1.
Association between dietary fiber intake and risk of coronary heart disease: A meta-analysis.
Wu, Y, Qian, Y, Pan, Y, Li, P, Yang, J, Ye, X, Xu, G
Clinical nutrition (Edinburgh, Scotland). 2015;(4):603-11
Abstract
BACKGROUND & AIMS The association between coronary heart disease (CHD) and dietary fiber intake is not consistent, especially for the subtypes of dietary fiber. The aim of our study was to conduct a meta-analysis of existing cohort published studies assessing the association between dietary fiber intake and risk of CHD, and quantitatively estimating their dose-response relationships. METHODS We searched PubMed and EMBASE before May 2013. Random-effect model was used to calculate the pool relative risk (RRs) for the incidence and mortality of CHD. Dose-response, subgroup analyses based on fiber subtypes, heterogeneity and publication bias were also carried out. RESULTS Eighteen studies involving 672,408 individuals were finally included in the present study. The pooled-adjusted RRs of coronary heart disease for the highest versus lowest category of fiber intake were 0.93 (95% confidence interval (CI), 0.91-0.96, P < 0.001) for incidence of all coronary events and 0.83 (95% CI, 0.76-0.91, P < 0.001) for mortality. Further subgroup analyses based on fiber subtypes (cereal, fruit, and vegetable fiber), indicated that RRs were 0.92 (95% CI, 0.85-0.99, P = 0.032), 0.92 (95% CI, 0.86-0.98, P = 0.01), 0.95 (95% CI, 0.89-1.01, P = 0.098) respectively for all coronary event and 0.81 (95% CI, 0.72-0.92, P = 0.001), 0.68 (95% CI, 0.43-1.07, P = 0.094), 0.91 (95% CI, 0.74-1.12, P = 0.383) for mortality. In addition, a significant dose-response relationship was observed between fiber intake and the incidence and mortality of CHD (P < 0.001). CONCLUSIONS Our results indicate that consumption of dietary fiber is inversely associated with risk of coronary heart disease, especially for fiber from cereals and fruits. Besides, soluble and insoluble fibers have the similar effect. A significant dose-response relationship is also observed between fiber intake and CHD risk.
2.
Dietary fiber intake reduces risk for gastric cancer: a meta-analysis.
Zhang, Z, Xu, G, Ma, M, Yang, J, Liu, X
Gastroenterology. 2013;(1):113-120.e3
Abstract
BACKGROUND & AIMS The association between dietary fiber intake and gastric cancer risk has been investigated by many studies, with inconclusive results. We conducted a meta-analysis of case-control and cohort studies to analyze this association. METHODS Relevant studies were identified by searching PubMed and Embase through October 2012. We analyzed 21 articles, which included 580,064 subjects. Random-effects models were used to estimate summary relative risks. Dose-response, subgroup, sensitivity, meta-regression, and publication bias analyses were performed. RESULTS The summary odds ratios of gastric cancer for the highest, compared with the lowest, dietary fiber intake was 0.58 (95% confidence interval, 0.49-0.67) with significant heterogeneity among studies (P < .001, I(2) = 62.2%). Stratified analysis for study design, geographic area, source and type of fiber, Lauren's classification, publication year, sample size, and quality score of study yielded consistent results. Dose-response analysis associated a 10-g/day increment in fiber intake with a significant (44%) reduction in gastric cancer risk. Sensitivity analysis restricted to studies with control for conventional risk factors produced similar results, and omission of any single study had little effect on the combined risk estimate. CONCLUSIONS In a meta-analysis, we show that dietary fiber intake is associated inversely with gastric cancer risk; the effect probably is independent of conventional risk factors. The direction of the protective association of dietary fiber was consistent among all studies, but the absolute magnitude was less certain because of heterogeneity among the studies. Further studies therefore are required to establish this association.
3.
Effect of dietary fiber on constipation: a meta analysis.
Yang, J, Wang, HP, Zhou, L, Xu, CF
World journal of gastroenterology. 2012;(48):7378-83
Abstract
AIM: To investigate the effect of dietary fiber intake on constipation by a meta-analysis of randomized controlled trials (RCTs). METHODS We searched Ovid MEDLINE (from 1946 to October 2011), Cochrane Library (2011), PubMed for articles on dietary fiber intake and constipation using the terms: constipation, fiber, cellulose, plant extracts, cereals, bran, psyllium, or plantago. References of important articles were searched manually for relevant studies. Articles were eligible for the meta-analysis if they were high-quality RCTs and reported data on stool frequency, stool consistency, treatment success, laxative use and gastrointestinal symptoms. The data were extracted independently by two researchers (Yang J and Wang HP) according to the described selection criteria. Review manager version 5 software was used for analysis and test. Weighted mean difference with 95%CI was used for quantitative data, odds ratio (OR) with 95%CI was used for dichotomous data. Both I(2) statistic with a cut-off of ≥ 50% and the χ(2) test with a P value < 0.10 were used to define a significant degree of heterogeneity. RESULTS We searched 1322 potential relevant articles, 19 of which were retrieved for further assessment, 14 studies were excluded for various reasons, five studies were included in the analysis. Dietary fiber showed significant advantage over placebo in stool frequency (OR = 1.19; 95%CI: 0.58-1.80, P < 0.05). There was no significant difference in stool consistency, treatment success, laxative use and painful defecation between the two groups. Stool frequency were reported by five RCTs, all results showed either a trend or a significant difference in favor of the treatment group, number of stools per week increased in treatment group than in placebo group (OR = 1.19; 95%CI: 0.58-1.80, P < 0.05), with no significant heterogeneity among studies (I(2)= 0, P = 0.77). Four studies evaluated stool consistency, one of them presented outcome in terms of percentage of hard stool, which was different from others, so we included the other three studies for analysis. Two studies reported treatment success. There was significant heterogeneity between the studies (P < 0.1, I(2) > 50%). Three studies reported laxative use, quantitative data was shown in one study, and the pooled analysis of the other two studies showed no significant difference between treatment and placebo groups in laxative use (OR = 1.07; 95%CI 0.51-2.25), and no heterogeneity was found (P = 0.84, I(2)= 0). Three studies evaluated painful defecation: one study presented both quantitative and dichotomous data, the other two studies reported quantitative and dichotomous data separately. We used dichotomous data for analysis. CONCLUSION Dietary fiber intake can obviously increase stool frequency in patients with constipation. It does not obviously improve stool consistency, treatment success, laxative use and painful defecation.