L-Citrulline Forms: An Overview
L-citrulline is a non-essential amino acid that raises plasma arginine more effectively than arginine supplementation itself, because it bypasses first-pass hepatic clearance. The body then converts plasma arginine to nitric oxide via nitric oxide synthase, increasing vasodilation, blood flow to working muscles, and aerobic capacity.
The main forms available are pure L-citrulline, citrulline malate (usually bonded 2:1 with malic acid), and less commonly citrulline hydrochloride (HCl). Choosing the best form depends on your goal and the actual citrulline content per serving.
Forms Compared
| Form | Citrulline content per gram | Common dose | Notes |
|---|---|---|---|
| L-Citrulline (pure) | ~1 g | 3–6 g | Highest dose per scoop |
| Citrulline Malate 2:1 | ~0.67 g | 6–8 g (= 4–5 g citrulline) | Malate may aid aerobic energy; study doses vary |
| Citrulline HCl | ~0.87 g | 3–5 g | Compact, less common |
Bioavailability Differences
All three forms are effectively absorbed orally. A pharmacokinetic study showed that oral L-citrulline raises plasma arginine as well as or better than equimolar arginine supplementation (Schwedhelm et al., 2008), and this holds true for both the pure and malate forms.
The malate component in citrulline malate has been proposed to support the Krebs cycle and reduce exercise-induced fatigue by helping clear ammonia, but well-controlled human trials specifically isolating the malate effect are limited. The primary benefit you receive from citrulline malate comes from the citrulline itself.
Cost Per Effective Dose
Pure L-citrulline delivers more citrulline per gram of powder, making it more cost-efficient when compared gram-for-gram with citrulline malate. However, if a product like MST L-citrulline 1100mg 120caps or MST Amino Pump L-Citrulline + L-Arginine 60caps is labelled with its L-citrulline content explicitly, the calculation is straightforward: ensure you are getting a meaningful amount per serving.
For bulk powder, Olimp Citrulline Malate 200g Jahutav limonaad provides the malate form in a convenient flavoured option, while 
OstroVit Citrulline 4400€15.90 In stock 150caps and MST L-Citrulline 240caps offer pure-form capsule convenience.
Which Form for Which Goal
- Pump and blood flow focus (strength training, hypertrophy): Pure L-citrulline or citrulline malate — both support nitric oxide production and muscle pump. Aim for the equivalent of 3–5 g of L-citrulline.
- Endurance and aerobic performance: Citrulline malate is more commonly studied in endurance contexts, potentially via the malate component. One RCT found that citrulline malate supplementation improved cycling time-to-exhaustion performance (Perez-Guisado and Jakeman, 2010).
- Convenience: Capsule forms like NOW Foods Arginine 500mg & Citrulline 120caps offer easy daily dosing without measuring.
What to Look for on the Label
- Check whether the dose listed is L-citrulline or citrulline malate. A label saying "6 g citrulline malate" means approximately 4 g of actual L-citrulline.
- Look for transparent labelling — products that list exact citrulline content, not hidden in a proprietary blend.
- Third-party tested products reduce the risk of label inaccuracies.
- Timing: take 30–60 minutes before training on an empty or light stomach for fastest uptake.
Explore the full range at the l-sitrulliin category on maxfit.ee.
References
Schwedhelm, E., et al. (2008). Pharmacokinetic and pharmacodynamic properties of oral L-citrulline and L-arginine: impact on nitric oxide metabolism. British Journal of Clinical Pharmacology, 65(1), 51–59. https://pubmed.ncbi.nlm.nih.gov/17662090/
Perez-Guisado, J., & Jakeman, P. M. (2010). Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness. Journal of Strength and Conditioning Research, 24(5), 1215–1222.
Moinard, C., et al. (2008). Dose-ranging effects of citrulline administration on plasma amino acids and hormonal patterns in healthy subjects: the Citrudose pharmacokinetic study. British Journal of Nutrition, 99(4), 855–862. https://pubmed.ncbi.nlm.nih.gov/17953788/
FAQ
Is citrulline malate better than pure L-citrulline for gym performance?
For most gym-goers, the citrulline content is what drives results, and both forms work when dosed to deliver the same amount of actual L-citrulline. Citrulline malate in endurance contexts may offer a marginal additional benefit from malate, but this has not been definitively isolated from the citrulline contribution.
Can I stack L-citrulline with L-arginine?
Both raise plasma arginine, but combining them does not produce a proportionally additive effect — and L-arginine alone has poor oral bioavailability. Most sports nutrition experts favour L-citrulline as the primary nitric oxide booster. Combination products like MST Amino Pump L-Citrulline + L-Arginine 60caps exist and are fine to use.
How long does it take for L-citrulline to work?
Plasma arginine peaks roughly 60–90 minutes after oral L-citrulline. Taking it 30–60 minutes before training is the standard protocol used in research.
