Drug treatment for depression usually focuses on 'normalising' serotonin. Manipulation of neurotransmitters, however, is poorly understood, difficult to regulate and unlikely to have long-lasting effects.
Recently, nutritionists have turned their attention to morphine-like substances derived from the incomplete digestion of proteins in cereal grains and dairy products as a possible cause of depression. These substances, called 'exorphins', were first recognised in the late 1970s (J Biol Chem, 1979; 254: 2446-9). Further research has identified five distinct exorphins in the pepsin digests of gluten (Life Sci, 1995; 57: 729-34) and eight other exorphins in the pepsin digests of milk (N Engl J Med, 1982; 307: 895).
Exorphins act as depressants and are believed to be responsible for the reported psychiatric symptoms, including 'brain fog', that often accompany immune reactions to these foods.
Depression is a common symptom of coeliac disease, a disorder where the inner lining of the small intestine (the mucosa) is damaged after eating wheat, rye, oats or barley (Am J Gastroenterol, 1999; 94: 839-43) as well as allergies. Investigations into the abnormal electrical brain activity seen in more than two-thirds of untreated children with coeliac disease has shown that, in most cases, such activity returned to normal when dairy and grain were removed from the diet (Psychiatr Pol, 1991; 25: 30-4; Z Klin Med, 1985; 40: 707-9). Abnormal brain activity may be an indication of neurological dysfunction associated with depression.
Clearly, not every child who is depressed will have coeliac disease but, for some, cutting out wheat and other grains, or avoiding dairy, may mean the difference between a normal life and a life on drugs.