Dear Dietitian,

I am being treated for depression, and a friend told me about nutritional psychiatry. As I understand it, certain foods supposedly improve mood. Is there any science behind this?

Thomas

Dear Thomas,

Nutritional psychiatry is a new field of interest, only about ten years old. According to the National Institute of Mental Health, as many as 17.3 million adults in the US reported at least one episode of major depression in 2017. Major depression is defined as a “period of at least two weeks when a person experienced a depressed mood or loss of interest or pleasure in daily activities and had a majority of specified symptoms, such as problems with sleep, eating, energy, concentration, or self-worth” (1).

Nutritional psychiatry focuses on the use of food and supplements to provide essential nutrients that may be lacking in one’s diet. It is part of an integrated approach in treating mental illness, particularly depression and anxiety, and should not be used as a sole treatment.

Nutritional approaches to treating anxiety and depression are variable, based on one’s needs. Some patients are instructed to follow a Mediterranean diet, which is high in fruits and vegetables, healthy fats, oily fish, nuts, and low in red meat. Another treatment approach includes supplementing the diet with specific nutrients, such as folate, omega 3-fatty acids, and vitamin D. These nutrients may help improve mood and relieve anxiety and depression.

In the SMILES (Supporting the Modification of lifestyle in Lowered Emotional States) study, sixty-seven participants, who suffered from moderate to severe depression, were randomly assigned to one of two groups. One group followed their usual diet. The other group followed a modified Mediterranean (ModiMed) Diet made up of fresh fruits, vegetables, whole grains, legumes, nuts, extra virgin olive oil, and oily fish. The diet differed from the traditional Mediterranean Diet in that it offered moderate amounts of lean red meat and reduced-fat dairy. At the end of three months, the ModiMed Diet had significantly reduced symptoms of depression (2). However, this study was limited by its small size and short duration.

While nutritional psychiatry may show promise, most of the studies in this area are observational and do not prove causation. More well-designed, randomized controlled trials (the gold standard of research) are needed to support a link between nutrition and depression and anxiety. 

Depression and anxiety are serious conditions whose causes are multifactorial. Factors may include:  genetics, trauma, early childhood losses, chemical imbalances in the brain, medical illness, and stress. If depression and anxiety are interfering with your everyday activities, seek the help of a qualified physician.

Until next time, be healthy!

Dear Dietitian

References

1. Major Depression (February 2019) https://www.nimh.nih.gov/health/statistics/major-depression.shtml
2. Jacka, F.N., O’Neil, A., Opie, R. et al. A randomised controlled trial of dietary improvement for adults with major depression (the ‘SMILES’ trial). BMC Med 15, 23 (2017). https://doi.org/10.1186/s12916-017-0791-y