Mediterranean Diet Shows Benefit for Depression


 
A Mediterranean-style diet has the potential to treat major depression, according to a new Australian study on the impact of food upon mood.

“We’ve known for some time that there is a clear association between the quality of people’s diets and their risk for depression,” Felice Jacka, PhD, (photo) the study’s lead author and the director of Deakin University’s Food and Mood Center in Melbourne, Australia, said. “This is the first randomized control trial to directly test whether improving the diet quality can actually treat clinical depression,” she added.

The study showed that 32.3% of the group that followed a modified Mediterranean diet achieved remission in their major depression symptoms, while only 8% who participated in a social support group experienced that result.

This finding is particularly relevant, according to Jacka and her co-authors, because only about half of those who have major depression are helped by psychotherapy or medication. New treatment options are needed, Jacka said. “Importantly, depression also increases the risk of, and in turn, also is increased by common physical illnesses such as obesity and type 2 diabetes and heart disease. Successfully improving the quality of patients’ diets also would benefit these illnesses,” added Jacka, who is a psychiatric epidemiologist and president of the International Society for Nutritional Psychiatry Research.

The researchers enrolled 67 participants of whom 71.6% were female and who overall had a mean age of 40.3. Of the sample, 55 already were using some form of treatment (21 psychotherapy and psychopharmacotherapy, 9 only psychotherapy, and 25 only psychopharmacotherapy). Only 1 person in the dietary group and 1 in the social group started taking medication during the trial, and 2 people in the social support group stopped their medication. The participants were recruited from the community. All met DSM IV criteria for a moderate to severe major depressive episode. Persons with bipolar disorder were not included in the sample.

Over the trial’s 12-week duration, the 33 assigned to the diet intervention received counseling sessions and recipes and food samples for using a Modified Mediterranean Diet that stressed 12 key food groups. The food categories included whole grains, vegetables, fruit, legumes, nuts, fish and lean red meats. The participants were discouraged from consuming sweets, fast food, and sugary drinks. The 34 in the social control group received “befriending” sessions for 4 weeks on a weekly basis and then every other week for the remainder of the trial.

Overall, 93.9% of those in the dietary intervention completed the 12-week trial, while 73.5% of the social support group did. The high rate of completion among those in the dietary intervention indicated that approach was acceptable to and could be carried out by participants with major depression, a condition that can include symptoms of poor motivation and fatigue, the study said.

The findings were limited by a potential for expectation bias among the dietary sample and because of the overall small sample size might not have been representative, the study said.

While the study should be considered preliminary and the results need to be replicated, the authors wrote that “The results of this RCT offer further support for the need to focus on addressing poor diet in clinical practice and provide some guidance regarding the strategies that may be used to support this imperative. They suggest the new possibility of adding clinical dieticians to multidisciplinary mental health teams and making dietician support available to those experiencing depressive symptoms in primary and other care settings.”

The study, "A randonmised controlled trial of dietary improvement for adults with major depression (the ‘SMILES’ trial)," was published in the January 30 issue of BMC Medicine.
 
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