Casein and whey are the two main types of protein in milk. Casein makes up around 80% of the protein in cows’ milk, while around 20% is whey. Beta-casein is one of the major casein proteins, comprising around 30% of the total protein in cows’ milk (Figure: 1). Other proteins present at low levels in milk include antibodies and iron carrying proteins.
Beta-casein is a 209 amino acid protein that comes in 2 main forms: A2 and A1 beta-casein. These differ from each other by a single amino acid (Figure: 2). Small differences in the amino acid composition of proteins can result in various protein forms exhibiting different properties following digestion.
The beta-casein type of protein produced in cows’ milk will depend on the genes inherited by the cow. As one gene for beta-casein production is inherited from each parent, each cow carries 2 copies of the beta-casein gene.
Of these 2 beta-casein genes, the following combinations are possible;
A simple DNA test which examines a cows’ beta-casein genes allows easy identification of which beta-casein form it carries.
The material contained within this website’s Health Professionals’ pages is intended solely for presentation to Health Care Professionals (HCPs). The purpose of the materials contained within these pages is threefold:
1) to highlight the extensive body of literature in the A1 beta-casein and beta-casomorphin related areas;
2) to review some of the relevant literature; and
3) to stimulate interest amongst HCPs to obtain and review some of the relevant literature directly.
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