Much of the evidence shows high rates of vitamin D deficiency in patients with erectile dysfunction. In fact, one study of 3,400 participants found that men with vitamin D deficiency were 32% more likely to have trouble with erections when all other risk factors were controlled for. It’s a little on the nose that you need vitamin D for your “D,” but hey—science can be funny too.
There have been some studies to suggest that a placebo effect that improves ED may work for some men. One study found that men taking an oral placebo pill showed as much improvement in ED symptoms as men who took actual medication to improve ED. Conversely, men who were given therapeutic suggestions to improve ED did not see signs of symptom improvement.