howtosupplement
Deficiency/Heart/Inflammation

Cod Liver Oil

Fish liver oil that provides omega-3s plus vitamins A and D, best for adults with low fish intake or limited sun exposure.

Cod Liver Oil

Cod Liver Oil

71
score
B
evidence
Caution
risk

Proven Benefits

01Supports vitamin D status
02Supports vitamin A status
03Lowers triglycerides
04May reduce joint pain/stiffness
05May support bone mineralization
06May lower blood pressure
07May lower CRP modestly

Chemical Forms

Recommended
  • Natural triglyceride cod liver oil
  • Liquid or softgels with declared EPA, DHA, vitamin A, and vitamin D content
Avoid
  • Fermented cod liver oil (variable vitamin content and oxidation testing)
  • Products that do not clearly state vitamin A and D per serving
Expert Note

Native triglyceride cod liver oil matches the form used in most traditional and clinical products, and clear labeling lets you dose the omega-3s and fat-soluble vitamins safely. Products with vague or variable vitamin content make it easy to overshoot vitamin A before reaching a meaningful omega-3 dose.

Protocol

Amount
5 mL
Frequency
Once daily
When
With a meal containing fat; if fishy burps occur, take it with the largest meal or keep the liquid refrigerated.

Condition-Based Dosing

General adult use
5 mL daily, using a product that clearly lists EPA, DHA, vitamin A, and vitamin D per serving.
Low sun exposure or winter months
Choose a product providing about 10-25 mcg vitamin D daily from the label dose.
Trying to lower high triglycerides
Prefer a dedicated EPA/DHA fish oil rather than pushing cod liver oil above the label dose.

Safety & Limits

Upper Safe Limit
Do not exceed a dose that pushes total preformed vitamin A above 3000 mcg RAE/day or vitamin D above 100 mcg/day (IOM ULs for adults).
Cycling
Safe for continuous use

Contraindications

Pregnancy or trying to conceive — excess preformed vitamin A can be teratogenic; avoid high-vitamin-A products unless clinician-guided
Isotretinoin or other retinoid drugs — additive vitamin A toxicity risk
Warfarin, apixaban, clopidogrel, or bleeding disorders — higher omega-3 intakes may increase bleeding tendency
Fish allergy — may trigger an allergic reaction
Hypervitaminosis A or chronic liver disease — retinol accumulation risk
Hypercalcemia, granulomatous disease, or high-dose vitamin D therapy — extra vitamin D may worsen calcium elevation

Synergies

Vitamin K2

Vitamin K2 complements the vitamin D in cod liver oil by helping direct calcium toward bone rather than soft tissue.

Magnesium

Magnesium is a cofactor in vitamin D metabolism, so low magnesium status can blunt the benefit of the vitamin D supplied by cod liver oil.

Avoid Combining With

  • ✕Orlistat (reduces fat absorption and lowers uptake of fat-soluble vitamins)
  • ✕Bile acid sequestrants like cholestyramine (reduce absorption; separate by 4+ hours)
  • ✕Mineral oil laxatives (can impair absorption of vitamins A and D)
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