What Is An No2 Supplement?

NO2 supplements, also referred to as NOX or nitric oxide supplements, are sports nutrition products intended to encourage production of nitric oxide, explains Bodybuilding.com. The fitness website notes that nitric oxide encourages circulation, which may be useful during athletic activity. Improved circulation can also increase nutrient delivery to muscle cells, which can increase muscle size gains. Consult a doctor before using NO2 or any other supplements, and adhere to label directions.

Purported Function

As the bodybuilding website Testosterone Nation explains, NO2 supplements typically contain ingredients that are precursors to nitric oxide, which means they encourage nitric oxide, or NO2, production. Testosterone Nation notes that nitric oxide is then supposed to cause vasodilation, or the expansion of your blood vessels. Vasodilation makes it easier for blood -- as well as the nutrients it carries -- to move through your blood vessels to working muscle cells. Because your muscle cells require nutrients, such as amino acids, for growth and recovery, the ease of circulation is purported to improve muscle growth.

Common Ingredients

The central ingredient in NO2 supplements is arginine, an amino acid. Bodybuilding.com explains that arginine is converted into citruline by your body. Because of this, some products contain citruline as well. Caffeine is also commonly included in NO2 supplements for pre-workout energy and intensity.

Benefits

Although many supplement manufacturers make lofty claims, few are supported by actual research. According to research published in the June 2009 issue of the "Journal of Nutritional Biochemistry," arginine supplementation did not increase nitric oxide production or athletic performance. However, a study published in the April 2010 issue of the "Journal of Strength and Conditioning Research" indicates that arginine supplementation may increase production of growth hormone and insulin-like growth factor 1, which are involved in muscle development.

Drawbacks

Testosterone Nation explains that arginine, a key ingredient in NO2 supplements, has been shown to cause gastrointestinal discomfort. In addition, arginine use may lead to reductions in your body's supply of water and sodium, an essential electrolyte and nutrient.

Types

According to supplement retailer GNC, the most popular brands of NO2 supplements include BSN NO-Xplode, MRI NO2 Black, Force Factor Nitric Oxide Booster and Nutrex Research Hemo Rage Black.