More than 300 million people worldwide have been diagnosed with depression, which is a leading cause of disability and disease burden. Elucidating dietary patterns that may reduce the risk of depression could help reduce the incidence of other diseases. PubMed/MEDLINE, ISI Web of Science, Scopus, Embase, and Google Scholar databases were searched to identify relevant publications up to May 2018. All observational studies that considered the Mediterranean diet as the exposure variable and depression as the main outcome or as one of the outcome variables were included in this systematic review and meta-analysis. Two authors independently screened 3229 publications. A total of 14 observational studies were included in the meta-analysis. Two authors independently extracted the data and assessed the risk of bias. The studies in the meta-analysis included a total of 56 043 participants. When 5 effect sizes from 4 cohort studies were combined, no significant association was observed between adherence to the Mediterranean diet and risk of depression (overall hazard ratio = 0.95; 95%CI, 0.79-1.16). When 3 effect sizes from 3 cohort studies that reported β coefficients were combined, again no significant association was found (β = -0.00; 95%CI, -0.12, 0.12). However, when 9 effect sizes from 9 cross-sectional studies were combined, an inverse significant association was found between adherence to the Mediterranean diet and risk of depression (overall odds ratio = 0.72; 95%CI, 0.60-0.87). The analysis of cohort studies revealed no significant association was found between adherence to the Mediterranean diet and risk of depression. However, an inverse significant association between adherence to the Mediterranean diet and odds of depression in cross-sectional studies.

Although several studies have investigated the association between Internet use and odds of overweight and obesity, results are inconsistent. This systematic review and meta-analysis was performed to summarize evidence on the association between Internet use and odds of overweight and obesity. A systematic literature search was conducted in PubMed/Medline, Web of Science, Scopus, and Google Scholar up to February 2019 to identify relevant publications. Finally, 9 cross-sectional studies were considered in this systematic review and meta-analysis. Combining 11 effect sizes from 9 studies, we found a significant, positive association between the highest Internet use, compared to the lowest (ranged from ≥5 h/d to no use among studies), and odds of overweight and obesity (OR: 1.47; 95% CI: 1.21-1.78; I2, 69.6%; P < 0.001), such that Internet users had 47% greater odds of being overweight or obese. We also observed a significant, positive association between the highest Internet use, compared to the lowest (ranged from ≥5 h/d to no use among studies), and overweight/obesity (OR: 1.15; 95% CI: 1.06-1.25; I2, 0.0%; P = 0.426), obesity (OR: 2.58; 95% CI: 1.88-3.54; I2, 0.0%; P = 0.637), and overweight (OR: 1.38; 95% CI: 1.16-1.64; I2, 13.1%; P = 0.330). A linear dose-response meta-analysis revealed that each additional 1 h/d of Internet use was associated with 8% increased odds of overweight and obesity (OR: 1.08; 95% CI: 1.05-1.11; I2, 3.8%; P = 0.403). Findings of this systematic review and meta-analysis indicated that Internet use was positively associated with increased odds of being overweight and obese.