Dose-response meta-analysis of coffee consumption and risk of colorectal adenoma.

BACKGROUND: The association between coffee and colorectal adenoma risk remains controversial. We conducted a meta-analysis of cohort and case-control studies to sum up the existing proof about this matter. METHODS: We searched Pubmed, Medline, and Embase for studies published before 1 September 2018 on coffee consumption and colorectal adenoma in any language. The different ORs were calculated for cohort and case-control studies in this study, and we use a random-effects model to aggregate the relative risks of individual studies and conduct dose response, heterogeneity, and publication bias. RESULTS: A total of 8 studies (6 case-control studies, 2 cohort studies) were identified, including 7090 subjects. In a summary analysis of all studies, high coffee intake (compared the highest with the lowest categories) was associated with a reduced risk of colorectal adenoma (odds ratio [OR] = 0.70, 95% confidence interval [CI] = 0.55-0.90). The results of subgroup analysis of adenoma location were similar with the pooled analysis, except for rectal adenoma. In the dose-response meta-analysis study, the estimated total odds ratio for increasing coffee consumption by 150 ml per day (about one cup) was 0.91 (95% CI = 0.87-0.95). CONCLUSIONS: The meta-analysis demonstrates possible evidence that increased coffee intake is related to a reduced risk of colon adenoma. However, because of latent confusion and different exposure classification, this finding should be carefully considered.

Effects of the resistant starch on glucose, insulin, insulin resistance, and lipid parameters in overweight or obese adults: a systematic review and meta-analysis.

BACKGROUND: The role of resistant starch (RS) in glucose, insulin, insulin resistance or sensitivity, and lipid parameters have been reported in several studies and remained controversial. A pooled analysis which assessed these parameters has not been performed. Thus, we conducted a meta-analysis to sum up existing evidence about the issue. METHODS: We searched in MEDLINE and PUBMED for studies that were published before November 2018. Meta-analysis of diabetics and nondiabetics trials were performed by use of a random-effects model. RESULTS: A total of 13 case-control studies that included 428 subjects with body mass index ≥25 were identified. RS supplementation reduced fasting insulin in overall and stratified (diabetics and nondiabetics trials) analysis (SMD = -0.72; 95% CI: -1.13 to -0.31; SMD = -1.26; 95% CI: -1.66 to -0.86 and SMD = -0.64; 95% CI: -1.10 to -0.18, respectively), and reduced fasting glucose in overall and stratified analysis for diabetic trials (SMD = -0.26; 95% CI: -0.5 to -0.02 and SMD = -0.28; 95% CI: -0.54 to -0.01, respectively). RS supplementation increased HOMA-S% (SMD = 1.19; 95% CI: 0.59-1.78) and reduced HOMA-B (SMD =-1.2; 95% CI: -1.64 to -0.77), LDL-c concentration (SMD =-0.35; 95% CI: -0.61 to -0.09), and HbA1c (SMD = -0.43; 95% CI: -0.74 to -0.13) in overall analysis. CONCLUSIONS: This meta-analysis has provided evidence that RS supplementation can improve fasting glucose, fasting insulin, insulin resistance and sensitivity, especially for diabetic with overweight or obesity. However, owing to potential sophistication, individual difference and composition of intestinal microbiota, this result should be carefully taken into account.