Major depression has recently been ranked as the second highest cause of loss of years of life from disability, and the prevalence of depression among women is about twice that of men. Between 1990 and 2013, these lost years of life from depressive disorders increased by 53.4%, according to the Global Burden of Disease report cited by the authors of the above study. It’s also notable that cardiovascular disease and depression share multiple etiopathologies and risk factors. These include poor nutrition, chronic inflammation, and low circulating levels of omega-3 fatty acids. Changing dietary habits is often difficult due to ingrained lifestyle habits, and may be especially challenging in depression as a result of altered affect and loss of motivation.

The traditional Mediterranean diet (sometimes called the “Med Diet”) is generally considered to be highly palatable as well as representing a behaviorally sustainable approach to healthy eating. In meta-analyses, it has been associated with better cardiovascular function and reduced risk for depression. It features polyphenol-rich extra virgin olive oil as the main dietary fat, and focuses on vegetables, fruits, olives, nuts, seeds, and whole grains. It includes only modest amounts of fish and red wine, and provides little or no red meat, sweets, dairy products, or processed foods. Hands-on learning experiences in adopting this dietary pattern have shown success in improving individuals’ food choices in several studies, including this research team’s own pilot work in subjects with serious mental illness.

With all this in mind, here’s how this team structured their RCT. They began with 152 adults aged 18-65 with self-reported depression, and compared the effects of either 1) 3 months of bi-weekly social support or 2) 3 months of bi-weekly Mediterranean diet food preparation workshops, provision of recipe ingredients and other recommended foods, online cooking resources, and 6 months of supplementation with fish oil capsules providing 900 mg docosahexaenoic acid (DHA) and 200 mg eicosapentaenoic acid (EPA). The social support group engaged in activities such as playing games and sharing photographs. Baseline and study diets were controlled. Assessments were conducted at baseline, at 3 months, and at 6 months’ follow-up, and included the Depression Anxiety Stress Scale (DASS-21), Assessment of Quality of Life (AQoL-8D), the Positive and Negative Affect Scale (PANAS), a validated Mediterranean Diet adherence questionnaire, and analysis of red blood cells for omega-3 fatty acid levels. At baseline, over 86% of study subjects scored in the severe or extremely severe categories of the DASS depression scale.