Attenuation of Lipid Metabolism by Novel Pleiotropic Effects of Konjac Glucomannan

Abstract

Background: Recently, we showed that konjac glucomannan (KGM) inhibited rice gruel-induced postprandial elevation of plasma glucose and insulin. To extend that research, we investigated the effects of adding KGM to rice gruel on pre- and postprandial circulating lipoprotein lipase (LPL), glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1), and triglyceride concentrations. Methods: Twenty-four Japanese male subjects without diabetes or gastrointestinal diseases (aged 46–56 years) were included. Subjects received rice gruel containing 0% or 0.8% of KGM (0%G and 0.8%G, respectively). Blood samples were obtained at preload and 30, 60, and 120 min after receiving rice gruel with or without 0.8% KGM. LPL, GPIHBP1, and triglyceride concentrations in these samples were measured. Results: Circulating triglycerides were significantly reduced at 30 min and then returned to the fasting value in the subjects who received 0%G, whereas lower triglyceride levels were sustained in those who received 0.8%G. Although circulating levels of LPL and GPIHBP1 were significantly reduced for 0%G, they were increased for 0.8%G. We found a significant negative correlation between circulating levels of fasting LPL and triglycerides and a significant positive correlation between circulating levels of fasting LPL and GPIHBP1. A significant negative correlation between circulating levels of triglycerides at 120 min and fasting LPL was shown in the 0.8%G group, but not in the 0%G group. A significant positive correlation between circulating levels of LPL at 0 min and 120 min was shown in the 0%G and 0.8%G groups.Conclusions: The results demonstrated a novel pleiotropic effect of KGM. Supplementation of KGM powder in rice gruel sustained lower levels of triglycerides accompanying elevation of LPL and GPIHBP1, which attenuated lipid metabolism. Additionally, fasting LPL is a predictor of postprandial circulating levels of LPL.Trial registration: UMIN registration number: UMIN000025950; registered at February 1st. 2017; https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000029247