Glucomannan
Content by: OpenSupplement Editorial Team | Medical review: pending | Last updated: April 13, 2026
TL;DR
Super-soluble fiber from the Konjac root
Moderate evidence for weight loss and cholesterol reduction
Unrivaled water-absorption capacity; can absorb 50x its weight
Safe but requires careful dosing to avoid choking
Affordable: ~$8-12/month
Best for: Appetite control, mild cholesterol support
What it is
Glucomannan is a dietary fiber often found in 'shirataki' noodles or as a supplement. It is the most viscous natural fiber known. Because it expands so much in the stomach, it is primarily used to promote a feeling of fullness and to slow gastric emptying.
Like psyllium, it binds to bile acids to lower cholesterol, but its 'main event' is weight management. It creates a thick gel that stays in the stomach longer than other fibers, sending 'I'm full' signals to the brain.
What the research says
A 2008 systematic review in the American Journal of Clinical Nutrition confirmed that glucomannan significantly lowers total cholesterol, LDL, and triglycerides. It is slightly more 'potent' per gram than psyllium for cholesterol, but often harder to take in large quantities.
Glucomannan is a solid tool for weight and sugar. Weight Loss. A 2005 study showed that glucomannan (1g taken before each meal) led to significant weight loss in overweight individuals over 5 weeks. Blood Sugar. It lowers the 'glycemic index' of meals, making it useful for preventing post-meal sugar spikes. Note. The weight loss benefits are only significant when combined with a calorie-controlled diet. [1][2][3]
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Glucomannan on Amazon
Safety
Safe, but with a warning: it can be a choking hazard if swallowed as a dry powder or in large tablet form because it expands so quickly. Always take with a full glass of water. Not recommended for those with esophageal disorders.
Interactions
- Medications: Same as psyllium; it can delay or reduce the absorption of oral drugs. Separate by 2-4 hours.
Dosing
Standard Dose: 1 gram taken 3 times daily, 30-60 minutes before meals. Form: Capsules are standard, but must be taken with 8oz of water.
Cost
Affordable. $8-12 per month.
The bottom line
Glucomannan is the 'ultimate filler.' If your main struggle with metabolic syndrome is hunger and overeating, it is a very useful evidence-based tool.
References
- Sood N, Baker WL, Coleman CI. Effect of glucomannan on plasma lipid and glucose concentrations, body weight, and blood pressure: systematic review and meta-analysis. Am J Clin Nutr. 2008;88(4):1167-1175.
- Keithley JK, Swanson B, Mikolaitis SL, et al. Safety and efficacy of glucomannan for weight loss in overweight and moderately obese adults. J Obes. 2013;2013:610908.
- Zalewski BM, Chmielewska A, Szajewska H. The effect of glucomannan on body weight in overweight or obese children and adults: a systematic review of randomized controlled trials. Nutrition. 2015;31(3):437-442.
Sources for this page include published meta-analyses, systematic reviews, and NIH dietary supplement fact sheets. All claims reflect the evidence as of early 2026.
This is not medical advice. Consult your healthcare provider before starting any supplement, especially if you take medications.