At the same time, many other doctors and researchers are now beginning to feel that undiagnosed milk allergies may be the underlying problem behind the link between milk and asthma. As Dr. Robert M. Giller writes in Natural Prescriptions, eliminating dairy products from the diets of many adult and child asthma patients helps "not because dairy products stimulate mucus production but because they're very common causes of allergy, upper-respiratory allergies and asthma (which may be an allergy in itself)."