Citrulline Malate for Women: Does Sex Make a Difference?
Citrulline malate is one of the most popular ingredients in pre-workout formulas, yet nearly all of the early research behind it was done on men. As more women lift, sprint, and train for endurance events, a fair question arises: does the supplement work the same way in a female body? Our editorial team looked at the evidence, the gaps, and the practical takeaways.
What citrulline malate is and how it works
L-citrulline is a non-essential amino acid that the body makes on its own and that also occurs in foods such as watermelon. Unlike most amino acids, it is not used to build proteins. Its main job is to serve as an intermediate in the urea cycle and as a precursor for L-arginine, which in turn feeds nitric oxide production in blood vessel walls.
Supplement makers usually bind citrulline to malic acid, an intermediate of the Krebs cycle. The resulting compound, citrulline malate, typically comes in 2:1 or 1:1 ratios. The idea is that citrulline supports blood flow and ammonia clearance while malate contributes to aerobic energy metabolism, although the separate role of malate has not been well isolated in human trials.
A key reason citrulline became popular is pharmacokinetic. Oral arginine is heavily broken down in the gut and liver, whereas citrulline bypasses much of that first-pass metabolism and is converted to arginine in the kidneys. Studies in healthy volunteers have shown that oral citrulline raises plasma arginine more effectively than arginine itself.
None of these mechanisms is specific to one sex. The enzymes, transporters, and vascular pathways involved are present in both men and women. Any differences in response would therefore come from secondary factors: body size, muscle fiber composition, hormonal milieu, and the type of training being performed.
What studies in women actually show
The research base specific to women is small but growing. One frequently cited trial by Glenn and colleagues tested a single dose of citrulline malate in resistance-trained women and reported more repetitions to failure in upper- and lower-body exercises, along with lower perceived exertion, compared with placebo. The effect size was modest but meaningful for training volume.
Other studies in mixed or female-only samples have produced less consistent results, particularly for short sprints and endurance time trials. Meta-analyses that pool male and female data, such as the review by Trexler and co-authors, suggest a small average benefit for high-intensity strength and power tasks, with substantial variability between protocols.
The honest summary is that no study so far has shown women to respond fundamentally differently from men. At the same time, female participants remain underrepresented, and many trials do not control for menstrual cycle phase or hormonal contraception, which limits how confidently the results can be generalized.
| Outcome | Evidence in women | Overall confidence |
|---|---|---|
| Repetitions to failure in lifting | Positive results in at least one controlled trial | Moderate |
| Perceived exertion | Often lower with supplementation | Low to moderate |
| Delayed-onset muscle soreness | Mixed, mostly male data | Low |
| Endurance time trials | Inconsistent | Low |
Hormones, the menstrual cycle, and blood flow
Estrogen influences vascular function in its own right. It up-regulates endothelial nitric oxide synthase and tends to support healthy vasodilation. Some researchers have speculated that premenopausal women might therefore get a smaller additional boost from a nitric oxide precursor, since their baseline vascular function is already favorable.
This hypothesis is plausible but largely untested. Very few trials have compared the response to citrulline in the follicular versus luteal phase, and the data that exist are too limited to draw firm conclusions. The same applies to women using combined oral contraceptives, which flatten natural hormone fluctuations.
Postmenopausal women are a different case. With falling estrogen levels, endothelial function tends to decline, and some small studies in older adults have examined citrulline for vascular health and muscle function. Results are preliminary, but this group may be one where the supplement deserves more attention.
For the individual athlete, the practical message is simple: if you notice that a pre-workout feels more or less effective at different points of your cycle, that is worth tracking in a training log. Subjective response, energy levels, and sleep quality all vary across the month and can easily be mistaken for a supplement effect.
Practical use for female athletes
Doses used in research are the same for men and women. Most performance studies used 6–8 g of citrulline malate taken roughly 60 minutes before exercise, while studies with pure L-citrulline typically used 3–6 g. Because the malate component adds weight, a 2:1 product delivers about two thirds of its mass as citrulline.
Some practitioners suggest that lighter athletes might start at the lower end of the range, which is a reasonable precaution, although there is no formal weight-based dosing. Taking the powder with water on a relatively empty stomach is common; gastrointestinal discomfort is the main tolerability issue at higher doses.
- Check the ratio: 2:1 and 1:1 products contain different amounts of citrulline per scoop.
- Read the full label: many pre-workouts combine citrulline with high doses of caffeine.
- Look for third-party testing: certification programs such as NSF Certified for Sport reduce the risk of contamination.
- Track your response: record reps, sets, and perceived effort for a few weeks before deciding.
In the United States, citrulline is sold as a dietary supplement under DSHEA rules, which means the FDA does not approve products before they reach the market. Quality, purity, and label accuracy depend on the manufacturer, so independent certification is especially valuable for competitive athletes subject to drug testing.
Safety, pregnancy, and special situations
In healthy adults, citrulline has a good safety record in short-term studies. Reported side effects are mostly mild stomach upset. Because it can modestly lower blood pressure, women taking antihypertensive drugs, nitrates, or PDE5 inhibitors should discuss it with a physician before use.
Data on pregnancy and breastfeeding are insufficient. Although citrulline occurs naturally in food, concentrated supplements have not been studied in these groups for athletic purposes, and the conservative approach is to avoid them unless a doctor recommends otherwise.
Women with low energy availability, a common issue in aesthetic and endurance sports, should remember that no supplement can compensate for inadequate food intake. Menstrual irregularities, frequent injuries, or persistent fatigue call for a medical evaluation rather than a new pre-workout.
Conclusions of the editorial team
Citrulline malate works through mechanisms that are shared by men and women, and the limited female-specific evidence points to similar, modest benefits for high-repetition resistance training.
Hormonal factors such as estrogen and the menstrual cycle could theoretically modify the response, but this remains an open research question rather than an established fact.
Standard research doses apply to women, with sensible attention to product ratio, caffeine content, and individual tolerance.
If this topic interests you, consider reading our guides on how to time citrulline malate, on caffeine sensitivity in women, and on energy availability in female athletes.
References
- Glenn JM, Gray M, Wethington LN, et al. Acute citrulline malate supplementation improves upper- and lower-body submaximal weightlifting exercise performance in resistance-trained females. Eur J Nutr. 2017;56(2):775–784.
- Pérez-Guisado J, Jakeman PM. Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness. J Strength Cond Res. 2010;24(5):1215–1222.
- Trexler ET, Persky AM, Ryan ED, et al. Acute effects of citrulline supplementation on high-intensity strength and power performance: a systematic review and meta-analysis. Sports Med. 2019;49(5):707–718.
- Gonzalez AM, Trexler ET. Effects of citrulline supplementation on exercise performance in humans: a review of the current literature. J Strength Cond Res. 2020;34(5):1480–1495.
- Schwedhelm E, Maas R, Freese R, et al. Pharmacokinetic and pharmacodynamic properties of oral L-citrulline and L-arginine. Br J Clin Pharmacol. 2008;65(1):51–59.
- Elliott-Sale KJ, Minahan CL, de Jonge XAKJ, et al. Methodological considerations for studies in sport and exercise science with women as participants. Sports Med. 2021;51(5):843–861.
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