Cramp bark (also known as Viburnum opulus) has long history of traditional use in North America.
Modern scientific studies have shown that cramp bark extract contains compounds that help promote kidney health1,2.* Its extract is rich in a variety of biological compounds, including beta-sitosterol, coumarins proteins and tannins, as well as elements like zinc.
Studies in the early 1960s examined the chemical content of cramp bark, and found that its constituents esculetin and scopoletins support normal smooth muscle tone1.* The antioxidant effect of flavonoids and carotenoids in cramp bark also help promote kidney health3.*
- Jarboe CH, Zirvi KA, Nicholson JA, Schmidt CM. J Med Chem. 1967;10(3):488-489. doi:10.1021/jm00315a045
- Nicholson JA, Darby TD, Jarboe CH. Proc Soc Exp Biol Med. 1972;140(2):457-461.
- Kızılay F, Ülker V, Çelik O, et al. Turkish J Urol. 2019;45(Supp. 1):S63-S69. doi:10.5152/tud.2019.23463