Part Used: Fresh green hull
Black Walnut or American Walnut (Juglans nigra) is a native of eastern North America, where it grows, mostly alongside rivers, from southern Ontario, Canada west to southeast South Dakota, south to Georgia, northern Florida and southwest to central Texas. It is a large deciduous tree attaining heights of 30–40 metres (100–130 feet). The bark is grey-black and deeply furrowed. The active constituents of Black Walnut Hull are aluminum, ascorbic acid, barium, calcium, chromium, phosphorus, potassium, and zinc. The part, Fresh Green Hull is used as intestinal stimulant due to its antimicrobial and anthelmintic actions.
Ancient Greeks and Romans used Black Walnut Hull to promote intestinal health and beneficial microbial activity. Asian peoples have also used the kernel and the green hull to help promote cleansing of the intestinal tract. The high tannin content of this ingredient is primarily responsible for its beneficial properties; although other constituents such as juglandin, juglone and juglandic acid are also most likely involved. Black Walnut is thought to have the ability to oxygenate the blood, which creates a state believed to be hostile to invasive organisms. The green husk contains organic iodine. Iodine is known to have properties which help produce an intestinal environment hostile to harmful bacteria. Black Walnut has been used to promote healthy sugar levels, to help melt away fatty materials, and to detoxify the colon. It is also useful for helping maintain an internal condition that is unfavorable to fungi. It is considered to be an antiseptic, a germicide, a parasitic, and a laxative.
H.Winter Griffith, M.D., associate professor of Family and Community Medicine at the University of Arizona's College of Medicine, writes that Black Walnut hull does indeed help with a variety of health conditions from ridding the body of intestinal parasites and tapeworms to reducing constipation and healing skin conditions like acne, canker sores, psoriasis, and other fungal infections. A new study published in the Journal of the American College of Cardiology found that eating walnuts after a meal high in unhealthy fats can reduce the damaging effects of such fats on blood vessels. In Traditional Chinese Medicine, walnut seeds are primarily considered a kidney tonic. They are also considered beneficial to the brain, back, and skin, and to relieve constipation if it is caused by dryness. Black Walnut hull has been advocated for the prevention and treatment of canine heartworms and a variety of intestinal helminthes.