What Is Chrysin?

Chrysin is a naturally occurring polyphenol found in the passion flower and in the sticky, resinous substance that bees use to build their hives. Specifically, chrysin belongs to a class of polyphenols known as flavonoids. A wide variety of health claims have been made for chrysin, and early studies-- most of them based on in-vitro testing--have been promising. However, more human tests of chrysin's effects will be needed before its medicinal value can be definitively determined.

Makeup

• Chrysin's chemical designation is 5,7-Dihydroxyflavone, and it is a bioflavonoid--the label given to flavonoids when they are used in foods or dietary supplements. Other well-known bioflavonoids are epigallocatechin-3-gallate (EGCG), which is found in green tea, and quercetin, a powerful antioxidant found in red onions and apples.

Early Studies

• Early in-vitro studies showed that chrysin was an effective inhibitor of the aromatization process through which the body converts testosterone into estrogen, according to naturalnews.com. Excessive levels of estrogen have been implicated as a causal factor in breast cancer. The news also caught the attention of the bodybuilding community, which is always on the lookout for substances that can increase testosterone levels or disrupt any process that leaches testosterone from the body. The enzyme that activates the testosterone-to-estrogen conversion is known as aromatase, and the early tests showed that chrysin is an effective aromatase inhibitor, at least in the test tube.

Human Tests Equivocal

• A study by Xia Wen and Thomas Walle, which was published in the July 25, 2006, issue of Drug Metabolism and Disposition, revealed that chrysin and other flavonoids were not as effective in human testing. These disappointing results were blamed on the "very low oral bioavailability, as has been shown in clinical studies of some of the more prominent polyphenols, for example, chrysin (5,7-dihydroxyflavone). . . . " However, Wen and Walle found that chrysin and other flavonoids were far better utilized by the human body when they were introduced in methylated form.

Chinese Study

• Further evidence of chrysin's anti-cancer effectiveness came in a Chinese study that was published in the January 2007 issue of Molecular Cancer Therapeutics. Medical researchers at China's Institute for Nutritional Sciences looked specifically at chrysin's use in treating human prostate cancer cells. They concluded that chrysin is a "potent inhibitor" of hypoxia-inducible factor-1alpha (HIF-1alpha). Their research showed that chrysin "inhibited insulin-induced expression of HIF-1alpha by reducing its stability," and they urged further study into chrysin's anti-cancer properties.

Anxiety-Reducing Effects

• In a study published in the October 2007 issue of AANA Journal, the official journal of the American Association of Nurse Anesthetists, U.S. Army researchers reported that chrysin appeared to have anxiety-reducing properties. In a study with live rats, chrysin was compared to midazolam, a powerful anxiolytic drug, marketed under various brand names, including Versed. The researchers concluded that chrysin had effects similar to those of midazolam but "of somewhat lesser magnitude." They concluded that further study is needed.