Let's look at the realities of cows' milk and see why it is food fit only for a calf. Nature made this for turning a 45 pound calf into a 300 pound cow in one year. Its content of sodium, fat and phosphorus is much higher than human breast milk, while it is lower in potassium. The protein in cows' milk is mostly Casein while the predominant protein in human milk is Lactalbumin, which is far more easily digested by babies. Nature designed the milk of each animal species specifically to meet the nutritional needs for the young of that species.
People are the only animal that drinks the milk of the mother of another species.
Most animals stop drinking milk altogether after weaning. It is not surprising that problems ensue from this inherently unnatural act. When milk and milk products are consumed, fragments of bovine protein can cross the surface of the membranes in the throat, tonsils, adenoids and other gateways into the immune system. A common reaction is an outpouring of mucus from the nasal and throat membranes. Other body membranes, i.e., the lining of the lungs and joints, can react to dairy protein and become swollen, contributing to asthma and rheumatoid arthritis.