Cod liver oil, sometimes also referred to as CLO, is a supplement with a long history that is still extremely popular and useful as a source of omega 3 fatty acids for improving your health and increasing your resistance to chronic diseases of all kinds.
It’s often argued as more effective than regular fish oil, and it has the benefits of the omega 3 fatty acids EPA and DHA, which are responsible for the health benefits of all types of fish oil.
We’ve examined the best cod liver oil products on the market and ranked them according to their quality.
1. Carlson Cod Liver Oil
Carlson Cod Liver Oil is an extremely well-regarded supplier of this supplement, and its bottle-based cod liver product is everything you’re looking for.
The 500 mL bottle delivers one hundred 5 mL servings, and the only other ingredient is natural lemon flavor–this helps keep the fishy taste of the oil at bay. The total fish oil content per serving is 4.6 grams, and of these, 1.1 grams are omega-3 fatty acids.
With a 500 mg of DHA and 400 mg of EPA, it’s not short on substance. For high-dose fish oil, this is a great way to go.
2. Nordic Naturals Cod Liver Oil
As one of the most widely-known omega 3 fatty acid companies, Nordic Naturals has a reputation for quality, and lives up to it here.
Its liquid cod liver oil supplement uses only natural flavorings and preservatives, like vitamin E and rosemary extract, to increase the shelf life of the oil.
There are 1060 mg of omega three fatty acids per 5 mL serving, which is quite good; the only thing that prevents it from being the top pick is its slightly lower amount of EPA.
3. Athelas Nutraceuticals Cod Liver Oil
Among the softgel-based cod liver oil supplements, the product made by Athelas Nutraceuticals is among the best. With 110 mg of EPA and 100 mg of DHA, the vast majority of the 240 mg of omega 3 fatty acids are comprised of the components you need to get optimal results.
It has no extraneous ingredients, which minimalists will love, though there might be a mild fishy taste to the capsule.
4. Barlean’s Cod Liver Oil
Barlean’s is a bottle-based cod liver oil that is based around freshness–the company even advertises the short shelf life (six months) compared to other companies, who allow their products on the shelf longer.
The omega 3 content is great, with 360 mg of EPA and 540 mg of DHA, though the bottle is only eight ounces, compared to the 16 fluid ounces of some other competitors. Despite this, you can’t go wrong with Barlean’s.
5. Dropi Pure Icelandic Cod Liver Oil
Marketed as a premium cod liver oil supplement, Dropi focuses on purity and high nutritional content. The overall omega 3 content is excellent, at 1150 mg per 5 mL serving, though the EPA and DHA values are middle-of-the-road for a bottle-based cod liver oil supplement.
The other notable facet of this supplement is its unusually high vitamin A content, at 73% of your recommended daily intake. This could be a benefit for some people and a problem for others, since vitamin A is a nutrient that can be harmful when consumed to excess.
So, if you already get a lot of vitamin A in your diet, you’ll want to look elsewhere.
6. Carlson Cod Liver Oil Softgels
While the softgel version of Carlson Cod Liver Oil uses the exact same high-quality oil, the gelatin-based softgel version of the supplement has a disappointingly low dosage.
While it’s certainly possible to just take more softgels, you’ll quickly reach a point where it just makes more sense to get the liquid version, even though measuring precise dosage with liquid supplements can be tricky.
7. Amazing Omega Norwegian Cod Liver Oil
Amazing Omega makes a softgel-based cod liver oil supplement that has a high content of fish oil per capsule, but a disappointingly low EPA and DHA concentration.
In each softgel, there is only 80 mg of EPA and 100 mg of DHA. Amazing Omega does supply fairly high amounts of vitamin A and vitamin D, but those are fringe benefits of taking cod liver oil. The main issue is the content of the omega 3 fatty acids, and specifically the EPA and DHA content.
8. AMRAP Nutrition Cod Liver Oil
AMRAP markets this cod liver oil supplement towards athletes, focusing on its anti-inflammatory properties.
While at first glance the contents look pretty good, a serving size of this is actually two softgels, not one, so you’re getting a half-dose (only 500 mg of cod liver oil) per capsule. It does have a pretty minimalist ingredient design, but the low dosage is a big downside
9. Blue Ice Fermented Cod Liver Oil
The main selling point of Blue Ice is that there version of cod liver oil is fermented. The company claims that the fermentation process “releases the oil” in the cod liver, but seeing as other companies fare just fine in their cod liver oil supplements without supplementation, it may not be necessary.
A report by an independent nutritionist in 2015 incited an uproar when it alleged that the product actually contained pollock oil instead of cod oil, and that it was rancid and contaminated with trans fats. While the company hired several independent labs to analyze their product and now has freshness dates printed on the label, it may be better to steer clear of this one.
10. Solgar Norwegian Cod Liver Oil
Solgar’s cod liver oil supplement is something of a let-down, because the company usually has uniformly high quality across all of its supplements. This one is a bit of an exception.
Each softgel has only 460 mg of cod liver oil, and as you might guess, the omega 3 fatty acid content is a lot lower than that. The EPA and DHA content is only 28 mg each, which makes it very hard to recommend this cod liver oil supplement.
Who should buy cod liver oil?
Cod liver oil is a plentiful source of omega 3 fatty acids, but you could also get the same benefits from krill oil, fish oil, or a vegan omega 3 supplement. Who should opt for cod liver oil? If you want additional micronutrient benefits from vitamin A and vitamin D, cod liver oil is for you.
All the usual benefits of omega 3 fatty acids still apply—you can expect cod liver oil to have the same beneficial effects on risk factors for cardiovascular disease and facilitate the same kinds of improvements in cognitive function and mental health that you’d get with any source of DHA and EPA, but with the added benefits of additional micronutrients.
While cod liver oil is plentiful in omega 3, as you’d expect from a fish-derived supplement, the liver tissue that produces it is also rich in vitamins and minerals.
Cod liver oil is also one of the few natural source of vitamin D—it is an exceptional source of vitamin D, with over 1300 IUs of vitamin D per tablespoon. That dosage level is something you’d only usually get from a dedicated vitamin D supplement.
The vitamin A content of cod liver oil is also excellent; a single serving contains nearly 300% of your recommended daily intake. The vitamin A content in cod liver oil might add to the skin health benefits that have been connected to other sources of omega 3 fatty acids.
How we ranked
To formulate our cod liver oil rankings, we combined the best-selling and most popular cod liver oil brands with smaller, specialty companies that focus on high-quality products.
After assembling the field, we looked for brands that used independent lab testing to ensure purity first of all—as with any fish-derived product, purity is particularly important due to the potential for heavy metals like mercury, along with organic contaminants like PCBs (polychlorinated biphenyls).
Both of these toxins have a tendency to accumulate in the fat tissue of fish, so testing is important to ensure that a cod liver oil supplement is free from contamination.
Next up, we examined the omega 3 fatty acid content of the cod liver oils still on our list. Specifically, we looked at the amount of DHA and EPA, in milligrams, per capsule or per fluid ounce of oil.
Nutrition researchers have traced many of the benefits of omega 3 fatty acids to these two specific molecules. EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are two specific types of omega 3 fatty acids which appear to exert most or all of the cardioprotective effects of omega-3 fatty acids, and they are both also directly metabolized by the brain.
For these reasons, we looked for cod liver oils that maximized the EPA and DHA content. This proved to be one of the most important distinguishing factors between cod liver oil brands, since the EPA and DHA content per serving varied wildly from the best to the worst products.
We also considered the delivery format of the cod liver oil—one of the secondary advantages to cod liver oil is that it is traditionally packaged as a free liquid, not bound up in capsules.
This allows for much more freedom in dosage compared to fish oil or krill oil products that usually only come in a capsule. This can be a boon for people who are looking to customize their cod liver dosing, or who want to mix it into smoothies or shakes.
On the flipside, though,there were several high-quality capsule-based products that still made the cut, since capsules do have certain advantages (not the least of which is masking the fishy taste of cod liver oil).
Finally, we made sure the remaining products had a clean supplement design without unnecessary additives. We made allowances for small amounts of lemon flavoring or other natural flavor sources to mask the taste of cod liver oil (which not everyone enjoys), but mandated that these flavoring agents be naturally derived products.
The final ten cod liver oils, ranked according to quality, combine the health benefits of omega 3 fatty acids with the distinct benefits of high vitamin A and vitamin D concentrations present in cod liver oil.
Cod liver oil was the original fish oil supplement. While recently, omega 3 fatty acids from fish oil in general have become very popular in their own right, cod liver oil popular far before fish oil or krill oil supplements.
Touted as beneficial to your health for decades, it’s now being used to reduce risk factors for chronic disease and fight inflammation.
Since the cod is, after all, a fish, you can expect many of the same benefits as fish oil. What distinguishes cod liver oil is its tendency to have much higher contents of vitamin A and vitamin D.
If you prefer to get your vitamins and minerals from natural sources, the vitamin D will be of particular interest: aside from certain kinds of mushrooms, there are very few other dietary sources of vitamin D (1).
Cod liver oil can help control and perhaps even prevent heart disease. Early research in animals found that cod liver oil could help control and even prevent heart disease. A study published in 1986 in the New England Journal of Medicine used a small group of pigs with high levels of blood lipids, which are known to contribute to artery hardening and heart disease.
About half the pigs were fed a cod liver oil supplement for eight months (2). The other half of the pigs were not fed any special supplement, and the hogs were given a diet that was intended to induced heart disease.
The researchers found that the cod liver oil supplement substantially reduced markers of heart disease in the pigs when compared to the control group, and they hypothesized that this happened because the cod liver oil modified the way the pigs’ bodies metabolized certain fat-related hormones.
Naturally, additional research in humans was warranted. Research published in Circulation, a journal published by the American Heart Association, studied the effect of a cod liver oil supplement in blood markers of heart disease in a small group of volunteers (3).
All volunteers consumed a “western diet,” which is known to promote heart disease. As in the study on pigs, the researchers found that blood lipid levels dropped and other biomarkers of cardiovascular well-being improved too.
Eventually, larger studies were carried out, and researchers identified the omega 3 fatty acid content as the reason for the impressive cardiovascular benefits of cod liver oil.
Cod liver oil has several mechanisms by which it can reduce the risk of heart disease. A scientific review article by Phillip C. Calder in the journal Clinical Science evaluated the range of mechanisms by which the omega 3 fatty acids in cod liver oil help reduce your risk for heart disease (4).
The omega 3 fatty acid content, according to Calder, lowers levels of blood triglycerides, helps decrease the production of inflammatory compounds in the blood, and even increases heart rate variability. All of these are positive steps when it comes to heart disease, since high triglycerides, lots of inflammation, and low heart rate variability are all associated with heart disease.
Calder also cites several epidemiological studies demonstrating the benefits of omega 3 fatty acid consumption, particularly in people who are at high risk for cardiovascular disease.
Cod liver oil might help prevent type I diabetes. One unexpected benefit of cod liver oil appears to be a potential for it to reduce your risk for type I diabetes, either when consumed by a pregnant woman before giving birth, or during childhood.
Research published from the National Institute of Health in Norway compared mothers of children with type 1 diabetes to a matched control group of mothers of children similar in many regards, except that they did not have type 1 diabetes (5).
The results showed that mothers of children without type 1 diabetes were more likely to take cod liver oil, perhaps indicating that there may be a protective effect associated with cod liver oil.
The same authors replicated this finding in a case control study of children with type 1 diabetes (6). Using a mail survey, the researchers again matched children with type 1 diabetes with children from similar backgrounds who did not have type 1 diabetes. The researchers found a protective effect; using cod liver oil conferred about a 25% reduction in risk of type 1 diabetes during the first year of a child’s life.
Too much cod liver oil is bad news if you are pregnant. Mothers and children should be especially conscious of the vitamin A content of any cod liver oil supplement they use, though; research in rats has found that excessive levels of vitamin A intake can cause birth defects (7).
If you don’t want to tally up your vitamin A intake so you can be sure taking a cod liver oil supplement is okay, you can also take a regular fish oil supplement, which shouldn’t have as much vitamin A in it.
The omega 3 fatty acids in cod liver oil is exceedingly safe. Aside from a few scattered reports of very mild and transient gastrointestinal discomfort, no side effects are known to be associated with omega 3 fatty acids.
The one thing you do need to be wary of is the vitamin A content of your cod liver oil supplement. Since vitamin A is fat soluble (hence why you’d find it in an oil supplement), your body can’t get rid of excess vitamin A very easily, so high doses of vitamin A can be harmful to your health, according to the United States National Institutes of Health (8).
According to the office of dietary supplements at the National Institutes of Health, the maximum recommended intake of vitamin A is 10,000 IUs per day, which a hefty serving of cod liver oil can sometimes exceed.
Too much vitamin A can cause dizziness, nausea, and headaches. Too much vitamin A is particularly dangerous for women who are pregnant, because vitamin A overload is associated with birth defects. As such, taking cod liver oil when you are pregnant is not recommended.
Though cod liver oil is also high in vitamin D, the safety limit for vitamin D intake is far higher than vitamin A. Several thousand IUs of vitamin D taken daily over a long period of time are necessary to cause vitamin D toxicity—sources cite upper intake limits between 10,000 to 40,000 IUs per day.
With cod liver oil, you’re far more likely to run into problems because of the vitamin A content before you have any issues linked to the vitamin D content.
The American Heart Association currently recommends 1000 mg of fish oil per day for people with cardiovascular disease.
Even for those who are healthy, that’s not a bad place to start (9). However, if you already know you have high blood lipids and want to be proactive about lowering your risk for heart disease, you can consider 2000-4000 mg of fish oil per day.
In the case of cod liver oil, keep in mind the caveats about vitamin A content–you don’t want to increase your intake of cod liver oil so high that you exceed your recommended daily intake of vitamin A. Don’t forget, you’ll have to take into account all of the other sources of vitamin A in your diet, too.
Q: What is cod liver oil good for?
A: Cod liver oil is a great supplement if you are looking for the benefits of omega 3 fatty acids as well as the micronutrient advantages you can get with vitamins A and D.
Omega 3 fatty acids have been connected with benefits ranging from reduced risk factors for cardiovascular disease to improvements in cognitive function and better mental health.
Vitamin A helps with vision and skin health, and vitamin D plays a critical role in bone health as well as cognitive function. While you could take separate supplements for these other micronutrients, cod liver oil is a traditional supplement that has all three in one.
Q: Should you take cod liver oil in the morning or at night?
A: With regards to the omega 3 fatty acid benefits, it doesn’t particularly matter whether you take cod liver oil in the morning or the evening.
Fish oil spends several days in your system before it is excreted, so as long as you take cod liver oil once per day, the levels of DHA and EPA in your blood will rapidly reach an equilibrium within a few days.
This equilibrium level of omega 3s won’t vary much from day to day, even if the time of day you take cod liver oil isn’t always consistent. The vitamin D in cod liver oil might matter more when it comes to optimal timing of doses, because it essentially acts as a hormone, and we know that many hormones in the body follow a circadian rhythm.
While research has acknowledged that vitamin D is linked to sleep quality, scientists admit that there is still far more we don’t know—whether it’s better to take vitamin D (and thus cod liver oil) in the morning or the evening is unclear (10).
Q: What are the benefits of cod liver oil vs fish oil?
A: Cod liver oil versus fish oil is a popular debate. Fish oil boasts a higher concentration of omega 3 fatty acids, including the compounds DHA and EPA, which many researchers believe are responsible for most or all of the health benefits of omega 3 fatty acids.
They point to evidence that EPA and DHA are directly metabolized by the brain, as well as pharmaceutical research that uses high-dosage forms of pure EPA or pure DHA that has been exceptionally promising in people who are at high risk for heart disease. On the other hand, cod liver oil offers some micronutrients that fish oil does not.
Cod liver oil is exceptionally high in vitamin A, and is by far the best all-natural source of vitamin D. The next closest foods in which vitamin D occurs naturally is mushrooms, which have only a tiny fraction of the vitamin D that you’ll find in cod liver oil. However, the high vitamin A content in cod liver oil can be a drawback as well—very high doses of cod liver oil can cause vitamin A toxicity, and cod liver oil is not recommended to women who are pregnant.
Q: Is cod liver oil bad for you?
A: Cod liver oil is safe and healthy for most people when taken at an appropriate dose. When cod liver oil is taken at a very high dose, it can be bad for you because of the high concentration of vitamin A.
While a strong dose of vitamin A is one of the main selling points of cod liver oil, too much vitamin A can be toxic to your body. Vitamin A is fat soluble, not water soluble, so unlike something like vitamin C, which can be eliminated in urine if you take too much of it at one time, the vitamin A in cod liver oil stays in your system for longer.
Moreover, because excessive supplemental intake of vitamin A has been linked to birth defects, cod liver oil should not’ be taken during pregnancy. Taking more than one or two standard doses of cod liver oil can put you over the maximum recommended intake of vitamin A per day, so cod liver oil is not as well-suited for high-dose delivery of omega 3s.
Q: Should I take cod liver oil?
A: Cod liver oil is best suited for people who want the benefits of a moderate dose of omega 3 fatty acids, plus vitamin A and vitamin D. If you insist that your micronutrients are naturally produced, cod liver oil is an excellent way to get a high dose of vitamin D from a totally natural product.
On the other hand, if you are trying to maximize your DHA and EPA intake, cod liver oil might not be the best choice. The high vitamin A concentration, while beneficial in small to moderate doses, precludes cod liver oil from being taken in high doses.
Q: Is cod liver oil beneficial for hair?
A: Though cod liver oil occasionally makes appearances on lists of nutrients and supplements that can improve hair health, the scientific evidence is fairly limited to support this claim.
One study on women with hair loss does suggest a potential role for omega 3 fatty acids generally, though—the study, published in the Journal of Cosmetic Dermatology in 2015, split a group of 120 women with hair loss into two groups (11).
One group received a placebo, while the other group received a supplement that combined omega 3, omega 6, and several antioxidants. After taking the supplement for six months, the group taking the combined supplement showed stronger and healthier hair compared to the placebo group.
While this study’s results make it hard to parse out the relative benefit of omega 3 in particular, and make inferring any specific benefits to cod liver oil even shakier, it’s nevertheless an interesting result that suggests there could be a connection to omega 3 intake and hair health, at least in women.
Q: What animal does cod liver oil come from?
A: Cod liver oil is extracted from the cod, which is a large fish often found in the Atlantic ocean. Cod has become more scarce recently, which has led to higher prices on cod liver oil.
The oil itself, as you can probably guess from the name, is extracted from the liver of the cod, which would otherwise go to waste when a cod is caught for food. Using the liver as the source of the oil is the reason cod liver oil is so rich in vitamins A and D. These vitamins tend to be concentrated in liver tissue, and since they are fat soluble, they are extracted alongside the oils in the liver.
Despite its decidedly old-school origins, cod liver oil is still an excellent supplement for anyone who wants to improve their cardiovascular health and fight inflammation.
The optimal dosage for most people is 1000 mg per day, but you should be conscious of the vitamin A content of your cod liver oil supplement. The best cod liver oil supplements deliver high doses of omega 3 fatty acids with only a moderate amount of vitamin A.
For BodyNutrition‘s #1 cod liver oil recommendation, click here.