Chrysin is available as a bodybuilding supplement and it is taken with the hope of raising testosterone levels or stimulating testosterone production; however, there is no clinical evidence for this effect.
Studies show that chrysin has no effect on estrogen levels in either animals or humans.[medical citation needed] Early evidence was reported in the early 1980s through in vitro studies. Follow-up studies determined that cell membranes effectively block chrysin from entering the cells and having any effect at all on estrogen levels in organisms.
In vivo studies lend support to the observation that chrysin has no effect on estrogen levels, but may have other detrimental effects to the body, particularly to thyroid function. For instance, a 30 day study administered chrysin to four groups of mice both orally and via injection to examine chrysin's effect on serum estrogen levels. The results showed that chrysin had no effect on estrogen levels. Further, the mice treated with chrysin became considerably fatter, possibly due to chrysin's ability to disrupt thyroid function.[full citation needed][unreliable source?] Another study on rats administered 50 mg of chrysin per kg body weight, considerably more than found in dietary supplements. Chrysin was found to have no ability to inhibit aromatase, possibly due to poor absorption or bioavailability.
Peak plasma chrysin concentrations after oral dose of 400 mg = 3–16 ng mL−1 
Plasma chrysin sulfate concentrations were 30-fold higher (AUC 450–4220 ng mL−1 h).
Excretion: urine peak concentration = 0.2–3.1 mg. Most of the dose appeared in feces as chrysin.
In vitro study shows that chrysin inhibits COX-2 expression and via IL-6 signaling, which may contribute to anti-inflammatory effects.
In a 1997 rodent study, chrysin injections displayed dose-dependent anxiolytic effects similar to that of diazepam. Unlike diazepam, the training and test performance of rats injected with chrysin was not significantly reduced. The authors proposed that chrysin does not produce the cognitive impairment usually associated with benzodiazepine medications. However, oral bioavailability of chrysin is still very poor.
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