Glucomannan's therapeutic uses
Glucomannan is a natural dietary fiber derived from the tubers of the Amorphophallus konjac plant, and it is recognized for its potential therapeutic uses. Primarily, it is proposed for managing high cholesterol levels, as studies have shown that glucomannan can reduce low-density lipoprotein (LDL) cholesterol and may even elevate high-density lipoprotein (HDL) cholesterol. Additionally, glucomannan is being explored for its benefits in weight management, as it expands in the stomach, promoting a feeling of fullness that could aid in weight loss efforts. Other areas of interest include its potential to regulate blood sugar levels, which may be beneficial for individuals with diabetes, as well as its possible role in managing blood pressure and treating constipation. Emerging research also suggests glucomannan could have cancer-fighting properties, although further investigation is needed. While generally considered safe, some users might experience mild gastrointestinal symptoms; thus, it is essential to approach supplementation with care. Overall, glucomannan presents a promising option for various health conditions, warranting further exploration and research.
Glucomannan's therapeutic uses
- DEFINITION: Natural plant product used to treat specific health conditions.
- PRINCIPAL PROPOSED USE: High cholesterol
- OTHER PROPOSED USES: Constipation, diabetes (blood sugar control), high blood pressure, hyperthyroidism, weight loss, possible cancer benefits
Overview
Glucomannan is a dietary fiber derived from the tubers of Amorphophallus konjac. Konjac flour (made from these tubers) is used to make a jelly called konyaku, a common food product in Japan. In 2020, the FDA approved glucomannan to be labeled as fiber, noting that it may help reduce blood cholesterol.
Fiber-containing foods, such as oats, are known to help reduce cholesterol and improve constipation. They may also help regulate blood sugar and reduce weight by creating a feeling of fullness. However, many people have difficulty consuming enough fiber from food, so they turn to fiber supplements, such as guar gum and pectin, to help meet their daily requirements. Glucomannan offers one advantage over these forms of fiber: much smaller doses are necessary. When glucomannan is placed in water, it can swell up to seventeen times its original volume. These qualities make it potentially quite convenient as a fiber supplement.
Requirements and Sources
Although glucomannan can be derived from other sources, such as yeast, most studies have used glucomannan purified from the konjac root.
Therapeutic Dosages
Most studies described in this article used 3 to 5 grams (g) per day in divided doses before meals. However, there are concerns regarding the form of glucomannan used.
Therapeutic Uses
Several small, controlled studies have found glucomannan to effectively improve cholesterol profiles. Glucomannan appears to reduce low-density lipoprotein (LDL or bad) cholesterol and, according to some studies, increase high-density lipoprotein (HDL or good) cholesterol. In addition, it may improve blood pressure.
Glucomannan might be useful for people trying to lose weight by expanding in the stomach. Many people report a feeling of fullness after taking glucomannan, and some studies found a significant weight loss among those taking glucomannan compared to those on a placebo. However, not all studies of glucomannan for weight loss have had positive results.
Glucomannan may also help the body to regulate blood sugar levels and, therefore, could help treat diabetes. Additionally, glucomannan might be helpful for individuals who experience episodes of low blood sugar following stomach surgery. Like other dietary fibers, glucomannan may help treat constipation.
Hyperthyroidism is a state in which thyroid hormone levels are too high. A preliminary trial found some evidence that when glucomannan is added to standard treatment, normal thyroid hormone levels are restored more rapidly.
Scientific Evidence
High cholesterol and high blood pressure. In a double-blind study, sixty-three people were given either 3.9 g per day of glucomannan or a placebo for four weeks and then switched to the other treatment. While taking glucomannan, participants showed significant reductions in total cholesterol, LDL cholesterol, and triglycerides compared with the placebo. Their systolic blood pressure (the upper number in the blood pressure reading) was also reduced. However, there was no significant increase in HDL cholesterol or improvement in the LDL-to-HDL cholesterol ratio.
Participants in another study were given either 3 g per day of glucomannan or a placebo over eight weeks. The glucomannan group showed improvements in total and HDL cholesterol and a reduction in systolic blood pressure. Those taking glucomannan also lost weight, whereas the placebo group gained weight over the course of the trial.
Several other controlled studies have found similar results. In addition, a mathematical review combining the results of fourteen studies found that glucomannan significantly reduced total and LDL cholesterol levels.
Weight loss. A few small, double-blind studies suggest that glucomannan may be helpful for people trying to lose weight; however, in other studies, no such benefit was seen. One double-blind, placebo-controlled trial of twenty women who were more than 20 percent over their ideal weight found glucomannan to be more effective than placebo at promoting weight loss. All participants were instructed not to change their eating or exercise habits while on the treatment. Those in the treatment group took 2 g of glucomannan three times a day for eight weeks and lost an average of 5.5 pounds during that period.
In comparison, those in the placebo group gained an average of 1.5 pounds, a significant difference. The glucomannan group also had a reduction of total and LDL cholesterol, as well as triglyceride levels. Benefits were also seen in a double-blind, placebo-controlled trial of twenty-eight overweight people who had just experienced a heart attack.
However, another double-blind trial of sixty obese children did not find a significant difference in weight loss between the glucomannan and the placebo groups. In this study, the children received either 1 g of glucomannan or 1 g of the placebo twice a day for eight weeks.
Double-blind, placebo-controlled studies conducted in 2022 and 2023 appeared to confirm the ability of glucomannan to reduce body weight and fat mass and lead to increased weight loss and improved body composition.
Diabetes. A study of individuals with diabetes tested the effectiveness of glucomannan fiber-enriched biscuits against wheat bran biscuits for blood sugar control. While using the glucomannan biscuits, people experienced a significant improvement in glucose control compared with those using the wheat bran biscuits. Other studies have also found evidence that glucomannan can improve blood sugar control. Additional double-blind, placebo-controlled studies conducted in 2020 and 2021 noted supplementation with glucomannan improved blood sugar control and reduced insulin resistance.
Cancer. In the early 2020s, research began emerging surrounding the promising cancer-fighting properties of glucomannan. Further research is required, but the natural substance's ability to inhibit early-stage tumor development gave researchers hope for further use in developing treatments.
Safety Issues
In Japan, food products containing glucomannan have a long history of use and are believed to be safe. However, there are some concerns about taking glucomannan as a supplement. Some people taking glucomannan complain of excess gas, stomach distension, or mild diarrhea. These symptoms usually diminish within a couple of days of treatment or with a dosage reduction.
In a few cases, glucomannan tablets have obstructed the esophagus when they expanded before reaching the stomach. In response to these reports, tablets of this type have been banned. Capsules, however, do not pose the same risk because their casing prevents the glucomannan from contacting water until it reaches the stomach. The dramatic expansion of glucomannan has also raised some concerns that it could obstruct the intestines; nonetheless, there have been no reports of this happening. One option to offset all expansion risk is to mix glucomannan powder in water so that it expands before it is ingested; however, this strategy reduces the convenience of this form of fiber.
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