Findings from observational studies investigating the association between fruit and vegetable consumption and risk of depression were inconsistent. We conducted a systematic review and meta-analysis to summarise available data on the association between fruit and vegetable intake and depression. A systematic literature search of relevant reports published in Medline/PubMed, ISI (Web of Science), SCOPUS and Google Scholar until Oct 2017 was conducted. Data from 27 publications (sixteen cross-sectional, nine cohort and two case–control studies) on fruit, vegetables and/or total fruit and vegetable consumption in relation to depression were included in the systematic review. A total of eighteen studies that reported relative risks (RR), hazard ratios or OR for the relationship were included in the meta-analysis. The pooled RR for depression in the highest v. the lowest category of fruit intake was 0·83 (95 % CI 0·71, 0·98) in cohort studies and 0·76 (95 % CI 0·63, 0·92) in cross-sectional studies. Consumption of vegetables was also associated with a 14 % lower risk of depression (overall RR=0·86; 95 % CI 0·75, 0·98) in cohort studies and a 25 % lower risk of depression (overall RR=0·75; 95 % CI 0·62, 0·91) in cross-sectional studies. Moreover, an inverse significant association was observed between intake of total fruit and vegetables and risk of depression (overall RR=0·80; 95 % CI 0·65, 0·98) in cross-sectional studies. In a non-linear dose–response association, we failed to find any significant association between fruit or vegetable intake and risk of depression (fruit (cross-sectional studies): P_non-linearty=0·12; vegetables (cross-sectional studies): P_non-linearty<0·001; (cohort studies) P_non-linearty=0·97). Meta-regression of included observational studies revealed an inverse linear association between fruit or vegetable intake and risk of depression, such that every 100-g increased intake of fruit was associated with a 3 % reduced risk of depression in cohort studies (RR=0·97; 95 % CI 0·95, 0·99). With regard to vegetable consumption, every 100-g increase in intake was associated with a 3 % reduced risk of depression in cohort studies (RR=0·97; 95 % CI 0·95, 0·98) and 5 % reduced odds in cross-sectional studies (RR=0·95; 95 % CI 0·91, 0·98). This meta-analysis of observational studies provides further evidence that fruit and vegetable intake was protectively associated with depression. This finding supports the current recommendation of increasing fruit and vegetable intake to improve mental health.

Although several observational studies have investigated the association between vitamin D status and schizophrenia, we are aware of no comprehensive meta-analysis in this regard. We aimed to conduct a systematic review and a meta-analysis of observational studies to summarize the available data on the association between serum vitamin D levels and schizophrenia. A systematic research on all published articles until October 2013 was conducted in PubMed, ISI (Web of science), SCOPUS, and Google Scholar. All observational studies that had measured serum vitamin D levels in schizophrenic patients were included in the systematic review. After considering exclusion criteria, we had 19 studies for the systematic review that were included in three separate meta-analyses: 1) a meta-analysis on mean levels of 25-hydroxyvitamin D [25(OH)D] (n = 13); 2) a meta-analysis on the prevalence of vitamin D deficiency (n = 8); 3) a meta-analysis on odds ratios (n = 8). Findings from a meta-analysis on means revealed that the overall mean difference in serum 25(OH)D levels between schizophrenic patients and control participants was -5.91 ng/mL [95% confidence interval (CI) -10.68, -1.14]. Subgroup analyses based on study design, the patient's hospitalization status, study quality, and study location did not explain between-study heterogeneity; however, type of biomarker assessed [25-hydroxyvitamin D3 vs 25-hydroxyvitamin D (D2 & D3)] could account for some degree of heterogeneity. RESULTS from the meta-analysis on the prevalence of vitamin D deficiency indicated that the overall prevalence of vitamin D deficiency in schizophrenic patients was 65.3% (95% CI 46.4%-84.2%). Findings from the meta-analysis on odds ratios indicated that vitamin D-deficient persons were 2.16 times (95% CI 1.32, 3.56) more likely to have schizophrenia than those with vitamin D sufficiency. No evidence of heterogeneity was detected. We found a strong association between vitamin D deficiency and schizophrenia. However, randomized clinical trials are required to confirm our findings.

No conclusive information is available about the relation between the consumption of whole grains and the risk of mortality. We aimed to conduct a me

This systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to summarize the effect of caffeine intake on weight loss. We searched the following databases until November 2017: MEDLINE, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials. The relevant data were extracted and assessed for quality of the studies according to the Cochrane risk of bias tool. We estimated an intake-status regression coefficient (Beta) for each primary study and estimated the overall pooled Beta and SE using random effects meta-analysis on a double-log scale. Heterogeneity between studies was assessed by the Cochran Q statistic and I-squared tests (I²). Thirteen RCTs with 606 participants were included in the meta-analyses. The overall pooled Beta for the effect of caffeine intake was 0.29 (95%CI: 0.19, 0.40; Q = 124.5, I² = 91.2%) for weigh, 0.23 (95%CI: 0.09, 0.36; Q = 71.0, I² = 93.0%) for BMI, and 0.36 (95% CI: 0.24, 0.48; Q = 167.36, I² = 94.0%) for fat mass. For every doubling in caffeine intake, the mean reduction in weight, BMI, and fat mass increased 2 Beta-fold (20.29 = 1.22, 20.23 = 1.17, and 20.36 = 1.28), which corresponding to 22, 17, and 28 percent, respectively. Overall, the current meta-analysis demonstrated that caffeine intake might promote weight, BMI and body fat reduction.