Here is a little history tidbit for you'll.
When the Vikings first made it to the Americas they encountered the local Indians. The Vikings tried to make friendly contact and invited the Indians to share some of their food. The next day the Indians attacked the Vikings because they thought that they had been poisoned by them. One of the foods that was shared was milk. The Indians are from Asia and are lactose intolerant, the Vikings are not.
This is a case of a persons genetics determining what food is good for them and what is not. With that thought in mind I recently changed from whey protein, a milk product, to egg white for my protein source. My body feels a lot better with the egg whites then with the whey. I'm a Celt and Celtic oral history has the Celts coming from Asia. Maybe that is why I'm lactose intolerant.