Chrysin

Chrysin is a flavonoid marketed as a 'natural aromatase inhibitor' to reduce estrogen and boost testosterone. In vitro, chrysin is a potent aromatase inhibitor (IC50 = 1μM). In vivo, it's COMPLETELY inactivated by glucuronidation in the intestine — oral bioavailability is essentially ZERO. A 2001 study found 1,000mg/day chrysin had NO effect on testosterone or estrogen in men. The in vitro → in vivo disconnect is absolute. Our assessment: does not work orally. The marketing is based on cell culture data that doesn't translate. --- *Reviewed by the Dose AI Research Team and Clinical Advisory Board* *Last updated: 2026-04-06*