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99%min L-Citrulline
Nanjing Gemsen
CAS 372-75-8
Introduction：
Product Name | L-Citrulline |
Synonyms | L Citrulline |
Appearance | White Crystals Or Crystalline Powder |
CAS | 372-75-8 |
Molecular formula | C6H13N3O3 |
Molecular Weight | 175.19 |
Purity | 99%min L-Citrulline |
Sample | Available |
L‑Citrulline is a non‑protein amino acid first isolated from watermelon – its name derived from Citrullus vulgaris. It is generated in the urea cycle from ornithine and carbamoyl phosphate, or as a by‑product of nitric oxide synthase (NOS) during the conversion of L‑arginine to nitric oxide (NO).
Through this pathway, L‑citrulline supports vasodilation by serving as an efficient precursor for L‑arginine and subsequently NO. These properties underlie its inclusion in formulations intended for circulatory comfort, male vitality, and overall wellness.
The compound is widely used in functional foods, dietary supplements, and pharmaceutical adjuvants, with GEMSEN supplying high‑purity fermentation‑derived L‑citrulline for such applications.
Specification:
| Items | Standard | Analysis Results |
| Description | White crystals or crystalline powder | crystalline powder |
| Identification(IR) | Concordant with the reference spectrum | concordant with the reference spectrum |
| Assay | 98.5~101.0% | 99.2% |
| PH | 5.0~7.0 | 6.2 |
| Specific Rotation | +24.5°~ +26.8° | +26.0° |
| State of solution (Transmittance T<sub>430</sub>) | ≥98.0% | 99.3% |
| Chloride(Cl) | ≤0.02% | <0.02% |
| Ammonium(NH<sub>4</sub>) | ≤0.02% | <0.02% |
| Sulfate(SO<sub>4</sub>) | ≤0.02% | <0.02% |
| Iron(Fe) | ≤10ppm | <10ppm |
| Heavy Metals | ≤10ppm | <10ppm |
| Arsenic(As) | ≤1ppm | <1ppm |
| Loss on Drying | ≤0.30% | 0.10% |
| Residue on ignition | ≤0.10% | 0.04% |
Application:
During intense physical activity, working muscles need increased oxygen and nutrient delivery. NO‑mediated vasodilation can enhance blood flow, and efficient ammonia clearance may delay perceived fatigue.
High‑intensity training (strength, sprint, CrossFit) – Single doses taken 30–60 min before exercise are common, though meta‑analyses indicate acute supplementation does not consistently improve performance. Multi‑day regimens (≥7 days) show a more promising trend.
Endurance sports (cycling, running, swimming) – Some studies observed improved oxygen uptake kinetics and time‑to‑exhaustion after 6 g/day pure L‑citrulline for one week.
Recovery and muscle soreness – Citrulline malate (6–8 g) taken before exercise has been associated with reduced delayed‑onset muscle soreness at 24–48 h in several trials, although effects on performance remain debated.
Multi‑session training days – L‑citrulline may help maintain arginine availability and lower perceived exertion.
Pure L‑citrulline powder blends easily with carbohydrates, electrolytes, and other amino acids.
NO relaxes vascular smooth muscle, thereby influencing blood vessel diameter and blood flow. L‑citrulline is used in formulations intended for circulatory wellness.
Middle‑aged and older adult products – Clinical meta‑analyses have associated 3–6 g/day pure L‑citrulline (≥4 weeks) with increased flow‑mediated dilation (FMD), a marker of vascular endothelial function, by approximately 0.9 percentage points.
Stress‑response formulations – Some products are designed for situations involving cold exposure or isometric exercise, where L‑citrulline has been examined for its effects on blood pressure reactivity.
Everyday wellness blends – Often combined with dietary nitrates (beetroot) or polyphenols (grape seed, pomegranate) for synergistic NO support.
L‑Citrulline is stable in aqueous solutions at pH 3–7, allowing use in ready‑to‑drink shots or effervescent tablets.
Adequate blood flow to penile tissues is a prerequisite for erectile function. By enhancing NO‑mediated vasodilation, L‑citrulline has been examined in studies on mild, occasional erectile difficulties.
Mild erectile complaints (non‑clinical, situational) – One randomised controlled trial reported that 1.5 g/day L‑citrulline (750 mg twice daily) for one month improved self‑reported erection hardness in 50% of participants with mild difficulties. This effect is less pronounced than that of prescription PDE5 inhibitors but offers a non‑drug alternative.
Combination with other nutritional co‑factors – Some products pair L‑citrulline with trans‑resveratrol or low‑dose L‑arginine. Preliminary evidence suggests such combinations may provide additional support for men already using PDE5 inhibitors.
Age‑related formulations – As endothelial function gradually declines with age, L‑citrulline is included in “vitality” capsules and powders.
NO influences insulin sensitivity and glucose uptake in skeletal muscle. L‑citrulline has been examined in studies on post‑meal glucose regulation.
Postprandial glucose management – Watermelon (a natural source of L‑citrulline) has been associated in a meta‑analysis with a reduction in post‑meal glucose of approximately 0.6 mmol/L. This effect has not been consistently reproduced with pure L‑citrulline supplements, possibly due to other bioactive compounds in whole fruit.
Long‑term glycaemic support – Limited evidence suggests that 3 g/day L‑citrulline for 8 weeks may lower fasting glucose and HbA1c in individuals with type 2 diabetes, but other trials have found no effect.
Insulin sensitivity in overweight individuals – Pre‑clinical studies indicate that L‑citrulline can reduce arginase activity and increase NO availability in adipose tissue, an area that warrants further human research.
Often combined with chromium, berberine, or dietary fibres in metabolic health blends.
Stiffness of the large arteries is a recognised predictor of cardiovascular events. By increasing NO, L‑citrulline may help maintain arterial elasticity.
Reducing arterial stiffness (pulse wave velocity, PWV) – A meta‑analysis of watermelon studies (5–6 g/day L‑citrulline equivalent for 4–6 weeks) found a significant reduction in PWV of 0.9 m/s – a change considered clinically meaningful.
Lifestyle synergy products – L‑Citrulline is often incorporated into holistic cardiovascular wellness programmes alongside dietary nitrates and regular exercise.
Formulations for older adults – Age‑related declines in NO production make L‑citrulline a candidate for senior‑oriented nutritional supplements.
Beyond NO‑related effects, L‑citrulline may directly stimulate muscle protein synthesis via the PI3K/mTOR pathway, independent of arginine conversion.
Low‑protein or restricted diets – In a human pilot study, L‑citrulline (10 g/day for 3 days) increased muscle protein synthesis by about 20% in healthy adults on a low‑protein diet, compared to an isonitrogenous control.
Age‑related muscle loss (sarcopenia) – Pre‑clinical research has shown that L‑citrulline combined with exercise can increase muscle mass and function. Clinical trials are ongoing.
Post‑illness or convalescence recovery – Some recovery formulas include L‑citrulline together with essential amino acids.
Q&A:
Q1. Is L‑citrulline the same as L‑arginine?
Not exactly. L‑citrulline is a precursor to L‑arginine. The body converts L‑citrulline into L‑arginine primarily in the kidneys, bypassing the extensive first‑pass breakdown that oral L‑arginine undergoes. Thus, L‑citrulline raises plasma arginine levels more efficiently.
Q2. How soon are changes in blood markers observed?
Peak plasma concentrations of both L‑citrulline and L‑arginine occur approximately one hour after oral ingestion. For exercise‑related outcomes, single‑dose studies have largely failed to show benefits; multi‑day supplementation (≥7 days) may be required. For vascular function, consistent use for 2–4 weeks is typical before measurable differences appear.
Q3. What is the recommended daily dose?
General circulatory wellness: 3–6 g pure L‑citrulline.
Mild erectile comfort (situational): 1.5–3 g/day (split into two doses).
Sports (pre‑workout, if attempted): 6–8 g citrulline malate (≈3.5–4.5 g actual citrulline) or 6 g pure L‑citrulline.
Starting point: 3 g/day, then increase to 6 g if well tolerated.
Q4. Are there any side effects?
Gastrointestinal upset (bloating, loose stools, nausea) is the most commonly reported side effect, occurring in less than 5% of users. Starting with a lower dose (3 g) and taking with food can minimise discomfort. High single doses (>10 g) may cause transient hypotension in sensitive individuals.
Q5. Can L‑citrulline be taken every day?
Yes. Most clinical studies have used daily supplementation for 1–8 weeks with no serious adverse events. Long‑term (>6 months) safety data are limited, but given its status as a food‑derived amino acid, daily use at recommended doses is generally considered safe.
Q6. What is the difference between L‑citrulline and L‑citrulline malate?
L‑citrulline malate is a 1:1 combination (by molecule) of L‑citrulline and malic acid. It contains only about 56.6% actual L‑citrulline by weight. The malate form is more acidic and hygroscopic. Despite marketing claims, no robust evidence shows that malate provides additional benefits over pure L‑citrulline for exercise or recovery. The pure form is easier to dose and less likely to cause heartburn.
Q7. Does L‑citrulline need to be taken on an empty stomach?
Not necessary. Absorption is efficient regardless of food intake. Some individuals prefer taking it with meals to reduce gastrointestinal discomfort. For pre‑workout use, taking it 30–60 minutes before training, with or without food, is common.
Q8. Does L‑citrulline interact with any medications?
Yes. Because L‑citrulline increases NO‑mediated vasodilation, it can potentiate the effects of:
Nitrates (e.g., nitroglycerin) – risk of excessive hypotension.
PDE5 inhibitors (e.g., sildenafil, tadalafil) – may cause added blood pressure lowering.
Antihypertensive drugs (ACE inhibitors, ARBs, calcium channel blockers) – additive effects.
A healthcare provider should be consulted before combining L‑citrulline with these medications.
Q9. Can L‑citrulline be obtained from food instead of supplements?
Watermelon is the richest natural source. However, to reach a typical dose of 3–6 g of L‑citrulline, approximately 1–2 kg (2–4 lbs) of fresh watermelon would need to be consumed daily – impractical for most people. Therefore, supplements are a more convenient way to achieve consistent levels.
Q10. How should L‑citrulline supplements be stored?
Pure L‑citrulline powder is non‑hygroscopic and can be stored at room temperature in a sealed container away from moisture and heat. L‑citrulline malate is hygroscopic and will clump if exposed to humidity; it should be kept tightly sealed, preferably with a desiccant.
Q11. Does L‑citrulline affect testosterone levels?
No direct effect on testosterone has been demonstrated. The improvements in erectile function or exercise performance reported in some studies are attributed to enhanced blood flow, not hormonal changes.
Q12. Is L‑citrulline suitable for vegetarians and vegans?
Yes. Most L‑citrulline supplements are produced via fermentation using non‑animal sources. Product labels should be checked for specific certifications if required.
Q13. What quality should be expected from a reputable supplier?
A reliable supplier (such as GEMSEN) provides certificates of analysis confirming identity, purity (≥99% L‑citrulline), and absence of heavy metals, microbial contaminants, and residual solvents. Third‑party testing by organisations like NSF or Informed Sport is an added assurance.
Q14. Can L‑citrulline be combined with other amino acids or supplements?
Common combinations include:
With L‑arginine (redundant, but some products include both).
With beta‑alanine or creatine in pre‑workout formulas.
With beetroot extract (nitrate source) for synergistic NO support.
With branched‑chain amino acids (BCAAs) for recovery.
No major adverse interactions have been reported, though the efficacy of these combinations has not been thoroughly studied.
Q15. Are the benefits of L‑citrulline proven beyond doubt?
Current evidence is strongest for increasing plasma arginine levels and improving flow‑mediated dilation (long‑term use). For exercise performance, results are mixed – most acute trials show no benefit, while some chronic studies suggest minor improvements. For mild erectile difficulties, one positive RCT exists but needs replication. L‑citrulline is best viewed as a supportive nutritional ingredient, not a “magic bullet.”
