A1 beta-casein, type 1 diabetes and links to other modern illnesses

The role of milk and milk proteins in relation to human health remains controversial. However, there is a large body of evidence, reviewed in this paper, specifically linking A1 beta-casein to a range of illnesses. A1 beta–casein is produced only by cattle of European origin. The proportion of European cattle producing A1 beta-casein varies by breed and country. High levels are found in many parts of northern Europe and also other parts of the world where particular breeds of European origin predominate. Cattle that produce A2 and not A1 beta-casein are known as A2 cattle. A2 beta-casein was the original variant. A1 beta-casein releases bovine beta-casomorphin7 (BCM7) on digestion. The amount and stability of BCM7 that is cleaved from A1 beta-casein is linked to the presence and levels of various enzymes, in particular dipeptidyl peptidase 4. BCM7 is a strong opioid. There are seven strands to the evidence linking A1 beta-casein and BCM7 to Type 1 diabetes. These include particularly strong correlations amongst developed countries between A1 beta-casein intake and Type 1 diabetes incidence (r²=0.84, p<0.00001). Supporting evidence comes from biochemistry (structure of A1 beta-casein and cleavage of BCM7), pharmacology (opioid characteristics and binding affinities of BCM7), animal trials (NOD mice and BB rats), immunology (people with Type 1 diabetes have enhanced levels of antibodies to beta-casein and in particular A1 beta-casein), and human studies (high milk intake in children linked to high incidence of diabetes). A plausible auto immune mechanism relates to the homology between an amino acid sequence in both BCM7 and the GLUT2 glucose transporting molecule produced within the pancreas. Countries with high levels of Type 1 diabetes are the same countries that have high levels of heart disease (r²=.74, p<0.001). This strongly suggests linked factors of causation. A1 beta casein intake also correlates strongly with heart disease (r² up to 0.86, p