Intolerant to Dairy? You Might Tolerate A2 Milk

Intolerant to Dairy? You Might Tolerate A2 Milk

I remember a time when there was only one milk to choose from in the grocery store, regular cow’s milk. Yes, there were different percentages of fat, and maybe some lactose-free options, but that was it. Now, there is an abundance of milk and milk alternatives to choose from, and it can be hard to keep up with all the new products, even for dietitians! The most recent addition to the dairy shelf that you may have noticed is A2 milk, a special type of cow’s milk, which has been shown to be better tolerated when compared to regular cow’s milk. Relatively new research is showing that it might not be the lactose in milk that is triggering gut symptoms for some people, and that those with suspected lactose intolerance might be able to tolerate A2 milk very well. Keep reading to find out more details about A2 milk, how it differs from regular cow’s milk, and why you may be able to tolerate it, even if you are lactose intolerant.

Lactose Intolerance

Lactose intolerance is commonly blamed for triggering digestive issues after drinking milk, and for many people it does. Lactose is the sugar naturally found in milk which can trigger symptoms in people with digestive disorders or for those who have a genetic predisposition to lactose intolerance. Lactose is also part of the FODMAP group of sugars that can trigger gut symptoms in some people with IBS. Symptoms of lactose intolerance typically occur within 15 minutes to one hour after consuming high lactose foods, such as milk or ice cream, and include feelings of bloating, cramping, and/or loose bowel movements. Lower sources of lactose, such as yogurt, aged cheddar, and butter, are usually well tolerated by people with lactose intolerance, and they don’t have to be avoided. Portion size is also key, and a few tablespoons of milk added to coffee is unlikely to trigger symptoms in someone with lactose intolerance.

Lactose-free milk is made by adding the enzyme lactase to it, which breaks down the lactose molecules, so that you are essentially drinking pre-digested lactose. Lactose-free milk tastes a little bit sweeter than regular milk, because the lactose sugar has been broken down. Interestingly, for people who have constipation and who are lactose-intolerant, having a glass of regular lactose-containing milk can help resolve the constipation. Although this is not commonly used in the clinical setting, it often works and can be a strategic tool to consider for people who experience chronic constipation.

Protein in Cow’s Milk

Cow’s milk contains around 20% whey protein and 80% casein protein. Beta-casein (B-casein) is found abundantly in cow’s milk and can be further classified into two types: A1 B-casein and A2 B-casein. Cow’s milk originally contained only A2 B-casein protein, until about 5,000-10,000 years ago, when genetic mutations in cows in Northern Europe led to the appearance of A1 B-casein, so now cow’s milk contains a mix of both A1 and A2 B-casein proteins, whereas previously it did not.1 A1 protein seems to trigger gut symptoms and inflammation, whereas A2 protein does not. You can now find A2 milk in the grocery store, compared to regular cow’s milk which contains a mix of A1 and A2 B-casein milk proteins. There is no isolated A1 milk commercially available, nor do I suspect there will be with the continued research in this area.

A1 vs A2 Milk

A1 B-casein protein triggers gut symptoms and mimics symptoms of lactose intolerance. When A1 B-casein is broken down and digested in humans, it results in the production of BCM-7 (betacaseomorphin-7), a peptide which can trigger gut symptoms and inflammation in the gut. BCM-7 is pro-inflammatory, and it has been shown to trigger inflammation through various pathways.2 A 2016 double-blinded randomized control trial crossover study published in Nutrition Journal studied the effects of A2 milk vs A1-containing milk on gut symptoms and cognition in 45 people with self-reported lactose intolerance in China.3 They asked the participants to drink two cups of milk per day (A1 or A2 milk) for 14 days and, after a washout period, they drank two cups per day, of whichever milk they had not consumed the first time, for another 14 days, and monitored symptoms. It is important to note here that both milks contained the same amount of lactose, and the only difference were the A2/A1 milk proteins.

The researchers used a smart pill to assess the effects on the gut as well as blood markers for inflammation. They monitored for symptoms of post-dairy digestive discomfort: bloating, abdominal pain, flatulence, a heavy stomach, and borborygmi, the noises and/or gurgling sounds that your stomach and intestines make. The researchers discovered that A2 milk did not trigger negative side effects, whereas A1 milk did. A1 milk increased gut symptoms, gastrointestinal inflammation, delayed transit time, decreased cognitive processing speed and accuracy (believed to be secondary to inflammation), and decreased fecal short-chain fatty acid (SCFA) production. SCFAs are beneficial by-products of fermentation that are naturally produced in your colon (large intestine). They have been shown to have anti-inflammatory effects and they help keep the cells lining your colon healthy and functioning well. A2 milk did not reduce fecal SCFA, which is great. Overall, this was a small study, but it is just one of many studies that have been published on this subject, and this information is worth considering when making your own personal food choices.

A2 Milk

A2 milk is an option for people who miss drinking regular milk and have experienced digestive issues after drinking regular milk in the past. Those with suspected or self-reported lactose intolerance may tolerate A2 milk without any problems. It is now commercially available in most grocery stores in Canada. It is available in different fat percentages, the same as regular cow’s milk. The only downside to purchasing A2 milk compared to regular milk is that it is more expensive, being a relatively new product, but it may be worth it for you. I do hope that the prices come down soon as more people start to discover it.


The novel A2 milk is now commercially available in Canada, and it has been shown to be well tolerated by those who have experienced digestive distress after consuming dairy products in the past. A1-contaning milk triggers inflammation and digestive issues that mimic symptoms of lactose intolerance and should be avoided in those with digestive disorders. Although A2 milk is more expensive than regular milk, it may be a good strategy for people who really miss drinking regular milk, and for those who want to benefit from the addition of more protein, calcium, and vitamin D in their diet. If you have suspected or self-reported lactose intolerance, it is possible that the A1 B-casein protein in milk is triggering symptoms instead of lactose, and you may want to consider trying A2 milk instead.

First published in the Inside Tract® newsletter issue 220 – 2021
By Anne-Marie Stelluti, RD
Anne-Marie Stelluti is a registered dietitian and business owner of Modern Gut Health, a private practice with special focus in digestive health nutrition.
Photo: © Tanya Sid |
1. Bentivoglio D et al. Is there a promising market for A2 Milk? Analysis of Italian Consumer Preferences. Sustainability. 2020;12: 6763.
2. Trivedi MS et al. Food-derived opioid peptides inhibit cysteine uptake with redox and epigenetic consequences. J Nutr Biochem. 2014;25:1011-8.
3. Jianqin S et al. Effects of milk containing only A2 beta casein versus milk containing both A1 and A2 beta casein proteins on gastrointestinal physiology, symptoms of discomfort, and cognitive behavior of people with self-reported intolerance to traditional cow’s milk. Nutrition Journal. 2016; 15:35.

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