The case for increasing your dose of vitamin C is pretty good. Evidence suggests that taking vitamin C increases nitric oxide levels in your blood vessels.
Part of the argument for vitamin C is a curious fact of nature – humans are one of the few species ON EARTH that don’t manufacture vitamin C in their bodies. Apparently a mutation millions of years ago in a common ape ancestor resulted in us missing the 4th enzyme needed to make vitamin C, which is why the other apes live in tropical areas (where there are lots of citrus fruits).
Anyway, Linus Pauling did some research on this years ago and calculated that the actual amount of vitamin C we should consume (based on how much other animals produce naturally in their bodies) is much higher than we often consume; further, in times of stress, we would need even more vitamin C. For example, a goat makes 13 g of vitamin C.
So, he suggested that humans take large supplements of vitamin C, just to reach natural levels. He took 6 g of vitamin C a day. You can read his stuff and decide for yourself, but it makes sense to me.
So, are your sexual problems caused by a vitamin C deficiency? It’s probably much more than that, but as far as I know it can’t hurt to pump up your vitamin C intake to 1 g or more. Just do it slowly, as a suddenly intake of 1 g of vitamin C will probably cause diarrhea. I am taking 500 mg/day but am switching to 1000 mg (1 g) soon. Good luck.