According to the World Health Organization, an estimated 350 million people of all ages suffer from depression, making it the leading cause of disability worldwide. It is also a major contributor to the overall global burden of disease.
What if following a specific healthy dietary pattern could protect our minds and alleviate much of this burden? According to research published last year in the open-access journal BMC Medicine, a large study of more than 15,000 people suggests depression could be linked with nutrient deficits. Preventing the onset of depression could be as simple as keeping to a Mediterranean diet or other nutritious lineup rich in fruit, vegetables, legumes and nuts and sparing in processed meats, say researchers.
Three diets were compared in the study: the Mediterranean diet, the Pro-vegetarian Dietary Pattern and the Alternative Healthy Eating Index-2010. Participants used a scoring system to measure their adherence to the selected diet (higher dietary scores indicated participants consumed a healthier diet).
The study included a cohort of 15,093 participants free of depression at the beginning of the study. Questionnaires to assess dietary intake were completed at the start of the project and again after 10 years. After a median follow-up of 8.5 years, a total of 1,051 participants reported a clinical diagnosis of depression or said that they’d used antidepressant drugs.
The Alternative Healthy Eating Index-2010 was associated with the greatest reduction of risk of depression. This eating pattern has various nutrients and foods in common with the Mediterranean diet; for example, omega-3 fatty acids, vegetables, fruits, legumes, nuts and moderate alcohol intake.
Lead researcher Almudena Sánchez-Villegas, PhD, University of Las Palmas de Gran Canaria, said that a “threshold effect”—wherein a noticeable difference occurs when participants start to follow a healthier diet—seemed to be evident. “Even a moderate adherence to these healthy dietary patterns was associated with an important reduction in the risk of developing depression,” she said. “However, we saw no extra benefit when participants showed high or very high adherence to the diets. So, once the threshold is achieved, the reduced risk plateaus even if participants were stricter with their diets and eating more healthily. This dose-response pattern is compatible with the hypothesis that suboptimal intake of some nutrients (mainly located in low adherence levels) may represent a risk factor for future depression.”
A limitation of this study was that the results were based on self-reported dietary intake and a self-reported clinical diagnosis of depression. More research is needed to predict the role of nutrient intake for neurophysiological requirements and to identify whether it is a suboptimal intake of minerals and vitamins or of proteins and carbohydrates that is linked to depression.