Cows milk can prevent your body from absorbing iron. Cow’s milk, and other foods high in calcium, are the only known substance to inhibit absorption of both non-heme and heme iron.
One cup of cow’s milk contains approximately 300 mg of calcium. Calcium has little or no effect on iron absorption when less than 50 mg is ingested.
So, if you enjoy cow’s milk try to have it away form meals. (And organic of course, preferably raw.)