Diet and Schizophrenia
There is now increasing evidence that dietary influences can affect the occurrence and course of schizophrenia. There are two studies showing that infants destined to become schizophrenic are significantly less likely to have been breast fed as babies. In adults who have developed schizophrenia, there is epidemiological evidence that dietary PUFA can influence clinical outcome.
Christensen and Christensen  investigated national diet relative to published figures on long term outcome of schizophrenia produced by the World Health Organisation. They found a very strong positive relationship between a better outcome of schizophrenia and national diet containing greater amounts of PUFA from fish and vegetable sources relative to the quantity of (mainly saturated) fats from land animals and birds. This accounted for 97% of the variance in outcome of schizophrenia between nations. We studied a group of schizophrenic patients and found a significant correlation between omega3 fatty acid intake in the diet and severity of schizophrenic symptoms . Supplementation with 10 grams/day of concentrated fish oil led to significant improvement in schizophrenic symptoms.
We have recently completed a double blind placebo controlled trial comparing an EPA enriched oil, a DHA enriched oil and corn oil placebo in the treatment of schizophrenic patients who were still symptomatic despite being given clinically optimal treatment with conventional antipsychotic medication . They stayed on their antipsychotic drugs during the three month trial period but were given the trial medication in addition. There was a 25% improvement in the EPA treated group and this was statistically significant relative to DHA or placebo.
This is a remarkable result with such small subject numbers in a group of patients who are known to be refractory to conventional treatment. There is also a case report of a single patient given EPA as the sole treatment for schizophrenia with remarkable and sustained benefit . It is not yet clear why EPA should be effective whilst DHA is not. One possibility is that EPA inhibits cPLA2 whereas DHA does not . There is evidence that currently used antipsychotic drugs will also reduce cPLA2 levels.
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