DrFeb
Health Guide

Fat liver oil

Cod liver oil is a distinct type of fish oil derived specifically from the liver of cod fish. Unlike standard fish oil, which is extracted from the fish's body tissues, liver oil is a nutritional powerhouse because it is naturally concentrated with two of the most vital nutrients for human health: Omega-3 fatty acids (EPA and DHA) and Vitamins A and D. Historically used as a folk remedy to prevent rickets and boost immunity, it remains one of the most potent natural supplements available. It matters because modern diets are often deficient in these specific fat-soluble vitamins, which are crucial for everything from your immune response to brain function.
Evidence BasedDietary Supplement
Fat liver oil
VERIFIED SOURCE

Bio-Activity Analysis

Vitamin D Content Comparison (per 100g)

SCIENTIFIC DATA VISUALIZATION

Y-Axis
IU (International Units)
Source →

Health Benefits & Sources

Why You Need It

  • Bone Health: Provides high levels of Vitamin D, essential for calcium absorption and strong bones.
  • Immune Support: Vitamin A is critical for maintaining the integrity of your skin and mucous cells, your body's first line of defense against pathogens.
  • Brain Function: DHA supports cognitive health and memory, while EPA helps regulate mood.

Deep Dive

Cod liver oil works by supplying the body with fat-soluble vitamins that are difficult to obtain from food alone, especially in limited sunlight climates. While standard fish oil is great for inflammation, cod liver oil offers a broader spectrum of support. It helps regulate immune system over-activation (potentially aiding autoimmune conditions) and supports hormonal balance. Because it contains natural Vitamin D (not synthesized), it is highly bioavailable, meaning your body can use it immediately.

Natural Food Sources

While you cannot eat a 'fruit' for cod liver oil, you can obtain these nutrients from the source animal or fortified foods. However, concentrated doses usually require the oil itself.

Food SourceNutrient FocusAmount per Serving
Cod Liver Oil (Liquid/Capsule)Vit A, D, Omega-31 Tbsp (High)
Wild SalmonOmega-3, Vit D3oz (Medium)
Egg Yolks (Pasture-raised)Vit D, A2 Large (Low-Medium)
Fortified MilkVit D1 Cup (Medium)

Supplementation

Dosage: A standard dose is 1 teaspoon (5ml) of liquid oil daily, or 1-2 capsules. Who should take it: Individuals with limited sun exposure, those with autoimmune issues, and people who do not eat fatty fish twice a week. Food First Approach: While the oil is a supplement, prioritize eating whole fatty fish and liver from healthy animals if you enjoy them.

Top Food Sources

Cod Liver Oil
1 tsp provides 100%+ DV of Vit A/D
Beef Liver
Rich in Vit A, contains some Vit D
Fatty Fish (Salmon/Mackerel)
Good Omega-3, lower Vit A
Butter (Grass-Fed)
Contains trace Vit A and D

Frequently Asked Questions

It depends on your needs. Regular fish oil usually has more Omega-3s (EPA/DHA) for heart health and inflammation. Cod liver oil has less Omega-3 but adds significant natural Vitamins A and D. If you need immune support, choose Cod Liver Oil; if you need high-dose anti-inflammatory support, choose standard fish oil.
Consult your doctor immediately. Because of the high Vitamin A content, it is generally NOT recommended during pregnancy as excess Vitamin A is teratogenic (harmful to the fetus).
The smell comes from the oxidation of the fats and impurities in lower quality oils. High-quality, molecularly distilled oils have significantly less odor.
Yes. Vitamin A and D are relatively stable, but Omega-3 fatty acids are sensitive to heat. Do not cook with cod liver oil. Take it cold or in capsule form.

Safety & Side Effects

Safety & Toxicity

WARNING: Because cod liver oil is high in Vitamin A, taking too much can lead to hypervitaminosis A (Vitamin A toxicity). Unlike Vitamin D, Vitamin A is stored in the body and can build up to dangerous levels.

Who should avoid it:

  • Pregnant women (High Vitamin A can cause birth defects).
  • People on blood thinners (Omega-3s have mild blood-thinning effects).
  • Those with kidney stones (due to Calcium/Vitamin D interaction).

Side Effects: 'Fish burps', heartburn, or nausea if taken on an empty stomach. Always take with a meal containing fat.

Scientific References

  • [1]Bjelakovic, G., et al. (2014). 'Vitamin D supplementation for prevention of mortality in adults.' Cochrane Database.
  • [2]Olafsson, S., & Halldorsson, T. (2013). 'Fish oil supplementation and health.' Acta Cardiologica.
  • [3]Penniston, K.L., & Tanumihardjo, S.A. (2006). 'The acute and chronic toxic effects of vitamin A.' The American Journal of Clinical Nutrition.