Certain combinations of food and nutrients can have a significant effect on mood and behaviour, according to a new report from Canadian researchers released earlier this week.
Simon Young, a scientist at McGill University in Montreal, examined the current scientific literature on food and mood and reported his conclusions in the January issue of the Canadian Medical Association Journal.
Young looked specifically at foods which can have pharmacological effects. For example, tryptophan, an amino acid and the building block of protein, is found in foods such as turkey and milk, but only tryptophan in its pure form can increase levels of the brain chemical serotonin.
Heightened levels of serotonin can have an anti-depressant effect on mood, Young said, and can help people struggling to fall asleep. The popular myths that a warm glass of milk can aid sleep or a turkey dinner will bring on drowsiness are not supported by science, he said.
Young's research also found no evidence to support the long-held belief that sugar leads to hyperactivity in children or that it will help adults get through a mid-afternoon slump.
However, there is clear scientific evidence to show that carbohydrates in their purest form can have a mild sedative effect on people. Carbohydrates and complex carbohydrates, such as those in a baked potato or piece of bread, appear to "cause a modest enhancement in memory," Young said.
The report also finds patients with depression have higher folic acid deficiencies than those who are not depressed. Folate deficiencies are associated with lower levels of serotonin.
An amino acid derivative called S-adenosylmethionine or SAMe, sold as a dietary supplement in the United States, can have an anti-depressant effect as well. Young said there even is a link suggesting insufficient folic acid depletes SAMe levels in the brain.
Young also found that essential fatty acids, such as those found in fish oils, can alter the composition of nerve cell membranes and that some American studies have suggested fish oil could reduce depressive symptoms.