L-Citrulline
Find L-citrulline as unflavoured powder, citrulline malate 2:1 and capsules. We explain how the forms differ, how much actual citrulline a serving holds and how people usually time it around their training.Read more →
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Understanding citrulline powder, capsules and malate 2:1
L-citrulline is an amino acid that your body also makes itself. Food supplies small amounts, with watermelon as the best known source. It belongs to the group of amino acids used around training, alongside glutamine and arginine. In the body, citrulline is converted into arginine. Servings used in the gym run to several grams a day, far more than fruit realistically gives you.
What we can say, and what we cannot
There are no authorised health claims for citrulline in the UK or the EU. EFSA assessed a claim about faster recovery from muscle fatigue for citrulline malate, and that claim was not approved. So you will not read promises on this page. We describe the substance, the forms and how people use it. In sports research the results for performance are mixed rather than settled, which is worth knowing before you buy a large tub.
Powder, capsules and malate 2:1
Two things decide what you actually get: the form and the grams of citrulline per serving.
- Pure L-citrulline powder: unflavoured, mildly sour, you weigh your own dose. Usually the lowest cost per gram.
- Citrulline malate 2:1: citrulline bound to malic acid. Roughly two thirds is citrulline, so 9 g of malate gives about 6 g citrulline.
- Capsules: no taste and easy to take with you, but most hold 500 mg to 1,500 mg, so a multi-gram serving means a handful.
Citrulline also sits inside many ready-made pre-workout blends, often at a modest dose per scoop. Compare the citrulline content on the label, not the scoop size.
How we choose citrulline at BONO
We judge these products on three points: the form, the dose per serving and the combinations that make sense. We prefer labels that state the grams of real citrulline, because a 2:1 malate figure looks stronger than it is. We stock unflavoured powder for people who dose precisely, and capsules for those who travel. We skip pre-workouts that hide half a gram of citrulline inside a blend without numbers. Every product passes our compliance team, we test in house and independent labs spot-check batches. You can read how we select brands.
Purity, origin and storage
In a single-ingredient powder, quality comes down to purity and origin. Nearly all citrulline is made by fermentation, usually from non-GMO glucose or corn, which makes it suitable for vegans. Serious producers publish a certificate of analysis per batch, with purity and checks on heavy metals. Ask for that document if a brand does not show it. Powder draws in moisture and clumps, so keep the tub closed and dry and use a scoop or a small scale.
Who it suits, and who can skip it
Citrulline is mostly bought by people who lift weights or do repeated sprints and intervals. Some also prefer it over supplements with arginine, because they find it easier on the stomach at higher amounts. It suits you less if you want one capsule a day: the studied amounts are large, which makes powder the practical choice. Give it two to four weeks of consistent use before you judge it, and take it 30 to 60 minutes before training on the days you use it.
Frequently asked questions
L-citrulline is a non-essential amino acid, which means your body can make it itself. You also take in small amounts through food, with watermelon as the best known source. Its name comes from the Latin word for watermelon. In the body, citrulline is converted into another amino acid, arginine. In supplements it appears as pure L-citrulline or as citrulline malate, where it is bound to malic acid.
It is mainly used in strength training and endurance sports, taken shortly before a session. We stay careful here for a reason: there are no authorised health claims for citrulline in the UK or the EU. EFSA reviewed a claim about faster recovery from muscle fatigue for citrulline malate and did not approve it. The study results on performance are mixed. So we can tell you what it is and how people use it, not what it will do for you.
It depends on how precisely you want to dose and how much taste you accept.
| Form | What is in it | Practical note | Suits |
|---|---|---|---|
| L-citrulline powder | Citrulline only | Slightly sour, mixes in water | Precise dosing, lowest cost per gram |
| Citrulline malate 2:1 | Citrulline plus malic acid | About two thirds is citrulline | Those following malate studies |
| Capsules | Citrulline in a shell | Several capsules per serving | Travel, no taste |
Read the citrulline content per serving, not the total weight.
Amounts in exercise studies are large compared with most supplements: several grams per day, taken roughly 30 to 60 minutes before training. For citrulline malate 2:1 the serving is bigger, because only part of it is citrulline. We do not give personal dosing advice, and no UK authority publishes a reference intake for citrulline. Follow the label of the product you buy, start at the lower end to check how your stomach reacts, and stay consistent for a few weeks.
Watermelon does contain citrulline, and the rind holds more than the red flesh. The problem is the amount. Gym servings run to several grams, while a normal portion of melon delivers a fraction of that. You would need an unrealistic quantity of fruit every day, rind included. Watermelon is a fine part of your diet, but it is not a practical way to reach the amounts used in research.
Citrulline is often used next to creatine monohydrate, beta-alanine and caffeine, because they are taken at different points in a training routine. Keep it simple: add one new ingredient at a time, so you can tell what does what. Watch out for double dosing. If your pre-workout already contains citrulline, count those grams before you add loose powder on top.
The most common complaint is mild stomach discomfort when someone starts at a high amount, which is why lower servings are a sensible start. Food supplements are not a substitute for a varied diet. If you are pregnant or breastfeeding, take medication, especially for blood pressure or heart complaints, or are under medical supervision, speak with your doctor or pharmacist before you use citrulline. Citrulline products are intended for adults, not for children.
Both are linked in the same pathway: citrulline is converted into arginine in the body. Taken directly, a large share of arginine is broken down in the gut and liver before it reaches the bloodstream, and higher amounts more often cause digestive complaints. Citrulline takes a different route, so users generally tolerate larger servings. That is the practical reason many buyers move from arginine to citrulline, not an approved health claim, and both remain honest options to try.
