This week’s show was suggested by Nutrition Diva listener Leslie Ghiringhelli, who wrote:
“I was recently at my local health food store and overheard a salesperson from a company that sells A2 milk touting its superiority over regular milk. She was saying that the protein that’s in regular milk (but not A2 milk) causes everything from diabetes to autism to autoimmune disease. As an RN and science-minded person, I was immediately skeptical. Could you do a show on this topic?”
I have to applaud Leslie’s skepticism. A2 milk is about twice the price of regular milk. But is it really better for us? Perhaps the more pressing question is whether there’s any truth the claim that regular milk is linked to these scary diseases.
What’s the Difference between A1 and A2 milk?
A1 and A2 are both types of casein, which is one of the major kinds of protein in milk. Proteins are made up of individual amino acids strung together into long strings. There are only a couple dozen different amino acids, but they can be combined in different sequences to form thousands of different proteins. It’s sort of like the way the twelve tones in a musical scale can be combined into an infinite number of melodies.
The only difference between the A1 and A2 milk protein is that the 67th amino acid in the chain is different. Your body digests casein (and all proteins) by snipping these long strings of amino acids into shorter segments called peptides, some of which may have biological activity. Collagen and insulin are both peptides, for example.
The slight difference in the amino acid sequence of A1 and A2 casein results in the creation of slightly different peptides when these milk proteins are digested. When we digest the A1 form of casein, it produces a peptide called BCM-7. This peptide is not produced in the digestion of A2 casein.
But so what? Does the BCM-7 peptide do any harm?