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L-Arginine & Nitric Oxide Levels

By Chris Daniels

Nitric oxide, NO, is an important signaling molecule in your body, especially in the cardiovascular system. Not to be confused with the analgesic nitrous oxide that you might have received in the dentist's office, nitric oxide is synthesized in the body from the amino acid L-arginine. Supplementation with L-arginine may help offset dysfunction of NO signaling from obesity, aging and smoking.

Function of Nitric Oxide

NO was discovered by Dr. Robert Furchgott as a factor that contributed to the dilation of blood vessels. NO also inhibits the formation of plaque in the arteries and inflammation of surrounding tissues by its action on platelets and immune cells. The thickening of blood vessel walls is also inhibited by NO.

Synthesis of Nitric Oxide

The cells that make up your blood vessels are continually producing a small amount of NO with the enzyme nitric oxide synthetase, NOS. The NOS enzyme turns the amino acid L-arginine into NO. Both increases in blood flow and other biochemical signals can stimulate your blood vessels to produce more up to 1,000 times the NO to stimulate vasodilation.

Intake of L-Arginine

It is rare to see L-arginine deficiency in the modern diet to the extent that health issues arise. Low protein intake or other unhealthy diets may prevent the full range of NO signaling due to unavailability of L-arginine. Not all protein sources contain large amounts of L-arginine. Foods high in L-arginine include walnuts, pecans, sesame seeds, raisins, cereals, chicken, corn, dairy, meat and peanuts.

Nitric Oxide and Disease

Heart disease, obesity, high blood pressure, high cholesterol or triglycerides, aging and smoking can decrease your body's ability to produce or respond to the NO signal. Congestive heart failure, heart disease, peripheral vascular disease, migraines and other diseases may be improved by supplementation with L-arginine to increase NO signaling. According to, initial results of L-arginine have been promising, but no well-controlled, large clinical trials have demonstrated its efficacy.


There is not a standard dose for L-arginine supplements to increase NO signaling. It is common to take 2 g or 3 g of L-arginine two to three times daily. Adding protein to your diet is also another way to increase available L-arginine. Large doses of L-arginine may worsen certain medical conditions, including asthma. Use L-arginine supplements under the supervision of your doctor if you are currently being treated for a medical condition or if you take any other medication on a daily basis.

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