I am taking courses to become an herbalist, and I’m currently studying information about milk–especially related to breastfeeding and drinking of milk after weaning. In the US, we drink a lot of milk, but much of it comes from Holstein and Friesian cows that are known to have A1 beta-casein profiles; A1 beta-casein is a genetic mutation where the 67th amino
acid in the 209 amino acid chain in the protein beta-casein changed. The change was from proline to histidine, and this change can allow for the creation of a 7 amino acid segment called beta-casomorphin-7, often abbreviated as BCM-7. This opioid does not occur in the human body naturally, so it interacts with the digestive system, organs, and even the brains of humans and is now being linked to things like Type 1 diabetes, autism, heart disease, obesity, and more.
One good thing about goat milk is that it is A2 beta-casein. A few cows, namely Jersey, Guernsey, and Brown Swiss CAN also be A2, but usually testing is done to ensure that they are not A1. Some may be 1/2 and 1/2, and then it would be up to the consumer whether or not they would want to drink that milk. Goat milk and sheep are both naturally A2, so while no milk is perfect, these could prove to be less harmful for lots of reasons. I’m including a few articles for more info.