What are the benefits of fish oil?

What are the benefits of fish oil? Research shows that fish oil can help benefit the body and mind

Fish oil
(Image credit: Getty)

There are many benefits of fish oil and you can take it in capsule form if you follow a plant-based diet and struggle to get your dosage of omega-3. Or, if you’re just not a fan of fish, the best fish oil supplements make a great alternative.

According to the National Center for Complementary and Integrative Health (opens in new tab), nearly 8% of adults in the US take a fish oil supplement. Researchers have found omega-3s, especially the types found in seafood (fish and shellfish) and fish oil supplements, support your brain, eyes, and heart and fight inflammation in your body. You need to add omega-3 to your diet via food or supplements, as your body cannot make it like it can create vitamin D, for example. 

The Dietary Guidelines for Americans (opens in new tab) recommend that adults eat eight or more ounces of a variety of seafood (fish or shellfish) per week for the nutrients seafood provides. 

7 benefits of fish oil

1. Good for heart health

Fish oil has been shown (opens in new tab) to help increase HDL cholesterol (sometimes called “good” cholesterol), lower blood fats, reduce blood pressure, helping prevent the hardening of the arteries. A 2019 meta-analysis (opens in new tab) concluded that marine-derived omega-3 could lower the risk of heart attack and heart disease deaths. 

People from countries with diets rich in omega-3 foods including fish and seafood - such as Japan and Greenland - show a lower risk of heart disease than Western countries such as the US and the UK where less is typically eaten (opens in new tab). What's more, the UK NHS acknowledges the beneficial effect of the long chain omega 3 fats (EPA and DHA) on maintaining a healthy heart (opens in new tab).

But what about fish oil supplements? A series of recent studies have called into question their heart-protecting qualities, including a major review (opens in new tab) of randomized studies in 2018 which showed omega 3 supplements had little or no effect on the risks of experiencing heart disease, stroke or death.  

But the story doesn’t end there. In 2019, another large study was published showing that taking a high dose supplement of pure EPA could reduce heart attacks, strokes and cardiac deaths in a high-risk population by over 25%. So where does that leave us? Dr Alex Richardson (opens in new tab), a passionate advocate of the benefits of fish oil for health, says: “There is solid scientific evidence that the omega 3 from fish oils - DHA and EPA, and especially EPA - is beneficial for a healthy heart. 

“The reason you get so many seemingly conflicting results with nutritional studies can be to do with the limitations of those studies - often reflecting budgets, practicalities or the ethics of trials on humans - but also because clinical trials vary so much in the populations studied - formulations and dosages used, outcome measures and compliance. 

“Whenever possible, it's always best to get nutrients from real food, rather than supplements. But for those who can't or won't eat fish and seafood at least twice a week or more, supplements can help to increase blood and tissue levels of these omega 3. International scientific experts recommend (opens in new tab) at least 500mg/day of EPA and DHA for general heart health in the general population.”

2. Helps brain function

Research (opens in new tab) has found that omega-3 is essential for typical brain function. In one study (opens in new tab), fish oil improved cognitive performance in healthy adults between the ages of 51 and 72 in just five weeks, compared with the effects of a placebo. Studies (opens in new tab) have also connected higher blood levels of omega-3s with a lower risk of depression and anxiety. When used in conjunction with standard antidepressant therapies, fish oil supplementation has been beneficial in treating depression compared to a placebo.

3. Improves bone density 

In the typical American diet, it's common to consume far more omega-6 fatty acids—which are found in plant oils, like corn and sunflower oils—than omega-3 fatty acids. Scientists (opens in new tab) think this imbalance may cause low bone density in both men and women. Older adults with higher omega-3 intakes have been shown (opens in new tab) to maintain greater bone density, making fish oil a possible way to tackle the issue of age-related bone loss.
 

Fish oil supplements

(Image credit: Getty Images)

4. May reduce inflammation 

Inflammation is your immune system’s way of fighting infection and treating injuries. However, chronic inflammation is associated (opens in new tab) with health conditions such as kidney disease, diabetes, and heart disease. Reducing inflammation may help treat symptoms of these diseases. Scientists believe (opens in new tab) that because fish oil has anti-inflammatory properties, it may help treat chronic inflammation conditions. Additionally, fish oil supplements can significantly reduce joint pain (opens in new tab) and stiffness in people with rheumatoid arthritis, which causes pain in the joints. This is why many of the best supplements for joints contain fish oil. 

5. May improve asthma symptoms

Several studies (opens in new tab) show that fish oil may reduce asthma symptoms, particularly in children. The supplements may also be helpful in pregnancy. In a review (opens in new tab) of 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, taking fish oil supplements during pregnancy may reduce (opens in new tab) the risk of allergies in babies. 

6. Can help with weight management

Some research (opens in new tab) has linked omega-3 to fat loss. And supplementing your diet with fish oil has also been shown (opens in new tab) to slow the normal decline in muscle mass and function in older adults. Other research has demonstrated that fish oil may also indirectly affect weight management (opens in new tab) by stimulating areas in the brain that control food intake.

7. Protects eye health

Some evidence suggests that getting an adequate intake of omega-3 may help protect eye health. Optometrists often recommend (opens in new tab) taking supplements containing omega-3 to support eye health, even though scientific evidence does not always support their use for this purpose. In some cases, eating a diet rich in fruit and vegetables may be as beneficial as supplements. For example, in 2019, scientists who looked at the data (opens in new tab) of 4,202 people in Holland found that those who consumed fresh fruits and vegetables and two weekly servings of fish were less likely to develop age-related macular degeneration than those who did not.

Is fish oil good for pregnancy?

The NHS recommends pregnant and breastfeeding women eat at least one portion of oily fish a week as omega 3 fatty acids EPA and DHA help a baby’s nervous system to develop (opens in new tab). (Although note they set an upper limit of two portions of oily fish and recommend certain fish to avoid.) But what if you don’t eat fish?

Dr Richardson says: “In 2018, a systematic review of randomised clinical trials (opens in new tab) showed that supplementation with omega-3 EPA and DHA during pregnancy reduces premature births and low birth weight. Prematurity and low birth weight raise the risk of physical and mental health disorders across a child’s life so pregnant women (and those of child bearing age) would do well to ensure they eat at least two portions of fish a week - one of which should be oily - or take an omega 3 supplement containing EPA and DHA omega-3s.”

If choosing a supplement, she advises looking for one that provides at least 250-300mg DHA and to ensure it states it is safe for use in pregnancy. “Some supplements, such as cod liver oil, can contain high doses of vitamin A and D which can be harmful in excess."

How much fish oil should you take?

In most cases, the best way to consume nutrients is through food, unless a doctor or nutritionist recommends you take supplements.

The American Heart Association recommends (opens in new tab) eating two servings of fish (particularly fatty fish) per week. A serving is 3 ounces cooked or about ¾ cup of flaked fish. Fatty fish like anchovies, herring, mackerel, black cod, salmon, sardines, bluefin tuna, whitefish, striped bass, and cobia are high in omega-3 fatty acids.

Researchers have found it challenging to define an optimal amount of omega-3 fatty acids per day. The American Heart Association (AHA) recommends adults take between 500–1,000 milligrams (opens in new tab) of omega-3 per day. However, other countries and organizations recommend different doses. It may also be necessary to increase the dosage if you are pregnant, nursing, or at risk of heart disease. 

You can take fish oil capsules with water during a meal. However, if you do not typically eat much fat at breakfast, you may wish to wait until lunch or their evening meal before taking it.

Some people experience gastrointestinal side effects when taking fish oil. If you experience this side effect, you may find it helpful to split your fish oil into two doses (opens in new tab) and take them at different times of the day.

Fish oil has a blood-thinning effect, so too much can increase bleeding risk, especially when combined with other blood thinners, like aspirin. Fish oil can also interact with some prescription medications, so discuss it with your doctor before you start taking the supplement. 

Catherine is a freelance journalist writing across titles such as Verywell Health, Healthline, The Daily Telegraph, Refinery29, Elle, and Vogue. She specializes in content covering health, fitness, wellness, and culture.
A once reluctant runner, Catherine has competed in 30 running events in the past five years and looks forward to one day running the London Marathon.

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