What is the difference between casein A1 and casein A2?

A question I often get asked by my patients or at my public talks is the whether it is okay to consume casein A2 dairy or what are my thoughts on A1 vs A2 dairy.

Most of the cow’s dairy on the North American market contains both A1 and A2 casein.

In a study that compared consumption of milk containing A1 β-casein versus milk containing A2 β-casein. The A1 β-casein was associated with increased gastrointestinal inflammation, worsening of digestive discomfort, delayed transit time and decreased cognitive processing. While those that consumed A2 β-casein dairy did not experience any of these symptoms.

A1 β-casein gets broken down into beta-casomorphin-7 (BCM-7), an opioid peptide which may have addictive properties and also causes inflammation while A2 does not get broken down into this compound.

Therefore, so far, in terms of the research A2 dairy does seem to be a healthier option.