Cardiology · Medical Literature
Effect of L‑arginine supplementation on homocysteine and asymmetric dimethylarginine in atherosclerotic lower limb ischemia.
Abstract
Chronic lower limb ischemia is a manifestation of systemic atherosclerosis frequently accompanied by lipid metabolism disorders, endothelial dysfunction, and disturbances in the L-arginine-nitric oxide (NO) pathway. Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, and homocysteine (Hcy) are recognized markers of vascular risk. This study aimed to evaluate the effect of 2 months of oral L-arginine supplementation (6g/day) on serum ADMA and Hcy concentrations in patients with atherosclerotic lower limb ischemia, depending on lipid metabolism disorder type. In a randomized, double-masked, placebo-controlled trial, 87 patients (50 men, 37 women) were assigned to L-arginine or placebo. Subgroups were defined according to lipid abnormalities: hypertriglyceridemia, hypercholesterolemia, and mixed hyperlipidemia. ADMA was measured by HPLC, and Hcy by fluorescence polarization immunoassay at baseline, 30, and 60 days. L-arginine supplementation significantly reduced ADMA levels in patients with hypercholesterolemia after 30 and 60 days (P<0.05) and in those with mixed hyperlipidemia after 60 days (P<0.05), but not in those with isolated hypertriglyceridemia. Changes in Hcy were not statistically significant. A significant positive correlation between ADMA and Hcy was present in all subgroups, most consistently in hypercholesterolemia. Two-month L-arginine supplementation decreases ADMA concentrations in patients with atherosclerotic lower limb ischemia, with efficacy dependent on the underlying lipid disorder phenotype, suggesting a metabolism-specific modulation of the ADMA-NO axis.
Clinical relevance
Chronic lower limb ischemia, a manifestation of systemic atherosclerosis, is associated with endothelial dysfunction mediated in part by elevated ADMA—an endogenous nitric oxide synthase inhibitor—and hyperhomocysteinemia, both independent vascular risk markers with limited therapeutic targets. This randomized, double-masked, placebo-controlled trial addresses a clinically meaningful gap by interrogating whether oral L-arginine supplementation can modulate the ADMA–NO axis in this high-risk population, stratified by lipid disorder phenotype. Clinicians managing peripheral arterial disease (PAD) should note these findings now, as ADMA reduction represents a potentially actionable endothelial protective mechanism beyond standard lipid-lowering and antiplatelet therapy.
Key findings
1. Study design: 87 patients (50 men, 37 women) with atherosclerotic lower limb ischemia were randomized in a double-masked, placebo-controlled trial to oral L-arginine 6 g/day or placebo for 60 days, with ADMA measured by HPLC and homocysteine (Hcy) by fluorescence polarization immunoassay at baseline, 30, and 60 days. 2. L-arginine supplementation significantly reduced serum ADMA concentrations in patients with hypercholesterolemia at both 30 days (P<0.05) and 60 days (P<0.05), demonstrating an early and sustained effect in this lipid subgroup. 3. In patients with mixed hyperlipidemia, a statistically significant reduction in ADMA was observed at 60 days (P<0.05), indicating a delayed but meaningful response compared to the hypercholesterolemia subgroup. 4. No statistically significant reduction in ADMA was observed in the isolated hypertriglyceridemia subgroup at either time point, suggesting phenotype-specific metabolic modulation of the ADMA–NO axis. 5. Changes in serum homocysteine concentrations were not statistically significant in any subgroup following L-arginine supplementation, indicating that the 6 g/day dose over 2 months does not meaningfully alter Hcy metabolism in this population. 6. A significant positive correlation between ADMA and Hcy was identified across all lipid subgroups, most consistently in the hypercholesterolemia subgroup, reinforcing the biological linkage between these two vascular risk biomarkers.
Practice implications
Oral L-arginine supplementation at 6 g/day for 60 days may be considered as an adjunctive endothelial-protective strategy in patients with atherosclerotic lower limb ischemia, but its ADMA-lowering efficacy appears to be lipid-phenotype dependent—clinicians should prioritize this intervention in patients with hypercholesterolemia or mixed hyperlipidemia, where significant ADMA reduction was demonstrated, rather than applying it indiscriminately to all PAD patients. This intervention should not be substituted for guideline-directed lipid-lowering therapy, as Hcy levels were unaffected, and the clinical impact on hard cardiovascular endpoints was not assessed in this trial. Future practice should incorporate ADMA and lipid phenotype profiling to individualize endothelial-targeted supplementation strategies in the PAD population.