What is it and where does it come from?
Nitric Oxide is a free form gas that is produced in the body and is used by the body to communicate with other cells in the body. To produce this gas, enzymes in the body break down the amino acid Arginine.
Nitric Oxide is a molecule consisting of one atom of nitrogen and one atom of oxygen. The production of Nitric Oxide occurs when the amino acid L-arginine is converted into L-citruline through an enzyme group known as Nitric Oxide Synthase (NOS). The chemical process of conversion is shown in figure 1.
What does it do and what scientific studies give evidence to support this?
Despite the claims of some in the supplement industry, there exists ample scientific literature to substantiate the efficacy of Nitric Oxide products. The following was written in May 1996 in a document prepared for the Royal Society and Association of British Science Writers:
"Summary research papers continue to flood the scientific journals and insights into the biological activity and potential clinical uses of nitric oxide (NO): a gas controlling a seemingly limitless range of functions in the body. Each revelation adds to nitric oxide's already lengthy resume in controlling the circulation of the blood, regulating activities of the brain, lungs, liver, kidneys, stomach and other organs.
The molecule governs blood pressure through a recently recognized process that contradicts textbook wisdom. It causes penile erection by dilating blood vessels and controls the action of almost every orifice from swallowing to defecation. The immune system uses nitric oxide in fighting viral, bacterial and parasitic infections, and tumors. Nitric oxide transmits messages between nerve cells and is associated with the process of learning, memory, sleeping, feeling pain, and, probably depression. It is a mediator in inflammation and rheumatism."
Since the above was written in 1996, Nitric Oxide containing products have continued to be touted by those in the medical profession, as well as by athletes looking to add muscle to their frames.
The above quotation states that Nitric Oxide controls the circulation of blood, transmits messages between nerve cells, and is a mediator of inflammation and is associated with the process of feeling pain. The popular erectile dysfunction drug sildenafil citrate (Viagra) contains nitric oxide and is responsible for increasing blood flow to the penis.
The fact that nitric oxide increases blood flow should make it of interest to bodybuilders, as increased blood flow will serve to deliver more nutrients to muscles, thus helping muscles become larger when subject to stress. The fact that Nitric Oxide acts to reduce inflammation should also make it of interest to bodybuilders as it has the potential to reduce the pain associated with subjecting muscles to extreme stress.
Nitric oxide also affects the endocrine system. It affects the release of gonadotroptin releasing hormone, as well as the release of adrenaline from the adrenal medulla.
Who needs it and what are some symptoms of deficiency?
Everyone requuires nitric oxide to carry out key physiological processes within the body. From a bodybuilder's perspective, nitric oxide supplementation may prove useful in increasing growth due to increases in blood flow to certain areas of the body. Further, men suffering from erectile dysfunction may also find supplementing with nitric oxide helpful.
Signs of deficiency include the inability to achieve and sustain erections, physical weakness and extreme fatigue. Most "nitric oxide" supplements contain the amino acid Arginine-alpha-keto-glutarate.
How much should be taken? Are there any side effects?
With any amino acid containing product, overdose is a possibility. Dosing with too much arginine can lead to diarrhea, weakness and nausea. Clear dosing guidelines have not been established, so it is best to do what is known as "tolerance mapping". Take a small dosage for one week, note the benefits and the side effects, and increase the dosage until the benefits are maximized and the side effects minimized. Over time the two will converge and you will hit the optimal dose. This process is similar to "receptor mapping" for bodybuilders who use insulin.
Many protein powders are fortified with amino acids, including arginine. With this in mind, pay particular attention to how much arginine you are ingesting from all supplements taken.