High fish consumption may reduce depression risk

1. In a pooled analysis, the highest level of fish consumption was significantly associated with lower rates of depression, even in gender specific subgroup analysis.

2. The significant findings are driven mostly by studies conducted in Europe, whereas studies conducted in other continents were less likely to reveal a significant association between fish consumption and depression.

Evidence Rating Level: 2 (Good)

Study Rundown: Depression is an unfortunately common disease, representing the single largest source of disability worldwide. With an estimated 350 million people suffering from depression, and treatment that is oftentimes lacking, there is a large interest in characterizing the modifiable risk factors that could help prevent depression. Many studies have probed associations between diet and depression, with some finding that suggest increasing fish consumption may be protective against the development of depression. However, many of these findings were inconsistent and inconclusive. This study performed a meta-analysis in order to better characterize the relationship between fish consumption and the risk of depression.

This study compared the results of 26 studies that looked into the association between fish consumption and depression. The studies ranged across continents and whether they studies the effects in men, women, or both. Though this meta-analysis did not specify exact quantities of fish that were considered low or high levels, nor did it attempt to standardize the way in which depression was diagnosed, it did find in its pooled analysis that those who consumed the highest level of fish in each study were less likely to be diagnosed with depression. The meta-analysis found consistent results when analyzing all adults, just men, or just women. It also conducted subgroup analyses that showed the strongest effects of this association in Europe, while it found no significant association in studies conducted in other continents.

This study is the first meta-analysis to characterize the association between fish consumption and depression. It was limited by its inability to address possible sources of confounding within each of the studies it reviewed, as well as by inconsistencies across the studies in how consumption was quantified and how depression was diagnosed. Though it suggests that national health policies encouraging increased fish consumption could reduce the burden imposed by depression, the study was unable to comment on exact physiological mechanisms for this association and is unable to account for inconsistencies in findings by geographic region.

Click to read the study in the Journal of Epidemiology & Community Health

Relevant Reading: Omega-3 fatty acids and depression: scientific evidence and biological mechanisms

In-Depth [meta-analysis]: This meta-analysis utilized data from 26 unique studies reported in 16 journal articles to better characterize the link between fish consumption and the risk of depression. Ten of the included studies were cohort studies, while the remaining 16 were cross-sectional. In all, 150,278 participants were analyzed. Pooled analysis on adults showed that the relative risk of developing depression was 0.83 (CI_95%  0.73 – 0.94) in the cohort that consumed the highest level of fish compared to the cohort with the lowest consumption.

When limiting the analysis to men, the relative risk of depression in those who consumed the most fish was of 0.80 (CI_95% 0.65 – 0.99), while in women the relative risk was 0.84 (CI_95% 0.77 – 0.92). Additionally, this study performed the same analysis among individual continents. Although the association between fish consumption and depression was not significant in the studies from North America, South America, and Asia, there was a significant association in Europe, where a relative risk of 0.72 (CI_95% 0.63 – 0.82) was calculated. Further analysis revealed no outsize influence from any one study included in the meta-analysis on the final pooled results, as well as no significant sources of publication bias.

Image: PD

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