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5 most important benefits of fish oil

Written by John Davis

Last updated: October 18, 2022

Fish oil has become one of the most popular and reliable supplements for heart health in recent years.

Bolstered by a wave of large-scale studies showing fish oil’s benefit, many people take a fish oil capsule on a regular basis for heart health.

But additional scientific research is showing that the benefits of fish oil extend far beyond cardiovascular health: it could be useful for sustaining your cognitive function as you age, and boosting your mood.

Fish oil is one of the key wellness supplements that our research team recommends, and here’s why.

Fish oil benefits

1. Fish oil improves heart health

The omega-3 fatty acids that constitute fish oil first entered the public eye thanks to their role in the health benefits of the Mediterranean diet (1).

The omega-3s in Mediterranean-style diets lead to an increased survival rate from cardiovascular disease, which spurred a huge raft of research on the heart health benefits of fish oil supplements.

2. Fish oil can help reduce blood triglycerides and systemic inflammation

Two of the main drivers of heart health are low triglycerides and low systemic inflammation, and fish oil can aid in both.

Two studies on fish oil supplements found that fish oil supplements produce a statistically significant decrease in blood triglycerides (2,3), while other research points to fish oil’s anti-inflammatory capabilities as contributing to its vascular health benefits (4).

3. Fish oil can lower blood pressure

When it comes to boosting heart health, dropping triglycerides is not all that fish oil does. Research published in the American Journal of Hypertension reviewed 70 different studies and found that fish oil supplementation reduces both systolic and diastolic blood pressure (5).

4. Fish oil can boost cognitive function and slow cognitive decline

Given the powerful anti-inflammatory effects of fish oil, its cognitive benefits should come as no surprise.

A 2010 study found that DHA enhances memory and learning in those with age-related cognitive decline (6), while another review study found evidence from observational studies suggesting omega 3 fatty acids can preserve cognitive function (7). Other research has found that lower serum DHA levels is connected to brain plaque formation (8).

5. Omega-3 fatty acids could boost the health benefits to your baby during pregnancy and breastfeeding

DHA plays role in pregnancy outcomes such as birth weight, pregnancy duration and neurocognitive function of the infant (9, 10).

Additionally, higher levels of DHA and EPA in breastmilk are associated with improved hand-eye coordination in infants (11).

Fish oil side effects

Most studies of fish oil find no side effects at all. Of the 300+ studies reviewed in one paper, over half reported zero adverse effects caused by fish oil (12).For such a powerful supplement, fish oil is pretty safe. Still, there are a few things to watch out for.

Don’t take fish oil with blood thinners. Both omega-3s as well as blood thinners reduce the ability of the body to clot which may lead to excessive bleeding during surgery or injury.

Fish oil might cause bloating, gas, or burping. The most common side effects of fish oil are mild gastrointestinal symptoms: burping, bloating, gas, etc. (13). Enterically-coated fish oil supplements can reduce the incidence of upper GI symptoms like burping since the product is designed to resist digestion until it reaches the small intestine.

Lower-quality fish oil might be contaminated with mercury, dioxins, or PCBs. These compounds are common contaminants which have been shown to damage the nervous system or cause cancer. Fortunately, high-quality fish oils like our top-ranked products are tested for the presence of all of these contaminants.

Oxidized fish oil loses its potency. Oxygen exposure damages omega-3 fatty acids, so keep your fish oil supplements in a closed container away from heat and light.

Fish oil dosage

Healthy people should aim for at least one gram of fish oil per day, and possibly up to three. Most studies on the clinical and health benefits of fish oil use between one and three grams of fish oil per day. The American Heart Association recommends one to three grams per day, though other studies have used higher doses (14,15).

A higher dose of two to four grams of fish oil is needed to lower blood triglycerides. For cutting down on unhealthy blood triglycerides, you’ll need a higher dose than a healthy person, in the range of two to four grams per day.

Aim for as much of your fish oil as possible to come from EPA and DHA. These two omega-3 fatty acids are the most potent ingredients in fish oil, and research suggests that the higher the EPA and DHA content of your fish oil supplement, the better your body’s response from a heart-health perspective (16).

Supplements vary a lot in EPA and DHA content, even for the same fish oil amount, so be sure to grab a high-quality one that are high in these key ingredients.

If you can, aim for 800 to 1800 mg total of DHA + EPA. These numbers are based on the ranges of EPA and DHA dosages in the studies we’ve reviewed above, and while research is still ongoing on the optimal ratio, the total amount of both does seem to be particularly impactful on fish oil’s efficacy.

Fish oil benefits FAQ

Q: How much fish oil per day should you take?

A: The American Heart Association currently recommends one gram of fish oil per day, though other research suggests that a dose of more like two to four grams per day is optimal for lowering blood triglycerides (17).

However, it’s not just about the raw fish oil dose; you’ve also got to pay attention to the EPA and DHA content.

The most successful studies on fish oil have used doses that total 800-1800 mg of EPA and DHA (combined), so aim for a fish oil supplement that’s high in both of these power ingredients. 

Q: How much fish oil is too much?

A: The American Heart Association recommends not taking more than three grams total of omega 3 fatty acids per day without talking to a doctor first (18).

At very high doses, fish oil can increase the risk of bleeding in some people. Do keep in mind that one gram of fish oil likely contains less than one gram of omega-3 fatty acids: the three gram per day recommendation applies to the omega-3 fatty acid content, not the total fish oil content.

Q: Is fish oil good for mental health?

A: Yes, fish oil has been studied for its ability to fight both anxiety and depression. Fish oil’s cognitive benefits in the long-term suggested to nutritionists that it could improve mood short-term, and scientific research indicates that the omega-3 fatty acids in fish oil can reduce feelings of anxiety and elevate mood in people with depression, especially when combined with positive dietary changes (19,20).

Q: Should you take fish oil in liquid or capsule form?

A: Fish oil is just as effective, in principle, regardless of its delivery mechanism, but for most people we recommend taking fish oil capsules for two reasons.

First, capsules help protect the omega-3 fatty acids in fish oil from oxidation during storage, which damages their potency over time. Second, it’s easier to get a precise dosage when you don’t have to manually measure out a liquid dose.

Related: Our best fish oil picks


Fish oil contains concentrated omega-3 fatty acids which have potent benefits for both your heart and your brain.

It’s a great supplement for long-term health, thanks to the strength of the clinical research behind fish oil supplementation and cardiovascular and cognitive wellness.

For best results, take a fish oil supplement that’s high in EPA and DHA, as these two fatty acids seem to be responsible for the primary benefits of fish oil.


John Davis

John Davis is a Minneapolis-based health and fitness writer with over 7 years of experience researching the science of high performance athletics, long-term health, nutrition, and wellness. As a trained scientist, he digs deep into the medical, nutritional, and epidemiological literature to uncover the keys to healthy living through better nutrition.