If it’s true that “you are what you eat” — and research is increasingly confirming that truism — then what you eat certainly has an impact on mental health. Finding a direct link between certain foods and the prevention or treatment of depression is hard, however.

A cause-and-effect relationship “is a hotly debated issue,” says Dr. Steven C. Schlozman, assistant professor of psychiatry at Harvard Medical School. “Some evidence suggests eating processed foods increases both the risk and eventual development of depression, but the problem with those studies is there are other things that could explain it, such as socioeconomic issues.” That is, a highly processed diet is correlated with lower-income populations, and those individuals have many other stressors in their lives that also contribute to depression.

But throughout society, the prevalence of depression over the past few decades has increased at precisely the same time our diets have moved farther away from fresh, whole foods. Plenty of individuals at the other end of the socioeconomic spectrum eat poorly, too. “If you are super busy and grabbing food on the run because you have to, that level of stress is associated with depression as well,” Schlozman says.

As with other health issues, like diabetes and cardiovascular disease, mental health is almost certainly affected by diet. The degree to which that is true, however, remains under investigation, and the prescriptive potential of a healthy diet — and indeed what constitutes a healthy diet — often depends on whom you ask.

[See: The 10 Best Diets for Healthy Eating.]

A New Study Supports Nutrition

“Can food help you beat depression? The answer is a resounding yes.”

So writes one of the leading proponents of the nutrition-depression connection. Dr. Drew Ramsey, an assistant clinical professor of psychiatry at Columbia University, has written several books and articles and given TEDx talks on the subject. “The most interesting thing to emerge [in depression research] recently is diet,” he says. “People who eat a lot of fast food have about a 60 to 80 increased risk of developing depression, and those who eat a Mediterranean diet have a reduced risk of 40 to 50 percent,” he says, noting the same numbers appear with diet and dementia.

An important study on depression and nutrition was published earlier this year. Known colloquially as the “SMILES” trial (a somewhat clumsy acronym for Supporting the Modification of lifestyle in Lowered Emotional States), it claims to be “the first randomized controlled trial explicitly designed to evaluate a dietary intervention, conducted by qualified dietitians, for reducing depressive symptomatology in adults with clinical depression.”

The study investigated whether a dietary improvement program helped in the treatment of major depressive episodes. Over 12 weeks, one group of depression patients received seven dietary-based sessions that included meeting with an accredited dietitian-educator who provided nutrition counselling and support. The control group received non-nutritional social support over the same visit schedule and length.

[See: Am I Just Sad – Or Actually Depressed?]

The subjects in the counselling group were encouraged to follow a modified Mediterranean diet, which was designed to be rich in vegetables, fruits and whole-grain cereals, and emphasized increased consumption of oily fish, legumes, raw and unsalted nuts and seeds, and extra virgin olive oil. It also included moderate amounts of reduced-fat natural dairy products and lean red meat. “This recommendation was based on epidemiologic evidence from nutritional psychiatry showing that women consuming less (or more) than the recommended intake of red meat were more likely to have clinical depressive and/or anxiety disorders, than those consuming the recommended amount. Moreover, red meat is a rich source of iron, zinc and vitamin B12, which are believed to play a potentially protective role in common mental disorders,” the study authors write.

“The results were remarkable,” Ramsey says. At trial’s end, about 30 percent of participants in the dietary support group were deemed in remission of major depression, compared to 8 percent of those in the social support group. Those who improved their diet the most experienced the greatest benefit. “This is a very positive trial,” he says.

5 Dietary Recommendations

Another study, from 2016, set out to create “practical dietary recommendations for the prevention of depression, based on the best available current evidence, in order to inform public health and clinical recommendations.” Those five guidelines are:

1. Follow “traditional” dietary patterns, such as the Mediterranean, Norwegian or Japanese diet.

2. Increase consumption of fruits, vegetables, legumes, whole-grain cereals, nuts and seeds.

3. Include a high consumption of foods rich in omega-3 polyunsaturated fatty acids.

4. Replace unhealthy foods with wholesome nutritious foods.

5. Limit your intake of processed foods, fast foods, commercial bakery goods and sweets.

[See: 11 Simple, Proven Ways to Optimize Your Mental Health.]

There is, quite obviously, nothing earth-shaking about these recommendations. They’re pretty much the same guidelines we all should follow for overall wellness and to prevent a host of diseases from diabetes to cancer. When it comes to depression, Schlozman says, eating a healthful diet “doesn’t hurt, and probably helps.” He is loath to single out any particular eating plan. “I can’t endorse any one diet, though the 100-percent Twinkie diet is probably bad for you. A balanced diet that agrees with you, eaten regularly, is the best way to protect against depression.”

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Diet and Depression: Is There a Link? originally appeared on usnews.com