Few studies assessed the associations between dietary vitamin K and depressive symptoms. We aimed to investigate the association between dietary vitamin K and depressive symptoms in a large cohort of North American People. In this cross-sectional analysis, 4,375 participants that were aged 45–79 years from the Osteoarthritis Initiative were included. Dietary vitamin K intake was collected through a semi-quantitative food frequency questionnaire and categorized in quartiles. Depressive symptoms were diagnosed using the 20-item Center for Epidemiologic Studies-Depression (CES-D) ≥ 16. To investigate the associations between vitamin K intake and depressive symptoms, logistic regression analysis were run, which adjusted for potential confounders. Overall, 437 (=10%) subjects had depressive symptoms. After adjusting for 11 confounders, people with the highest dietary vitamin K intake had lower odds of having depressive symptoms (OR = 0.58; 95%CI: 0.43–0.80). This effect was only present in people not taking vitamin D supplementation. In conclusion, higher dietary vitamin K intake was significantly associated with a lower presence of depressive symptoms, also after accounting for potential confounders. Future longitudinal research is required to explore the directionality of the association.

The literature regarding the potential health benefits of chocolate consumption are unclear and the epidemiological credibility has not been systematically scrutinized, while the strength of the evidence is undetermined. We therefore aimed to map and grade the diverse health outcomes associated with chocolate consumption using an umbrella review of systematic reviews. Umbrella review of systematic reviews of observational and intervention studies (randomized placebo-controlled trials, RCTs). For each association, random-effects summary effect size, 95% confidence interval, and 95% prediction interval were estimated. We also assessed heterogeneity, evidence for small-study effect and evidence for excess significance bias. For significant outcomes of the RCTs, the GRADE assessment was furtherly used. From 240 articles returned, 10 systematic reviews were included (8 of which included a meta-analysis), including a total of 84 studies (36 prospective observational studies and 48 interventional). Nineteen different outcomes were included. Among observational studies, including a total of 1,061,637 participants, the best available evidence suggests that chocolate consumption is associated with reduced risk of cardiovascular disease (CVD) death (n = 4 studies), acute myocardial infarction (n = 6), stroke (n = 5) and diabetes (n = 6), although this was based on a weak evidence of credibility. Across meta-analyses of intervention studies, chocolate consumption was positively associated with flow-mediated dilatation at 90-150 min (n = 3) and at 2-18 weeks (n = 3), and insulin resistance markers (n = 2). However, using the GRADE assessment, the evidence for these outcomes was low or very low. Data from two systematic reviews, reported that chocolate consumption was not associated with better depressive mood or cognitive function. There is weak evidence to suggest that chocolate consumption may be associated with favorable health outcomes.

Background: The objective was to capture the breadth of outcomes that have been associated with metformin use and to systematically assess the quality, strength and credibility of these associations using the umbrella review methodology.Methods: Four major databases were searched until 31 May 2020. Meta‐analyses of observational studies and meta‐analyses of randomized controlled trials (RCTs) (including active and placebo control arms) were included.Results: From 175 eligible publications, we identified 427 different meta‐analyses, including 167 meta‐analyses of observational studies, 147 meta‐analyses of RCTs for metformin vs placebo/no treatment and 113 meta‐analyses of RCTs for metformin vs active medications. There was no association classified as convincing or highly suggestive from meta‐analyses of observational studies, but some suggestive/weak associations of metformin use with a lower mortality risk of CVD and cancer. In meta‐analyses of RCTs, metformin was associated with a lower incidence of diabetes in people with prediabetes or no diabetes at baseline; lower ovarian hyperstimulation syndrome incidence (in women in controlled ovarian stimulation); higher success for clinical pregnancy rate in poly‐cystic ovary syndrome (PCOS); and significant reduction in body mass index in people with type 1 diabetes mellitus, in women who have obesity/overweight with PCOS and in obese/overweight women. Of 175 publications, 166 scored as low or critically low quality per AMSTAR 2 criteria.Conclusions: Observational evidence on metformin seems largely unreliable. Randomized evidence shows benefits for preventing diabetes and in some gynaecological and obstetrical settings. However, almost all meta‐analyses are of low or critically low quality according to AMSTAR 2 criteria.