Nicotine interferes with other bodily functions as well, which makes it a multiple culprit in erectile dysfunction. Another pleasure poison to be avoided in favor of an improved sexual function is coffee. Unless they have own experience in the field, a large number of men would not believe that food could be a major influence on sexual function. But as a matter of fact, food will exert a stronger influence than many of the substances sold as sexuality-enhancing supplements. Take for example nuts.
Vitamin E is an, albeit weak, vasodilator.
Arginine is an amino acid that is used by the body to form nitric oxide. Nitric oxide works as the primary neurotransmitter facilitating erections. Theoretically, pure l-arginine, taken as nutritional supplement, should facilitate the erectile response. However, this doesn't seem to work as it should. I have experimented myself with various dosages of arginine, probably with up to ten grams a day.