Piperine is the compound in black pepper that slows the body's breakdown of some other compounds. Taken with curcumin, it raised curcumin absorption by 2000% in human volunteers.
Also called black pepper extract.
Piperine is a known inhibitor of glucuronidation in the liver and intestine, one of the ways the body processes and clears compounds such as curcumin (Shoba 1998).
The key study, from 1998, tested it in rats and in healthy human volunteers (Shoba 1998). In people, 2 g of curcumin on its own gave serum levels that were undetectable or very low. With 20 mg of piperine, levels were much higher from 15 minutes to an hour after the dose, and bioavailability rose by 2000%. In rats, given much higher doses by body weight, the rise was 154% (Shoba 1998). The study reported no adverse effects at the doses used.
There is a wrinkle. A 2025 study found that curcumin monoglucuronide, a product of glucuronidation, blocks MMP13 directly (Roy 2025). How piperine's effect interacts with that hasn't been tested.