Therapeutic Benefits of l-Arginine: An Umbrella Review of Meta-analyses.

OBJECTIVE: l-Arginine is a semi-essential amino acid that is the substrate for nitric oxide production by vascular endothelial and immune cells. Nitric oxide production by these cells is essential for both blood pressure regulation and immune regulation. However, there is much discrepancy in the literature when it comes to randomized controlled studies, and so this umbrella review of published meta-analyses was performed to examine the efficacy of l-arginine's role as a therapeutic agent.

METHODS: There was an overall search of the literature from January 1, 1980 through December 31, 2015 of three separate databases-PubMed, Cochrane Library, and Cumulative Index to Nursing and Allied Health Literature-using the following search strategy: (arginine) AND (meta-analysis OR systematic review). Only English language publications were retrieved that provided quantitative statistical analysis of outcomes on blood pressure and immune function.

RESULTS: The 7 meta-analyses that were included in this umbrella review reported significant positive benefits for reducing systolic and diastolic blood pressure in hypertensive adults by 2.2 to 5.4 mm Hg and 2.7 to 3.1 mm Hg, respectively, reducing diastolic blood pressure in pregnant women with gestational hypertension by 4.9 mm Hg, and reducing the length of stay in the hospital for surgical patients; in addition, 2 of the 3 meta-analyses indicated a 40% reduction in the incidence of hospital-acquired infections. However, these positive results should be considered with caution because statistically significant heterogeneity was observed in 5 of the 7 meta-analyses.

CONCLUSIONS: Some evidence appears to support the benefit of l-arginine supplementation for reducing systolic and diastolic blood pressure in hypertensive adults and reducing the incidence of hospital-acquired infections and the length of stay in the hospital for surgical patients. Given the limitations of the included studies, interpretations should be made with caution.