An antioxidant supplement containing propionyl-carnitine, arginine, and niacin (EAC) improved the effectiveness of Viagra in 68 percent of men suffering from erection problems. Italian researchers found that Viagra by itself improved erectile function in 45 percent of men, while EAC improved function in 32 percent. Poor blood vessel health decreases the release of nitric oxide, which helps control blood flow to the penis.
Viagra promotes erections by increasing nitric oxide release from the cells lining the blood vessels. EAC helps buffer the effects of free radicals— destructive chemicals produced naturally during metabolism— that promote blood vessel disease, interfere with the release of nitric oxide, and cause erection problems. EAC are common ingredients in many popular sex supplements. (Journal Sexual Medicine 7: 1247-1253)