Milk is a beverage valued for its nutritional value and health benefits. Milk is often a basic part of our diet since childhood. Contains essential nutrients like calcium, protein and vitamins. However, recent advances in scientific research are shedding light on different types of milk and how they affect human health. In particular, the discovery of A1 and A2 milks and the interest they have generated among consumers raises intriguing questions about how these variations may impact our health.
What is A1 and A2 milk?
Milk contains caseins, whey proteins, fat globule membrane proteins, enzymes, minor proteins and nitrogenous compounds. Beta-casein, a major component of casein, contains up to 35% of total casein. There are multiple genetic variants of beta-casein, including A1 and A2, of which A1 and A2 are the most commonly found variants in dairy cows. This leads to milk being classified as either A1 or A2.
Biochemical composition of A1 and A2 beta-casein
Beta-casein is a protein consisting of 209 amino acids. And the A1 variant differs from A2 by one amino acid. A1 beta-casein contains a histidine at position 67. This results in the release of a seven-amino acid peptide called BCM-7 (beta casomorphin-7) through enzymatic cleavage. The proline at position 67 in A2 beta-casein prevents BCM-7 from being released.
Cow breeds and type of milk
Actually, all milk was A2. But a genetic mutation caused A1 milk to appear. Different breeds have different proportions of A1 and A2 milk. For example, the Holstein Friesian has a lower proportion of A2 milk than other breeds. Brown Swiss, Fleckweh and Guernsey breeds have a high proportion of A2 milk. A1 milk is absent or very rare in unique Asian and African herds. And alternative sources of A2 milk include sheep, buffalo, and goats, as well as milk from indigenous Asian and African cattle breeds. Efforts are underway in many countries to develop herds that produce only A2 milk.
What diseases can be caused by drinking cow’s milk with A1 or A2?
The debate surrounding A1 and A2 milks revolves around the digestion of β-casein, a protein found in milk. During the digestion process, bioactive peptides can be released. One such peptide, called BCM-7, consists of seven amino acids. And it is said to be released more frequently during the digestion of A1 milk compared to A2 milk. BCM-7 has effects similar to opioids. Studies have shown that it affects 25% of the human population. Some research groups hypothesize a potential link between BCM-7 and diseases such as type 1 diabetes, heart disease, infant mortality, autism, and gastrointestinal problems. Although BCM-7 affects the digestive system, the extent to which BCM-7 is absorbed into the bloodstream remains under research. Studies show that BCM-7 is not normally found in the blood of healthy adults who consume cow’s milk. But there are signs of their presence in infants. In addition, studies suggest that breastfeeding is superior to artificial feeding in terms of infant nutrition in the first year of life. and supports the hypothesis that deletion of bovine casomorphin may be a risk factor for psychomotor developmental delay and other diseases such as autism. Therefore, to promote healthy growth and development, the World Health Organization (WHO) recommends exclusive breastfeeding for the first six months and continuing up to two years.
The question of whether A2 milk is healthier than A1 milk has been a topic of debate among farmers, breeders, societies and the media for years. The main difference between these two milk variants is a single amino acid difference in beta casein. At some point in the evolutionary process, a mutation occurred and became A1 milk. Whereas A2 milk is considered a more natural form. A1 milk and the BCM-7 peptide have been suggested to be associated with heart disease, diabetes, autism, sudden infant death syndrome, and inflammation of the digestive system. However, findings on this topic are inconclusive and further research is needed.
English summary: Milk proteins and human health
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2023-06-03 09:46:51
