What's the latest on milk containing only the A2 protein and gut health?

Last updated 31/01/2025

There are different types of proteins in milk, including A1 and A2. Regular milk contains both A1 and A2 proteins, but there are also cows that produce milk with only the A2 protein.[1] 

Several studies, both in Australia and internationally, have looked at the differences between A1 and A2 proteins and how they affect gut health. Some of these studies found that people who have trouble digesting lactose or are intolerant to lactose experienced improvements in digestive symptoms like stomach discomfort when they consumed milk with only the A2 protein.[2] 

While more research is needed with larger groups of people and over a longer period of time, these findings are promising for those who experience discomfort after drinking regular milk.

If you experience digestive discomfort, there are some things you can try. You can spread out your milk consumption throughout the day, have milk with a meal,[3] or try other dairy products like yogurt and hard cheeses, which have lower levels of lactose.[4] For some people, milk that contains only the A2 protein may be a better choice. 

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References

[1] Givens I, Aikman P, Gibson T et al. Proportions of A1, A2, B and C β-casein protein variants in retail milk in the UK. Food Chem. 2012; 139:549-552 

[2] Ramakrishnan M et al. Milk Containing A2 β-Casein ONLY, as a Single Meal, Causes Fewer Symptoms of Lactose Intolerance than Milk Containing A1 and A2 β-Caseins in Subjects with Lactose Maldigestion and Intolerance: A Randomized, Double-Blind, Crossover Trial. Nutrients. 2020 Dec 17;12(12):3855. 

[3] O’Connor L, Eaton T, Savaiano D. Improving Milk Intake in Milk-Averse Lactose Digesters and Maldigesters. JNEB. 2015;47(4):325-330.e1. 

[4] Szilagyi A, Ishayek I. Lactose intolerance, dairy avoidance, and treatment options. Nutrients. 2018;10:1994