Written By: N. Lothungbeni Humtsoe | Published : December 17, 2025 9:09 AM IST
A1 Vs A2 Milk: Milk is a nutrition-rich fluid that female moms produce to feed their young ones. This superfood is loaded with essential nutrients and protein that is known for improving bone health and weight loss. Milk is also a good source of vitamin A, magnesium, zinc, and thaimine. Additionally, it also provides protein and fatty acids that are associated with several health benefits, including diabetes and heart disease. A1 and A2 are both cow milk, but they differ in beta-casein structure which affects our digestive system.
According to a previous study, casein is the largest group of proteins in milk which makes up about 80% of the total protein content. The National Institute of Health (NIH) explains, "More than 95% of the cow milk proteins are constituted by caseins and whey proteins. Among the caseins, beta casein is the second most abundant protein and has excellent nutritional balance of amino acids."
A study published in the Journal of Food Engineering and Technology states that A1 beta-casein and A2 beta-casein are the most common forms of milk among the thirteen beta-caseins found in cow's milk. It explains " -casein is an important part of the caseins, which makes up about 37% of the total caseins. Within -casein, there are a number of variants which are genetically determined. However, there are thirteen genetic variants of -casein found in cow's milk."
A1 beta-casein is a type of milk that comes from Holstein, Friesian, Ayrshire and British Shorthorn breeds of cows that originate from Norton European. Whereas, A2 beta-casein is a type of milk that is produced by Jersey, Guernsey, Charolais and Limousine breeds of cows that originate from the Channel Island and Southern France.
According to Healthline, A1 beta-casein may contribute to digestive symptoms, like gas, bloating and diarrhoea in some people. The reason behind this health issue is due to lactose intolerance, which is the inability to digest milk sugar. The amount of lactose in A1 and A2 milk is the same, but many people report that A2 milk causes less bloating when compared to A1 milk. A previous study that examined 41 people found that A1 milk causes softer stools than A2 milk in some individuals. Additionally, a Chinese study also found that A2 milk causes less digestive discomfort after meals.
There is still less evidence that claims either A1 or A2 milk is better for health. However, A1 milk was previously associated with inflammation, Type-1-diabetes, heart disease, autism, gastrointestinal discomfort and other diseases in the consumer. This is the reason why people have a growing interest in A2 milk which was previously reported for its positive impact on health.
"In contrast to the A2 milk, digestion of A1 milk releases beta-casomorphin 7... which is thought to be responsible for potential adverse outcomes in humans, such as the increased risk of diabetes. In contrast, the consumption of milk containing exclusively the A2 beta-casein variant (A2 milk) has been promoted as being associated with positive health effects in humans, including reduced gastrointestinal symptoms," the NIH concludes.
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