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  • Writer's pictureDr. P.K. Shrivastava


A. Introduction:

Various components of the beta-casein fraction from bovine milk were separated by preparative reversed-phase high-performance liquid chromatography (RP-HPLC). They included the genetic variants beta A1, beta A2, beta A3, and an unknown component previously denoted beta X [S. Visser et al., J. Chromatogr. 548 (1991) 361-370]. It shows that the identification and nomenclature of A1 & A2 proteins in cow’s milk was published in 1991.

1. Casein is the largest group of protein in milk, which forms about 80% of total protein.

2. Beta Casein-is the second most prevalent protein in 13 different forms.

3. Regular milk contains both A1 and A2 beta-casein, but A2 milk contains only A2 beta- casein.

4. Some studies suggest that A1 beta-casein may be harmful and that A2 beta-casein is a safer choice.

5. Thus, there is some public and scientific debate over these two types of milk.

6. A2 milk is produced and marketed by the A2 Milk Company and contains no A1 beta-casein.

B. The main difference between A1 and A2 milk proteins:

The main difference between the two being one of the 209 Amino acids that make up the Beta Casein protein; a Proline occurs at position 67 in the chain of Amino acids that make-up the A2 Beta Casein, while in A1 Beta Casein a histidine occurs at that position.

Studies have found that digestive enzymes that cut up the proteins interact with Beta casein precisely at that point, so that A1 and A2 beta-caseins are processed differently.

A seven Amino acid peptide Beta-Casomorphin- 7 (BCM-7) can be cut away from the A1 Beta Casein protein by those enzymes, but the enzyme can not cut the A2 protein at that location. So, the Beta- Casomorphin is not formed from A2 protein.

C. Beta-Casomorphin-7:

BCM-7 is an opioid peptide, released during the digestion of A1 beta-casein. That is why some people believe A1 milk to be less healthy than A2 milk. Studies have not found BCM-7 in the blood of healthy adults who drink cow’s milk, but a few tests indicate that BCM-7 may be present in infants. While BCM-7 has been extensively researched, its overall health effects remain unclear.

D. Indian Opinion:

All indigenous breed cows’ and buffaloes’ milk have A2 protein milk (ref statement of MD Amul, Shri RS Sodhi:

“A2” milk is marketing gimmick:

“Ninety per cent of India’s milk, including all buffaloes’, has A2 protein, the premium is a gimmick says Shri R.S. Sodhi, MD, Amul, while speaking at The Print OTC. He also said that buffalo milk is more nutritious than cow milk and its production & consumption have risen in India over the last few years (reports Mr Samyak Pandey on 22 January, 2021 2:12 pm IST).

He mentions that A2 milk marketing gimmick came from New Zealand as the market was saturated there so they brought this term to bring exclusivity to their product. Be assured that in India what you are drinking is A2 milk as all buffalo and indigenous cow milk is 100 per cent A2 milk,” Sodhi said in a virtual “Off the Cuff” conversation with The Print Editor-in-Chief Mr Shekhar Gupta.

“All HF (Holstein-Friesian) crossbred cows produce 50 per cent A2 milk and 50 per cent A1 milk. So, 90 per cent of milk in India is A2 milk,” he said, adding that the premium on A2 milk is just “marketing gimmick” without additional “health or nutritious benefit”.

A1 and A2 are two types of beta-casein, a sub-group of casein that is the largest protein found in milk. All cows originally produced only A2 protein. However, over time due to genetic mutation, many cows started producing both A1 and A2 proteins, with some producing A1 only.

E. Conclusion:

A few studies suggested that A1 beta-casein and the peptide BCM-7 may be linked to diabetes, heart disease, autism, and SIDS (Sudden Infant Death Syndrom). Still, results are mixed and more research is needed.

Further, it was found that consumption of milk containing A1 β-casein was associated with increased gastrointestinal inflammation, worsening of PD3 (post dairy digestive discomfort) symptoms, delayed transit, and decreased cognitive processing speed and accuracy. The elimination of A1 β-casein from diet attenuated these effects, some symptoms of lactose intolerance may stem from inflammation it triggers and these symptoms can be avoided by consuming milk containing only the A2 type of beta casein. (Ref: Trial registration:

F. References:

(1) J Chromatogr A. 1995 Sep 8;711(1):141-50. doi: 10.1016/0021-9673(95)00058-u. Identification of a new genetic variant of bovine beta-casein using reversed-phase high-performance liquid chromatography and mass spectrometric analysis, S Visser 1, C J Slangen, F M Lagerwerf, W D Van Dongen, J Haverkamp



(4) Murray Laugesen 1, Robert Elliott, N Z Med J. 2003 Jan 24;116(1168):U295. Ischaemic heart disease, Type 1 diabetes, and cow milk A1 beta-casein:

(5) B J Venn1, C M Skeaff, R Brown, J I Mann, T J Green, Atherosclerosis, 2006 Sep;188(1):175-8.doi: 10.1016/j.atherosclerosis.2005.10.020. Epub 2005 Nov 18.A comparison of the effects of A1 and A2 beta-casein protein variants on blood cholesterol concentrations in New Zealand adults.

The Article “About A1 & A2 milk confusion” is compiled by Dr PK Shrivastava, Dairy Business Consultant, Bangalore,;; +918073147467

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