Tribulus terrestris
Tribulus is a source of steroidal saponins such as protodioscin. Tribulus allegedly increases testosterone via stimulation of the pituitary gland to produce luteinizing hormone (LH), which, in turn, acts on the testes. This claim is based on older Bulgarian research that has not been replicated in the West. Although it’s known to raise testosterone in animals, recent studies on humans have shown that Tribulus has no significant effects on testosterone or LH levels, body composition, or exercise performance.
See Paul’s Tribulus review for more information.
Protodioscin
A steroidal saponin found in various herbs (Tribulus terrestris and fenugreek) used in “male” enhancement/testosterone-boosting supplements. Protodioscin’s reputed aphrodisiac effects may be due to its conversion to DHEA in the body and/or via the release of nitric oxide in penile tissues.
Indole-3-Carbinol
A phytochemical found in cruciferous vegetables (i.e., cabbage, broccoli, brussels sprouts, kale). Indole-3-carbinol (I3C) is the precursor to diindolylmethane (DIM) – to which it is rapidly metabolized in vivo. Like DIM, I3C has been investigated for possible prevention/treatment of breast/prostate cancers.
For more information, visit the Linus Pauling Institute Micronutrient Information Center.
Cnidium monnieri
Cnidium seeds—or “She Chuang Zi”—are used in Chinese traditional medicine to treat skin disorders and boost libido. Several bioactive coumarins have been identified in Cnidium, but osthol is the best known and characterized.
Osthole appears to be orally bioavailable and may improve bone strength, inhibit tumor growth, reduce allergic reactions and have antioxidant/hepatoprotective effects. It also appears to increase nitric oxide levels in penile tissue, and may act as a phosophodiesterase inhibitor similar to Viagra…which may account for Cnidium’s reputation as an aphrodisiac. In addition, one, small study published in an obscure, Chinese language journal reported osthole increased gonadotropin and testosterone levels in rats given high doses.
Cnidium extracts are used in various “male” sexual enhancement products, as well as an increasing number of bodybuilding supplements. Unfortunately, there are no human studies, nor any clue about what constitutes an active, oral dose in humans to achieve any of the above effects.
Icariin
The flavonoid compound in Horny Goat Weed thought to be responsible for its aphrodisiac effects. Icariin is a phosphodiesterase-5 (PDE-5) inhibitor, and may act as a sort of “herbal Viagra” to enhance/maintain erectile function. Cell culture and animal experiments have shown icariin is biologically active, and also has anti-osteoporotic, neuroprotective and antioxidant activities.
