Diet and the risk of unipolar depression in adults: systematic review of cohort studies

J Hum Nutr Diet. 2013 Feb;26(1):56-70. doi: 10.1111/j.1365-277X.2012.01283.x. Epub 2012 Oct 18.


Background: Nutrition may be a risk factor for unipolar depression. We aimed to review the association between dietary variables and the risk of depression.

Methods: Fifteen databases were searched up to May 2010. Only longitudinal studies for which outcomes were unipolar depression and/or depressive symptoms in adults were eligible for inclusion. Eleven studies were included and critically evaluated. Participants were in the age range 18-97 years and the study sample size was in the range 526-27 111. Follow-up ranged from 2 to 13 years. The diversity of dietary variables and nonlinear associations precluded formal meta-analysis and so a narrative analysis was undertaken.

Results: Variables inversely associated with depression risk were the consumption of nutrients such as folate, omega-3 fatty acids and monounsaturated fatty acids; foods such as olive oil and fish; and a diet rich in fruits, vegetables, nuts and legumes. Some of these associations varied by sex and some showed a nonlinear association.

Conclusions: At the study level, weaknesses in the assessment of exposure and outcome may have introduced bias. Most studies investigated a cohort subgroup that may have resulted in selection bias. At the review level, there is a risk of publication bias and, in addition, narrative analyses are more prone to subjectivities than meta-analyses. Diet may potentially influence the risk of depression, although the evidence is not yet conclusive. Strengthening healthy-eating patterns at the public health level may have a potential benefit. Robust prospective cohort studies specially designed to study the association between diet and depression risk are needed.

Publication types

  • Review
  • Systematic Review

MeSH terms

  • Depression / etiology*
  • Depression / prevention & control
  • Depressive Disorder / etiology*
  • Depressive Disorder / prevention & control
  • Diet / adverse effects*
  • Diet / standards
  • Dietary Fats
  • Fatty Acids
  • Female
  • Folic Acid
  • Humans
  • Male
  • Meta-Analysis as Topic


  • Dietary Fats
  • Fatty Acids
  • Folic Acid