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Citrulline

Supplement amino acid fitnessheart & metabolic
Aka: L-citrulline, citrulline malate
Brands seen in Singapore: California Gold Nutrition, NOW Foods, Life Extension, EVLution Nutrition, Nutricost
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
Small, uncertain gains in exercise performance
When to take
Acute use before a session reads steadier than daily use
Take with
Water · trials dose it about 60 min before testing
Pros & cons
Pros
  • 30 RCTs pooled — small overall performance gain
  • 8 g citrulline malate is the common trial dose
  • Acute dosing evidence is steadier than chronic
Cons
  • GRADE certainty ranged from low to very low
  • Effect on perceived exertion was not significant
  • ODS: little research support for performance use
Sources
  1. Citrulline malate and exercise performance: systematic review and three-level meta-analysis (Nutrients 2026) · read 2026-08-27
    what it says
    “CM supplementation was associated with a small improvement in overall exercise performance (g = 0.16, p = 0.01) … The pooled effect on perceived exertion was not statistically significant … GRADE certainty ranged from low to very low”
  2. NIH ODS — Dietary Supplements for Exercise and Athletic Performance (Health Professional) · read 2026-08-27
    what it says
    “Dilates blood vessels to increase delivery of oxygen and nutrients to skeletal muscle … Little research support for use to enhance performance … Gastrointestinal discomfort”
  3. HSA — Guidelines on prohibited and restricted ingredients in health supplements and traditional medicines (Oct 2025, Annex A/B) · read 2026-08-27
    what it says
    “Annex B: List of substances with potential safety issues and recommended risk mitigation measures”
  4. HSA — Guidelines on health supplements (Tables 4–5, maximum daily dose limits) · read 2026-08-27
    what it says
    “Table 4: Vitamins Limits … Table 5: Minerals Limits”
  5. iHerb Singapore — Nitric Oxide Supplements category (default order) · read 2026-08-27
    what it says
    “California Gold Nutrition … NOW Foods … Life Extension … EVLution Nutrition … Nutricost”
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Updated 2026-08-29. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.