More than just a supplement, cod liver oil is a historical piece of nutrition that has accompanied generations for its preventive and therapeutic value. Despite its reputation for intense flavor, it has earned a place of its own for its richness in omega-3 (EPA and DHA) and in key fat-soluble vitamins such as A and D.
If you're curious how to make it at home and, above all, how to make the most of it, here's a complete guide: What it is, how it is obtained, differences with fish oil, nutritional values, scientifically backed benefits, dosage, side effects, interactions, pet options, and of course, a detailed homemade recipe with safety precautions.
Cod liver oil: what it is, how it is obtained, and how it differs from fish oil
Cod liver oil comes, as its name indicates, from the cod liver (usually from the Atlantic) that lives in cold waters. From this organ an oil naturally rich in EPA and DHA and with abundant vitamins A and D, stored in the liver itself.
It should be distinguished from the so-called “fish oil”: the latter is obtained from the meat or skin of various fish and can provide omega-3, but does not usually contain the vitamin A in relevant quantitiesThis difference in raw materials explains the unique nutritional profile of cod liver oil compared to regular fish oil.
Historically, when purification techniques were rudimentary, its content of vitamins A and D could be very high, and it was advised to take it only in winter months to avoid excesses. Today, thanks to the modern molecular purification, it is possible to reduce vitamins to suitable ranges, eliminate contaminants (such as metals or PCBs) and adjust the formulation, making it more suitable for continuous use following professional guidelines.
Composition and outstanding nutritional values
Cod liver oil is not just omega-3: its lipid matrix includes saturated, monounsaturated and polyunsaturated fats, vitamins, and trace minerals. Approximately 100 g provides:
- 22,6 g of saturated fat.
- 46,7 g of monounsaturated fat.
- 22,5 g of polyunsaturated fat, highlighting EPA ~6,9 g y DHA ~11 g.
- 30 mg of vitamin A.
- 250 micrograms of vitamin D.
- Small amounts of sodium, potassium and iron.
Since it is a fatty substance (approx. 900 kcal per 100 g), facilitates the absorption of fat-soluble vitamins such as A and DThis fatty “vehicle” is one of the reasons for its high nutritional effectiveness.
Omega-3 ALA, EPA, and DHA: Functions, Conversion, and Why Prioritize EPA+DHA
Long-chain omega-3s EPA and DHA contribute to cardiovascular, brain and visual function. The European Food Safety Authority (EFSA) supports benefits such as support for heart, brain and vision with specific intakes, and scientific evidence associates omega-3 actions antithrombotic and antiarrhythmic, improvements of the HDL, effects anti-inflammatory useful in the intestine, immune modulation, control of cell proliferation, protection against macular degeneration and possible improvements in symptoms of neurological and psychiatric disorders.
Although ALA (alpha-linolenic acid) is the plant precursor of EPA and DHA, endogenous conversion is limited: only a ~5% of ALA converts to EPA and less than 0,1% to DHA. Therefore, in practice, it is recommended to ensure a direct intake of Ready-to-use EPA+DHA through oily fish (salmon, mackerel, herring) or quality supplements, especially when the diet does not meet the necessary quantities.
Vitamins A and D: an essential tandem
In addition to omega-3, the oil provides Vitamin A, key to iron metabolism, support of immune system, the maintenance of the skin and mucous membranes, dental health and a correct visionWe can also get it from dairy products, meats, and fish, or as beta-carotene in green leafy vegetables, carrots, or apricots.
La vitamin D Cod liver oil helps to absorb and utilize calcium and phosphorus, contributes to the health of bones and teeth, and supports the function muscular and immune. Its food sources are not abundant, and skin synthesis depends on the UVB rays; therefore, this oil can be a great ally in populations with little sun exposure or at certain times of the year.
Benefits with evidence and traditional uses
Cod liver oil supplements may help the functioning of the heart, brain and vision and keep them at bay triglycerides, with reductions that in some cases reach very significant percentages. In people with mild hypertension, a modest but significant decrease of blood pressure.
It has also been linked to improvements in kidney markers in type 2 diabetes (such as reducing protein in urine). Beyond that, there are extended uses—such as support in rheumatoid arthritis, mood, childhood otitis, lupus or arrhythmias— with results not yet conclusive, so caution and health advice are advisable.
In the cosmetic and wellness field, some people use it as skin and hair tonic, and even use topical in small wounds, although this does not replace an appropriate treatment plan or medical evaluation when appropriate.
For dogs, cats and horses: when it is useful
In veterinary medicine, it is used cautiously to support the growth and skin/hair in dogs (including pregnancy), cover vitamin A deficiency and care for the fur in cats, and as a reinforcement in sight, bones, mane and hooves in horses. As always, the key is in the correct dosage and veterinary supervision, given the risk of excess vitamins A and D.
How to choose a good supplement: purity, concentration, and sustainability
In the market you will find formats in liquid, soft/hard capsules, pearls or “opercula”, and even children's versions. You can buy them at herbalists, pharmacies/parapharmacies, or trusted online stores. The important thing is to prioritize pharmaceutical quality and the security of the channel.
To compare products, look at the content of EPA and DHA per capsule (not per container). Multiply by the number of capsules to find the total EPA+DHA in the bottle and calculate the price per 1.000 mg of omega-3This way, you can decide which one offers the best value for money without resorting to misleading comparisons.
Also value the purity (contaminant and metal testing), independent seals such as IFOS or USP when available, the sustainable origin of cod, the low content in mercury/PCB, and the freshness (expiration date and rancidity control). In some countries, the FDA does not regulate supplements like drugs, so brand reputation and transparency will weigh heavily.
Indicative doses and usage guidelines
Each product is a world: the pattern depends on the concentration in EPA and DHA and the purpose. The more concentrated it is, fewer capsules you'll need. Furthermore, use will vary depending on age, clinical context, and objectives, always with professional endorsement.
Widely accepted references indicate that there is a need 250 mg daily of EPA+DHA for heart support, 250 mg of DHA for brain and vision, around 2 g/day of EPA+DHA to maintain normal triglycerides and 3g/day to support normal blood pressure. In studies with cod liver oil in liquid form, ~20 ml/day for triglycerides and up to ~30 ml/day for hypercholesterolemia, always under supervision.
Taking it with meals helps reduce reflux or aftertasteAnd if the flavor is too intense for you, there is flavored formulas or capsules that make it much more bearable, with options that have won awards for their palatability.
Safety, side effects and warnings
In healthy people and at appropriate doses, it is usually well tolerated. However, side effects may occur. belching, halitosis, heartburn, digestive or minor discomfort epistaxisIt usually improves when taken with food or by changing the format.
Overdoses can lead to nausea, loose stools and more risk of bleeding due to the antiaggregant/anticoagulant effect of omega-3. In addition, excess Vitamin A may cause headache, drowsiness, skin problems, visual disturbances, bone or joint pain, jaundice and other symptoms; and excess vitamin D It can raise blood calcium levels with nausea, vomiting, weakness, confusion, polyuria, and kidney damage.
During pregnancy and lactation Caution must be exercised: excess vitamin A is contraindicated There is no conclusive data to guarantee the safety of cod liver oil. Always consult your doctor before using it during these stages.
Interactions with drugs and herbal products
Cod liver oil may interact with antihypertensives (boosting the pressure drop), with anticoagulants and antiplatelet agents (increasing bleeding), and with plants or supplements that slow down clottingIf you are taking chronic medication, consult your healthcare professional.
| Group | Possible effect | Examples |
|---|---|---|
| Antihypertensives | Can enhance hypotension | Captopril, Enalapril, Losartan, Valsartan, Diltiazem, Amlodipine, Hydrochlorothiazide, Furosemide |
| Anticoagulants/antiplatelets | Increased risk of bleeding and bruises | Aspirin, Clopidogrel, Diclofenac, Ibuprofen, Naproxen, Dipyridamole, Heparin, Enoxaparin, Dalteparin, Ticlopidine, Warfarin |
| Plants and supplements | Can slow down clotting | Angelica, Borage Seed Oil, Clove, Dan Shen (Salvia miltiorrhiza), Garlic, Ginger, Ginkgo, Red Clover (Trifolium pratense), Turmeric, Willow |
Homemade Recipe: How to Extract Oil from Cod Liver (with Precautions)
First of all, an important note: making oil at home involves risks of contamination and rancidity if temperature, hygiene and storage are not well controlled. The liver can also accumulate environmental toxinsFor safety reasons, it is best to opt for purified products with quality controls. If you still want to follow a traditional homemade method, do so in small quantities and with extreme caution.
What do you need: fresh cod liver from a reliable and sustainable source, water, sea salt, cheesecloth or coffee filter, sterilized dark glass jar, a double boiler or steamer, and optionally some vitamin E drops (tocopherol) as a natural antioxidant.
Steps (steaming and decantation method):
- Wash the liver and remove any visible debris. Cut into medium pieces.
- Place the pieces in a steamer (without direct contact with the water). Steam at a gentle temperature for 30–60 minutes, until they release fatty juices.
- Collect the liquid that drains. Lightly mash the cooked liver and keep it at room temperature. water bath at 50–60 ºC for a few minutes to promote oil exudation.
- Let it rest and decantThe oil will rise to the top layer. Filter through cheesecloth or a coffee filter to separate impurities.
- If desired, add 1–2 drops of Vitamin E per 100 ml to delay oxidation. Pack in a dark jar up to the rim (minimize air), closes hermetically and refrigerate.
Conservation and use: Store at 0–4 ºC and consume within 4–6 weeksIf you detect a rancid odor, a pungent/strange taste, unusual cloudiness, or signs of fermentation, discard the product. Do not heat at high temperatures: use it in measured doses (for example, 1 teaspoon/day at most in healthy adults) and avoid its use during pregnancy/lactation unless medically indicated.
Safety notes: Homemade liver fermentation (old method) is not recommended due to microbiological risk (e.g., toxins and botulism) and formation of biogenic amines. Limit yourself to extraction by steam/decantation, with strict hygiene and preferably as an occasional demonstration, not as a permanent substitute for a supplement purified and tested.
Approximate performance: This may vary depending on the liver and the process, but the yield is usually not high; it is normal to obtain modest amounts after decantation and filtration.
If your goal is a regular and controlled intake of EPA, DHA and vitamins, commercial cod liver oils with purity analysis, EPA/DHA labeling per dose and guarantee of low pollutant content.
Information to end on a good note: this oil has been a “classic” on its own merits, but its responsible use implies knowing dosage, possible effects and interactions, choose certified quality and, if you dare to try the homemade recipe, always do it with caution and health criteria to enjoy its benefits without surprises.