L-arginine is an amino acid found in various foods and also available as a dietary supplement, which your body uses for many important functions. It has been used to treat a variety of health conditions and also shows promise in improving clogged arteries. Research results are mixed, with some studies showing positive effects of L-arginine on blood vessels and others indicating no difference or that L-arginine actually worsened certain artery problems. Check with your doctor before taking L-arginine supplements, particularly if you know you have cardiovascular disease.
Significance
L-arginine is known as a semi-essential amino acid because if you're healthy, your body normally manufactures enough on its own. Arginine is unique among all amino acids for its ability to relax smooth muscle cells within the artery walls and widen blood vessels, a process called vasodilation. This is important for heart health, because when arteries get clogged from a buildup of a waxy substance called plaque, causing atherosclerosis, it can reduce or block blood flow to your heart and lead to a heart attack, stroke and even death.
Benefits for Arteries
Healthy arteries are dependent upon the thin layer of cells that line their interior surface called the endothelium and the nitric oxide they produce. L-arginine is essential for the production of nitric oxide and also in promoting endothelial function, one reason the supplement is sometimes used to treat coronary artery disease. This protective effect apparently increases as you age. A study published in the "British Journal of Nutrition" in May 2011 showed that L-arginine reduced the mean frequency of cholesterol-induced artery lesions in older rabbits but not in younger animals. L-arginine was also shown to improve exercise tolerance in patients with stable coronary artery disease in a study published in the "International Journal of Cardiology" in September 2000.
Risks for Arteries
Peripheral artery disease, PAD, is a narrowing of arteries of the pelvis and legs. Due to L-carnitine's known effects in reducing atherosclerosis, researchers at the Stanford University School of Medicine in California investigated L-arginine on PAD. They found that L-arginine was not helpful in improving nitric oxide availability for the peripheral arteries as compared to a placebo group. Patients taking the supplement also had worse measures of the absolute claudication distance, or distance at which the patients could no longer walk due to pain, than patients in the placebo group.
Warning
There have been a few reports of a severe allergic reaction after receiving L-arginine injections. Side effects from oral supplements are milder and include nausea, stomach cramps and an increased number of stools. The Mayo Clinic notes that if you have liver or kidney disease, you may be more sensitive to certain complications from L-arginine and should only supplement under your doctor's supervision. The Sloan-Kettering Memorial Cancer Institute reports that limited studies indicate L-arginine supplementation may increase breast tumor growth.
References
- Mayo Clinic: L-Arginine
- Sloane-Kettering Cancer Center: L-Arginine
- "Circulation"; L-Arginine Supplementation in Peripheral Arterial Disease: No Benefit and Possible Harm; A.M. Wilson, et al.; July 2007
- "Journal of Nutrition"; Arginine and Endothelial and Vascular Health; H.L. Gornik and M.A. Creager; October 2004
- "British Journal of Nutrition"; Atheroprotective Effects of Dietary L-Arginine Increase with Age in Cholesterol-Fed Rabbits; S.G. Cremers, et al.; May 2011
- "International Journal of Cardiology"; Effects of Oral L-Arginine Supplementation on Exercise-Induced QT Dispersion and Exercise Tolerance in Stable Angina Pectoris; B. Bednarz, et al.; September 2000
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