Coffee drinking and cancer risk: an umbrella review of meta-analyses of observational studies.

BACKGROUND: Epidemiological studies on the association between coffee intake and cancer risk have yielded inconsistent results. To summarize and appraise the quality of the current evidence, we conducted an umbrella review of existing findings from meta-analyses of observational studies. METHODS: We searched PubMed, Embase, Web of Science and the Cochrane database to obtain systematic reviews and meta-analyses of associations between coffee intake and cancer incidence. For each association, we estimated the summary effect size using the fixed- and random-effects model, the 95% confidence interval, and the 95% prediction interval. We also assessed heterogeneity, evidence of small-study effects, and excess significance bias. RESULTS: Twenty-eight individual meta-analyses including 36 summary associations for 26 cancer sites were retrieved for this umbrella review. A total of 17 meta-analyses were significant at P ≤ 0.05 in the random-effects model. For the highest versus lowest categories, 4 of 26 associations had a more stringent P value (P ≤ 10- 6). Associations for five cancers were significant in dose-response analyses. Most studies (69%) showed low heterogeneity (I2 ≤ 50%). Three and six associations had evidence of excessive significance bias and publication bias, respectively. Coffee intake was inversely related to the risk of liver cancer and endometrial cancer and was characterized by dose-response relationships. There were no substantial changes when we restricted analyses to meta-analysis of cohort studies. CONCLUSIONS: There is highly suggestive evidence for an inverse association between coffee intake and risk of liver and endometrial cancer. Further research is needed to provide more robust evidence for cancer at other sites.

Population attributable risk of excess weight, abdominal obesity and physical inactivity for type 2 diabetes in Chinese men and women.

BACKGROUND: Given the high prevalence of type 2 diabetes mellitus (T2DM) in the Chinese population, it is necessary to estimate the T2DM incident attributable to obesity and physical inactivity. METHODS: We analyzed the data from the Shanghai Men's and Women's Health Studies, including 56,691 men and 70,849 women aged 40-74. The hazard ratios (HRs) and the population attributable risks (PARs) were calculated by Cox regression model and model-based estimation. RESULTS: A total of 3,315 male and 5,925 female cases were identified during 519,157 and 981,504 person-years, up to 31 December 2017. Excess weight, abdominal obesity were associated with the increased risks of T2DM both in women and men, while physical inactivity was only associated with an increased risk in men. A large proportion of T2DM incident cases can be attributed to excess body weight (women: 48.6%; men: 41.5%) and abdominal obesity (women: 50.4%; men: 30.3%). Physical activity was negatively associated with the risk of T2DM (Ptrend<0.01). The PARs adjusted for confounders were 3.6% for physical inactivity in men and 1.7% in women. CONCLUSIONS: Excess weight and abdominal obesity accounted for a large proportion of T2DM incident cases in men and women; a small part of T2DM cases were attributed to physical inactivity in men. Weight control is of great significance in curbing the epidemic of diabetes.

Gender differences of relationship between serum lipid indices and type 2 diabetes mellitus: a cross-sectional survey in Chinese elderly adults.

BACKGROUND: To investigate the gender differences of the relationships between clinical serum lipid indices and type 2 diabetes mellitus (T2DM) in Chinese elderly adults. METHODS: Between 2014 and 2016, participants selected from three communities in an urban district of Shanghai were measured for serum lipid indices of low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), total cholesterol (TC), and triglyceride (TG). Age and multivariate adjusted logistic regression models were utilized to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) of serum lipid indices on T2DM prevalence. RESULTS: In total, 4,023 male and 3,862 female participants were included in this study, with the T2DM prevalence proportions of 13.03% and 11.73%, respectively. In association analysis, the serum levels of LDL-c, HDL-c, TC were significant between non-T2DM individuals and T2DM patients in men, but the HDL-c and TG in women. LDL-c/HDL-c, TG/HDL-c, and TC/HDL-c ratios were associated with the T2DM prevalence only in women. In the multivariate analysis, a higher serum LDL-c level was positively associated with a reduced risk of T2DM prevalence in men with OR (95% CI) of 0.57 (0.39-0.85) (P=0.006). Higher ratios of LDL-c/HDL-c, TG/HDL-c, and TC/HDL-c were all more likely associated with the decreased risks of T2DM prevalence with the ORs ranging from 0.45 to 0.62 in men (all P<0.05), but not in women. CONCLUSIONS: High LDL-c concentration was significantly associated with a lower T2DM prevalence in men. A gender difference of the associations between the lipid ratios and T2DM prevalence was observed for LDL-c/HDL-c and TC/HDL-c ratios, which might be validated in female T2DM prevalence in the future.

Tea Drinking and Risk of Cancer Incidence: A Meta-Analysis of Prospective Cohort Studies and Evidence Evaluation.

Here we provide a comprehensive meta-analysis to summarize and appraise the quality of the current evidence on the associations of tea drinking in relation to cancer risk. PubMed, Embase, and the Cochrane Database of Systematic Reviews were searched up to June 2020. We reanalyzed the individual prospective studies focused on associations between tea drinking and cancer risk in humans. We conducted a meta-analysis of prospective studies and provided the highest- versus lowest-category analyses, dose-response analyses, and test of nonlinearity of each association by modeling restricted cubic spline regression for each type of tea. We graded the evidence based on the summary effect size, its 95% confidence interval, 95% prediction interval, the extent of heterogeneity, evidence of small-study effects, and excess significance bias. We identified 113 individual studies investigating the associations between tea drinking and 26 cancer sites including 153,598 cancer cases. We assessed 12 associations for the intake of black tea with cancer risk and 26 associations each for the intake of green tea and total tea with cancer risk. Except for an association between lymphoid neoplasms with green tea, we did not find consistent associations for the highest versus lowest categories and dose-response analyses for any cancer. When grading current evidence for each association (number of studies ≥2), weak evidence was detected for lymphoid neoplasm (green tea), glioma (total tea, per 1 cup), bladder cancer (total tea, per 1 cup), and gastric and esophageal cancer (tea, per 1 cup). This review of prospective studies provides little evidence to support the hypothesis that tea drinking is associated with cancer risk. More well-designed studies are still needed to identify associations between tea intake and rare cancers.