Associations of coffee consumption with circulating level of adiponectin and leptin. A meta-analysis of observational studies.

The association between coffee consumption and the circulating level of adiponectin and leptin has been evaluated in several epidemiological studies with conflicting results. Therefore, the aim of this study was to examine the associations of coffee consumption with the circulating level of adiponectin and leptin. A comprehensive literature search up to January 2018, using PUBMED, EMBASE and Web of Science databases, was conducted to identify the relevant observational studies that examined the associations of coffee consumption with the circulating level of adiponectin and leptin. A total of twelve cross-sectional studies were included in this meta-analysis. According to the combined standard mean difference (SMD) between the highest and the lowest coffee intake category, coffee consumption was associated with a higher circulating adiponectin level (SMD = 0.11, 95%CI: 0.06-0.17; P < .001). Subgroup analysis confirmed such findings in females (SMD = 0.11, 95%CI: 0.02-0.20; P = .01), but not in males (SMD = 0.03, 95%CI: -0.08 to 0.14; P = .59). In addition, the combined SMD showed that coffee consumption was negatively associated with the circulating level of leptin (SMD = -0.19, 95%CI: -0.28 to -0.10; P < .001). The results of this meta-analysis suggested that coffee consumption was associated with a higher circulating level of adiponectin. Additionally, we showed that coffee consumption was inversely associated with the circulating level of leptin. More well-designed prospective cohort studies and randomised controlled trials are needed to further elaborate the concerned issues.