Abstract:
Advances in molecular biology and genetics have made it possible to evaluate many ingredients commonly used in human nutrition at the molecular level and to examine their potential benefits or harms in terms of health. In this context, cow's milk, which is one of the essential protein sources in the human diet, has been the subject of many scientific studies. In recent years, many researchers from different countries have focused on highly polymorphic bovine β-casein variants. Among these, the most famous are the A1 and A2 variants in the bovine β-casein gene. These variants differ by a single-nucleotide polymorphism (SNP) at the 67th amino acid position. The mutation in the gene coding for β-casein [g.8101C >A (p.His67Pro)] has been designated as the alteration from CCT on the A1 allele to CAT on the A2 allele. This is a missense mutation that leads to the production of mutant β-casein by changing its proline amino acid to histidine. This change results in altered digestion patterns and the release of beta casomorphin-7 (BCM-7) due to A1 variant-based milk. This substance shows opioid character and has been directly or indirectly associated with many diseases. While A2 milk is considered healthy milk in many countries; traditional milk containing A1 is considered unhealthy. In fact, it is challenging to claim that there is enough scientific evidence to come to this conclusion. Nevertheless, intensive selection has been performed to obtain A2A2 homozygous herds in dairy cattle around the world, and rapid progress is achieved by selecting both cows and bulls for A2A2. It is important to note that A2 milk production has created a huge market considering both farm and market dynamics. Therefore, A2 milk is a multidisciplinary subject that includes both genetics and nutrition. The aim of this presentation is to convey the current situation about A2 milk production and to make a molecular-level evaluation of the subject. At the same time, scientific papers with different results published in recent years will be discussed.
