Daily intake of nutritional supplements do not prevent any major depressive episode, concluded a recent study.

As part of the study, Over 1,000 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.

"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", said study author Mariska Bot.

Depression is a common 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.

Behavioural therapy to encourage a healthy dietary behaviour and improve diet was not effective at preventing depression overall, there was some evidence during the research 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. Based on a large number of studies and careful analysis, 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.