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Carnitine

Supplement amino acid derivative fitnessenergybrain & mood
Aka: L-carnitine, L-carnitine tartrate
Brands seen in Singapore: California Gold Nutrition, NOW Foods, EVLution Nutrition, Nutricost, Nutrex Research
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
Mixed results in exercise · the body makes what it needs
Pros & cons
Pros
  • Moves fatty acids into mitochondria for energy
  • Some trials: lower lactate, faster recovery
  • Healthy bodies synthesise enough — no dri set
Cons
  • Performance evidence is mixed — more studies needed
  • Cochrane: routine use in dementia not justified
  • About 3 g a day can cause nausea and fishy odour
Sources
  1. NIH ODS — Carnitine (Health Professional), role in energy production · read 2026-08-27
    what it says
    “Carnitine plays a critical role in energy production. It is an essential cofactor that helps transport long-chain fatty acids into the mitochondria so that they can be oxidized to produce energy in the form of adenosine triphosphate (ATP)”
  2. NIH ODS — Carnitine, endogenous synthesis and DRI status · read 2026-08-27
    what it says
    “Endogenous carnitine synthesis … is sufficient to meet the carnitine needs of healthy people … In 1989, the Food and Nutrition Board (FNB) … concluded that carnitine is not an essential nutrient … did not establish Dietary Reference Intakes (DRIs) for carnitine”
  3. NIH ODS — Carnitine, dietary intake · read 2026-08-27
    what it says
    “A typical omnivorous diet provides about 24 to 145 mg carnitine daily for a person weighing 165 pounds”
  4. NIH ODS — Carnitine, athletic performance section · read 2026-08-27
    what it says
    “L-carnitine supplements reduced lactate levels and heart rate; increased lipid metabolism, VO2max, oxygen consumption … improved performance; and hastened recovery in some of the studies … the evidence on supplemental carnitine's effectiveness for performance enhancement is mixed”
  5. NIH ODS — Carnitine, acetyl-L-carnitine and dementia (Cochrane Review) · read 2026-08-27
    what it says
    “results from studies conducted more recently were less positive than those from earlier studies … they concluded that the routine clinical use of acetyl-L-carnitine supplements to treat the signs and symptoms of dementia was not justified”
  6. NIH ODS — Carnitine, upper intake level · read 2026-08-27
    what it says
    “Carnitine does not have an established tolerable upper intake level”
  7. NIH ODS — Carnitine, side effects · read 2026-08-27
    what it says
    “However, doses of approximately 3 g/day of carnitine supplements can cause nausea, vomiting, abdominal cramps, diarrhea, and a fishy body odor … It can also cause muscle weakness in people with uremia and seizures in those with seizure disorders”
  8. NIH ODS — Carnitine, interactions with medications (anticonvulsants; pivalate-conjugated antibiotics) · read 2026-08-27
    what it says
    “Treatment with the anticonvulsants valproic acid, phenobarbital, phenytoin, and carbamazepine reduces blood levels of carnitine … Chronic administration of these antibiotics can lead to carnitine depletion”
  9. HSA Health Supplements Guidelines (GL-CHPB-3-001 Rev. 020, January 2026), Tables 4–5 · read 2026-08-27
    what it says
    “HS for use by the general adult population should not contain vitamins and minerals exceeding the stipulated limits stated in Tables 4 and 5”
  10. HSA Guidelines on Prohibited and Restricted Ingredients in Health Supplements and Traditional Medicines (Oct 2025), Annexes A/B · read 2026-08-27
    what it says
    “The objective of this guideline is to highlight the substances of concern when used in HS and TM and is not meant to be an exhaustive list”
  11. iHerb Singapore — L-Carnitine category page (default sort, 104 results) · read 2026-08-27
    what it says
    “L-Carnitine … 1 - 48 of 104 results”
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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.