Citrulline
Evidence is limited and conflicting; a small gain in repetitions is possible
What it is
A supplement often taken as citrulline malate, a compound with malate. Citrulline malate is 56.64% citrulline: 1 g provides 566 mg of citrulline (NIH ODS).
Benefits
Research is limited and conflicting (NIH ODS). For strength work a meta-analysis found a small effect: 6–8 g of citrulline malate added 3 repetitions on average (6.4%). Another meta-analysis found no gain in muscle strength, and none was found for endurance. A 2026 meta-analysis: improvements, if any, are small and the evidence is limited.
Dose
There is no official recommended dose: per the 2026 meta-analysis, reliable dosing has not been established. Strength studies used 6–8 g of citrulline malate 40–60 minutes before exercise; a review in JISSN cites 6–8 g a day with regular use.
When to take it
In studies: 40–60 minutes before exercise. Whether timing changes the result has not been shown: the 2026 meta-analysis found no difference.
Who it's for
There is no clear answer: who might benefit from citrulline remains to be determined (NIH ODS). A meta-analysis did find a small gain in the number of repetitions in strength exercises.
Who can skip it
People training for endurance: meta-analyses found no benefit. People expecting more strength: that hasn't been shown either. Overall, research gives no strong support for taking citrulline to improve performance (NIH ODS).
Forms
L-citrulline and citrulline malate, a combination of L-citrulline with malate (malic acid), are sold. Malate is thought to add an effect of its own, but that is a hypothesis about mechanism, not a proven advantage. A 2021 review points to a quality problem: for some manufacturers the stated citrulline-to-malate ratio was not confirmed.
Safety
Safety has not been adequately studied, especially over months of use (NIH ODS). In one study 6 of 41 participants reported stomach discomfort. Short studies of up to 6 g a day for 4 weeks found no adverse effects. We found no data for pregnancy, teenagers, medical conditions or medicines: see a doctor first.
This is a summary of public sources, not medical advice. If you have a health condition, are pregnant or take medication, talk to a doctor before taking a supplement.
Sources
- Dietary Supplements for Exercise and Athletic Performance — Health Professional Fact Sheet . NIH ODS, 2024.
- Acute Effect of Citrulline Malate on Repetition Performance During Strength Training: A Systematic Review and Meta-Analysis . International Journal of Sport Nutrition and Exercise Metabolism, 2021.
- Effects of Citrulline Malate Supplementation on Muscle Strength in Resistance-Trained Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials . Journal of Dietary Supplements, 2022.
- Effects of citrulline on endurance performance in young healthy adults: a systematic review and meta-analysis . Journal of the International Society of Sports Nutrition, 2023.
- Effects of Citrulline Malate Supplementation on Exercise Performance: A Systematic Review and Three-Level Meta-Analysis . Nutrients, 2026.
- Multi-ingredient pre-workout supplements, safety implications, and performance outcomes: a brief review . Journal of the International Society of Sports Nutrition, 2018.
- A critical review of citrulline malate supplementation and exercise performance . European Journal of Applied Physiology, 2021.
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