals would be expected regardless of the milk type. Still, participants reported fewer digestive issues, such as bloating and flatulence, after consuming A2 milk than after drinking regular milk containing both proteins.
That said, interpreting the inflammatory data requires caution. While some statistically significant differences appeared between the groups, these changes weren’t necessarily meaningful from a clinical standpoint. The authors emphasised the need for larger, longer-term studies before drawing firm conclusions.
If you drink regular milk without any digestive discomfort, there’s no compelling reason to make the switch. Current evidence doesn’t suggest A2 milk offers added health benefits, especially considering it often costs nearly twice as much as standard milk.
However, for people who experience bloating or mild stomach upset after milk consumption, A2 milk might be worth trying. It could also be an option for those who are lactose-intolerant, though lactose-free milk may be a more reliable choice since it removes the sugar responsible for most of the symptoms. What’s really needed is a head-to-head study comparing lactose-free milk with A2 milk in people with confirmed lactose intolerance.
Another key takeaway: both existing human studies were small and short-term. More robust research is essential before any strong health claims can be made about A2 milk.
If you’re questioning how dairy fits into a balanced diet overall, you might find Is Dairy the New Carbs? an interesting read.
At this stage, A2 milk isn’t a miracle product; it’s just another choice on the shelf. For most people, regular milk remains perfectly fine and far more affordable. What truly matters is that milk, in whatever form, stays part of your diet. Dairy foods are one of the best sources of easily absorbed calcium, vital for strong bones and osteoporosis prevention.
Aim for around three serves of dairy each day to meet your calcium needs, whether that’s with regular, A2, or lactose-free milk.
Dr Nick Fuller is the founder of Interval Weight Loss and is a leading obesity expert at the University of Sydney with a Ph.D. in Obesity Treatment. Dr Fuller is also the author of three best-selling books and his work been published in top ranked journals in the medical field, including JAMA, Lancet and American Journal of Clinical Nutrition.