Effect of glucomannan on plasma lipid and glucose concentrations, body weight, and blood pressure: systematic review and meta-analysis

Background: Several clinical trials have investigated the impact of glucomannan on plasma lipids, body weight, fasting blood glucose (FBG), and blood pressure (BP), but have yielded conflicting results and had only modest sample sizes. Objective: The objective was to perform a meta-analysis of randomized controlled trials of glucomannan to better characterize its impact on plasma lipids, FBG, body weight, and BP. Design: A systematic literature search of MEDLINE, EMBASE, CINAHL, Web of Science, the Cochrane Library, and the Natural Medicines Comprehensive Database was conducted from the earliest possible date through November 2007. A random-effects model was used to calculate the weighted mean difference (WMD) and 95% CIs as the difference between the mean for the glucomannan and control groups. Standard methods for assessing statistical heterogeneity and publication bias were used. Results: Fourteen studies (n = 531) met the inclusion criteria. The use of glucomannan significantly lowered total cholesterol [weighted mean difference (WMD): −19.28 mg/dL; 95% CI: −24.30, −14.26], LDL cholesterol (WMD: −15.99 mg/dL; 95% CI: −21.31, −10.67), triglycerides (WMD: −11.08 mg/dL; 95% CI: −22.07, −0.09), body weight (WMD: −0.79 kg; 95% CI: −1.53, −0.05), and FBG (WMD: −7.44 mg/dL; 95% CI: −14.16, −0.72). The use of glucomannan did not appear to significantly alter any other study endpoints. Pediatric patients, patients receiving dietary modification, and patients with impaired glucose metabolism did not benefit from glucomannan to the same degree. Conclusions: Glucomannan appears to beneficially affect total cholesterol, LDL cholesterol, triglycerides, body weight, and FBG, but not HDL cholesterol or BP.