Those sickened by US milk may not be lactose intolerant—in fact, if they were to head abroad, one in four might find the stuff easier to drink. That's because of a protein known as A1 that's typically predominant in the milk of Holstein cows, which are widespread in the US, explains Mother Jones. In Asia and Africa, you'll often find milk that instead has more A2 protein; it's also predominant in Jersey and Guernsey cows, not to mention human and goat milk. "More than 100 studies suggest links between the A1 protein and a whole range of health conditions," says a New Zealand professor.
Those conditions include heart disease, autism, and diabetes. Drinking A1 releases a chemical known as beta-casomorphin7, which appears to exist in higher amounts in the blood of people with autism and schizophrenia, for instance. Milk with more A2 is hard to find in the US right now, though A2 Holsteins do exist, and with money and time, the US dairy industry could make a transition. Meanwhile, a New Zealand company is preparing to send A2 milk our way this year, the New Zealand Herald reports. "We've already been talking with farmers," says the head of A2 Corporation, and "we're starting to engage with (US) retailers." (As for lactose intolerance, raw milk may hurt drinkers more than it helps.)