Beta casein is a 229 chain of amino acids with a proline at number 67 – at least the proline is there in “old- fashioned” cows. These cows with proline at number 67 are called A2 cows and are the older breeds of cows (e.g. Jerseys, Asian and African cows). Some five thousand years ago, a mutation occurred in this proline amino acid, converting it to histidine. Cows that have this mutated beta casein are called A1 cows, and include breeds like Holstein.
The side chain that comes off this amino acid is called BCM 7. BCM 7 is a small protein (called a peptide) that is a very powerful opiate and has some undesirable effects on animals and humans. What’s important here is that proline has a strong bond to BCM 7 which helps keep it from getting into the milk, so that essentially no BCM 7 is found in the urine, blood or GI tract of old-fashioned A2 cows. On the other hand, histidine, the mutated protein, only weakly holds on to BCM 7, so it is liberated in the GI tract of animals and humans who drink A1 cow milk, and it is found in significant quantity in the blood and urine of these animals.
This opiate BCM 7 has been shown in the research outlined in the book to cause neurological impairment in animals and people exposed to it, especially autistic and schizophrenic changes. BCM 7 interferes with the immune response, and injecting BCM 7 in animal models has been shown to provoke Type 1 diabetes.