A healthy diet may help relieve the symptoms of depression.
There is good evidence from observational studies that diet can affect mood, and now a randomized controlled trial suggests that healthy eating can modestly improve clinical levels of depression.
The study, in PLOS One, randomized 76 college students with poor diet and depression symptoms to two groups. One group was put on a Mediterranean-style diet high in fruits, vegetables, fish, olive oil, nuts and seeds, and low in refined carbohydrates, sugar and saturated fat. The other continued their usual eating habits.
At the beginning and end of the three-week trial, all participants were assessed with well-validated scales measuring depression, anxiety, current mood, memory and self-efficacy (confidence in one’s ability to exert control over behavior).
Symptoms of depression improved, on average, in the diet group, shifting from the moderate severity range to the normal range. Depressive symptoms among the controls, meanwhile, remained stable, staying within the moderate severity range. On tests of anxiety and stress, the diet group had significantly lower scores than the controls, after controlling for levels of anxiety and stress at the start of the study.
There were no differences between the two groups in memory or self-efficacy scores. The study controlled for smoking, physical activity, B.M.I. and other factors.
The lead author, Heather M. Francis, a lecturer at Macquarie University in Sydney, Australia, said that the effect was modest, and people continued their usual treatments during the study.
“It’s not a cure,” she said, “but it’s certainly a significant improvement.”