The associations between sarcopenia and metabolic syndrome (MetS) in non-obese middle-aged and older adults remain controversial. Thus, this meta-analysis aimed to evaluate the overall prevalence of MetS and the correlations between sarcopenia and MetS in middle-aged and older non-obese adults. We performed a systematic searched strategy using PUBMED, EMBASE and Web of Science databases for relevant observational studies investigating sarcopenia and MetS up to 11 May 2017. The polled prevalence of MetS and odds ratios with 95% confidence intervals (CI), as well as subgroup analyses were calculated using a random effects model. Twelve articles with a total of 35,581 participants were included. The overall prevalence of MetS was 36.45% (95% CI, 28.28–45.48%) in middle-aged and older non-obese adults with sarcopenia. Our analysis demonstrated a positive association between sarcopenia and MetS (OR = 2.01, 95% CI, 1.63–2.47). The subgroup analysis showed that both larger cohort size and the use of dual-energy X-ray absorptiometry to measure body composition can enhance the relationship. Our study revealed that a higher proportion of MetS in middle-aged and older non-obese people with sarcopenia. Moreover, sarcopenia was positively associated with MetS in this population. Further large-scale prospective cohort studies are needed to investigate the causality between sarcopenia and MetS.

Microplastics (MP) are pervasive environmental pollutants that have raised concerns regarding their potential health effects. However, limited studies have investigated the relationship between MP exposure and depression, particularly in college students. Our study aims to examine the association between MP exposure and depressive symptoms in college students. A total of 1420 college students from Jiangsu College of Nursing, China, were included in this cross-sectional study. Depressive symptoms were assessed using the Patient Health Questionnaire-2 (PHQ-2), and MP exposure was estimated based on daily airborne MP concentration and drinking-water MP levels. Multivariate logistic regression models were used to estimate the associations between MP exposure and depressive symptoms. The prevalence of depressive symptoms among college students was 61.8 %. The median (interquartile range) of total MP exposure was 17403.7 (14174.8-20995.9) particles/day. Airborne MP exposure exhibited positive associations with depressive symptoms, while no significant association was found between drinking-water MP exposure and depressive symptoms. Compared with participants in the lowest quartile of MP exposure, those in the highest quartile of total MP exposure had 38 % higher odds of experiencing depressive symptoms (odds ratio [OR] = 1.38, 95 % CI: 1.21-1.57). When treated as a continuous variable, each 1000-particle increase in total MP exposure was associated with a 7.0 % increase in the odds of depressive symptoms (OR = 1.07, 95 % CI: 1.04-1.10). Stratified analyses indicated that the association between MP exposure and depressive symptoms was stronger among male students and freshmen. This study suggests MP exposure is a contributing factor for depressive symptoms in college students.