Glucomannan is a sugar made from the root of the konjac plant (Amorphophallus konjac). Glucomannan powder, capsules, tablets and other products are used as food supplements.
Studies have found glucomannan fibre can make a person feel more full; satiety then helps with weight loss. It may also help with cholesterol control.
Research published in the International Journal of Obesity on 20 obese patients found weight loss of around 5.5 pounds over eight weeks. Cholesterol levels were also significantly reduced.
Claims about nutritional and health benefits are regulated by the European Food safety Authority (EFSA).
It has approved two claims for glucomannan:
- It contributes to weight loss as part of an energy restricted diet when food provides a total daily intake of 3g of glucomannan in three doses of 1g each
- It contributes to the maintenance of normal blood cholesterol levels when food provides a daily intake of 4g of glucomannan.
Glucomannan has also been studied to see if it helps with other health conditions, but the EFSA says there's not enough scientific evidence for claims about glucomannan and:
- Maintenance of normal bowel function
- Helping to control blood glucose/insulin levels and the reduction of glycaemic responses after meals
- Helping to restore the intestinal flora in the gut
Glucomannan carries a risk of choking for people with swallowing difficulties or if it is eaten without enough fluids. People using konjac glucomannan should be advised to drink plenty of water to make sure the supplement gets to the stomach.