Scientific investigators in the 1970s began to ask if a correlation existed between food and behavior. They have discovered quite a few coincidences. New and increasingly more sophisticated studies have revealed the effective existence of a food-behavior correlation in children and older adults. In a review of 10 years of studies conducted between 1985 and 1995, Breakey found evidence of a relationship between what children eat and the way in which they behave. “The most important discovery,” he concluded, “has been the presence—in nearly all studies—of one statistically meaningful variation of behavior as a result of a dietary change” (p. 193). Moreover, these studies have revealed a consistency of response to dietary variations which is also statistically significant. Although other studies have established a correlation between changes in the diet and improvements in hyperactivity and insomnia, Breakey’s unexpected discovery was that the parameter primarily influenced by the intake of certain foods is mood, most of all stress and irritability. According to a recently published study by noted psychoneuroimmunologist Janice Kiecolt-Glaser, diets that promote inflammation (i.e., stress) are high in refined starches, sugar, saturated and transfats, and are low in omega-3 fatty acids, natural antioxidants, and fiber from fruits, vegetables, and whole grains.
A study by Christensen & Christensen investigated the correlation between the course of schizophrenia and national statistics relative to fat consumption. They have found that countries with better prognosis for schizophrenia were those in which the national diet included a higher proportion of fat from fish and from vegetables. In essence, the patients who consumed greater amounts of omega-3 fatty acids showed less severe symptoms, a finding supported by a variety of other studies. If anti-oxidant agents can help in blocking the damage caused by free radicals, the treatment with these food supplements could restore cellular structure. Such a therapy, along with counseling on dietetic factors and lifestyle, could beneficially influence the prognosis of schizophrenia.
New research is also focusing attention on the role that anti-oxidants in the diet may play in the treatment of mood disorders. It is hypothesized that fatty acids may have stabilizing effects on mood with a mechanism similar to that of lithium and of valproic acid, by modifying the pathways of transmission of neuronal signals. In their action on bipolar disorder, they appear to mimic lamotrigine’s mood stabilizing and antidepressant properties. The mechanisms of action must be further clarified, as it is still unclear whether fatty acids show a specific pharmacological effect or a mere compensation of nutritional deficits. The concomitant intake of anti-oxidants vitamins (vitamins C and E) may optimize the effect of fatty acids, further preventing oxidation. A double-blind 4-month clinical study of 30 patients with bipolar disorder has shown the effectiveness of fatty acid supplements in comparison to a placebo (olive oil), added to the usual therapies. The experiment group of patients had a significantly longer period of remission as compared to the control group. Kiecolt-Glaser also cites epidemiological studies that demonstrate significant inverse relationships between annual fish consumption and major depression—the more fish eaten, the lower the prevalence of serious clinical depression.
Adjuvant nutritional therapies have also been studied in patients who showed a relapse despite continuing antidepressant treatment. A double-blind study that added omega-3 or a placebo to the conventional treatment has shown statistically significant improvements in the experiment group in as little as three weeks. Also, melatonin seems to perform as a scavenger of free radicals, beyond its well-known properties of regulation of gonadal function and of biological rhythms (e.g., as a sleep aid). Research data suggest that melatonin may positively influence neurodegenerative processes that are involved in the formation of free radicals and the release of excitatory aminoacids.