Several observational studies over the years have suggested that diet can influence mental state and risk for depression. Lending support to the idea was the first controlled clinical trial on the link between diet quality and depression.
Dubbed SMILES (Supporting the Modification of lifestyle In Lowered Emotional States), the Australian study, published in 2017 in BMC Medicine, enrolled people who had moderate to severe depression and poor diets at the start and randomized them into two groups:
- A diet group received personalized nutrition counseling on how to follow a modified Mediterranean diet. Participants were encouraged to eat whole grains, vegetables, fruits, legumes, low-fat and unsweetened dairy foods, nuts, fish, lean meats, and olive oil; reduce refined grains, sweets, fried or fast foods, processed meats, and sugary drinks; and consume moderate alcohol.
- A social support (control) group discussed neutral topics such as sports and music with a trained “befriender” or engaged in board games and other activities.
After 12 weeks, the diet group had a greater reduction in depression and anxiety symptoms than the social support group, even with variables such as weight loss taken into account. Moreover, more participants in the diet group achieved depression remission (32 percent versus 8 percent). Diet may influence depression by affecting inflammatory and oxidative stress pathways, brain plasticity, and possibly the gut microbiome, according to the researchers.
Keep in mind: It’s not known if the effects of the diet would persist over time. Also, no diet is a substitute for antidepressant medication if one has been prescribed.