A word of caution: Allergic reactions
The reason for allergies to food is proteins in them and so since milk is a good source of protein it also causes some food allergies.
Besides, the milk sugar, lactose is harmful for people with lactose intolerance. Common symptoms associated with an allergic reaction to food include: chronic gastrointestinal disturbances, frequent infections, e.g. ear infections, bladder infections, bed-wetting, asthma, sinusitis, eczema, skin rash, acne, hives, bursitis, joint pain, fatigue, headache, migraine, hyperactivity, depression, insomnia.
Cow's milk is one of the foods most commonly associated with allergic reactions. Other foods commonly associated with allergic reactions include: wheat, soy, shrimp, oranges, eggs, chicken, strawberries, tomato, spinach, peanuts, pork, corn and beef.