a2 has been around in australia for ages (started in new zealand afaik), and from personal anecdote, i can say that it works. i could drink cows milk (and did a couple of times per day in flat whites) but by the end of the day, it made me feel a little off and i frequently had a “enough milk for today” moment. after starting on a2 i get none of that, and what’s more it makes it easier to drink regular milk for a few days after a week of only a2

nothing scientific, but i’m going to continue paying a bit more for my milk :p