That said, I think that guys like myself who eat a ton of plant foods have to be consider the fact that they may not always be getting all the niacin they could.  Men with lower niacin status can probably give their erectile strength and cardiovascular health a nice boost by consuming more niacin-rich plant foods.  There are many plant foods, such as broccoli and mushrooms that are quite high in niacin.  I actually consume nutritional yeast and BPA-free sardines daily and get a nice amount of niacin this way on top of my regular diet.  Therefore, I feel that I am likely maximizing my erectile strength by combining the best of both worlds, i.e. some NO-boosting plant foods and high niacin foods as well.  (Both  sardines and nutritional yeast also have a decent amount of protein as well, which is important to me since I enjoy lifting weights.)

Niacin -- with or without the addition of drugs to treat impotence -- poses serious health risks, including stomach ulcers and liver damage. If you have Type 2 diabetes, taking niacin could cause drastic elevations in your blood sugar levels. Less serious side effects include stomach upset and skin flushes -- your face and chest turn red and your skin itches, tingles or burns. You can purchase niacin without a prescription, but some over-the-counter formulas -- no-flush varieties that contain niacinamide -- will unlikely help lower your cholesterol.
In fact, dyslipidemia is commonly found in ED patients, and studies show that statins can help to improve the response of PDE5 inhibitors in those suffering from ED precisely because they improve atherosclerosis. Consequently, statins can be used as a treatment in patients with an unsatisfactory response to PDE5 inhibitors, yet there are problems with statins too, among them raised liver enzymes and muscle problems, some of which can be quite serious and even deadly (rhabdomylosis).
You may find that using a vacuum device requires some practice or adjustment. Using the device may make your penis feel cold or numb and have a purple color. You also may have bruising on your penis. However, the bruises are most often painless and disappear in a few days. Vacuum devices may weaken ejaculation but, in most cases, the devices do not affect the pleasure of climax, or orgasm.
Yohimbe bark is an herbal supplement. Its species name is Pausinystalia yohimbe. Yohimbe comes from the bark of the evergreen Corynanthe yohimbe tree, which is in the plant family called Rubiaceae. The active ingredient in yohimbe, called yohimbine, is also used to make certain medications. Civilizations in Western Africa have used it for centuries. Today it’s studied for its ability to help treat conditions including erectile dysfunction/impotence, diabetes, depression, hypotension, and overuse of certain medications.
Yohimbine may be stacked with other supplements to improve erection quality and/or expedite fat loss. If you're consuming yohimbine to improve your erection quality, then stack it with horny goat weed. [3] Animal models support a yohimbine dose of 0.2mg/kg of bodyweight stacked with a 55 to 110mg dose of horny goat weed to significantly increases erection strength. [16]
However, you might actually be better off going one step back in the chain reaction and taking an L-citrulline supplement. While your body converts L-arginine to nitric oxide, it also metabolizes it too fast when the amino acid is taken in an oral supplement, according to a 2011 study from the University of Foggia in Italy. L-citrulline, which the body converts to L-arginine, is actually a better option to follow the same metabolic pathway and serve as a treatment for ED, the same study found.

All hormone determinations were performed by radioimmunoassay using kits provided by commercial suppliers. All blood samples were drawn between 8 am and 1 pm, quickly spun down, frozen, and then stored. All determinations were performed at the same time after the end of the study. The serum LH kit was obtained from Nichols Institute (now Quest; Tarzana, CA, USA) (normal male range, 1.4–11.1 mIU/ml). The serum free testosterone kit was obtained from Diagnostic Products Corporation (DPC, Los Angeles, USA) (normal male range, 15–40 pg/ml). The serum cortisol kit was bought from DPC (normal morning range, 10–24 mcg/dl; normal afternoon range, 5–12 mcg/dl). The serum dehydroepiandrosterone sulfate kit was obtained from DPC (normal range, 150–350 mcg/dl from adolescence to the peak at age 50 y, with a progressive decrease with advancing years).
L-arginine, or arginine, is an amino acid found in red meat, poultry, fish, and dairy products that helps expand blood vessels and increase blood flow. “The body uses this semi-essential amino acid as the primary building block for nitric oxide,” explains Harry Fisch, M.D., clinical professor of urology and reproductive medicine at Weill Cornell Medical College/New York Presbyterian Hospital.
Can one of the B vitamins actually improve erectile dysfunction?  The research makes a strong case that Niacin, a.k.a. Vitamin B3, does indeed do just that for a big percentage of men. Of course, this is a inexpensive help to erectile issues, as high niacin foods and supplements are cheap and readily available.  Below I summarize the most prominent human evidence to date that shows which men will likely benefit and why:
According to the Centers for Disease Control and Prevention, ingesting levels of zinc in excess of the recommended dietary amount will result in diarrhea, vomiting, and stomach cramps. The maximum amount of daily zinc consumption recommended is 40 milligrams per day. Symptoms of too much zinc intake include nausea and headaches. If you have reason to suspect you have ingested too much zinc, contact a medical professional.