CITRULLINE-THE NEW AGE SUPPLEMENT
Updated: Jun 7
I'm sure that if you have been reading research or are a fitness enthusiast, you have heard Citrulline advertised all over the supplement market as of late. The next obvious question is what it does and whether it is worthwhile for any of your training goals. Understand that much of the potential benefit of Citrulline centers around general health measures; however, research has aimed at looking at whether or not it has any merit when it comes to aerobic exercise and strength training specifically.
L-Citrulline vs. Citrulline Malate
For those of you that don't know, Citrulline is a non-essential amino acid derived from the kidneys that is particularly known to assist with ammonia and even lactate removal and Nitric Oxide synthesis in the body. Malate is added to further enhance ammonia removal for ATP Production, but whether or not one is superior is definitely up for debate at this point. 1
"There is limited evidence that citrulline supplementation can reduce ratings of perceived exertion, decrease muscle soreness, and increase power output and total repetitions performed in resistance training.234] More research is needed to determine whether different supplement dosages, different formulations, or longer periods of ingestion can further improve exercise performance. A considerable body of research suggests that citrulline supplementation mildly reduces blood pressure.5 More research is needed on citrulline’s potential effects for erectile dysfunction, but a small amount of research suggests a beneficial effect.6 "
The other handful of studies dealt with aerobic exercise performance and metrics. Although Citrulline sounds great on paper, the results indicated that any aerobic effect was minimal at best.
ON A FINAL NOTE
"Researchers have hypothesized that combining citrulline with malate results in a synergistic effect, which includes an increased rate of ATP production and recovery of phosphocreatine during exercise.[3][5] However, there’s a lack of direct evidence to support this hypothetical superiority of citrulline malate over citrulline for improving energy availability during exercise.[4] The summarized study is notable because it’s one of the few studies to examine the effects of chronic citrulline supplementation and to evaluate whether citrulline malate is more effective than citrulline alone. 8
To date, only one other study has evaluated the effects of chronic citrulline supplementation on resistance exercise adaptations. In an 8-week randomized controlled trial in 75 resistance-trained men who performed resistance exercise 4 days per week, supplementing with 2 grams of citrulline and 200 mg of glutathione or 2 grams of citrulline malate daily did not improve changes in body composition and strength, compared to a placebo.[6] There were also no differences between groups for the amount of training volume completed.
One reason for the lack of effect in that study could be the dosage of citrulline used. In resistance exercise studies, the participants typically take 8 grams of citrulline malate in a 2:1 ratio of citrulline to malate, which equates to about 5.3 grams of citrulline.[4] Consequently, the abovementioned study may not have found a benefit of citrulline supplementation because the dose was too low.
However, even 5.3 grams of citrulline may be a suboptimal dose. A dose-response study that had the participants supplement with 2, 5, 10, or 15 grams of citrulline reported that the highest blood levels of citrulline occurred with 15 grams, and the peak level with 15 grams was 28% higher than the peak level with 10 grams.[7] Accordingly, a higher dose of citrulline may be more likely to have benefits on resistance exercise performance.
The results of the summarized study provide some support for this possibility because the doses of citrulline were higher than those used in previous studies, and the effect on upper body muscular endurance (+5 to 6 repetitions) was slightly greater than the effect reported in acute studies (+3 repetitions). 8 However, because there wasn’t a group that supplemented with a lower dose of citrulline, further research is needed to confirm whether higher doses of citrulline or citrulline malate are better than the usual dose of 8 grams of citrulline malate.
The results also indicate that supplementing with citrulline alone is as effective as citrulline malate for improving resistance exercise performance. In further support of the possibility that these supplements are equally effective, the researchers collected blood samples immediately after the workout, and levels of nitric oxide, lactate, and urea did not differ between the citrulline and citrulline malate groups.
Our take:
This was a notable study because it was the first to compare the effects of longer-term supplementation with citrulline and citrulline malate on resistance exercise adaptations. The results suggest that supplementing with citrulline is just as good as citrulline malate for improving resistance exercise performance.
In addition, the results align with previous results from short-term studies that supplementing with citrulline malate can increase the number of repetitions performed over multiple sets of resistance exercise. 1 9 "
SCIENTIFIC REFERENCES:
#2-Eric T Trexler, Adam M Persky, Eric D Ryan, Todd A Schwartz, Lee Stoner, Abbie E Smith-RyanAcute Effects of Citrulline Supplementation on High-Intensity Strength and Power Performance: A Systematic Review and Meta-AnalysisSports Med.(2019 May)
#3-^Rhim HC, Kim SJ, Park J, Jang KMEffect 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-Dec)
#4- ^Fredrik Tonstad Vårvik, Thomas Bjørnsen, Adam M GonzalezAcute Effect of Citrulline Malate on Repetition Performance During Strength Training: A Systematic Review and Meta-AnalysisInt J Sport Nutr Exerc Metab.(2021 May 19)
#5- ^Barkhidaria@5- n B, Khorshidi M, Shab-Bidar S, Hashemi BEffects of L-citrulline supplementation on blood pressure: A systematic review and meta-analysis.Avicenna J Phytomed.(2019)
#6-^Oral L-Citrulline Supplementation Improves Erection Hardness in Men With Mild Erectile Dysfunction
#7-Fredrik Tonstad Vårvik, Thomas Bjørnsen, Adam M GonzalezAcute Effect of Citrulline Malate on Repetition Performance During Strength Training: A Systematic Review and Meta-AnalysisInt J Sport Nutr Exerc Metab.(2021 May 19)
#8-Bayat D, Azizi M, Behpour N, Tinsley GMChanges 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 Dec)
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