Black Walnut is a rich source of the trace mineral chromium and is also high in iodine. The ancient Greeks used the hulls to support the intestinal system and skin conditions. Herbalists classify black walnut as an astringent because it is rich in tannin, a toning substance. Due to its astringent qualities, black walnut may help the body protect itself from harmful agents, such as parasites.
Black walnut provides the same laxative action as cascara sagrada, but it works more subtly.