Can you take glucomannan while breastfeeding?

What LactMed says

The National Library of Medicine’s own summary, quoted in full. We do not write a verdict of our own on this question, and we do not compress theirs into a label.

Glucomannan is a soluble, highly viscous fiber commonly derived from Amorphophallus konjac root. Glucomannan has no specific lactation-related uses. It is most often used to lower cholesterol, to treat constipation and diabetes, and is contained in products to promote weight loss. No data exist on the safety and efficacy of glucomannan in nursing mothers or infants. However, because glucomannan is not absorbable, it will not reach the breastmilk and is very unlikely to affect the nursing infant.

Dietary supplements do not require extensive pre-marketing approval from the U.S. Food and Drug Administration. Manufacturers are responsible to ensure the safety, but do not need to prove the safety and effectiveness of dietary supplements before they are marketed. Dietary supplements may contain multiple ingredients, and differences are often found between labeled and actual ingredients or their amounts. A manufacturer may contract with an independent organization to verify the quality of a product or its ingredients, but that does not certify the safety or effectiveness of a product. Because of the above issues, clinical testing results on one product may not be applicable to other products. More detailed information about dietary supplements is available elsewhere on the LactMed Web site.

Quoted from Glucomannan — Drugs and Lactation Database (LactMed®), National Institute of Child Health and Human Development, revised December 15, 2024.