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Cod liver oil

Supplement fish oil bone & jointimmune
Aka: CLO
Brands seen in Singapore: California Gold Nutrition, Carlson, NOW Foods, Nordic Naturals, Jigsaw Health
Third-party tested: Nordic Naturals certifies other products with NSF Certified for Sport, but nothing for cod liver oil.Certification is granted per product, so check the tub you actually own. Not being listed is not the same as failing.
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
Fish oil that also carries vitamin A and vitamin D
Take with
Counts toward daily vitamin A and d intake as well
Pros & cons
Pros
  • Supplies EPA, DHA, vitamin A and vitamin D together
  • HSA lists vitamin A and d under bone and teeth claims
  • Omega-3 supplements haven't been found to carry mercury
Cons
  • Vitamin A adds up — the adult UL is 3,000 mcg/day
  • HSA caps supplement vitamin A at 1.5 mg (5000 IU)/day
  • Unpleasant taste, bad breath, heartburn and diarrhoea
Sources
  1. NIH ODS — Omega-3 Fatty Acids (Health Professional) · read 2026-08-27
    what it says
    “LC omega-3s are present in several dietary supplement formulations, including fish oil, krill oil, cod liver oil … Cod liver oil supplements provide vitamin A and vitamin D in addition to LC omega-3s”
  2. NIH ODS — Omega-3 Fatty Acids (Health Professional) · read 2026-08-27
    what it says
    “Although seafood contains varying levels of methyl mercury (a toxic heavy metal), omega-3 supplements have not been found to contain this contaminant because it is removed during processing and purification”
  3. NIH ODS — Omega-3 Fatty Acids (Health Professional) · read 2026-08-27
    what it says
    “Commonly reported side effects of omega-3 supplements are usually mild. These include unpleasant taste, bad breath, heartburn, nausea, gastrointestinal discomfort, diarrhea, headache, and odoriferous sweat”
  4. NIH ODS — Omega-3 Fatty Acids (Health Professional) · read 2026-08-27
    what it says
    “The IOM did not establish a UL for any omega-3s … FDA has concluded that dietary supplements providing no more than 5 g/day EPA and DHA are safe when used as recommended”
  5. NIH ODS — Omega-3 Fatty Acids (Health Professional) · read 2026-08-27
    what it says
    “Two large clinical trials … found that taking 4 g/day of omega-3 supplements for several years slightly increased the risk of atrial fibrillation in people with CVD or at high risk of CVD”
  6. NIH ODS — Omega-3 Fatty Acids (Health Professional) · read 2026-08-27
    what it says
    “Fish oil might prolong clotting times, as indicated by an elevated international normalized ratio (INR), when it is taken with warfarin … patients taking these products with anticoagulants should be monitored periodically for changes in INR”
  7. NIH ODS — Omega-3 Fatty Acids (Health Professional) · read 2026-08-27
    what it says
    “The AIs apply only to ALA because ALA is the only omega-3 that is essential. The IOM did not establish specific intake recommendations for EPA, DHA … 19–50 years 1.6 g (male) 1.1 g (female)”
  8. NIH ODS — Omega-3 Fatty Acids (Health Professional) · read 2026-08-27
    what it says
    “The U.S. Food and Drug Administration (FDA) has established a Daily Value (DV) of 65 g for total fat but not for omega-3s”
  9. NIH ODS — Vitamin A and Carotenoids (Health Professional), Table 3 · read 2026-08-27
    what it says
    “Table 3: Tolerable Upper Intake Levels (ULs) for Preformed Vitamin A … 19+ years 3,000 mcg 3,000 mcg 3,000 mcg 3,000 mcg”
  10. NIH ODS — Vitamin A and Carotenoids (Health Professional), excess intake · read 2026-08-27
    what it says
    “Experts advise women who are or might be pregnant and those who are lactating not to take high doses (more than 3,000 mcg RAE [10,000 IU] daily) of vitamin A supplements”
  11. HSA — Health Supplements Guidelines (Jan 2026), Table 4 vitamins limits · 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 … Vitamin A (retinol) 1.5mg (5000IU) … Vitamin D 0.025mg (1000IU)”
  12. HSA — Health Supplements Guidelines (Jan 2026), list of health claims attributable to vitamins/minerals · read 2026-08-27
    what it says
    “Help build strong bones and teeth • Vitamin A, D • Calcium … Provitamin A/vitamin A to help maintain eyesight, skin, membranes and immune function • Betacarotene, vitamin A”
  13. 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
    “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.”
  14. iHerb Singapore — Cod Liver Oil category page · read 2026-08-27
    what it says
    “Cod Liver Oil”
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Updated 2026-08-30. 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.