12 Important Benefits of Fish Oil, Based on Science
Fish oil is one of the most commonly consumed dietary supplements.
It’s rich in omega-3 fatty acids, which are very important for your health.
If you don’t eat a lot of oily fish, taking a fish oil supplement could help you get enough omega-3 fatty acids.
Here are 12 health benefits of fish oil.
Fish oil is the fat or oil that’s extracted from fish tissue.
It usually comes from oily fish such as herring, tuna, anchovies, and mackerel. However. it’s also sometimes produced from the livers of other fish, as is the case with cod liver oil.
The World Health Organization (WHO) recommends eating 1–2 portions of fish per week. This is because the omega-3 fatty acids in fish provide many health benefits, including protection against a number of diseases.
However, if you don’t eat 1–2 servings of fish per week, fish oil supplements can help you get enough omega-3s.
Around 30% of fish oil is made up of omega-3s, while the remaining 70% is made up of other fats. What’s more, fish oil usually contains some vitamin A and D.
It’s important to note that the types of omega-3s found in fish oil have greater health benefits than the omega-3s found in some plant sources.
The main types of omega-3s in fish oil are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), while the type found in plant sources is mainly alpha-linolenic acid (ALA).
Although ALA is an essential fatty acid, EPA and DHA have many more health benefits (
It’s also important to get enough omega-3s because the Western diet has replaced a lot of omega-3s with other fats, such as omega-6s. This distorted ratio of fatty acids may contribute to numerous diseases (
Heart disease is the leading cause of death worldwide (
Studies show that people who eat a lot of fish have much lower rates of heart disease (
Multiple risk factors for heart disease appear to be reduced by the consumption of fish or fish oil. The benefits of fish oil for heart health include:
- Improved cholesterol levels. It can increase levels of HDL (good) cholesterol and may also lower levels of LDL (bad) cholesterol (
10, 11, 12, 13, 14, 15, 16, 17).
- Decreased triglycerides. It can lower triglycerides by 15–30% (
12, 16, 18).
- Reduced blood pressure. Even in small doses, it helps reduce blood pressure in people with elevated levels (
19, 20, 21).
- Plaque prevention. It may prevent the plaques that can cause arteries to harden, as well as make arterial plaques more stable and safer in those who already have them (
22, 23, 24).
Although fish oil supplements can improve many of the risk factors for heart disease, there is no clear evidence that they can prevent heart attacks or strokes (
Fish oil supplements may reduce some of the risk factors associated with heart disease. However, there is no clear evidence that they can prevent heart attacks or strokes.
Your brain is made up of nearly 60% fat, and much of this fat is omega-3 fatty acids. Therefore, omega-3s are essential for typical brain function (
In fact, some studies suggest that people with certain mental health conditions have lower omega-3 blood levels (28,
Interestingly, research suggests that omega-3s can prevent the onset or improve the symptoms of some mental health conditions. For example, it can reduce the chances of psychotic disorders in those who are at risk (
In addition, supplementing with fish oil in high doses may reduce some symptoms of both schizophrenia and bipolar disorder, though there is a lack of consistent data available. More study is needed in this area (
Fish oil supplements may improve the symptoms of certain mental health conditions. This effect may be a result of increasing omega-3 fatty acid intake.
Like your brain, your eyes rely on omega-3 fats. Evidence shows that people who don’t get enough omega-3s have a greater risk of eye diseases (
However, this positive effect was not found for dry eye disease in particular (35).
Furthermore, eye health begins to decline in old age, which can lead to age-related macular degeneration (AMD). Eating fish is linked to a reduced risk of AMD, but the results from fish oil supplements are less convincing (
One older study found that consuming a high dose of fish oil for 19 weeks improved vision in people with AMD. However, this was a very small study (38).
Two larger studies in 2013 examined the combined effect of omega-3s and other nutrients on AMD. One study showed a positive effect, while the other found no effect. Therefore, the results are unclear (
Eating fish may help prevent eye diseases. However, it’s unclear whether fish oil supplements have this same effect.
Inflammation is your immune system’s way of fighting infection and treating injuries.
However, chronic inflammation is associated with health conditions such as obesity, diabetes, depression, and heart disease (
Reducing inflammation can help treat symptoms of these diseases.
Because fish oil has anti-inflammatory properties, it may help treat conditions involving chronic inflammation (
For example, increased weight or stress can sometimes contribute to higher levels of inflammation.
In two older studies — one in people with obesity and one in people experiencing stress — fish oil was found to reduce the production and gene expression of inflammatory molecules called cytokines (
Moreover, fish oil supplements can significantly reduce joint pain, stiffness, and medication needs in people with rheumatoid arthritis, which causes pain in the joints (
While inflammatory bowel disease (IBD) is also triggered by inflammation, there is no clear evidence to suggest that fish oil improves its symptoms (
Fish oil has strong anti-inflammatory effects and can help reduce symptoms of inflammatory diseases, especially rheumatoid arthritis.
Your skin is the largest organ in your body, and it contains a lot of omega-3 fatty acids (
Skin health can decline throughout your life, especially during old age or after too much sun exposure.
That said, fish oil supplements may be beneficial in a number of skin disorders, including psoriasis and dermatitis (
Your skin can become damaged by aging or too much sun exposure. Fish oil supplements may help maintain healthy skin.
Omega-3s are essential for early growth and development (
Therefore, it’s important to get enough omega-3s during pregnancy and while breastfeeding.
Taking fish oil supplements during these times may improve fetal brain development. However, it’s unclear whether learning or IQ will also be improved (
Taking fish oil supplements during pregnancy and breastfeeding may also improve infant visual development and help reduce the risk of allergies (
Omega-3 fatty acids are vital for an infant’s early growth and development. Fish oil supplements in pregnant people or infants may improve hand-eye coordination, although their effect on learning and IQ is unclear.
Your liver processes most of the fat in your body and can play a role in weight gain.
Liver disease is increasingly common — particularly nonalcoholic fatty liver disease (NAFLD), in which fat accumulates in your liver (
Fish oil supplements can improve liver function and inflammation, which may help reduce symptoms of NAFLD and the amount of fat in your liver (
Liver disease is common in people with obesity. Fish oil supplements may help reduce fat in the liver and symptoms of NAFLD.
Depression is expected to become the second-largest cause of illness by 2030 (
Interestingly, older studies have shown that people with major depression appear to have lower blood levels of omega-3s. However, the results have been inconsistent so far (
Moreover, some studies have shown that oils rich in EPA help reduce depressive symptoms more than DHA. Again, more research is needed (
Fish oil supplements — especially those rich in EPA — may help improve symptoms of depression.
A number of neurodevelopmental conditions in children, such as attention deficit hyperactivity disorder (ADHD), involve hyperactivity and inattention.
Given that omega-3s make up a significant proportion of the brain, getting enough of them may be important for preventing these conditions in early life (64).
Fish oil supplements may improve perceived hyperactivity, inattention, impulsiveness, and aggression in children. This may benefit early life learning. But more research is needed (
Neurodevelopmental conditions in children can affect their learning and development. Fish oil supplements have been shown to help reduce hyperactivity, inattention, and other related behaviors.
As you age, your brain function slows down and your risk of Alzheimer’s disease increases.
People who eat more fish tend to experience a slower decline in brain function in old age (
However, studies on fish oil supplements in older adults haven’t provided clear evidence that they can slow the decline of brain function (
Nevertheless, some very small studies have shown that fish oil may improve memory in healthy older adults (71,
People who eat more fish have slower age-related mental decline. However, it’s unclear whether fish oil supplements can prevent or improve mental decline in older adults.
Asthma, which can cause swelling in the lungs and shortness of breath, is becoming much more common in infants.
A number of studies show that fish oil may reduce asthma symptoms, especially in early life (74).
However, not all studies have found similar results (75).
In an older review in nearly 100,000 people, a mother’s fish or omega-3 intake was found to reduce the risk of asthma in children by 24–29% (
Furthermore, fish oil supplements in pregnant people may reduce the risk of allergies in infants (77).
A higher intake of fish and fish oil during pregnancy may reduce the risk of asthma and allergies in children.
During old age, bones can begin to lose their essential minerals, becoming more likely to break. This can lead to conditions such as osteoporosis and osteoarthritis.
Calcium and vitamin D are very important for bone health, but some studies suggest that omega-3 fatty acids can also be beneficial.
People with higher omega-3 intakes and blood levels may have better bone mineral density (BMD) (
However, it’s unclear whether fish oil supplements improve BMD (
In one study, researchers found that omega-3 supplementation increased BMD in women with no symptoms or bone pain, but it did not appear to do so in women with osteoporosis. More research is needed (
A number of small, older studies suggest that fish oil supplements reduce markers of bone breakdown, which may prevent bone disease (
Higher omega-3 intake is associated with higher bone density, which could help prevent bone disease. However, it’s unclear whether fish oil supplements are beneficial.
If you do not eat 1–2 portions of oily fish per week, you may want to consider taking a fish oil supplement (
Below is a list of things to consider when taking a fish oil supplement:
EPA and DHA dosage recommendations vary according to your age and health.
For most adults, WHO recommends a daily intake of 1.1–1.6 grams (1,100–1,600 mg) of omega-3 fatty acids. However, it may be necessary to increase the dosage if you are pregnant, nursing, or at risk of heart disease (
Fish oil supplements come in a number of forms, including ethyl esters, triglycerides, reformed triglycerides, free fatty acids, and phospholipids.
Your body doesn’t absorb ethyl esters as well as other forms, so try to choose a fish oil supplement that comes in one of the other listed forms (85).
Many supplements contain up to 1,000 mg of fish oil per serving but only 300 mg of EPA and DHA.
Read the label and choose a supplement that contains at least 500 mg of EPA and DHA per 1,000 mg of fish oil.
Some fish oil supplements may not contain the ingredients that they say they do (
To avoid these products, choose a supplement that is third-party tested or has a seal of purity from the Global Organization for EPA and DHA Omega-3s (GOED) (87).
Omega-3 fatty acids are prone to oxidation, which makes them go rancid.
To avoid this, you can choose a supplement that contains an antioxidant, such as vitamin E. Also, keep your supplements away from light — ideally in the refrigerator.
Don’t use a fish oil supplement that has a rancid smell or is out of date.
Choose a fish oil supplement that has a sustainability certification, such as from the Marine Stewardship Council (MSC) or the Environmental Defense Fund.
The production of fish oil from anchovies and similar small fish is more sustainable than that from large fish.
Other dietary fats can improve your absorption of omega-3 fatty acids (
Therefore, it’s best to take your fish oil supplement with a meal that contains fat.
When reading fish oil labels, be sure to choose a supplement that has a high concentration of EPA and DHA and has purity and sustainability certifications.
Omega-3s contribute to typical brain and eye development. They fight inflammation and may help prevent heart disease and a decline in brain function.
Because fish oil contains a lot of omega-3s, people who are at risk of these health conditions can benefit from taking it.
However, eating whole foods is almost always better than taking supplements, and eating two portions of oily fish per week can provide you with enough omega-3s.
In fact, fish is as effective as fish oil at preventing many diseases — if not more so.
That said, fish oil supplements are a good alternative if you don’t eat fish.