I read on WebMD that at least 50% of men suffer from ED. And it can start as early as your 20s. It's not a post-40 issue; it's a men's issue because ED can happen to any man at any time.
In a study "men receiving the herb took 900 milligrams, three times a day, for eight weeks felt improvement in their ED symptoms compared to those who took the placebo. Researchers concluded that red ginseng may be an effective alternative treatment for impotence."
Before you buy a bottle of pills, check the milligrams. Some contain pills as low as 200. If you were to follow this study for yourself, you'd have to take 14 pills a day! That seems a bit excessive. Maybe get a 550 milligram capsule and test your body with 2-3 a day.