Introduction: The efficacy and safety of arginine supplements in erectile dysfunction (ED) remain debatable.
Aim: To assess the potential role of arginine supplements on ED as alternatives to phosphodiesterase inhibitors.
Methods: Studies published up to April 2018 that evaluated the efficacy of arginine supplements were identified from multiple databases (Google Scholar, PubMed, Medline, Embase, Kiss, DBpia, and Cochrane databases). Studies comparing arginine supplements with placebo or no treatment; focusing only on patients with mild to moderate severity of ED; and presenting outcomes such as improvement rate, International Index of Erectile Function (IIEF) score, and adverse effects were included. Subgroup analysis for arginine alone and arginine in combination with other substances was further conducted to increase interpretability.
Main Outcome Measure: The strength of the association between arginine supplements and ED was assessed using relative odds ratios and weighted mean differences with 95% CI.
Results: In total, 10 randomized controlled trials met the inclusion criteria, reporting the outcomes of 540 patients with ED. The analysis demonstrated that arginine supplements with dosage ranging from 1,500 to 5,000 mg significantly improved ED compared with placebo or no treatment (odds ratios, 3.37 [1.29, 8.77], P = .01, I2 = 44). Arginine supplements also caused significant improvements in the IIEF subdomain scores of overall satisfaction, intercourse satisfaction, orgasmic function, and erectile function, whereas the IIEF sexual desire score remain unchanged. The adverse effect rate in the arginine-treated group was 8.3%, and that in the placebo group was 2.3%, none of which were severe.
Clinical Implications: Arginine supplements can be recommended to patients with mild to moderate ED.
Strength & Limitations: The strength of this study is that it is the first meta-analysis to assess the potential role of arginine supplements in ED compared with placebo or no treatment. A limitation is that the treatment dosage and duration varied among studies, which may have contributed to study heterogeneity.
Conclusion: The results of our systematic review and meta-analysis provide evidence on the effectiveness of arginine supplements for mild to moderate ED.
Nitric oxide related ergogenic aids such as arginine (Arg) have shown to impact positively on sport performance through several physiological and metabolic mechanisms. However, research results have shown to be controversial. The great differences regarding required metabolic pathways and physiological demands between aerobic and anaerobic sport disciplines could be the reasons. The aim of this systematic review and meta-analysis was to evaluate the effects of Arg supplementation on aerobic (≤VO2max) and anaerobic (>VO2max) performance. Likewise, to show the effective dose and timing of this supplementation. A structured search was carried out in accordance with PRISMA® (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement and PICOS guidelines in PubMed/MEDLINE, Web of Science (WOS), and Scopus databases from inception to January 2020. Eighteen studies were included which compare Arg supplementation with placebo in an identical situation and testing its effects on aerobic and anaerobic performance tests. Trials analyzing supplementation with other supplements were removed and there was not athlete’s level, gender, ethnicity, or age filters. The performed meta-analysis included 15 studies and random effects model and pooled standardized mean differences (SMD) were used according to Hedges’ g. Results revealed that Arg supplementation could improve aerobic (SMD, 0.84; 95% CI, 0.12 to 1.56; magnitude of SMD (MSMD), large; I2, 89%; p = 0.02) and anaerobic (SMD, 0.24; 95% CI, 0.05 to 0.43; MSMD, small; I2, 0%; p = 0.01) performance tests. In conclusion, acute Arg supplementation protocols to improve aerobic and anaerobic performance should be adjusted to 0.15 g/kg of body weight ingested between 60–90 min before. Moreover, chronic Arg supplementation should include 1.5–2 g/day for 4–7 weeks in order to improve aerobic performance, and 10–12 g/day for 8 weeks to enhance anaerobic performance.
Background: Previous studies suggest that L-arginine, an amino acid and a substrate of nitric oxide synthase, may have blood pressure (BP)-lowering effect. Because some studies were performed with limited number of patients with hypertension and therefore limited statistical power with sometimes inconsistent results, we aimed to examine the effect of oral L-arginine supplementation on BP by conducting a meta-analysis of randomized, double-blind, placebo-controlled trials.
Methods: PubMed, Cochrane Central Register of Controlled Trials, and the ClinicalTrials.gov databases were searched through June 2011 to identify randomized, double-blind, placebo-controlled trials of oral L-arginine supplementation on BP in humans. We also reviewed reference lists of obtained articles. Either a fixed-effects or, in the presence of heterogeneity, a random-effects model was used to calculate the combined treatment effect.
Results: We included 11 randomized, double-blind, placebo-controlled trials involving 387 participants with oral L-arginine intervention ranging from 4 to 24 g/d. Compared with placebo, L-arginine intervention significantly lowered systolic BP by 5.39 mm Hg (95% CI -8.54 to -2.25, P = .001) and diastolic BP by 2.66 mm Hg (95% CI -3.77 to -1.54, P < .001). Sensitivity analyses restricted to trials with a duration of 4 weeks or longer and to trials in which participants did not use antihypertensive medications yielded similar results. Meta-regression analysis suggested an inverse, though insignificant (P = .13), relation between baseline systolic BP and net change in systolic BP.
Conclusions: This meta-analysis provides further evidence that oral L-arginine supplementation significantly lowers both systolic and diastolic BP.