Be sure to read BOTH links that are listed by another poster.
I am now drinking raw milk, cream and having raw butter. Raw milk has lactase in it which takes care of the lactose. I am going to experiment with this for the next few months and see where it takes me.
There was an old doc in the '20s who used milk as a total cure for many, many ailments -- in the original Mayo Clinic -- much the same as the OJ Fast in that it was the only food allowed. Cows that graze on organic pastures and are hormone-free and antibiotic-free would be the only ones from whom I want to have my milk. It is the same milk that I used to have as a kid, with the cream rising to the top -- yummy!
When milk is heated for pasturization, there are a lot of dead bugs in it; when it is heated to 245 for ultrapasturization, there are even more dead bugs in it. That draws more microbes to the body to clean out the junk. Constipation is often an issue with pasturization, not for me with raw milk.
A touchy subject, for sure and each researcher presents their own agenda. So, do the reading and make your own decision. Much depends on your own reaction to milk. A varied diet is the best.