Vitamin A deficiency has been a trigger of impotence in some men. Vitamin A! "Vitamin A deficiency has been the trigger of impotence in some males," says Elson Haas, M.D., Director of the Preventive Healthcare Center. Much more frequently than not Erectile Dysfunction is short-term. Muira Puama for occasion helps a man have harder erections and increased libido because it is regarded as a nerve stimulant.