A1 vs A2 milk and its impact on human health


Milk is an integral part of a balanced diet regime for all age groups like infants, children, adults or older. Healthy milk comes from a healthy cow, and its quality and type depend on its origin. Although there is a variety of options available these days, as per milk specification and classification. In this article, we will discuss the facts and reasoning behind the A1 and A2 milk classifications.

In term of origin, A1 and A2 type of milk is obtained from cow, but they considerably in terms of its chemical composition, and it is the type of protein that is the most deciding factor for their classification. Ion exchange chromatography, the method can be used to distinguish between the two types of milk because of the difference in the protein structure. Casein makes about 80% of the total milk protein, among the various type of casein protein Beta-casein is second most abundant protein and exists in 13 various forms, among these various forms A1 beta-casein & A2 beta-casein are the most common form of protein. In initial studies it has been investigated that indigenous Indian breed of cows and buffalo (Gir, Sahiwal,), has A2 allele and produce A2 milk, whereas A1 allele is more frequent in exotic breeds of cattle (Holstein, Friesian, Ayrshire), and they produce A1 milk. Recently, A2 milk is marketed as healthier and safer option and has been claimed to have more health benefits as compared to A1 milk.

Adverse health effects from A1 milk

A1 and A2 beta-casein protein differ in their chemical composition at 67th amino acid, A1 beta-casein contain histidine amino acid and A2 beta-casein protein contains proline amino acid. Histidine breakdown release histamine, which can potentially lead to various allergic reaction in kids like allergic asthma, dermatitis, cough, and allergic rhinitis. There is one metabolite or an opioid peptide named Beta-casomorphin-7 (BCM-7)   which is released from the metabolism of A1 beta-casein protein, which has been claimed to have adverse health effects on the body and may cause digestive issues, autism, infant death, cardiovascular problem and type 1 diabetes. . Because of these health effects, the A2 milk has been claimed to be better than A1 milk.

Type 1 diabetes

Type 1 diabetes is caused by a lack of insulin in children and it has been observed that children consuming A1 milk are more prone to type 1 diabetes, however, it has not been proved so far that A1 beta-casein protein cause type 1 diabetes but children consuming more of A1 milk are at higher risk

Heart disease 

It has been observed that consumption of A1 milk increases the risk of cardiovascular disease. Studies on rabbit has shown that accumulation of fat in blood vessel was more on the consumption of A1 beta-casein than A2 beta casein. Accumulation of fat may block the heart vessels or clog the arteries i.e. increasing the risk of cardiovascular disease.

Sudden infant death syndrome

Sudden unexpected death of Infants under twelve months without an underline cause is termed as sudden infant death syndrome. Some investigation has shown that BCM-7 a metabolite of A1 beta casein is associated with the cases of SIDS. Increased level of BCM 7 was also measured in blood of infants died because of sleep apnea due to stopped breathing. These studies indicate that few infants are more sensitive to the effects of A1 beta casein found in cow milk.


Autism a physiological condition described by reduced social interaction and repetitive behaviour in children’s. According to one study Infants who were consuming cow’s milk were found to have high level of BCM 7 metabolite as compared to breastfed infants. Infants with high level of BCM 7 were found to have impaired coordination, and learning ability.

 Digestive discomfort

Lactose intolerance is an identified cause of digestive discomfort like diarrhoea bloating and gas. Scientists have investigated that apart from lactose intolerance some proteins may be the cause of digestive disturbance and milk intolerance. A study finding indicates that individuals consuming A1 milk were having more digestive discomfort like softer stools or diarrhoea as compared to those who were consuming A2 milk. Researchers have investigated that A1 beta-casein causes inflammatory changes in the intestine


The maximum milk available and consumed in India and word wide is A1 milk. The reason behind it is that exotic breed of cattle like Holstein Frisian are mostly reared by the farmers because of its high production potential as compared to native Indian breeds which produce A1 milk. Indian native breed of cattle produce less quantity of milk but A2 milk. Therefore,A1/A2 milk is recently quite fascinating concept and crucial from public health point of view and a detailed investigation is needed on the BCM 7 interaction with various organ system in human body, So that the various health concern associated with A1 beta casein protein can be ruled out. Detailed data collection regarding problem related with A1/A2 beta-casein milk consumption is required.


Dr. Dinesh Kumar *

* Veterinary Surgeon (Government of Haryana)

Dr. Rajender Kumar **

* ICAR-NDRI, Karnal, Haryana

Chandni Dularia***

***Research Scholar, ICAR-NDRI, Karnal, Haryana

Share your comments

FactCheck in Agriculture Project

Subscribe to our Newsletter. You choose the topics of your interest and we'll send you handpicked news and latest updates based on your choice.

Subscribe Newsletters