What is nitric oxide?
Nitric oxide is a gas and free radical neurotransmitter naturally produced in the body. It is synthesized from the amino acid L-arginine and oxygen by isoforms of nitric oxide synthase. Nitric oxide synthesis is enhanced by chemicals from Panax ginseng and garlic. The production of nitric oxide is reduced in people with diseases such as diabetes, cardiovascular diseases, erectile dysfunction, hemolysis, and hyperargininemia.
Biological effects of nitric oxide
Research on nitric oxide effects on human health and disease has been a very active area for the last 20 years. A growing amount of evidence is revealing an increasing number of physiological roles and biological effects of nitric oxide and unravelling the mechanisms underlying its effects.
Nitric oxide relaxes blood vessels and improves blood circulation in the body, especially the extremities. It is known to be a primary neurotransmitter and vasodilator involved in penile erection and maintenance. Erectile dysfunction is associated with increase of oxidation or decrease in production of nitric oxide.
Nitric oxide plays an important role in the regulation of thrombosis (blood clotting) and haemostasis (a process that stops bleeding) by regulating platelet aggregate formation.
Garlic’s ability to reduce cardiovascular risk, including abnormal plasma lipids, oxidized low density lipoproteins (LDL), abnormal platelet aggregation and a high blood pressure is credited to its role in stimulating synthesis of nitric oxide. The aphrodisiac effect of the traditional Chinese herb Panax ginseng is also suggested to be due to the herb’s stimulating effect on the synthesis of nitric oxide.
There is also evidence that indicates nitric oxide regulates homeostatic processes in the eye and abnormality in its synthesis could lead to a variety of eye diseases such as glaucoma, retinal degeneration and uveitis.
As a neurotransmitter in the central nervous system, nitric oxide has effects on learning and memory capacity.
Other suggested biological effects of nitric oxide include mitochondria biogenesis, which in turn improves ATP (energy carrier in cells) production and oxygen consumption. The purported involvement of nitric oxide in energy metabolism suggests that it plays an important role in inflammation and obesity, fat cell metabolism, the body's response to calorie restriction and mitochondrial dynamics, all of which are key factors in age-related diseases such as diabetes, cancer, heart disease and neurodegeneration.
Nitric oxide sources
One way to increase the release of nitric oxide in the body is to increase its precursor L-arginine level. Food sources high in L-arginine can be found in this article.
References
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F. Drago, C. Bucolo (2010). Therapeutic potential of nitric oxide modulation in ocular diseases. Drug News Perspect., 23(7):430-7.
George F. Lasker, Jason H. Maley, and Philip J.Kadowitz (2010). A Review of the Pathophysiology and Novel Treatments for Erectile Dysfunction. Adv Pharmacol Sci. 2010; 2010: 730861.
Khalid M. Naseem, Wayne Roberts (2010). Nitric oxide at a glance. Platelets, 2010 Nov 4.
Noboru Toda, Kazuhede Ayajiki, and Tomio Okamur (2005). Nitric oxide and penile erectile function. Pharmacology & Therapeutics, 106 (2): 233-266.