This semi-essential amino acid optimizes blood flow to vital organs, tissues, and muscles by converting into nitric oxide. The “L” in front of the amino acid name denotes the molecule’s form; it means levoratory.
The body generally produces healthy amounts of arginine, but supplementation may provide additional health and ergogenic benefits.
Because of its vasodilatory effects, it has caught the attention of several health professionals and body builders alike.
This chemical building block continues to make waves as more supportive studies are published. Here is a look at some key benefits arginine offers:
As L-arginine is converted to nitric oxide, vascular smooth muscle relaxes, allowing for enhanced blood flow to important organs like the penis.
In one study, 50 men suffering from organic erectile dysfunction supplemented L-arginine over a 6-week period. Arginine supplementation resulted in notable improvement in sexual function; specifically, nitrate and nitrite levels doubled by the trial’s end.
Studies surrounding arginine’s ability to increase human growth hormone production are ongoing, but results are promising.
Researchers note a moderate L-arginine dose increased resting growth hormone levels by 100%.
Additional studies show synergistic effects of arginine plus lysine on human growth hormone release. Researchers believe this combination influences human growth hormone and also triggers pituitary somatotropin and insulin release.
Research shows taking arginine influences time to exhaustion and anaerobic threshold, both of which appear interrelated.
In a double-blind, cross over study, an arginine beverage or a placebo beverage were consumed by 9 male test subjects who underwent moderate and intense exercises 1 hour post ingestion.
Results show plasma nitrate content was higher in the arginine beverage group when compared to placebo, systolic blood pressure was lowered, and time to exhaustion during intense exercise increased.
Arginine is generally safe for most users when taken short term and in small doses. Arginine has been shown to cause side effects in some cases. Side effects include:
- Abdominal pain
- Airway inflammation
- Low blood pressure
- Blood abnormalities
Those pregnant or breastfeeding should avoid arginine use to be safe. There isn’t enough information to determine whether long-term supplementation may have adverse side effects in pregnant or breastfeeding women.
Arginine supplementation may be unsafe in children when used in high doses.
If you have low blood pressure, taking arginine may be dangerous as it may lower blood pressure even further.
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-  Stephen J. Bailey, et al. “Acute L-arginine supplementation reduces the O2 cost of moderate-intensity exercise and enhances high-intensity exercise tolerance.” Journal of Applied Physiology. August 19, 2010. Jap. 00503.2010.
-  “L-Arginine.” WebMD.