Milk tends to be loaded with hormones, which can cause a lot of problems.
And milk is the leading cause of osteoporosis. The protein in milk blocks calcium absorption, but not phosphorus. This leads to a release of parathyroid hormone, which breaks the bones down to release calcium in to the blood. They try to compensate for this problem with the addition of vitamin D. But they add the inactive vitamin D2, because it is the cheapest. But this also means it is not going to do much good.
The proteins and sugars in milk can also generate acids that may affect bone strength.
These facts can help explain why the US and Finland, who are the highest milk consumers in the world also have the highest osteoporosis rates.
Milk is also considered one of the primary causes of heart disease. The problem is thought to be from the enzyme xanthine oxidase, which can damage the arterial linings.