By: David A Fein, MD
Medical Director
Princeton Longevity Center
Erectile dysfunction affects at least 2 out of every 3 men at some point in their life. And virtually every male notices significant changes in erectile function with age. While many biological systems contribute to the complex mechanism of erection, optimizing overall vascular health is key to keeping your peak sexual performance. One of the most important factors in keeping your arteries at their peak is a small molecule that regulates blood flow called nitric oxide. Nitric Oxide has many roles in maintaining regulating vascular function throughout the body. It also plays a role in reducing inflammation, prevents clotting inside blood vessels and may also help to prevent stiffening of the arteries with age. As we age, nitric oxide production tends to diminish. But other conditions, such as diabetes, hypertension, smoking and obesity will also tend to lower nitric oxide production even more. You can help to improve nitric oxide production by exercising more, losing weight, not smoking and limiting alcohol intake. Taking the right nutritional supplements can help even more.
Erections are primarily a function of hydraulics- increasing blood flow into the penis is what makes it all happen. Sexual stimulation activates nerve fibers originating in the spinal cord that switch on the production of nitric oxide in the arteries of the penis. The increasing nitric oxide level activates an enzyme which converts a substance known as GTP into cGMP. Then, cGMP causes the muscles around the arteries to relax and increase blood flow. As long as there are high enough levels of cGMP the increased blood flow helps to maintain an erection.
Drugs like Viagra and Cialis work by blocking another enzyme called PDE5 which breaks down cGMP. By maintaining higher levels of cGMP those drugs help to sustain increased blood flow. But to work effectively, those drugs still require adequate production of nitric oxide to create cGMP in the first place.
Nitric oxide is primarily made from a common amino acid, L-arginine. Taking L-arginine supplements will enhance nitric oxide production and improve arterial function. However, L-arginine has limited effectiveness because it is rapidly metabolized by the liver and does not remain in the bloodstream for longer than about 30 minutes.
A better choice is another amino acid, L-citrulline. This amino acid is gradually converted to to L-arginine by the kidneys, in essence acting like a time-release form of L-arginine.
In 2011, a study published by Dr Luigi Cormio showed an improvement from mild erectile dysfunction to normal function in 50% of men taking L-citrulline 1.5 grams per day compared with only 8% in those taking a placebo. Other studies have shown that combining L-citrulline with PDE5 inhibitors such as Viagra can work significantly better than Viagra alone.
L-arginine is commonly available in the vitamin section of most pharmacies. Because fewer people are aware of the better effects from L-citrulline and most stores don’t get requests for it, it is not as widely available. However, you can generally find it at reputable sources such as Vitamin Shoppe and GNC.
Another option is Aged Garlic Extract. The enzyme that converts L-Arginine to nitric oxide is called nitric oxide synthetase. Studies have shown that garlic extracts can improve the function of this enzyme and increase nitric oxide levels throughout the body by about 30-40%. The effect starts within about 30 minutes and lasts for 2-3 hours. The effects of garlic extract on nitric oxide levels and blood pressure may vary depending on the specific type of garlic extract, dosage, and individual factors. Kyolic Aged Garlic Extract 2 capsules per day has been shown to improve blood pressure control, reduce the progression of coronary artery disease as well as improving overall vascular function.
L-citrulline and aged garlic extract are generally safe and well tolerated. If you have noticed that time has been taking a toll on your sexual performance, adding these supplements along with good nutrition, exercise and healthy lifestyle may help to turn back the clock.
