Konjac glucomannan is produced from the root of the konjac plant, which is native to tropical areas in Asia. It is high in soluble fiber. This dietary supplement has been studied in patients with cancer for the prevention and management of constipation.
Chen, H.L., Cheng, H.C., Wu, W.T., Liu, Y.J., & Liu, S.Y. (2008). Supplementation of konjac glucomannan into a low-fiber Chinese diet promoted bowel movement and improved colonic ecology in constipated adults: A placebo-controlled, diet-controlled trial. Journal of the American College of Nutrition, 27, 102–108.
To examine the effects of konjac glucomannan (KGM) supplementation on bowel habits and colonic environment in adults with constipation, and to examine the method by which KGM modulates bowel habits.
Patients who self-reported having constipation for more than six months were recruited from an outpatient clinic. The study comprised a three-week placebo (gelatin capsules containing corn starch) period, a one-week adaptation period in which KGM was gradually increased from 1.5 to 3 g per day, and a three-week KGM period (1.5 g KGM per meal or 4.5 g per day). Capsules were taken with 150 ml of water. Patients followed a typical low-fiber Chinese diet and were instructed to maintain their usual physical activity, lifestyle, and sleeping habits. Capsule consumption (compliance) was verified daily.
This was a single-blind, placebo-controlled, crossover study.
Adding KGM (4.5 g per day) to a low-fiber diet may increase frequency of bowel movements and improve colonic ecology.
KGM (4.5 g per day) may increase frequency of bowel movements in adults with mild constipation (participants did not use laxatives or enemas). The ecology of the colon may improve with KGM supplementation because the proportion of fecal clostridia and fecal pH decreased. Additional studies are warranted that include an oncology population and a larger sample size.