Oral L-arginine improves endothelium-dependent dilation in hypercholesterolemic young adults.
What this study found
Oral L-arginine for 4 weeks significantly improved endothelium-dependent dilation (EDD) of conduit arteries in hypercholesterolemic young adults, increasing EDD from 1.8%±1.3% to 5.7%±3.0% (P<0.001). Placebo produced no significant change. Lipid levels and GTN-mediated dilation remained unchanged. Improvement occurred in about 67% of subjects (18/27). The authors conclude that chronic dietary L-arginine improves large-vessel endothelial function in at-risk individuals and may favorably influence atherogenesis; however, effects were not sustained after cessation and long-term benefits remain…
- Study & population
- 27 hypercholesterolemic adults (18 men, 9 women), age approximately 19–40 years, with endothelial dysfunction and elevated LDL-cholesterol; lifelong nonsmokers; not hypertensive or diabetic; some on stable statin therapy; randomized, placebo-controlled, double-blind crossover trial with two 4-week treatment periods separated by a 4-week washout.
- Intervention
- Oral L-arginine, 7 g three times daily, for 4 weeks; taken as a powder dissolved in water.
- Key limitation
- Small sample size (n=27) and short duration (4 weeks per treatment); nitrosoprotein measures available only for a subset (n=11); some participants on stable statin therapy, introducing heterogeneity; results pertain to young adults with endothelial dysfunction and may not generalize to older individuals or…
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Open PDFOriginal abstract
In hypercholesterolemic rabbits, oral L-arginine (the substrate for endothelium derived nitric oxide) attenuates endothelial dysfunction and atheroma formation, but the effect in hypercholesterolemic humans is unknown. Using high resolution external ultrasound, we studied arterial physiology in 27 hypercholesterolemic subjects aged 29+/-5 (19-40) years, with known endothelial dysfunction and LDL-cholesterol levels of 238+/-43 mg/dl. Each subject was studied before and after 4 wk of L-arginine (7 grams x 3/day) or placebo powder, with 4 wk washout, in a randomized double-blind crossover study. Brachial artery diameter was measured at rest, during increased flow (causing endothelium-dependent dilation, EDD) and after sublingual glyceryl trinitrate (causing endothelium-independent dilation). After oral L-arginine, plasma L-arginine levels rose from 115+/-103 to 231+/-125 micromol/liter (P<0.001), and EDD improved from 1.7+/-1.3 to 5.6+/-3.0% (P<0.001). In contrast there was no significant change in response to glyceryl trinitrate. After placebo there were no changes in endothelium-dependent or independent vascular responses. Lipid levels were unchanged after L-arginine and placebo. Dietary supplementation with L-arginine significantly improves EDD in hypercholesterolemic young adults, and this may impact favorably on the atherogenic process.