Chrysin is a flavonoid derived from the blue passion flower (Passiflora caerulea) that supports healthy testosterone levels in men. Chrysin works by inhibiting the action of the enzyme aromatase, which is responsible for the undesirable process of converting testosterone to estrogen. Healthy testosterone levels in men is key to lean muscle mass formation, stamina, and healthy libido. Log on to http://www.tasmanhealth.co.nz/jarrow-chrysin-500/ for more details!!