Glucomannan

Glucomannan is the Western name for vegetable fibers derived from an Asian plant family known as konjac. Glucomannan does not dissolve in water, but forms a thick, gooey gel when exposed to fluids. The body does not digest glucomannan, so the resulting large soft mass moves through the intestines and may trigger intestinal muscle contractions. Therefore, glucomannan is thought to be an effective bulk-type laxative, even though it may take up to 12 hours to be effective.

Glucomannan vs. Obesity and Cholesterol

Glucomannan has also been studied for treating obesity, diabetes, and high cholesterol. Studies in both adults and children with severe obesity showed varying degrees of weight loss associated either with taking supplemental glucomannan or with replacing some of the usual diet with foods made from glucomannan (konjac) flour--the dried and ground tuber (underground stem) of the plant. Generally, glucomannan is believed to discourage overeating because it creates a feeling of fullness after the fiber in it swells. Because stomach contents may stay in the stomach longer, the individual does not feel hungry as often. However, in most of the research studying glucomannan for weight loss, study participants also drank large amounts of water and followed a reduced-calorie diet.

Blood Sugar Levels

Possibly due to the same delay in stomach emptying, glucomannan may improve blood sugar levels in individuals with diabetes. Because the absorption of carbohydrates from foods is slower when glucomannan is taken, blood sugar levels may not rise as high or as fast as usual. Some preliminary results from animal studies also suggest that glucomannan may increase the sensitivity of body tissues to the insulin that is produced or taken. In several studies, taking glucomannan has also appeared to lower blood levels of total cholesterol, low-density lipoproteins (LDL, or "bad" cholesterol), and triglycerides. Although more research on this possible use of glucomannan is needed, glucomannan may increase the elimination of cholesterol and its components from the body. It may also keep bile acids from being reabsorbed in the intestines, further reducing cholesterol levels in the blood, because the body uses cholesterol to produce more bile.