L-Arginine and Nitric Oxide (NO)

The benefits of L-arginine are generally well-known, at least among athletes who use it to achieve optimum performance. L-arginine is a form of amino acid that is normally produced naturally in the body and can also be obtained through diet and supplements.

L-Arginine works by combining with a family of enzymes called Nitric Oxide synthases to produce Nitric Oxide along with citrulline (another amino acid). Nitric Oxide was only discovered in the late 1990s by researchers looking for the physical mechanism that caused L-arginine to promote blood vessel relaxation.

Nitric Oxide relaxes blood vessels, keeps arteries flexible and increases blood flow. It is of particular interest to bodybuilders and sports participants because it boosts natural muscle gain, increases endurance levels and improves overall strength. Information is communicated by the nervous system at a faster pace, increasing alertness, while glucose is removed from the blood to improve blood flow.

Increased blood flow means that vital nutrients (such as oxygen, glucose, amino acid and creatine) are carried more quickly to the muscles, promoting growth and energy production. At the same time, the by-products of metabolism that fatigue the muscles (such as carbon dioxide and lactic acid) are removed in an efficient manner. The result is that muscles grow bigger, stronger and recover more quickly.

Increasing the production of Nitric Oxide can be achieved by taking supplements of the various amino acids - Arginine, Citrulline and Aspartic Acid. Rather than taking these separately, products are available that provide them together in a fixed dose tablet. This has the advantage of providing the various components in the most appropriate proportions. Nitric Oxide production is limited by the availability of Nitric Oxide synthase enzymes and too much Arginine can be overwhelming so getting the mix right is crucial. Products also generally ensure that supplements are time-released so that Nitric Oxide is produced over a longer period and the beneficial effects are increased.

These supplements have few side effects when taken at normal levels (L-arginine has a recommended single dose of 4-6 grammes). However, the liver and intestines break down some of the amino acids before they are absorbed by the blood vessels. This means that a good proportion does not get to the muscles it is intended to benefit and so higher doses (often up to 20 grammes) may well be taken to compensate for the loss and get the full benefit. Exceeding the recommended dose can lead to possible side effects such as heartburn, ulcers and gallstones.