Vitamin A deficiency has been a trigger of impotence in some men. Vitamin A! "Vitamin A deficiency has been the cause of impotence in some males," states Elson Haas, M.D., Director of the Preventive Medical Center. More often than not Erectile Dysfunction is temporary. Muira Puama for instance helps a man have harder erections and increased libido because it is considered a nerve stimulant.