Clear Link Between Mood and Food

Fran Lowry

March 20, 2012

March 20, 2012 — New research shows there is a strong link between higher levels of nutrient intake and better mental health, thereby adding to the growing body of evidence demonstrating the critical role of diet in mood disorders.

"People who suffer from mood disorders function better when they are eating better," coauthor of the study Bonnie Kaplan, PhD, from the University of Calgary in Alberta, Canada, told Medscape Medical News. "It really is true that you are what you eat."

Dr. Bonnie Kaplan

The study is published in the February issue of the Canadian Journal of Psychiatry.

Dr. Kaplan's research has long been focused on the relationship between nutrition and mental health.

In the current study, she and colleague Karen M. Davison, PhD, RD, from the British Columbia Centre for Excellence in Women's Health, Vancouver, Canada, looked at 97 adults diagnosed with mood disorders who were living in the community.

An interview with a clinical psychologist was used to confirm individual patients' diagnosis. Similarly, an interview with a registered dietician confirmed participants' intake of major nutrients, including carbohydrates, fat, and protein, as well as individual nutrients, including vitamins and minerals.

All participants kept 3-day food diaries to record what they ate; they also filled out a food frequency questionnaire. In addition, Global Assessment of Functioning (GAF) scores and symptoms of depression and mania as reflected in scores on the Hamilton Depression Rating Scale and the Young Mania Rating Scale were assessed.

"This gave a pretty thorough evaluation of their nutrient intake and their psychiatric function," Dr. Kaplan said.

Eschew Processed Foods

The study showed that the vitamins and minerals in participants' diets were consistently and reliably associated with their GAF scores, Dr. Kaplan said.

Significant correlations were found between GAF scores and calories, carbohydrates, fibre, total fat, linoleic acid, riboflavin, niacin, folate, vitamin B6, vitamin B12, pantothenic acid, calcium, phosphorus, potassium, and iron (P < .05 for all), and magnesium (r = 0.41, P < .001) and zinc (r = 0.35, P < .001).

"All were statistically correlated and all in the same direction. It's way beyond what you would expect by chance," Dr. Kaplan commented. "The correlations were not huge, but the consistency and reliability were remarkable."

When use of dietary supplements was added to nutrient intakes from food, GAF scores remained positively correlated with all dietary minerals (P < .05).

Dr. Kaplan said she would like to see more research on nutrition and mental health.

Also, patients need to be taught to improve their diet.

"We all should be eating better and considering supplements where needed because obviously our brains are dependent upon vitamins and minerals. This study was a clear demonstration of their role in how we feel," she said.

"Doctors should consider counselling their patients to eat unprocessed, natural, healthy foods and refer them to a nutrition professional if specialized dietary consultation is needed."

Independent Depression Risk Factors

Commenting on the study's findings for Medscape Medical News, Felice N. Jacka, PhD, from Deakin University School of Medicine in Victoria, Australia, who has done extensive research on diet quality and mental health outcomes, thought the research was interesting.

Dr. Felice Jacka

However, she added that she was "concerned that the way the data are reported does not adequately highlight the main findings of the study."

"Although the correlations are tabulated and discussed at length, it is the multivariable analyses that are really the ones to focus on. This is where the relationships between nutrient intake and mental health parameters are adjusted for important variables, such as age, gender, and income. In this study, once these variables are accounted for, there are no relationships between nutrient intakes and mental health."

Like Dr. Kaplan, Dr. Jacka would like to see more research in this field.

"Although we know that physical activity is highly beneficial as a treatment strategy in depression, we do not yet know whether dietary improvement is also an effective treatment strategy.

"From the epidemiological evidence, we see that both physical activity and diet quality seem to be independent risk factors for depression, so it is plausible that dietary improvement may be as effective as exercise in treating depression," she said.

Her group has currently started such a trial to try to answer this question.

It will also be important to understand how the association between nutrient intake and mental health works and also to examine whether the relationship between diet and mental health is mediated by biological mechanisms, such as inflammation, oxidative stress, and neurotrophins, Dr. Jacka said.

The study was funded by the Danone Research Institute. Dr. Kaplan and Dr. Jacka have disclosed no relevant financial relationships.

Can J Psychiatry. 2012;57:85-92. Abstract

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