Horny goat weed might benefit ED through its inhibition of phosphodiesterase-5 (PDE-5). This is the same mechanism exerted by pharmaceuticals like Viagra.[1] PDE-5 inhibition increases levels of cyclic GMP, which enhances smooth muscle relaxation and blood flow to the penis and promotes erection. Horny goat weed may also increase the activity of nitric oxide synthase enzymes and elevate the production of nitric oxide, which also promotes smooth muscle relaxation.[2][3]
The potential cardioprotective qualities of horny goat weed may be related to a decrease in vascular smooth muscle cell proliferation, reduced platelet activation, lipid modulation, and improvements in endothelial function.[4] The suspected neuroprotective mechanisms of horny goat weed could include the upregulation of antioxidant activity[5] and the inhibition of inflammation and oxidative stress in the brain.[6][7]