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Citrulline and citrulline malate

Also called: L-citrulline, citrulline malate 2:1, citrulline DL-malate, arginine precursor.

An arginine precursor sold for the "pump" and muscular endurance; the measured effect is small, and the weight on the label often includes the malate.

Performance Recovery

What it is

Citrulline is a non-proteinogenic amino acid that the body converts into arginine, the substrate for nitric oxide synthesis. Taken by mouth, it raises plasma arginine; the mechanisms put forward are vasodilation and ammonia clearance. People buy it on its own or, very often, in pre-workout products, for the muscle pump, strength endurance and recovery.

What the label does not say

The malate counts in the weight: at the advertised 2:1 ratio, 8 g of citrulline malate, the typical trial dose, provide about two thirds citrulline, or about 5.3 g. The Gough review (2021) reports that an independent analysis measured ratios of about 1.6:1, and as low as 1.1:1, in products sold as 2:1, and recommends that researchers have the powder verified before studying it.
The trial dose is not the store-shelf dose: 6 to 8 g of citrulline malate or 2.4 to 6 g of L-citrulline in the Trexler meta-analysis (2019), 8 g of citrulline malate in most of the 30 trials in the 2026 meta-analysis, versus 4.0 g on average per pre-workout serving, often without a declared quantity because of proprietary blends. Health Canada, for its part, caps L-citrulline at 3 g per dose and 6 g per day.
What the trials show is small: Hedges' g of 0.20 (95% CI 0.01 to 0.39) across 12 studies and 198 participants, with each trial taken alone crossing the line of no effect; 0.16 (CI 0.05 to 0.27) across 30 trials and 644 participants, low certainty, with no clear effect on strength or power. The NIH sums it up as "little support", and Gough (2021) notes that no performance trial measured the vasodilation or ammonia clearance put forward.
Blood pressure moves a little: Examine reports a slight drop in pressure, mostly in people with hypertension. That is what justifies Health Canada's cautions for people on cardiovascular medications, anticoagulants or medications for erectile dysfunction.

The forms on the shelf

L-citrulline: 100% citrulline. In the trials, 2.4 to 6 g at least 30 minutes before exercise (Trexler 2019).
Citrulline malate: a salt of citrulline and malic acid. Health Canada counts 1.7 g of L-citrulline per 3 g of citrulline malate, and Examine 1.76 g of citrulline malate per 1 g of citrulline: the product is never 100% citrulline.
In pre-workouts: 71% of the 100 products analyzed by Jagim (2019) contain it, at 4.0 ± 2.5 g per serving on average; 37.5% reached 6 g.

Published reference values

Health Canada: L-citrulline from 150 mg to 6 g per day, maximum 3 g per dose; above 3 g per day, consult for use beyond 8 weeks. Permitted claim: supports an increase in performance in intense anaerobic efforts with short rest periods.
Trials: 6 to 8 g of citrulline malate or 3 to 6 g of L-citrulline about one hour before exercise (Examine, Trexler 2019). Tolerance described as good by Examine, without the digestive upset of high-dose arginine. No recommended intake or upper limit in the sense of the dietary reference intakes.

When

About 60 minutes before exercise in the trials (40 to 120 minutes depending on the protocol). Chronic use (3 to 56 days) did no better than a single dose in the 2026 meta-analysis.

Keep apart from

Cardiovascular medications, anticoagulants, medications for erectile dysfunction: Health Canada requires advice before use for citrulline combined with more than 0.42 g of arginine; no time interval is quantified.

To mention to a professional

Cardiovascular disease, especially if you are increasing your physical activity, low blood pressure, use of cardiovascular medications, anticoagulants or medications for erectile dysfunction, pregnancy and breastfeeding: check with a health care professional.

What it is sold for, and what the data show

Citrulline is sold for the muscle pump, strength endurance and recovery. The meta-analyses find an effect, but a small one, obtained with 8 g of citrulline malate whose ratio had been verified, and the NIH sums up the literature as "little support". At the 4 g average of pre-workouts, with citrulline-to-malate ratios below what the label says, the gap between the promise and the data widens.

From the plate first

Watermelon is just about the only food that provides notable amounts of it according to Examine.

Sources

Educational information, drawn from the sources above. It does not replace the advice of a health professional, who remains the reference for your situation, your medications, pregnancy or breastfeeding.