Most people consume the amino acid arginine in their daily diets through foods like beef, poultry, eggs and milk, and this provides a sufficient amount of arginine in the body to facilitate nitric oxide production. Because arginine acts as a precursor to nitric oxide in your body, some supplement companies claim that taking additional arginine will lead to increased nitric oxide levels. These companies primarily back their claims with anecdotal evidence rather than well-controlled scientific studies.
Cardiovascular Disease Treatment
Supplemental arginine can increase your nitric oxide levels if you have certain cardiovascular conditions that impair your ability to produce the compound naturally. In 2005, researchers from Japan and the US jointly published an extensive study of arginine, citrulline and antioxidant supplementation for atherosclerosis in the journal "PNAS." The researchers gave each supplement daily to 49 male rabbits with the artery clogging disease. After 12 weeks, the rabbits significantly increased the amount of nitric oxide in their blood and showed improved blood flow in their arteries.
Sports Supplements
Sports supplement manufacturers promote arginine supplements like L-arginine, arginine alpha-ketoglutarate and arginine ketoisocaproate as being able to significantly increase the amount of nitric oxide in your body. These companies claim that the nitric oxide will increase blood flow to your muscles so you can work out harder and see greater muscle development. Registered dietitian Ellen Coleman states that these claims are likely untrue, because your body regulates the nitric oxide concentration in your blood. Therefore, healthy individuals like bodybuilders and athletes cannot increase nitric oxide levels beyond a certain point and would simply be wasting money on an arginine supplement.
Other Claimed Uses
Researchers have explored the nitric oxide producing potential of arginine for several low blood flow conditions. For example, subjects with intermittent claudication --- a painful condition in which your legs do not receive enough blood --- showed some improvement after taking arginine in a 1998 study. Some small trials have shown similar improvements in the treatment of male and female sexual dysfunction. However, contradictory trials showing no effect from arginine supplementation exist in most cases; and the few positive studies tend to have design flaws that make their results questionable.
Arginine Safety
Arginine is a fairly safe supplement, and doses up to 20 g per day appear to cause no greater side effect than mild gastrointestinal distress. Clinical trials of the more complex forms of arginine, like arginine alpha-ketoglutarate, have seen subjects consume up to 12 g daily without problems. However, arginine has many functions in your body beyond nitric oxide production, and supplements may therefore present other safety issues. For example, arginine can increase stomach acid production, alter potassium levels and increase insulin sensitivity. Always consult a medical professional before taking an amino acid supplement such as arginine.
References
- New York University Langone Medical Center: Arginine
- Huntington College of Health Sciences; Nitric Oxide Boosters; Gene Bruno, M.H.S.; 2009
- California State University; Evaluating Popular Sports Supplements; Ellen Coleman, M.A., M.P.H., R.D., C.S.S.D.; 2008
- "PNAS"; L-Citrulline and L-Arginine Supplementation Retards the Progression of High-Cholesterol-Diet-Induced Atherosclerosis in Rabbits; Toshio Hayashi et al.; September 2005
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