Plain language summary
The role of diet in preventing mental disorders has been increasingly explored in the past few years. Few observational studies have associated the traditional Mediterranean diet (MD) with a reduced risk of depression, however this available information is limited and inconclusive. The aim of this trial was to compare the efficacy of two variations of the MD on depression among patients at high risk of cardiovascular disease. The diets included MD supplemented with extra-virgin olive oil or mixed nuts, and a control group advised to follow a low-fat diet. The study included 3923 participants aged 55-80 the median follow-up was 5.4 years. The findings of this trial did not show a significant decrease in depression risk among participants assigned to either MD group compared with the control. However when the specific cohort of subjects with type 2 diabetes was analysed, the depression risk was significantly reduced compared with the control group. Based on this study, the authors suggest a beneficial effect of the MD on depression for patients with type 2 diabetes though further investigation is required.
Abstract
BACKGROUND A few observational studies have found an inverse association between adherence to a Mediterranean diet and the risk of depression. Randomized trials with an intervention based on this dietary pattern could provide the most definitive answer to the findings reported by observational studies. The aim of this study was to compare in a randomized trial the effects of two Mediterranean diets versus a low-fat diet on depression risk after at least 3 years of intervention. METHODS This was a multicenter, randomized, primary prevention field trial of cardiovascular disease (Prevención con Dieta Mediterránea (PREDIMED Study)) based on community-dwelling men aged 55 to 80 years and women aged 60 to 80 years at high risk of cardiovascular disease (51% of them had type 2 diabetes; DM2) attending primary care centers affiliated with 11 Spanish teaching hospitals. Primary analyses were performed on an intention-to-treat basis. Cox regression models were used to assess the relationship between the nutritional intervention groups and the incidence of depression. RESULTS We identified 224 new cases of depression during follow-up. There was an inverse association with depression for participants assigned to a Mediterranean diet supplemented with nuts (multivariate hazard ratio (HR) 0.78; 95% confidence interval (CI) 0.55 to 1.10) compared with participants assigned to the control group, although this was not significant. However, when the analysis was restricted to participants with DM2, the magnitude of the effect of the intervention with the Mediterranean diet supplemented with nuts did reach statistical significance (multivariate HR = 0.59; 95% CI 0.36 to 0.98). CONCLUSIONS The result suggest that a Mediterranean diet supplemented with nuts could exert a beneficial effect on the risk of depression in patients with DM2. TRIAL REGISTRATION This trial has been registered in the Current Controlled Trials with the number ISRCTN 35739639.
Methodological quality
Jadad score
:
3
Allocation concealment
:
Yes
