Nitric oxide (NO) naturally occurs in the body and plays a key role in vascular health. According to the National Institutes of Health, NO is a cell signaling molecule that is synthesized from L-arginine, a naturally occurring amino acid found in spinach, chicken, shellfish, nuts, seeds and some grains. It acts as a messenger between cells to help dilate blood vessels and increase blood flow.
NO supplements do not actually contain nitric oxide. They contain L-arginine (or other forms of arginine) which is later converted into nitric oxide in the body. According to Medline Plus, L-arginine is possibly effective in treating the following:
- Better surgery recovery
- Congestive heart failure
- Angina/chest pain
- Bladder inflammation
- Weight loss in people with HIV (when combined with HMB and glutamine)
- Erectile dysfunction
- Digestive tract inflammation in preemies
- Helps improve kidney function in kidney transplant patients who take cyclosporine
- Leg cramping due to blocked arteries
Several studies on NO have been performed. Here are some highlights:
- Using inhaled nitric oxide in infants after congenital heart surgery was shown to decrease the risk of pulmonary hypertensive crisis.
- Studies show a clear connection between NO levels and cardiac function but researchers admit much more study is needed to definitively determine if NO can prevent or treat heart disease or congestive heart failure.
- According to an abstract published by the American Heart Association, NO activity is deficient in people with coronary artery spasm (angina). As a result, it's believed L-arginine may help improve the symptoms of angina or chest pain.
- NO appears to play a primary role in maintaining erection. A PubMed abstract determined high doses of L-arginine caused improvement in men with erectile dysfunction who also had reduced urine nitrate production.
- L-arginine was found to reverse the antinatriuretic effect of cyclosporine in kidney transplant patients. In addition, studies showed people with kidney disease to have reduced NO production. As a result, the possibility of using L-arginine supplementation to help treat kidney disease is being explored and studied further.
A Body Builder's Best Friend or Hype?
NO supplements are used by many body builders and fitness enthusiasts (men and women) to build muscle, increase strength and improve recovery time. Since NO increases blood flow to muscles, it's believed taking NO supplements can help increase muscle mass. However, a study on eight healthy men concluded that arginine supplementation does not increase NO synthesis in the body or increase blood flow to muscles.
Evidence supporting NO supplements as a means to increase muscle mass is mostly anecdotal. However, many body builders and athletes continue to use them and tout their success. More research is needed to definitively prove or disprove their efficacy.
Side Effects and Interactions
When taken as directed for a short period of time, WebMD classifies NO supplements (in the form of L-arginine) as "possibly safe." But users may experience these side effects:
- Abdominal pain
- Blood abnormalities
- Inflammation of airways
- Worsening of asthma
- Low blood pressure
- Increases bleeding risk
- Changes blood sugar levels
- Blood in urine
- Hormone changes
- Leg restlessness
- Lower back pain
- Night sweats and flushing (due to arginine withdrawal)
- Severe tissue damage or numbness (due to arginine injection)
- Medications or herbs that affect blood sugar levels
- Blood thinning medications or herbs that thin the blood
- High blood pressure medications
- Erectile dysfunction drugs
- Nitroglycerin or nitrates
- Antacids or proton pump inhibitors
- Estrogen drugs
- Anti-inflammatories or aspirin
- H2 blockers
If you have any of the above conditions or take any of the above medications, it's critical that you consult your doctor before using NO supplements to avoid potentially dangerous side effects or interactions.
A Potential Powerhouse
Studies clearly show that nitric oxide is critical to cardiovascular health, erectile function and other physiological functions. NO supplementation is proven to be a viable treatment for some health conditions and shows potential in treating others. However, much more study is needed to determine if the benefits outweigh the risks.
NO supplements can interact with many common drugs and make many common health problems worse. If you're trying to decide whether or not nitric oxide supplements can help you, it's very important to discuss the pros and cons with your doctor.