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The Relationship Between Nutrition and Mental Disorders


Our grandmothers said it so often that we can hardly hear the importance of the topic anymore: Eat right! Sleep right! Everything in moderation!

It seems now that Grandma was on the cutting edge of science.

Most physicians and scientists recognize that good nutrition is the foundation of physical health; oddly, the fundamental importance of nutrition for mental health has escaped many. One reason this is particularly odd is that the brain, which is only about 2% of our bodies by weight, actually accounts for at least 25% of our metabolic demands. If anything, one would expect that nutrition would be more important for brain function than for other body parts.

My research in the department of pediatrics at the University of Calgary is based on the theory that nutrient deficiency (in part, genetically determined) may be the basis for some mental and behavioural disorders. There are several lines of reasoning for this research: The number of mental disorders is increasing; the nutrient content of food is decreasing; and some research shows amelioration of mental symptoms with nutrient supplementation.

I personally have always been interested in the relationship between nutrition and the brain. In fact, 30 years ago I considered doing a postdoc on the topic but concluded at that time that the important discoveries were likely to be made by biochemists, not behavioural scientists. So I pursued a postdoc in neurophysiology and have worked in both psychophysiology and experimental psychology. My clinical research has continued to gravitate toward nutrition-related topics, however, and in the 1980s, I was heavily involved in studying the possible role of food ?additives? in hyperactivity.

The picture has changed in this millennium, and there are many nutrition-related topics that behavioural scientists could explore. The role of nutrition in human behaviour is an intriguing subject that is on the verge of experiencing explosive interest, and it therefore presents itself as an area for upcoming career opportunities.

Mental Disorders Are Increasing

Every time someone says that a problem such as depression is increasing, this counterargument is always presented: ?No, there?s no evidence that it is increasing, but probably we?re just more sensitive to it nowadays, so people seek help more readily and it is diagnosed more often.? But is that true?

In fact, current data suggest that severe psychiatric disorders such as bipolar disorder (which used to be called manic depression) and schizophrenia are indeed increasing. Epidemiological surveys from the late 19th century placed the prevalence rate at about 1.8 per 1000 people. In contrast, major U.S. surveys in the last 20 years peg the prevalence at around 15 per 1000. When we examine a more narrow range of history, comparing people who sought outpatient treatment for depression, the rate tripled from 7.3 per 1000 to 23.3 in just one decade (1987-1997). It is also important to note that many studies have shown that at least one-third of the homeless have severe psychiatric disturbances, as do a significant proportion of the prison population.

The impact of mental illness is enormous. Depression is, of course, a life-threatening disorder. In a recent Swiss study, over 400 people who were hospitalized for a mood disorder were tracked 22 years later. The mortality rate was 76%, and the two leading causes of death were suicide and circulatory disorders. In the U.S., recent figures show that suicide was the 11th leading cause of death.

The Nutrient Content of Food is Decreasing

The fact that recent work has shown that our food?s nutrient content is decreasing has been said to be to be predictable: Soil that has never been cultivated in human history is rich in micronutrients (vitamins and minerals). Years of agricultural use results in depletion of many essential micronutrients. Remineralization of the soil with zinc, copper, selenium, vitamins, manganese, chromium, and so on is virtually unheard of. Where, then, are our fruits and vegetables and grains supposed to get the nutrients that our brains and bodies require as part of a daily diet?

Finding the Key to Good Mental Health

If one wanted to determine whether mental symptoms were in some way tied to insufficient nutrient intake, the logical first step would be to evaluate serum levels of key nutrients in people with mental disorders. There are a few good studies in the last 80 years showing that people with schizophrenia, for instance, had significantly low serum iron, or low cerebrospinal fluid (CSF) and serum magnesium. However, the findings are inconsistent across studies. It is possible that current laboratory assays are either not sufficiently sensitive or not an adequate reflection of the needs of brain cells, particularly in those individuals with an inherited predisposition for mental problems.

So the evaluation of this relationship has to rely, at least in part, on studies of the effects of nutrient supplementation, and this has become the focus of my research activities. There are now a number of investigations showing improved mental function with broad spectrum multi-ingredient formulations of vitamins and minerals, as well as research on single ingredients. These studies have been done in ?normal? students, in residents of young offender centres, and in people with mental disorders.

Nutrition research involves a very interdisciplinary team. I work with other PhD experimental psychologists, psychiatrists, nutrition scientists, neuroscientists, and other scientists. The students involved thus far have been graduate students in clinical psychology and community health science.

Our own preliminary results at the University of Calgary show that a multi-ingredient formulation holds promise for helping people with significant mood swings, such as those with bipolar disorder or children with explosive rage. Randomized placebo-controlled trials are in the planning stages, and much more research is needed on this important topic.

Complementary and Alternative Medicine Research in Action

There is obviously a very large gap between demonstrating that nutrient supplementation improves mental disorders on the one hand, and proving that mental disorders are in fact due to nutritional deficiencies. Much research needs to be done to further explore this exciting area. When an individual from a family that appears to carry predisposing genes for mental disorders benefits clinically from nutrient supplementation, this may be an important clue for the role of those genes in determining metabolic needs of neurotransmitter pathways in the brain.

Many career opportunities will be developing in the next 10 to 20 years in the broad area of complementary and alternative medicine. With the establishment of the National Center for Complementary and Alternative Medicine within the National Institutes of Health in the United States and the Natural Health Products Directorate of Health Canada, two federal governments in North America have taken a strong position in support of future research on these topics.

Complementary and alternative approaches need to be investigated by using Western scientific methods. There is increasing recognition of the importance of research on alternative ways of thinking about health, such as nutritional supplementation. Recent position papers by large groups such as the U.S. government have stressed how important it is to explore these topics scientifically.

With respect to mental and behavioural disorders, there is a need for clinicians (psychiatry, psychology) and clinical researchers (methodologists, experimental psychologists) to devote time to the topic. Behavioural genetics in the area of psychiatric disorders, and particularly in relation to metabolism, will be an important area.

Is nutrient supplementation really an ?alternative? mental health approach? Only so long as people continue to believe that good nutrition is important only for physical health.