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Digestion/Heart/Weight

Glucomannan

Soluble fiber from konjac root that promotes fullness, supports bowel regularity, and helps lower cholesterol in adults with low fiber intake.

Glucomannan
60
score
B
evidence
Caution
risk

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This supplement may interact with medications, medical conditions or sensitive populations. Review safety before use.

Quick Take

Worth it if you need more fiber for constipation or cholesterol; modest help for weight loss alongside diet changes.

Glucomannan is a highly viscous soluble fiber extracted from konjac (elephant yam) and used in foods such as shirataki noodles. In the gut, it absorbs water and forms a gel that slows gastric emptying and reduces the absorption of cholesterol and glucose. Clinical trials and meta-analyses support modest improvements in bowel regularity, LDL cholesterol, and weight loss. It may also blunt post-meal glucose spikes. People with low fiber intake, constipation, elevated LDL, or weight-loss goals are most likely to benefit.

Potential benefits

01
Promotes bowel regularity
02
Lowers LDL cholesterol
03
Supports weight loss
04
May lower post-meal glucose spikes
05
May support gut microbiome
06
May lower blood pressure

Protocol

Amount
1 g
Frequency
3 times daily, before meals
When
15-30 minutes before meals with at least 8 oz (240 mL) of water to prevent choking and allow gel formation.

Onset Time

Bowel effects in 12-72 h; weight and cholesterol in 4-8 weeks

Who Should Consider

Adults with chronic constipation
Overweight adults in a calorie deficit
People with elevated LDL cholesterol
Adults with low dietary fiber intake
People with post-meal glucose spikes

Food Sources

  • Konjac root (elephant yam), rarely eaten whole outside Asia
  • Shirataki noodles (~3% fiber by weight, mostly water)

How It Works

Glucomannan's exceptional water-absorption capacity allows it to expand into a viscous gel in the stomach and small intestine. This gel slows gastric emptying and the absorption of cholesterol and glucose, while adding bulk to stool. The increased viscosity also promotes satiety signals and can reduce overall caloric intake at subsequent meals.

Updated 5/19/2026

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