Butternut (Juglans cinerea) is a tree native to eastern North America. Herbalists historically used extracts of the inner bark as a laxative or digestive aid, but no modern clinical evidence supports any health benefit. Authoritative health organizations do not recommend these uses.
The tree contains juglone, a compound that can irritate the skin and may be toxic to the kidneys. Internal use carries real risks, and no reliable dose has ever been established. Anyone considering it should seek professional guidance.