L-Citrulline is a non-essential amino acid the body can make on its own, named after the Latin “citrullus” for watermelon (Citrullus lanatus), where it was first identified — though the natural amounts in watermelon are modest compared with supplement doses. Citrulline is one of three amino acids in the urea cycle, alongside arginine and ornithine — the liver’s main pathway for clearing ammonia, a toxic metabolic by-product of protein breakdown, converting it into urea for elimination via the kidneys. Citrulline is converted into arginine in the kidneys, which raises arginine availability more effectively than taking arginine directly, since orally ingested arginine is largely metabolised by the gut and liver before reaching general circulation, while citrulline bypasses this.

Explore our full sports nutrition range in store.

Citrulline is widely used in sports nutrition because of its role in two metabolic pathways relevant to physical performance. The first concerns the urea cycle and ammonia clearance: intense exercise accelerates amino acid breakdown and ammonia build-up in the muscles, which contributes to both peripheral and central fatigue — by supporting the urea cycle, citrulline may help delay the onset of fatigue during prolonged or repeated effort. The second concerns nitric oxide (NO) metabolism: by raising circulating arginine, citrulline is an indirect precursor to nitric oxide, a molecule produced by the cells lining blood vessels that relaxes vascular smooth muscle, supporting healthy blood flow to working muscles, along with oxygen and nutrient delivery. Research commonly uses doses of 3 to 8g of free citrulline per day, or 6 to 8g as citrulline malate; this Now Foods product offers 750mg capsules for flexible, individual dosing.

Browse our full Now Foods range in store.

Now Foods, founded in 1968 in Bloomingdale, Illinois, has built a reputation over more than fifty years as a leading natural supplement brand, with production in GMP-certified facilities. The 750mg-per-capsule dose gives users real flexibility to adjust intake to their body weight and activity level, and the vegetable capsule format offers a practical alternative to weighing out powder. Now Foods’ labelling transparency is another point of trust: every ingredient is clearly listed, dosages are precise, and products are independently tested for purity.

Also available as a powder: BioKyowa L-Citrulline Powder 90g by Nutrielement.

Take 1 to 2 capsules, 1 to 2 times a day, between meals. For sports use, it’s common to take a dose about an hour before exercise to allow time for absorption and metabolic conversion.

Do not exceed the recommended daily dose. Food supplement — not a substitute for a varied, balanced diet and a healthy lifestyle. Consult a healthcare professional before use if pregnant, breastfeeding, on medical treatment, or managing a health condition. Store in a cool, dry place, away from light. Keep out of reach of children. Citrulline is generally well tolerated at typical supplement doses; start with the minimum dose and increase gradually while observing your own tolerance, and stop use and seek advice if you notice any digestive discomfort or other adverse effect.

Is citrulline different from citrulline malate?

Yes. Pure L-Citrulline (as in this Now Foods product) is citrulline alone, while citrulline malate combines L-Citrulline with malic acid, usually in a 2:1 ratio — malic acid being a Krebs-cycle intermediate involved in cellular energy production. Some prefer citrulline malate for this dual contribution, others prefer pure L-Citrulline for a more precise effective-citrulline dose.

Is citrulline suitable for vegetarians?

Yes. Citrulline 750mg by Now Foods uses hypromellose vegetable capsules and contains no animal-derived ingredients — the L-Citrulline itself is produced by synthesis, not from animal sources.

Can citrulline be taken outside of a sports context?

Citrulline is a naturally occurring amino acid, and some people include it in daily supplementation for other reasons. As always, we recommend asking a healthcare professional whether citrulline supplementation suits your personal situation.

Herba Barona is an independent specialist supplement shop in the heart of Paris — established in 2006. What you order is genuinely on our shelves: we ship from our own stock, with no dropshipping and no long waits.

Visit us at 10 rue Théophile Roussel, Paris 12 — or use Click & Collect and pick up your order in-store. We also deliver across France and Europe. Friendly, expert advice in English from our team.

Where is the shop?

Herba Barona is at 10 rue Théophile Roussel, 75012 Paris — a two-minute walk from Ledru-Rollin (line 8), close to Bastille. Open Tuesday to Saturday, 9:30 am–6:30 pm.

Can I order online or collect in store?

Yes. We ship across France and Europe under the same conditions as our French store, or choose Click & Collect to pick up your order for free at our Paris shop.