"So what's the harm in homogenization? Cow's milk contains an enzyme of large molecular size called xanthine oxidase (XO). XO is normally attached to the fat globules in milk. However, when these fat globules are in their natural large-sized state prior to homogenization, they are not easily absorbed by the gut wall. After homogenization, the milk fat is easily absorbed, and the attached XO gains much greater access to the bloodstream. Some researchers [such as Dr. Kurt Oster and Dr. Donald Ross] have asserted that XO, after getting into the bloodstream, directly promotes hardening of the arteries by replacing a substance called plasmalogen that is normally found there. The research supporting this connection between XO and hardening of the arteries is not clear-cut, but whether or not there is a definite cause-and-effect relationship between the two should not be a critical factor in deciding whether you should drink milk. This possible XO link to heart disease is but one more potential connection of milk to disease and premature death."