"What I do remember reading years ago, was a book by Dr. Abram Hoffer, who apparently reversed his own mother’s Alzheimer’s with Niacin, vitamin B3. Niacin is a vasodialator - it enlarges constricted capillaries, so more blood can get through. It has been researched and used since the 1950s for heart assistance. An interesting side effect is enhanced orgasm, due to increased histamine production."
That's exactly how nitric oxide works with the various erection dis-function meds. BTW, B-12 injections are amazing for energy. However, they last only a day or two.