Elephant yam (Konjac), a plant tuber native to Asia, is known scientifically as Amorphopallus konjac or rivieri. Glucomannan (GM), a soluble, fermentable, viscous dietary fiber is obtained from it. GM fiber passes to the colon, where colon bacteria ferment it and gastrointestinal enzymes digest it. GM fiber is also used in jelly, tofu, noodles, as flour, as food stabilizer and as a binder. It is a polysaccharide chain of beta-D-glucose and beta-D-mannose.

The authors studied patients, who were given doses of 2-4 g. per day, to attempt to confirm the previously noted evidence that GM promotes weight loss. The doses were well tolerated and were associated with significant weight loss in obese and overweight patients. GM may work by causing a feeling of fullness of the stomach with few calories consumed and by increasing “fecal energy loss.” GM reduces absorption of fats and proteins and improves the glycemic index.

Capsules and powders of GM are sold as supplements, with the usual dose for weight loss being 1 gm three times a day taken 1 hour before meals. People treating Type two diabetes can take 3.6 to 13 gm/day. The tablets of GM swell rapidly with moisture and can get caught in the esophagus. GM causes drops in blood sugars and should not be used with other treatments to lower blood sugars. GM also reduces the effectiveness of other medications taken simultaneously.

The authors found that patients taking 3 gm./day for 8 weeks lost over 5.5 lbs. of body weight and GM lowered patient’s total cholesterol, reduces LDL-cholesterol and increases HDL-cholesterol. GM also improved glycemic status and other results have been drops in systolic blood pressure. Negative events with GM have included mild bloating, excess gas and diarrhea. Guar gum and psyllium fibers have not been found to work for weight loss.

CONCLUSION: Glucomannan is a safe and effective fiber product for weight loss when used with normal calorie diets, especially in overweight and obese people. Three to four weeks do not seem to be a long enough treatment; an eight-week trial works better.

NOTE: Read the the immunoprotective effects of glucomannan and seabuckthorn.

To read the author’s abstract of the article click on the link to the author’s title of the article above.

PMID: 16320857.

Summary #230.