Citrulline (L-citrulline and citrulline malate)
Summary
Evidence for citrulline in exercise is limited and conflicting. Pooled trials of citrulline malate show a small overall performance gain and a few extra repetitions in strength sets, but no benefit for endurance. Plain L-citrulline and citrulline malate performed alike in head-to-head trials. Long-term safety has not been adequately studied.
Key facts
- L-citrulline and citrulline malate (citrulline bound to malic acid), including products labelled 2:1[1]
- Citrulline malate is 56.64% citrulline by weight. L-citrulline and citrulline malate gave similar results in two head-to-head trials (D)[1][6][7]
- Overall exercise performance ↑ small (C); repetitions to failure ↑ small (C); endurance: no difference (C); muscle soreness and perceived exertion ↓ (C)[2][3][4][5]
- One cup of diced seedless watermelon has about 365 mg citrulline[1]
- 6 graded human outcomes on this page
- October 8, 2026
How it works
ProposedAbout 80% of the body's citrulline is converted in the kidneys into arginine, which is used to make nitric oxide, a dilator of blood vessels; this might explain any exercise effect (proposed). More citrulline than arginine is absorbed from the gut, so citrulline may raise blood arginine more efficiently. Higher nitric oxide markers have not been directly tied to better performance. Malate is a Krebs-cycle intermediate that might aid energy production (proposed).[1]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Overall exercise performance (citrulline malate) | Improved | Grade C | Meta-analysis · n = 644 · 2026 Participants in 30 randomized controlled trials Form: citrulline malate · Dose: Varied; no dose-related difference found · Duration: Acute (single dose) and chronic protocols Citrulline malate was linked to a small overall improvement in exercise performance (g = 0.16), with wide prediction intervals and limited statistical power. Perceived exertion did not change significantly. GRADE certainty was low to very low. | 42356270 (opens PubMed)Source [2] |
| Perceived exertion and muscle soreness after exercise | Worsened | Grade C | Meta-analysis · n = 206 · 2020 Participants in 13 studies Form: citrulline (most often citrulline malate) · Dose: Most often 8 g citrulline malate · Duration: Not stated in the abstract Citrulline lowered perceived exertion and muscle soreness at 24 hours after exercise, but not soreness at 72 hours or blood lactate. | 33308806 (opens PubMed)Source [5] |
| Endurance: time to exhaustion and time to completion | No effect | Grade C | Meta-analysis · n = 158 · 2023 Young healthy adults in 9 studies Form: citrulline (L-citrulline or citrulline malate) · Dose: Varied across studies · Duration: Acute ingestion No significant difference from control in time to exhaustion (SMD 0.03) or time to completion (SMD -0.07). | 37155582 (opens PubMed)Source [4] |
| Repetitions to failure in strength training | Improved | Grade C | Meta-analysis · n = 137 · 2021 Strength-trained men (101) and women (26) and untrained men (9) in 8 double-blind, placebo-controlled studies Form: citrulline malate · Dose: 6–8 g, 40–60 minutes before exercise · Duration: Single dose Citrulline malate increased total repetitions by about 3 (6.4%) versus placebo, a small effect (SMD 0.196). Lower-body results showed a tendency for an effect; upper-body results were not significant. | 34010809 (opens PubMed)Source [3] |
| L-citrulline vs citrulline malate: strength and power in one session | No effect | Grade D | Crossover RCT · n = 43 · 2025 Young trained men and women (21 women) Form: L-citrulline vs citrulline malate vs placebo · Dose: 5.3 g citrulline, with or without 2.7 g malate, 45 minutes before exercise · Duration: Single doses Neither form improved maximal strength, jump or ballistic performance, repetitions, bar velocity or perceived exertion compared with placebo. | 39662304 (opens PubMed)Source [6] |
| L-citrulline vs citrulline malate over 6 weeks of training | Improved | Grade D | RCT · n = 33 · 2025 Resistance-trained men Form: L-citrulline vs citrulline malate vs placebo · Dose: 8 g L-citrulline or 12 g citrulline malate daily · Duration: 6 weeks Both forms increased upper-body repetitions to failure versus placebo, with no difference between them. One-rep-max strength did not differ between groups; post-exercise nitric oxide markers were higher with citrulline malate than placebo. | 40470618 (opens PubMed)Source [7] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| L-citrulline | 100%[1] | In head-to-head trials, results matched citrulline malate at equal citrulline doses (single session) and at 8 g vs 12 g daily over 6 weeks.[6][7] | Up to 6 g/day for 4 weeks and 1.35 g/day for 6 weeks caused no adverse effects in short studies of nonathletes (ODS).[1] | Endurance tests; repetitions; comparisons with citrulline malate |
| Citrulline malate (1:1) | 56.64%[1] | No head-to-head absorption data in our sources; outcome trials found no clear advantage over L-citrulline.[6][7] | Stomach discomfort in 6 of 41 men after 8 g in one trial.[8][1] | Most performance trials (usually 6–8 g) |
| Citrulline malate 2:1 and tri-citrulline malate | Varies[1] | Studies have not determined whether these are superior to standard citrulline or citrulline malate (ODS).[1] | No form-specific tolerance data in our sources.[1] | Not studied in the trials graded here |
- L-citrulline1,000 mg
- Citrulline malate (1:1)566.4 mg
Compound weight → elemental active
500 mg l-citrulline ≈ 500 mg elemental active
Studied doses
Doses studied in human trials ranged from 3 to 9 g of L-citrulline and 6 to 8 g of citrulline malate taken before exercise, up to 12 g of citrulline malate daily for 6 weeks. Most studies lasted from 1 to 16 days.[1][3][7][9]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
None found in our sources.
Who should be careful
- Long-term use
- Studies have not adequately assessed the safety of citrulline, particularly when taken as a supplement for months at a time (ODS).[1]
- Stomach upset
- In one trial, 6 of 41 men reported stomach discomfort after 8 g of citrulline malate.[8][1]
- Before you start
- Talk to your pharmacist or clinician before adding this supplement, especially if you take prescription medicines, are pregnant or breastfeeding, or have a chronic health condition.[1]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Articles about Citrulline (L-citrulline and citrulline malate)
Plain-English answers to common questions, built on the evidence above.
Frequently asked questions
Does citrulline malate help in the gym?
Pooled trials found a small effect: about 3 extra repetitions (6.4%) across strength sets after 6–8 g taken 40–60 minutes before. A meta-analysis of 4 trials found no effect on maximal strength, and ODS calls the overall evidence limited and conflicting.[3][10][1]
Does citrulline improve endurance?
A meta-analysis of 9 studies found no benefit for time to exhaustion or time-trial performance. One small ODS-cited trial found slightly shorter treadmill time with L-citrulline than placebo.[4][9][1]
L-citrulline or citrulline malate?
Citrulline malate is 56.64% citrulline, so 1 g gives 566 mg. Two head-to-head trials found no difference between the forms, and studies have not shown that 2:1 products are better.[1][6][7]
Can citrulline reduce muscle soreness?
A meta-analysis of 13 studies found less soreness 24 hours after exercise and lower perceived exertion, but no change at 72 hours. An ODS-cited trial in 41 men taking 8 g citrulline malate, reported 40% less soreness at 24 and 48 hours.[5][8]
How does citrulline work?
The kidneys convert most citrulline into arginine, which the body uses to make nitric oxide. Supplements can raise nitric oxide markers, but that has not been directly linked to better performance.[1]
Sources
- [1]Dietary Supplements for Exercise and Athletic Performance: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements, 2024. fact-sheet
- [2]Effects of Citrulline Malate Supplementation on Exercise Performance: A Systematic Review and Three-Level Meta-Analysis.. Nutrients, 2026. meta-analysis
- [3]Acute Effect of Citrulline Malate on Repetition Performance During Strength Training: A Systematic Review and Meta-Analysis.. Int J Sport Nutr Exerc Metab, 2021. meta-analysis
- [4]Effects of citrulline on endurance performance in young healthy adults: a systematic review and meta-analysis.. J Int Soc Sports Nutr, 2023. meta-analysis
- [5]Effect of citrulline on post-exercise rating of perceived exertion, muscle soreness, and blood lactate levels: A systematic review and meta-analysis.. J Sport Health Sci, 2020. meta-analysis
- [6]Malate or Not? Acute Effects of L-Citrulline Versus Citrulline Malate on Neuromuscular Performance in Young, Trained Adults: A Randomized, Double-Blind, Placebo-Controlled Crossover Trial.. Int J Sport Nutr Exerc Metab, 2025. crossover-RCT
- [7]Changes in resistance training performance, rating of perceived exertion, and blood biomarkers after six weeks of supplementation with L-citrulline vs. L-citrulline DL-malate in resistance-trained men: a double-blind placebo-controlled trial.. J Int Soc Sports Nutr, 2025. RCT
- [8]Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness.. J Strength Cond Res, 2010. crossover-RCT
- [9]L-citrulline reduces time to exhaustion and insulin response to a graded exercise test.. Med Sci Sports Exerc, 2006. RCT
- [10]Effects of Citrulline Malate Supplementation on Muscle Strength in Resistance-Trained Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.. J Diet Suppl, 2022. meta-analysis
What changed
- First draft. Every evidence-row PMID checked with NCBI E-utilities (esummary + efetch abstract) and re-read in an independent adversarial pass.