Horny Goat Weed (Epimedium) is a plant long used in traditional Chinese medicine. Its best-known active compound is icariin, which is why most of the modern research on this herb focuses specifically on icariin rather than the whole plant.
A study published in The Journal of Sexual Medicine (Shindel et al., 2010) examined purified icariin in animal and laboratory models and found it acted as a mild PDE5 inhibitor — the same general mechanism used by some prescription medications for blood flow — along with neurotrophic (nerve-supporting) effects in the tissue studied.
Important context: that research was conducted in laboratory and animal models, not in human clinical trials. It tells us icariin has a plausible biological mechanism worth studying further — it does not prove a specific dose in a supplement produces the same effect in humans.
Horny Goat Weed is HorseWood's lead ingredient for blood flow support.
See HorseWood Pricing & AvailabilityHealthy blood flow is relevant to general physical performance, not just one specific use, so including a botanical with a documented (if early-stage) mechanism makes formulaic sense alongside HorseWood's other ingredients.
Horny Goat Weed's active compound icariin has real, published research behind a blood-flow-related mechanism — but that research is still in the lab and animal stage. It's a reasonable traditional ingredient with early science behind it, not a guaranteed effect.
Source: Shindel AW et al., "Erectogenic and neurotrophic effects of icariin, a purified extract of horny goat weed," J Sex Med, 2010.
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