MooDFOOD, the largest randomized clinical trial to study the effects of nutritional strategies on the prevention of major depressive disorder concludes that daily intake of nutritional supplements cannot prevent depression.

Over 1000 participants who were overweight or had obesity and were identified as being at elevated risk for depression but who were not currently depressed, from four European countries -the Netherlands, the United Kingdom, Germany and Spain, took part in the study. Participants were randomized to either take nutritional supplements containing folic acid, vitamin D, zinc, selenium or to a pill placebo, and half of participants also received a behavioural lifestyle intervention intended to change dietary behaviours and patterns.

Researcher Mariska Bot from Amsterdam UMC reported: "Daily intake of nutritional supplements over a year does not effectively prevent the onset of a major depressive episode in this sample. Nutritional supplements were not better than placebo. Therapeutic sessions aimed at making changes towards a healthy dietary behaviour did also not convincingly prevent depression." Dr. Bot is first author of a paper showing these results in today's issue of the Journal of the American Medical Association (JAMA).

Depression is a common disorder

More than 40 million Europeans experience a major depressive disorder. One in ten men and one in five women suffer from clinical depression at least once during their lifetime. Depression is one of the most prevalent and disabling disorders in the EU.

Given the increasing prevalence of depression, more people are actively searching for ways to decrease their risk through lifestyle modification, but are often overwhelmed by confusing and contradictory information. To help European citizens the MooDFOOD project has developed evidence-based nutritional strategies to help prevent depression.

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Prevention of depression through a healthy diet

The MooDFOOD prevention trial formed a crucial part of the five year MooDFOOD project, which investigated the relationship between nutrition and depression. MooDFOOD was funded by the European Commission and led by the Vrije Universiteit Amsterdam.

Although the behavioural therapy to encourage a healthy dietary behavior and improve diet was not effective at preventing depression overall, there was some evidence that it prevented depressive episodes in those participants who attended a recommended number of sessions. This may suggest the food behavioural therapy only works if the participants get sufficient exposure and are able to sufficiently improve their diet and dietary behaviour.

MooDFOOD project coordinators professor Marjolein Visser and professor Ingeborg Brouwer of the Vrije Universiteit Amsterdam said:

"Several studies within, and outside the five year MooDFOOD project show that consuming a healthy dietary pattern is important for European citizens, not only for physical health, but it may also help to prevent depressive symptoms. " Based on a large number of studies and careful analysis, MooDFOOD researchers have come to three important conclusions at the end of their project. First, a healthy dietary pattern, typified by a Mediterranean style diet high in fruit, vegetables, whole grains, fish, pulses and olive oil, and low in red meat and full-fat dairy products, may reduce the risk of developing depression. Second, in people with obesity, weight loss can lead to a reduction in depressive symptoms. Third, current evidence does not support the use of nutritional supplements in order to prevent depression.

Practical tools

These recent results have important implications for all Europeans. The MooDFOOD team has translated these findings into tools for the general population, health professionals (GPs, dieticians and psychologists), researchers and policy makers.