Effect of L-arginine on immune function: a meta-analysis.

L-arginine plays an important role in immune regulation by affecting the immune response and inflammation. This meta-analysis was performed to assess whether L-arginine supplementation could improve the outcomes of immune function, and to evaluate the safety of L-arginine supplementation. Four databases (PubMed, EMBASE, Web of Science, the Cochrane Library) for all randomized controlled trials investigating the effects of supplementation with L-arginine published from 1966 to September 2013 were searched. The quality of controlled trials was assessed with the Jadad method. Meta-analyses were performed with fixed- or random-effects models according to heterogeneity of studies. Data from 11 trials involving 321 patients were enrolled. Meta-analysis showed that the L-arginine supplement group had a significantly greater CD4⁺ T-cell proliferation response (MD 5.03; 95% CI 1.11, 8.95; p<0.05), and that the incidence of infectious complications was lower (OR 0.40; 95% CI 0.17, 0.95; p<0.05) than control.