Can Diet Affect Depression?

Apr 22, 2018

Two recent studies examined the impact of diet on depression. The first looked at diet and prevalence of people developing depression; the second looked at subjects who were already depressed.

DASH Diet and Depression

In one study, researchers found that people who ate vegetables, fruit and whole grains had lower rates of depression over time, according to research presented at the American Academy of Neurology’s 70th Annual Meeting in April.

The study found that people whose diets adhered more closely to the Dietary Approaches to Stop Hypertension (DASH) diet were less likely to develop depression than people who did not closely follow the diet. In addition to fruit and vegetables, the DASH diet recommends fat-free or low-fat dairy products and limits foods that are high in saturated fats and sugar.

“Making a lifestyle change such as changing your diet is often preferred over taking medications, so we wanted to see if diet could be an effective way to reduce the risk of depression,” said study author Laurel Cherian, MD, of Rush University Medical Center in Chicago.

For the study, 964 participants with an average age of 81 were evaluated yearly for an average of 6.5 years. They were monitored for symptoms of depression, such as being bothered by things that usually didn’t affect them and feeling hopeless about the future. They also filled out questionnaires about how often they ate various foods, and the researchers looked at how closely the participants’ diets followed plans like the DASH diet, the Mediterranean diet and the traditional Western diet.

Participants were divided into three groups based on how closely they adhered to the diets. Subjects in the two groups that followed the DASH diet most closely were less likely to develop depression than those in the group that did not follow that diet closely. The odds of becoming depressed over time were 11% lower among the top group of DASH adherers compared with the bottom group. On the other hand, the more closely people followed a Western diet—a diet high in saturated fats and red meats and low in fruits and vegetables—the more likely they were to develop depression.

Cherian noted that the study does not prove that the DASH diet leads to a reduced risk of depression; it only shows an association.

Mediterranean Diet and Depression

In another study researchers found that a Mediterranean-style diet rich in vegetables, legumes, fruit, nuts, fish oil and extra virgin olive oil improved mental health in people suffering depression. The study, published in Nutritional Neuroscience by researchers from the University of South Australia (UniSA), showed that, as volunteers improved their diet, their depression substantially decreased. They also reported improved quality of life.

“People tend to be skeptical about associations between diet and mental health,” says UniSA senior research fellow Natalie Parletta, PhD, who led the study. “This is one of the first randomized controlled trials worldwide to show a causal effect.”

In the study, volunteers aged 18–65 who suffered from depression were randomly allocated to a Mediterranean diet group or a social group—because peer support can also help with depression.

The diet group received education in nutrition and fortnightly cooking workshops for 3 months, while the other group met for fortnightly social gatherings.

Both groups showed improvements in mental health, but alleviation of depressive symptoms was significantly greater in the diet group. Better mental health correlated with healthier diet, strengthening the notion that diet was a key contributor.

Improvements in both diet and depression were still seen at a 3-month follow-up.

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