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Also known as Arginine, L-Arginine Hydrochloride
Conditionally essential amino acid and substrate for nitric oxide synthase; oral supplementation has been studied for effects on vascular function, blood pressure and exercise performance.
We link to relevant studies and leave interpretation to you and your healthcare professional.
The large figures are what the studies reported for each thing they measured. Open a card for every result.
No figure given: Mean arterial pressure (no clear benefit); Heart rate (no clear benefit); Heart rate recovery (no clear benefit).
Audited published research for L-Arginine by condition. Drill into a pair page for the full breakdown.
Each bar counts published studies for this compound in that condition.
Summaries of published trial results for this compound, grouped by condition. In these tables every number is exactly as the researchers published it. The headline figures above show a simple average where several studies measured the same thing in the same unit, and say so; nothing else is calculated or converted.
How to read this table
In short: benefit is what was observed; evidence is how much you should trust the observation. A “Benefit seen” tag on a weak study counts for far less than the same tag on a meta-analysis.
| Outcome measured | What trials found | Effect size | People studied | Duration | Type of evidence | Study |
|---|---|---|---|---|---|---|
| diastolic BP (DBP) | L-arginine supplementation improved diastolic BP (DBP) (-2.64 mmHg; 95% CI: -3.94, -1.40; P < 0.001) compared with placebo. (95% CI: -3.94, -1.40; P < 0.001)Benefit seen | -2.64 mmHg | — | — | Meta-analysis · 2022 | PMID 34967840 |
| systolic BP (SBP) | L-arginine supplementation improved systolic BP (SBP) (-6.40 mmHg; 95% CI: -8.74, -4.05; P < 0.001) compared with placebo. (95% CI: -8.74, -4.05; P < 0.001)Benefit seen | -6.40 mmHg | — |
Associated conditions and community-reported outcomes, wrapped together on one page. Aggregates appear only once enough reports arrive.
How this compound is sold in the UK, and where our readers typically find it.
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No figure given: Muscle soreness (no clear benefit); Maximum repetitions (no clear benefit); Perceived exertion (no clear benefit); Blood lactate (no clear benefit); Blood ammonia (no clear benefit); Blood glucose (unclear); Blood glycerol (no clear benefit); Electromyographic signal (no clear benefit); Free fatty acids (unclear); Growth hormone (GH) area under the curve (possible harm); Growth hormone (GH) concentration (no clear benefit); Growth hormone-inhibiting hormone (somatostatin) (unclear); Insulin (unclear); Nitric oxide metabolites (NOx) (no clear benefit); Testosterone-to-cortisol ratio (no clear benefit).
Every result| — |
| Meta-analysis · 2022 |
| PMID 34967840 |
| Heart rate recovery (HRR) | L-arginine (L-ARG) did not significantly improve Heart rate recovery (HRR) (p = 0.944) compared with placebo in Thirty-two. (p = 0.944)No clear benefit | no number reported | Thirty-two | — | RCT · 2024 | PMID 39683461 |
| Mean arterial pressure (MAP) | L-arginine (L-ARG) did not significantly improve Mean arterial pressure (MAP) (p = 0.687) compared with placebo in Thirty-two. (p = 0.687)No clear benefit | no number reported | Thirty-two | — | RCT · 2024 | PMID 39683461 |
| Pulse pressure (PP) | L-arginine (L-ARG) did not significantly improve Pulse pressure (PP) (p = 0.929) compared with placebo in Thirty-two. (p = 0.929)No clear benefit | no number reported | Thirty-two | — | RCT · 2024 | PMID 39683461 |
| Root mean square of successive differences in the RR interval (RMSSD30) of heart rate variability (HRV) | L-arginine (L-ARG) did not significantly improve Root mean square of successive differences in the RR interval (RMSSD30) of heart rate variability (HRV) (p = 0.562) compared with placebo in Thirty-two. (p = 0.562)No clear benefit | no number reported | Thirty-two | — | RCT · 2024 | PMID 39683461 |
| arterial pressure | L-arginine did not significantly improve arterial pressure (p > 0.05) compared with placebo in Eight (90 min). (p > 0.05)No clear benefit | no number reported | Eight | 90 min | RCT · 2016 | PMID 26563117 |
| forearm skin vascular conductance | L-arginine did not significantly improve forearm skin vascular conductance (p > 0.05) compared with placebo in Eight (90 min). (p > 0.05)No clear benefit | no number reported | Eight | 90 min | RCT · 2016 | PMID 26563117 |
| heart rate | L-arginine did not significantly improve heart rate (p > 0.05) compared with placebo in Eight (90 min). (p > 0.05)No clear benefit | no number reported | Eight | 90 min | RCT · 2016 | PMID 26563117 |
| mean skin temperature | L-arginine did not significantly improve mean skin temperature (p > 0.05) compared with placebo in Eight (90 min). (p > 0.05)No clear benefit | no number reported | Eight | 90 min | RCT · 2016 | PMID 26563117 |
| oxygen consumption | L-arginine did not significantly improve oxygen consumption (p > 0.05) compared with placebo in Eight (90 min). (p > 0.05)No clear benefit | no number reported | Eight | 90 min | RCT · 2016 | PMID 26563117 |
| plasma L-ARG concentrations | L-arginine improved plasma L-ARG concentrations (+223 ± 80%) compared with placebo in Eight (90 min).Benefit seen | +223 ± 80% | Eight | 90 min | RCT · 2016 | PMID 26563117 |
| rectal temperature | L-arginine did not significantly improve rectal temperature (p > 0.05) compared with placebo in Eight (90 min). (p > 0.05)No clear benefit | no number reported | Eight | 90 min | RCT · 2016 | PMID 26563117 |
| sweat loss | L-arginine did not significantly improve sweat loss (p > 0.05) compared with placebo in Eight (90 min). (p > 0.05)No clear benefit | no number reported | Eight | 90 min | RCT · 2016 | PMID 26563117 |
| Outcome measured | What trials found | Effect size | People studied | Duration | Type of evidence | Study |
|---|---|---|---|---|---|---|
| blood levels of creatine kinase (CK) | L-arginine supplementation did not significantly improve blood levels of creatine kinase (CK) (P > 0.05) compared with placebo; the difference versus placebo was not statistically established (72 h). (P > 0.05)No clear benefit | no number reported | — | 72 h | RCT · 2018 | PMID 29544063 |
| blood levels of lactate | L-arginine supplementation did not significantly improve blood levels of lactate (P > 0.05) compared with placebo; the difference versus placebo was not statistically established (72 h). (P > 0.05)No clear benefit | no number reported | — | 72 h | RCT · 2018 | PMID 29544063 |
| electromyographic signal (i.e., root mean square (RMS) and median frequency (MF) slope) | L-arginine supplementation did not significantly improve electromyographic signal (i.e., root mean square (RMS) and median frequency (MF) slope) (P > 0.05) compared with placebo; the difference versus placebo was not statistically established (72 h). (P > 0.05)No clear benefit | no number reported | — | 72 h | RCT · 2018 | PMID 29544063 |
| muscle soreness | L-arginine supplementation did not significantly improve muscle soreness (P > 0.05) compared with placebo; the difference versus placebo was not statistically established (72 h). (P > 0.05)No clear benefit | no number reported | — | 72 h | RCT · 2018 | PMID 29544063 |
| number of maximum repetitions | L-arginine supplementation did not significantly improve number of maximum repetitions (P > 0.05) compared with placebo; the difference versus placebo was not statistically established (72 h). (P > 0.05)No clear benefit | no number reported | — | 72 h | RCT · 2018 | PMID 29544063 |
| perceived exertion | L-arginine supplementation did not significantly improve perceived exertion (P > 0.05) compared with placebo; the difference versus placebo was not statistically established (72 h). (P > 0.05)No clear benefit | no number reported | — | 72 h | RCT · 2018 | PMID 29544063 |
| testosterone:cortisol ratio | L-arginine supplementation did not significantly improve testosterone:cortisol ratio (P > 0.05) compared with placebo; the difference versus placebo was not statistically established (72 h). (P > 0.05)No clear benefit | no number reported | — | 72 h | RCT · 2018 | PMID 29544063 |
| GH concentration | L-arginine did not significantly improve GH concentration compared with placebo in Fourteen.No clear benefit | no number reported | Fourteen | — | RCT · 2014 | PMID 24225560 |
| GH-inhibiting hormone concentration | L-arginine showed an unclear effect on GH-inhibiting hormone concentration compared with placebo in Fourteen.Unclear | no number reported | Fourteen | — | RCT · 2014 | PMID 24225560 |
| Integrated area under the curve for GH | L-arginine showed harm (adverse effect) on Integrated area under the curve for GH (288.4 ± 368.7; 487.9± 482.0; p < .05) compared with placebo in Fourteen. (p < .05)Possible harm | 288.4 ± 368.7 | Fourteen | — | RCT · 2014 | PMID 24225560 |
| Plasma L-arginine concentration | L-arginine improved Plasma L-arginine concentration (~120%) compared with placebo in Fourteen.Benefit seen | ~120% | Fourteen | — | RCT · 2014 | PMID 24225560 |
| Ammonia levels | Arginine did not significantly improve Ammonia levels compared with placebo in Twelve.No clear benefit | no number reported | Twelve | — | RCT · 2009 | PMID 19777799 |
| Creatine kinase levels | Arginine did not significantly improve Creatine kinase levels compared with placebo in Twelve.No clear benefit | no number reported | Twelve | — | RCT · 2009 | PMID 19777799 |
| Free fatty acid (FFA) levels | Arginine showed an unclear effect on Free fatty acid (FFA) levels compared with placebo in Twelve.Unclear | no number reported | Twelve | — | RCT · 2009 | PMID 19777799 |
| Glucose concentration | Arginine showed an unclear effect on Glucose concentration compared with placebo in Twelve.Unclear | no number reported | Twelve | — | RCT · 2009 | PMID 19777799 |
| Glycerol levels | Arginine did not significantly improve Glycerol levels compared with placebo in Twelve.No clear benefit | no number reported | Twelve | — | RCT · 2009 | PMID 19777799 |
| Insulin concentration | Arginine showed an unclear effect on Insulin concentration compared with placebo in Twelve.Unclear | no number reported | Twelve | — | RCT · 2009 | PMID 19777799 |
| Lactate levels | Arginine did not significantly improve Lactate levels compared with placebo in Twelve.No clear benefit | no number reported | Twelve | — | RCT · 2009 | PMID 19777799 |
| NOx (NO2(-) + NO3(-)) levels | Arginine did not significantly improve NOx (NO2(-) + NO3(-)) levels compared with placebo in Twelve.No clear benefit | no number reported | Twelve | — | RCT · 2009 | PMID 19777799 |