Fat liver oil

Other Names

No alternative names.

Synopsis

Cod Liver Oil

1. Identity: Nomenclature, Source, and Forms

Botanical and Chemical Identity

Cod liver oil (CLO) is a nutritional supplement extracted from the liver of the Atlantic cod, Gadus morhua. It is sometimes referred to by its Latin pharmacopoeial name Oleum Jecoris Aselli (literally "oil of the cod liver"), a designation found in 19th- and early 20th-century European pharmacopoeias. Cod liver oil contains three key nutrients that set it apart from other supplements: omega-3 fatty acids (EPA and DHA), vitamin A in its preformed retinol form, and vitamin D3. It is extracted from the livers of Atlantic and Pacific cod, which is why it carries fat-soluble vitamins that regular fish oil does not.

Though similar in fatty acid composition to other fish oils, cod liver oil has higher concentrations of vitamins A and D. According to the United States Department of Agriculture, a tablespoon (13.6 grams or 14.8 mL) of cod liver oil contains 4,080 μg of vitamin A and 34 μg (1,360 IU) of vitamin D. The Dietary Reference Intake of vitamin A is 900 μg per day for adult men and 700 μg per day for women.

Cod liver oil is a mixture of glycerides of many fatty acids, predominantly oleic acid, gadoleic acid, and palmitoleic acid. Cod liver oil is approximately 20% omega-3 fatty acids. Omega-6 fatty acids are present in much smaller quantities, typically comprising less than 2% of total fatty acids. The primary omega-6 in cod liver oil is linoleic acid, with trace amounts of arachidonic acid. The omega-6 to omega-3 ratio in cod liver oil is generally favourable, often around 1:10 or lower, which contrasts sharply with typical Western diets where ratios may exceed 15:1. Saturated fatty acids account for approximately 20–25% of the total fat content, predominantly palmitic acid (C16:0) and myristic acid (C14:0).

Natural Source

Cod liver oil is sourced specifically from the liver of the Atlantic cod, which acts as a storage organ for fat-soluble compounds. This natural origin explains why the oil is inherently rich in vitamins A and D, unlike oils extracted from the body tissues of fish. Cod liver oil is made from the liver of Atlantic cod, a large fish that lives in the very cold ocean waters near Norway and Iceland. The leading producers of cod liver oil supplements are northern countries like Norway and Iceland.

Common Forms and Preparations

Cod liver oil has been prepared and presented in a variety of forms across its history. The most common way of distributing cod liver oil has historically been in bottles. Daily use allows entry of air into the bottle with resulting oxidation and rancid taste. Gelatin capsules are also used, though this increases product cost considerably. Cod liver oil has been manufactured as an emulsion, with the Norwegian Pharmacopoeia of 1913 (page 106) and its 1919 Commentary (page 152) documenting emulsified preparations made primarily to improve the taste.

As early as 1844, encapsulation in gelatin was described as a means of masking the oil's flavour. A published note from 1844 described capsules of cod liver oil prepared at a New York pharmacy, observing that the capsule form wholly obviated the unpleasant taste of this medicine. Modern commercial preparations include liquid oils (plain or flavoured, e.g. lemon), soft-gel capsules, enteric-coated capsules, and tablets. Cod liver oil is high in omega-3 fatty acids, a valuable aspect in nutrition but one that makes it subject to oxidation, rancidification, and destruction of vitamin A when exposed to air.

In the old days the oil was prepared by the putrefaction of the livers of the cod. Peter Moller, in 1853, was the first to render the oil from the fresh livers by means of steam. The steam process represented a significant advance in producing a purer and less rancid product. Cod liver oil naturally contains many different chemicals and nutrients. The amount of each nutrient in a specific cod liver oil product can change for many reasons, including the area where the cod lived, the weather conditions at that time, and the way that the liver was processed.

2. Traditional and Historical Use

Pre-modern and Folkoric Origins

Although benefits of cod liver oil as food were known as early as the seventh century, cod liver oil was only proposed as medicinal for rickets in Northern Europe at the end of the eighteenth century. Northern European fishing communities used cod liver oil for generations to restore health and alleviate aches and pains before the doctors and chemists of 19th-century Europe began to take an interest.

In northern European countries, cod liver oil had a long history of folklore medical uses, including being applied to the skin and taken orally as a treatment for rheumatism and gout. Prior to industrial processes, much of the world used a variety of fermenting, wild fermenting, and cooking methods to process and preserve fish products including oil. These methods have been documented throughout history and in all regions of the world. Even the indigenous people of North America fermented and cooked fish to make a cherished fish oil that was traded all over the area.

19th-Century Medical Adoption

As early as 1782, English physicians began studying cod liver oil and prescribing it for rheumatism. During the 19th century, cod liver oil became a widely accepted treatment for rickets, tuberculosis, joint and muscle pain, and skin wounds. Historically, it was given to children in the United States in the 19th century as a patent medicine, and by the end of the century was being praised by doctors in medical journals.

In the 1800s, cod liver oil became popular as a bottled medicinal product for oral consumption — a teaspoon a day — with both pale and brown oils being used. The trigger for the surge in oral use was the observation made in several European countries, starting with Germany in the 1820s and spreading to other countries into the 1860s, that young children fed cod liver oil did not develop rickets.

Cod liver oil, rich in vitamin D, was first advocated for the treatment of tuberculosis (TB) in 1770, and it was widely used for this purpose in the nineteenth century. An 1849 medical paper published in what is now archived on PubMed Central described its use in pulmonary consumption at University College London, reflecting the degree to which it had entered mainstream clinical practice. Early records from 1724–1926 note that Schenk and Schutte wrote that cod liver oil given by mouth for five weeks could cure rickets. Trousseau, in 1868, elegantly described how he came to treat rickets with cod liver oil.

Early 20th Century and Rickets Eradication

At the turn of the 20th century, rickets was rampant among the poor children living in the industrialized and polluted northern cities of the United States. With the discovery of vitamin D and the delineation of the anti-rachitic properties of cod liver oil by the 1930s, it became possible to not only treat but also eradicate rickets in the United States. In northern Europe and the United States, the practice of giving children cod liver oil to prevent rickets persisted well into the 1950s. This overlapped with the fortification of cow's milk with vitamin D, which began in the early 1930s.

Historically, people living in northern Europe have relied on cod liver oil as a vitamin D supplement during the winter months when sunlight is scarce. Still produced today in much the same formula, commercial emulsions remain rich in vitamins A and D, calcium, phosphorus, and omega-3 fatty acids, with therapeutic claims echoing a long tradition of use: promoting healthy growth, building resistance to disease, and guarding against the ravages of age.

Generations of children in cities in the north of Europe learned to hate the taste and smell of the black oily liquid and then grew up to be parents who, in turn, hated to force it down their children's throats. History's perception of cod liver oil as an "unspeakably detestable thing to take" suggests palatability has been a concern for centuries, driving product development throughout history.

3. Key Constituents and Active Compounds

Omega-3 Fatty Acids: EPA and DHA

In the early 1970s, researchers Bang and Dyerberg determined that fish and fish oil contained two omega-3 fatty acids called eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Since their discovery, EPA and DHA have become some of the best studied nutrients in history, with over 30,000 scientific papers to their names. EPA and DHA have been researched for everything from heart disease to rheumatoid arthritis.

EPA is a 20-carbon omega-3 fatty acid that serves as a precursor for series-3 prostaglandins and series-5 leukotrienes, which possess anti-inflammatory and vasodilatory properties. EPA competes with arachidonic acid (an omega-6 fatty acid) for incorporation into cell membranes and for metabolism by cyclooxygenase and lipoxygenase enzymes. This competitive inhibition reduces the production of pro-inflammatory eicosanoids such as prostaglandin E2 and leukotriene B4.

DHA is a 22-carbon omega-3 fatty acid that is highly concentrated in neural tissue, particularly the brain and retina. It constitutes approximately 40% of the polyunsaturated fatty acids in neuronal cell membranes and 60% in photoreceptor outer segments. DHA is essential for normal brain development during pregnancy and infancy, and maintains structural and functional integrity of neural membranes throughout life.

EPA and DHA are able to inhibit partly a number of aspects of inflammation including leucocyte chemotaxis, adhesion molecule expression and leucocyte–endothelial adhesive interactions, production of eicosanoids like prostaglandins and leukotrienes from the n-6 fatty acid arachidonic acid, production of inflammatory cytokines and T cell reactivity. In parallel, EPA gives rise to eicosanoids that often have lower biological potency than those produced from arachidonic acid, and EPA and DHA give rise to anti-inflammatory and inflammation-resolving resolvins and protectins.

Long-chain fatty acids influence inflammation through a variety of mechanisms; many of these are mediated by, or at least associated with, changes in fatty acid composition of cell membranes. Changes in these compositions can modify membrane fluidity, cell signaling leading to altered gene expression, and the pattern of lipid mediator production. Cells involved in the inflammatory response are typically rich in the n-6 fatty acid arachidonic acid, but the contents of arachidonic acid and of the n-3 fatty acids EPA and DHA can be altered through oral administration of EPA and DHA.

Vitamin D

A teaspoon of cod liver oil supplies about 450 IU of vitamin D3, the same form the skin produces in sunlight. That covers a significant portion of the 600 to 800 IU most adults need daily. Vitamin D plays a direct role in regulating the body's absorption of calcium and phosphorus, which are necessary for the mineralization and maintenance of strong bones. Historically, this property was leveraged to prevent and treat conditions like rickets, a softening of bones in children caused by severe vitamin D deficiency.

Vitamin A (Preformed Retinol)

Vitamin A is a vital nutrient for immune system function, cellular growth, eye health, and reproduction. The preformed vitamin A in cod liver oil is the main reason one cannot treat it like a regular fish oil and simply take more for extra omega-3s. The tolerable upper intake level for preformed vitamin A in adults is 3,000 mcg per day. The oil's components also contribute significantly to immune regulation and function. Vitamins A and D work together to support both the innate and adaptive branches of the immune system.

Lipid-Lowering Mechanisms

Cod liver oil has been found to reduce the hepatic synthesis of VLDL with subsequent changes in the plasma lipid composition. Mean plasma triglyceride concentrations were reduced and those of high-density-lipoprotein (HDL) cholesterol were increased by supplementation. These fatty acids actively incorporate themselves into the cell membrane and decrease membrane lipid fluidity. It has also been suggested that cod liver oil prolongs primary bleeding time, leads to low platelet aggregation and low platelet thromboxane A2 synthesis. EPA competitively inhibits the production of prostaglandins and leukotrienes derived from arachidonic acid and may result in a reduction of inflammation via these and other mechanisms.

4. Scientific Evidence by Area of Use

4.1 Rickets Prevention and Bone Health

The most historically established evidence for cod liver oil relates to the prevention and treatment of rickets. Although benefits of cod liver oil as food were known as early as the seventh century, cod liver oil was only proposed as medicinal for rickets in Northern Europe at the end of the eighteenth century. The relationship between rickets and nutritional deficiency was suspected and demonstrated between 1880 and 1915, at the same time of the discovery of other vital substances (vitamins) needed to prevent beriberi, scurvy, and pellagra. With the discovery of vitamin D and the delineation of the anti-rachitic properties of cod liver oil by the 1930s, it became possible to not only treat but also eradicate rickets in the United States.

The mechanism is well characterised: one of the best-known benefits of cod liver oil relates to skeletal support, largely driven by the vitamin D content. Vitamin D plays a direct role in regulating the body's absorption of calcium and phosphorus, which are necessary for the mineralization and maintenance of strong bones. In a Norwegian study, it was found that 5 ml of cod liver oil increased the vitamin D level by 17 nmol/litre — a moderate increase that has a very low probability of toxicity, yet is still large enough to treat vitamin D deficiency. The evidence for cod liver oil's role in preventing nutritional rickets is considered strong and well-established, underpinning its long-standing position in public health recommendations in Norway and other Scandinavian countries.

4.2 Rheumatoid Arthritis and Joint Inflammation

Several human clinical trials have examined cod liver oil's effect on rheumatoid arthritis (RA), providing the most robust body of interventional evidence for any single condition studied with cod liver oil specifically.

The objective of one key study was to determine whether cod liver oil supplementation helps reduce the daily NSAID requirement of patients with RA. It was a dual-centre, double-blind placebo-controlled randomised study of 9 months' duration. Ninety-seven patients with RA were randomised to take either 10 g of cod liver oil containing 2.2 g of n-3 essential fatty acids or air-filled identical placebo capsules. Fifty-eight patients (60%) completed the study. Of 49 patients in the cod liver oil group, 19 (39%) and of 48 patients in the placebo group, 5 (10%) were able to reduce their daily NSAID requirement by more than 30% (P = 0.002). No differences between the groups were observed in the clinical parameters of RA disease activity or in the side-effects observed. The study concluded that cod liver oil supplements containing n-3 fatty acids can be used as NSAID-sparing agents in RA patients.

A separate pilot study reported the following: In this pilot study, 43 patients with rheumatoid arthritis ingested 1 g of cod liver oil (one capsule) daily for 3 months. Decreases occurred in morning stiffness (52.4%; P<10⁻³), painful (42.7%) and swollen (40%) joints (P = 10⁻³ each), and pain intensity (67.5%). Ratings of "good" or "very good" were awarded by 68% of the patients for efficacy and by 95% for tolerability. Eleven patients reported non-severe adverse effects that in 3 cases may have been related to the study preparation. This was a pilot study without a placebo group, limiting its conclusions.

Few placebo-controlled randomised trials assessing the effect of fish oils on RA disease activity have been published. Of those that have, the majority have shown an improvement in at least two clinical variables or a reduction in the NSAID requirement. Overall, the evidence from human trials for a modest NSAID-sparing effect of cod liver oil in RA is considered moderate, with the main limitation being small sample sizes and relatively short trial durations.

4.3 Cardiovascular Disease and Lipid Parameters

Observation from past years revealed that human populations such as those of Eskimos have a lower incidence of coronary heart disease, attributed to their seafood-rich diet. One such food is cod liver oil. The discovery of EPA and DHA by Bang and Dyerberg in the 1970s emerged directly from observing low cardiovascular disease rates in Greenlandic Inuit populations with high marine-fat diets.

A 30-day comparative study published in PMC examined cod liver oil's effect on lipid parameters in patients with hyperlipidaemia. After being examined for 30 days, both groups showed a significant reduction in total cholesterol, LDL, and triglyceride levels. An increase in the levels of HDL was also noted. However, upon the intake of cod liver oil, the interventional group showed a significantly higher reduction in cholesterol and lipid compared to the placebo group.

Omega-3 fatty acids in cod liver oil may reduce blood triglycerides by 15–30%, and can raise HDL cholesterol, which is linked to a lower risk of heart disease. However, the broader picture is more complex. Meta-analyses have not shown clear benefits of cod liver oil on cardiovascular disease outcomes, and the evidence for hard cardiovascular endpoints (mortality, non-fatal myocardial infarction) from cod liver oil specifically — as opposed to concentrated, high-dose omega-3 pharmaceutical preparations — remains limited and inconclusive. The REDUCE-IT trial demonstrated that 4 g of icosapent ethyl (a purified EPA product) lowered the risk of ischaemic events in subjects with hypertriglyceridaemia; however, this product consisted of 100% EPA and corresponds to approximately 10 times more EPA than the contents in a recommended daily dose of CLO. These findings from high-dose pharmaceutical omega-3 products should not be directly extrapolated to standard cod liver oil supplements.

4.4 Inflammation and C-Reactive Protein

A prospective observational trial published in PMC, the North Sea Race Endurance Exercise Study (NEEDED) 2014 sub-study, found that regular cod liver oil consumption was associated with reduced basal and exercise-induced C-reactive protein (CRP) levels — a biomarker of systemic inflammation — in a cohort of recreational endurance athletes. Omega-3 fatty acid supplements attenuate inflammation by modulating cell membrane function, down-regulating pro-inflammatory cytokines (such as IL-6), reducing production of arachidonic acid derivatives and reactive oxygen species. Omega-3 fatty acid supplements contain a variety of EPA and DHA, and these substances have different effects on the inflammatory response. EPA is a precursor of leukotrienes, attenuating cyclooxygenase-2 and arachidonic metabolism, while DHA is the precursor for protectins. This study was observational and does not establish causation.

4.5 Mental Health and Depression

Several observational studies have investigated a potential association between cod liver oil use and depressive symptoms. The Hordaland Health Study, a large Norwegian population-based cross-sectional survey, provides the most directly CLO-specific human data. This study aimed to evaluate the association between intake of cod liver oil, rich in omega-3 fatty acids, and high levels of symptoms of depression and anxiety in the general population. Researchers used data from the Hordaland Health Study 1997–1999, a population-based cross-sectional health survey from Norway including 21,835 subjects aged 40–49 and 70–74 years. Symptoms of depression and anxiety were measured by the Hospital Anxiety and Depression Scale (HADS). Logistic regression was used to study associations. A total of 3.6% had high levels of depressive symptoms. The prevalence of such depressive symptoms among the subjects who used cod liver oil daily was 2.5%, as compared to 3.8% in the rest of the population. As a cross-sectional study, causality cannot be established. Clinical evidence from short-term trials supports the notion that omega-3 supplementation in addition to standard pharmacological treatment improves the outcome for depression, though other trials have not found this. This may be due to a variation in the dosage of omega-3 administered or to the content of DHA versus EPA in the omega-3 oil used. The evidence base for CLO specifically in depression is preliminary and largely observational.

4.6 Eye Health

Some research suggests that omega-3 fatty acids reduce risk factors for glaucoma, such as eye pressure and nerve damage. Furthermore, diets high in vitamin A may reduce the risk of glaucoma and age-related macular degeneration (AMD), compared to diets lower in vitamin A. Although vitamin A is useful for eye health, high doses are not recommended, as they may cause adverse effects. DHA is a 22-carbon omega-3 fatty acid that is highly concentrated in neural tissue, particularly the brain and retina. It constitutes approximately 40% of the polyunsaturated fatty acids in neuronal cell membranes and 60% in photoreceptor outer segments. Evidence in this area for cod liver oil specifically is largely indirect, based on the known biology of its constituent compounds rather than dedicated CLO clinical trials.

4.7 Immune Function and Infection

Cod liver oil, defined as a nutritional supplement rich in omega-3 essential fatty acids as well as vitamins A and D, has been studied for its potential in reducing antibiotic use during otitis media seasons. The oil's components also contribute significantly to immune regulation and function. Vitamins A and D work together to support both the innate and adaptive branches of the immune system. The omega-3 fatty acids EPA and DHA help modulate the body's inflammatory response by suppressing proteins that promote chronic inflammation. Evidence from randomised controlled trials specifically on cod liver oil and immune outcomes in humans remains limited.

4.8 Other Investigated Areas

Its potential benefits in lowering the incidence of multiple sclerosis, improving renal function in diabetic patients, and exhibiting anti-cancer activity have been proposed as areas warranting further therapeutic investigation. Literature has reviewed the effectiveness of n-3 PUFAs in controlling inflammatory and autoimmune diseases such as rheumatoid arthritis, asthma, inflammatory bowel disease, psoriasis, cardiovascular disease, diabetes, multiple sclerosis and systemic lupus erythematosus. However, for these areas, much of the evidence comes from studies of n-3 PUFAs in general rather than cod liver oil specifically, and evidence strength is variable, ranging from preliminary to mixed. Ongoing research strongly suggests that there may be more to the therapeutic value of cod liver oil than its vitamins alone.

5. Body Systems Associated with Cod Liver Oil

Musculoskeletal system: Vitamin D and calcium metabolism underpinning bone mineralisation; NSAID-sparing in rheumatoid arthritis and joint inflammation.
Cardiovascular system: Triglyceride reduction, HDL elevation, antiplatelet effects, and antiatherosclerotic properties attributed to EPA and DHA.
Immune system: Significant contribution to immune regulation and function, with vitamins A and D working together to support both the innate and adaptive branches of the immune system.
Nervous system and mental health: DHA as a structural component of neuronal membranes; observational associations with reduced depressive symptoms.
Visual system: DHA in photoreceptor membranes; vitamin A as a precursor to retinal visual pigment.
Endocrine/metabolic system: Vitamin D deficiency is linked to bone fractures in the elderly and abnormal brain development in offspring; it may also lead to the development of metabolic syndrome, which involves the combination of high blood pressure, high glucose levels, and high cholesterol.

6. Dosage Forms and Dosages Reported in Studies

Cod liver oil products vary widely in concentration, and the amounts of constituent nutrients differ by brand and formulation. The following dosages are those reported in identified clinical and observational studies:

NSAID-sparing in rheumatoid arthritis (Galarraga et al., 2008): Ninety-seven patients with RA were randomised to take either 10 g of cod liver oil containing 2.2 g of n-3 essential fatty acids or placebo capsules, over 9 months.
Pilot RA symptom study: Forty-three patients with rheumatoid arthritis ingested 1 g of cod liver oil (one capsule) daily for 3 months.
Vitamin D status (Norwegian study): In a Norwegian study, it was found that 5 ml of cod liver oil increased the vitamin D level by 17 nmol/litre — a moderate increase with a very low probability of toxicity, yet large enough to treat vitamin D deficiency.
Average nutrient content per teaspoon (WebMD/pharmacopoeial reference): On average, one teaspoon of pure cod liver oil contains 10 mcg (400 IU) of vitamin D and 600 mcg of vitamin A — more than half of the entire daily recommended intake of these vitamins for most adults.
USDA tablespoon data: A tablespoon (13.6 g or 14.8 mL) of cod liver oil contains 4,080 μg of vitamin A and 34 μg (1,360 IU) of vitamin D.

Each cod liver oil product is different, and a specific product may contain much lower or higher levels of these vitamins. Much lower levels may not be helpful for increasing vitamin A and vitamin D levels. Much higher levels may cause serious side effects.

7. Safety Considerations and Interactions

Vitamin A Toxicity (Hypervitaminosis A)

The preformed vitamin A in cod liver oil is the main reason it cannot be treated like a regular fish oil for obtaining extra omega-3s. The tolerable upper intake level for preformed vitamin A in adults is 3,000 mcg per day. For children aged 1 to 3, it drops to just 600 mcg. Going over these thresholds regularly can stress the liver and, during pregnancy, poses a risk of birth defects.

Chronic vitamin A toxicity can cause liver damage, bone pain, skin changes, and increased intracranial pressure. Pregnant women are particularly vulnerable, as excessive vitamin A intake during pregnancy is associated with teratogenic effects and birth defects. The NHS specifically advises pregnant women to avoid vitamin A supplements and liver products. Symptoms of vitamin A toxicity include headache, blurred vision, nausea, dizziness, and skin peeling.

An early case report of hypervitaminosis A documented in the NIH's LiverTox database describes a 3-year-old boy on high doses of vitamin A from daily cod liver oil who developed anorexia followed by listlessness, bone pain, hyperostosis on X-ray, alopecia, hepatosplenomegaly and anaemia, and improved on stopping cod liver oil supplements.

Vitamin D Toxicity

Vitamin D toxicity (hypervitaminosis D) is a contraindication. Those with very high vitamin D levels should not take cod liver oil, and a healthcare provider can order a blood test to check vitamin D levels. Both vitamin A and vitamin D toxicity can result from the consumption of large amounts of cod liver oil.

Gastrointestinal Effects

Common side effects include having a bad taste in the mouth or bad breath, heartburn, nausea, upset stomach, and diarrhoea. Storage and shelf life require attention, as omega-3 fatty acids are susceptible to oxidation. Rancid cod liver oil loses nutritional value and may cause gastrointestinal upset.

Bleeding Risk and Anticoagulant Interactions

Bleeding complications are a potential concern, though clinically significant bleeding is uncommon at typical supplement doses. Omega-3 fatty acids possess mild antiplatelet properties, which may affect bleeding time. This risk may increase with higher doses or when combined with anticoagulants or antiplatelet medications. Bleeding risk may be increased with high-dose omega-3 supplementation, particularly in individuals taking anticoagulants (warfarin, DOACs), antiplatelet agents (aspirin, clopidogrel), or non-steroidal anti-inflammatory drugs. If taking warfarin, monitoring INR when starting or stopping cod liver oil is advisable.

Interactions with Medications

Cod liver oil should not be taken with oral retinoids (such as isotretinoin, acitretin, or alitretinoin) due to increased vitamin A toxicity risk. Dosing should be separated from orlistat or bile acid sequestrants (like cholestyramine) by at least 2 hours, as these can reduce absorption. The nutrients contained in cod liver oil can cause interactions with medications. Anticoagulants, for example, can have their activity increased if large amounts of cod liver oil are taken. Because it is rich in vitamin D, cod liver oil is also not recommended for people with hypercalcaemia.

Variability in Product Composition

Going over the vitamin A upper intake level regularly can stress the liver and, during pregnancy, poses a risk of birth defects. Because vitamin A concentrations vary significantly between brands, checking the label matters more with cod liver oil than with most supplements. Some products are formulated to keep vitamin A moderate while boosting omega-3 content. Others retain the naturally high vitamin A levels found in cod liver.

The idea that cod liver oil is the "best" or "only" source of omega-3s is untrue, as other fish oils and vegetable sources freely supply equivalent or superior levels without the heavy vitamin A load. This is a clinically relevant distinction, as consumers seeking omega-3s without the attendant risk of vitamin A accumulation may be better served by fish body oils.

References

Health Conditions

Health conditions that Fat liver oil may help support.

No conditions available.

Body Systems

Body systems that Fat liver oil may help support.

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