Benefits and side effects of fish oil supplements. Should you take them?

Fish oil supplements are loaded with omega-3 fatty acids, healthy fats your body relies on absorbing through diet.

The two types of omega-3 fatty acids found in fish or fish oil, per the Cleveland Clinic , are:

• EPA (eicosapentaenoic acid)
• DHA (docosahexaenoic acid)

Your body uses these nutrients to keep your lungs, heart, brain, immune system and other functions running smoothly.

If you do not get enough omega-3 fatty acids through diet, taking fish oil supplements may be beneficial.

If possible, increase how much fish is in your diet before taking supplements. The U.S. Food and Drug Administration recommends adults eat 8 ounces of fish every week, or roughly two servings.

Here is a guide to benefits and potential side effects of taking fish oil supplements.

What are the benefits of taking fish oil supplements?

1. May benefit mental health

Research from The Journal of Clinical Psychiatry shows that people with low levels of omega-3 fatty acids are more likely to experience depressive and anxiety disorders. Taking fish oil supplements may complement traditional methods in treating depression, found a study from the Journal of Integrative Neuroscience.

In a review of 13 clinical studies, researchers found that those who regularly took fish oil supplements experienced improved symptoms of depression — comparable to the impacts of antidepressants.

“Use of a diet rich in non-predatory fish or fish oil may prevent or moderate both depression or bipolar disorder and may be effective in stabilizing mood and enhancing the effectiveness of conventional anti-depressants,” per the Mental Health America organization.

2. Supports eye health

Those who consume an insufficient amount of omega-3 fatty acids are more likely to experience eye diseases, found a study from the Journal of Translational Vision Science and Technology.

In the study, adults with either a current or prior glaucoma diagnosis were randomly divided and asked to take a fish oil supplement or placebo pill daily for three months. At the end of the trial, researchers found that group taking the fish oil supplements experienced a significant decrease in intraocular pressure — a risk factor in developing glaucoma.

While fish oil supplements can benefit eye health in many ways, research does not show that fish oil supplements can effectively treat dry eye disease, per Penn Medicine . However, research from the American Journal of Clinical Nutrition found that women who reported consuming higher levels of omega-3 fatty acids had fewer symptoms of dry eyes compared to women who consumed lower levels of omega-3 fatty acids.

3. May reduce arthritis pain

Taking fish oil supplements may relieve painful symptoms of arthritis by reducing inflammation in the body, per the Arthritis Foundation .

A review of 23 studies from the British Journal of Nutrition found that in those suffering from rheumatoid arthritis taking fish oil supplements helped improve the following symptoms:

• Joint swelling
• Joint pain
• Morning stiffness in joints
• Reduced use of anti-inflammatory drugs

“Studies suggest fish oil supplements might help reduce pain, improve morning stiffness and relieve joint tenderness in people with rheumatoid arthritis,” per the Mayo Clinic . “While relief is often modest, it might be enough to reduce the need for anti-inflammatory medications.”

4. Supports pregnancy

Sufficient intake of omega-3 fatty acids while pregnant is essential to the healthy development of the baby, according to the American Pregnancy Association .

“Omega-3s are important for early growth, particularly during the first trimester of pregnancy, as well as beyond,” per Healthline. “Taking fish oil supplements while pregnant or nursing may help improve the child’s cognitive development, though more research is necessary to determine this definitively.”

Additionally, taking fish oil supplements may decrease risk of postpartum depression. A 2018 review found that increasing omega-3 fatty acids intake while pregnant and postpartum is associated with decreased symptoms of postpartum depression.

5. Could slow mental decline

Preventing mental decline is another potential benefit to increased omega-3 fatty acid intake. Those who eat more fish tend to experience a slower mental decline as they age, a study from the journal Nutrients found.

A review of 48 studies from the American Journal of Clinical Nutrition found that taking omega-3 fatty acid supplements — such as fish oil — could help reduce risk of dementia and other age-related cognitive decline by 20%.

A 2018 study reported taking omega-3 supplements may lower the risk of Alzheimer’s disease and other forms of cognitive decline in aging adults.

“Everything we do and consume affects our brain,” Dr. Natalie King, a neuroscientist, told Medical News Today . “Omega-3 fatty acids, in particular, have been found to be beneficial when it comes to improving mental function as well as supporting an overall wellness plan when considering disease pathologies like mood disorders and others affecting learning and memory.”

Potential side effects of fish oil supplements

A 2024 study published by the British Medical Journal found that regularly taking fish oil supplements may not be beneficial to heart health in healthy adults.

More than 415,000 men and women participated in the study. All participants joined between 2006 and 2010 — participants gave researchers access to their health records — and were followed until 2021. Roughly a third of participants reported taking fish oil supplements regularly.

Researchers found that among participants without history of heart disease, those who took fish oil supplements experienced a 13% increased risk of developing atrial fibrillation and a 5% higher risk of stroke when compared to those who did not take fish oil supplements.

Among participants with a history of heart disease, results were different. Those who regularly took fish oil supplements experienced a 15% lower risk of suffering severe heart problems, including atrial fibrillation, heart attack and heart failure.

“Correlation does not prove causation,” Dr. JoAnn Manson, chief of the division of preventive medicine at Harvard Medical School and physician at the Brigham and Women’s Hospital who co-led the trial, told Time magazine .

“I don’t think the public should be alarmed about this study because most organizations currently do not recommend omega-3 supplements for primary prevention of heart disease. They currently recommend one to two servings of fish a week.”

According to the Mayo Clinic, fish oil supplements may also cause these mild side effects:

• A fishy aftertaste
• Bad breath
• Heartburn
• Nausea
• Diarrhea
• Rash