A2 milk consumption and its health benefits: an update

Abstract

Milk is a widely consumed nutrient-rich food containing protein variants such as casein A2 and A1. A1 differs from A2 in an amino acid at position 67 (Pro67 to His67). The breakdown of β-casein yields β-casomorphins (BCM), among which BCM-7 is extensively studied for its effects on the human body. Animal studies have shown that A1 β-casein milk increases digestive transit time and enhances myeloperoxidase activity. Individuals with lactose intolerance prefer A2 milk to conventional A1 milk, as BCM-7 in A1 milk can lead to inflammation and discomfort in sensitive individuals. A2 milk, which contains A2 β-casein, is believed to be more easily digestible than A1 β-casein. Its popularity has grown owing to reports linking A1 casein to diseases such as type 1 diabetes, heart disease, and autism. A2 milk has gained popularity as an alternative to A1 milk, primarily because of its potential benefits for individuals with certain diseases. This review aims to provide an updated understanding of A2 milk consumption and its health benefits. This review aims to provide an updated understanding of A2 milk consumption and its health benefits.

Keywords: A2 milk; Health benefit; Inflammation; Lactose intolerance; β-casomorphin-7.

Fig. 1

Protein composition of bovine milk. Sky blue and yellowish-green areas indicate caseins and whey proteins, respectively. The numbers show the percentage of each protein in the milk based on protein content of 100%. The data are extracted from Franzoi et al. (2019)

Fig. 2

Different casein forms and their genetic variants and genes

Fig. 3

Difference in the amino acid sequences of A1 and A2 variants and formation of β-casomorphin-7