Both cod liver oil and fish oil are oils that come from fish. They are a great source of omega-3 fatty acids, which can reduce the risk of some chronic diseases.
Although cod liver oil is a type of fish oil, what is commonly referred to as “fish oil” comes from a variety of sources.
There are some differences between cod liver oil and fish oil. For example, they contain different levels of omega-3 fatty acids and different vitamins.
This article describes the differences between cod liver oil and fish oil. It lists the benefits and risks of each, and provides ways in which a person can include them in their diet, through food or supplements.
Both cod liver oil and fish oil are sources of omega-3 fatty acids. Omega-3 fatty acids are a group of fatty acids that, in small amounts, are important for human health.
Most studies focus on three types of omega-3 fatty acids: alpha linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA). The benefits of each acid can vary slightly, so getting all three can improve health.
A person must get these acids from the diet; the body does not make them. ALA converts to EPA and then to DHA, but the conversion rate is low. To get optimal Omega-3 benefits, a person must consume DHA and EPA.
Cod liver oil is a type of fish oil. The main differences between cod liver oil and other fish oils are:
- Different vitamins: Cod liver oil contains vitamins A and D.
- Omega-3 content: Cod liver oil comes from cod liver, which is less fat than other types of fish, such as tuna and mackerel. For that reason cod liver oil offers a lower dose of omega-3 fatty acids.
- Other health benefits: In addition to its purported benefits of omega-3 fatty acids, cod liver oil has long been a popular folk remedy for controlling constipation and
induce labor.
Although cod liver oil is a type of fish oil, people usually use the term ‘fish oil’ to refer to fattier fish oils, such as those from tuna and mackerel.
Some research shows that omega-3 fatty acids can improve heart health by lowering blood pressure or reducing the risk of a heart attack. Most of this type of research focuses on populations that have a lot of fish oil in their diet, not people who supplement with fish oil.
Not all research supports these potential benefits, however.
Omega-3 supplements, including fish oil, can also:
Researchers continue to study omega-3 fatty acids for a wide variety of conditions, but the data to date is inconclusive. For example, a 2019 meta-analysis of omega-3 fatty acids suggests they may improve symptoms of depression, but other studies have been inconclusive or undermined this claim.
Like other fish oils, cod liver oil can reduce the risk of certain medical conditions.
The study also found that cod liver oil users had more health problems and were more likely to report bone diseases and benign growths.
The study authors suggest that people with health problems are more likely to use cod liver oil. Additionally, they found that cod liver oil users lived healthier lifestyles, suggesting that other differences may explain the different health outcomes between the groups.
Vitamin D plays an important role in health. About a quarter of Americans
- reduce the risk of osteoporosis, especially when someone takes it with calcium
- lowering the risk of developing certain types of tumors
- improving the health of the immune system
- support glucose metabolism
Read more about the benefits of fish oils here.
Since cod liver oil and fish oil are both fish oils containing omega-3 fatty acids, the risks are similar. They contain:
- Fish allergies: Fish oil supplements can cause certain fish allergies. In some people the reaction can be severe.
- Stomach problems: Some people who take fish oil supplements experience stomach problems such as bloating, gas, diarrhea, or constipation.
- Taste of the bathroom: Fish oil can leave a fishy taste in the mouth, and a person may notice bad breath immediately after taking the supplement.
- Blood pressure:
Limited research suggests that omega-3 fatty acids can lower blood pressure. People on blood pressure medications should consult a doctor before trying these supplements. - Blood clotting: Omega-3 fatty acids can also affect blood clotting, so people with clotting disorders, bleeding disorders, and those on clotting medications should consult a doctor before using fish oil.
- Interactions with other medications: Doctors have not identified all possible drug interactions associated with fish oil, so people taking medications vital to their health should consult a physician before taking the supplement.
There are three main types of cod liver oil and fish oil supplements:
Food
A person can get cod liver oil from eating cod liver. A number of foods, including most fish, are good sources of omega-3 fatty acids and may provide better benefits than supplements. Fatty fish such as tuna and mackerel contain the most omega-3 fatty acids.
Oils
A number of manufacturers make pure fish oil formulas, or fish oil that contains other supplements. These oils usually contain higher concentrations of fish oil, but can taste bad.
Pills
Fish oil capsules can be a more palatable option for those who don’t want to take oily supplements.
Alternatives
Vegans and vegetarians may not want to eat fish oil. Flaxseed oil contains omega-3 fatty acids, but not the EPA and DHA in fish oil. Algae oil contains DHA, but no EPA.
The latest Institute of Medicine review to determine the correct dosage of omega-3 fatty acids was based on unclear data. Instead, the organization looked at the mean intakes in healthy groups and recommended the following daily intakes:
Eating two to three servings of fish per week can also help a person get the recommended amount of omega-3 fatty acids.
Supplements vary in the amount of omega-3 fatty acids present, as well as the type of omega-3 fatty acids. It is important to check the label. Users should also look for other ingredients as taking too many supplements can increase the risk of vitamin overdose.
Most research shows that food is the healthier source of fish oil and that the apparent benefits of omega-3s may be less apparent when someone is taking supplements. For example, the cardiovascular benefits of omega-3 fatty acids are only present in people who eat omega-3 rich foods, not supplements.
Omega-3 fatty acids from cod liver oil and fish oil can provide important health benefits, and there is little evidence that they can harm healthy people.
Consider increasing fish intake to get the most benefits. People who want to try supplements should talk to a doctor first.
For those who don’t want to eat fish products, there are other great sources of omega-3 fatty acids, such as algae oil.