Much of modern psychiatry rests on the assumption that mental illness is a biological or genetic disease. Nowhere is this more evident than with schizophrenia, a catch all term used to describe individuals who supposedly have lost contact with reality, and suffer from delusions, hallucinations, illogical thought processes and generally disturbed behaviour.

The "sick brain" theory justifies the medical approach to mental illness, with its armament of powerful antipsychotic drugs, lobotomy or electroshock (see box, p 2). As Peter Breggin says in Toxic Psychiatry (Fontana 1993), "If irrationality isn't biological, then psychiatry loses much of its rationale for existence as a medical speciality."

In some cases medicine may be correct in blaming body chemistry, but in seeking the cause in the brain itself, it could be fingering the wrong culprit. A growing number of studies suggest that some of the behaviour that we label "schizophrenic" may be caused or exacerbated by food allergies or nutritional deficiencies.

The most well known advocate of this approach is the late Dr Carl Pfeiffer of the Brain Bio Centre in Princeton, New Jersey. Dr Pfeiffer postulated that most psychotic patients have either abnormally high or low levels of histamine the body chemical mobilized in allergic reactions which is vital to the functioning of the nervous system. He also found that they were likely to have too much copper and deficiencies in zinc and other nutrients. By manipulating their diet and adding supplements, Dr Pfeiffer has achieved notable improvements in many patients.

One of the most thorough researchers into this area is Dr Melvyn R Werbach, assistant clinical professor of psychiatry at University of California at Los Angeles School of Medicine. With his permission, WDDTY has excerpted from the most important findings of his research into nutritional influences on mental illness.

Remember that Dr Werbach's findings are simply meant to be a source book of evidence, not a treatment programme. Never suddenly stop taking drug treatment before you are certain that nutritional problems have been sorted out or psychotic symptoms may recur. Anyone suffering from psychosis should work in tandem with a trained professional who will examine your dietary history and investigate nutritional deficiencies with appropriate laboratory tests, before launching into any nutritional therapies. It's vital to work with someone highly experienced, as too much of certain nutrients (such as folic acid) can actually bring on symptoms of schizophrenia.

WDDTY does not advocate that people with major psychotic problems ignore all drug therapy, which used judicially can be life saving in the initial stages of the illness and is sometimes the only means of leading a normal life. However, investigating food sensitivities and nutritional deficiencies can be a first port of call in treating schizophrenics, if not the root cause. Nutritional doctors Stephen Davies and Alan Stewart have found that correction of the underlying nutrient imbalances, food allergies and hormone shortages "can, but not always, result in being able to gradually withdraw, in a controlled way, the antipsychotic medication without relapse".

Some research suggests that foods, especially those containing gluten and milk or dairy products, may contribute to schizophrenic symptoms. Wheat or milk could trigger mental illness, because amino acids contained in these foods are similar to a substance, melanocyte stimulating hormone release inhibiting factor (MIF), that alters brain activity (N Engl J Med, 1982; 307 (14): 895).