Locations:
Search IconSearch

Fish Oil Pills Aren’t Doing What You Think They’re Doing

OTC options are unhelpful at best, while some prescriptions can raise your arrhythmia risk

Person holding a handful of fish oil capsules after pouring them from a pill bottle.

As a superstar of the supplement aisle, fish oil is said to have all sorts of benefits for your heart health. But does it really live up to the hype?

Advertisement

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

It turns out that at best, fish oil pills aren’t likely to do much good for your health — and at worst, they can actually increase your risk for stroke.

Preventive cardiologist Luke Laffin, MD, separates fact from fiction when it comes to fish oil supplements.

What does fish oil do?

Proponents claim that fish oil can lower your risk of heart disease by decreasing blood pressure and cholesterol. That’s because fish oil supplements are a pill form of omega-3 fatty acids, which have been studied for decades and have proven benefits for heart health.

Omega-3 fatty acids are essential nutrients found in fish like herring, wild salmon, bluefin tuna and mackerel. Your body can’t make them on its own, which is why fish that are high in omega-3 fatty acids are such an important part of a healthy diet.

“Populations that eat a lot of fish that contain omega-3 fatty acids have a lower instance of heart disease,” Dr. Laffin notes. Consuming 1 to grams of omega-3s per day can:

Over-the-counter (OTC) fish oil supplements contain a low dose (about 1 gram) of two different omega-3 fatty acids: docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Prescription fish oil pills contain about 4 grams of either a DHA/EPA combo or pure EPA.

Advertisement

Do fish oil supplements work?

When it comes to OTC fish oil supplements, there’s just one caveat: There’s no real proof that they do much of anything.

“We know that people who consume high levels of omega-3 fatty acids by eating fish have a lower risk of cardiovascular events,” Dr. Laffin says, “but that hasn’t been borne out in studies about over-the-counter doses of fish oil.”

The existing data just isn’t very convincing, he states.

“There have been very large studies done by very reputable organizations, and they just didn’t show any difference in cardiovascular risk reduction or other health benefits.”

Prescription fish oil comes with extra concerns

When it comes to prescription fish oil, there’s some conflicting and controversial information to sort through.

“This is an area of controversy,” Dr. Laffin says. “Many cardiologists have taken the position that the evidence is not very good for the benefits of prescription fish oils. We need more studies in order to be able to give a strong recommendation to take these products.”

A large study showed that people who took a pure-EPA fish oil pill reduced their risk of cardiovascular disease by 25%, compared to people who took a placebo.

That seems like good news. But the placebo was actually not a placebo at all; it was mineral oil, which has since been shown to have some negative cardiovascular effects, like increasing inflammation.

“If the placebo is doing bad things, it may make the drug look good,” Dr. Laffin explains.

A 2021 study found that high doses of fish oil have no effect on reducing major cardiac events in people who are at high risk for them. That study looked at more than 13,000 patients who were already taking statins to lower their cholesterol. The placebo was corn oil, which is thought to be more neutral than mineral oil. That study found no significant reduction in:

The study ended early when researchers found that fish oil wasn’t showing any benefits and was shown to increase chances of atrial fibrillation, a form of arrhythmia (irregular heartbeat) that can lead to a stroke.

“People who are at a high risk for heart disease don’t have a whole lot of great treatment options aside from statins, so in some cases, the benefits of pure EPA fish oil may outweigh potential risks,” Dr. Laffin says, “but I prescribe it very sparingly.”

Fish oil side effects

Taking OTC supplements is always risky, as they’re not regulated by the U.S. Food and Drug Administration (FDA).

“You want to take medications that have proven benefits,” Dr. Laffin advises. “When it comes to fish oil, at best you’re just losing money on supplements that don’t do anything. At worst, they can have negative impacts.”

Advertisement

Some fish oil supplements have been tested by consumer organizations and found to be contaminated with mercury. And even safe, low-dose fish oil supplements (though again, there’s no way to tell!) can have unpleasant side effects, including:

  • A fishy aftertaste, including “fish burps.”
  • Bad breath.
  • Nausea.
  • Upset stomach.

Higher-dose prescription fish oil comes with additional risks:

  • Atrial fibrillation: Prescription fish oil comes with an increased risk of atrial fibrillation, an irregular heart rhythm that can lead to a stroke.
  • Bleeding: Fish oil can also increase your risk of bleeding.

If you’re at high risk for heart disease, talk to your doctor about the best options for lowering your risk. And if you just want to be sure you’re getting all the benefits of omega-3 fatty acids, it’s best to skip the fish oil supplements and just make salmon for dinner instead.

Advertisement

Learn more about our editorial process.

Related Articles

Wooden spoonful of activated charcoal tablets and capsules, and small dish of loose activated charcoal
December 2, 2024/Digestive
Should You Take Activated Charcoal for a Stomach Bug (or Any Other Reason)?

Charcoal pills are used in certain emergency room settings but aren’t recommended for home use

Sources of vitamin D, including foods like fish and dairy, sunshine and supplements
October 25, 2024/Nutrition
What Does Vitamin D Do?

The benefits of vitamin D include stronger bones, a hardier immune system and better overall health

Scoop and container of bovine colostrum powder on counter
October 7, 2024/Wellness
Bovine Colostrum: Why You Should Skip This Pricey Supplement

More research is needed around the nutrient-dense cow’s milk that may help boost your immune system and improve your gut health

Spoonful of bee pollen granules held up over bee pollen granules
October 3, 2024/Wellness
Bee Pollen: What It Is and Why You Really Don’t Need It

Fans may call it ‘nature’s multivitamin,’ but this bee byproduct’s benefits aren’t proven, and it can bring some serious allergy risks

Hands holding small bowl of propolis and dropper bottle of liquid propolis
September 26, 2024/Living Healthy
Propolis: What Is It and Is It Worth Using?

The science doesn’t support most claims about this bee byproduct, and supplements present potential risks

Jar of royal jelly with spoon on top, with capsules and flowers on table
September 25, 2024/Wellness
Are There Benefits to Royal Jelly?

This much-hyped bee byproduct has one possible health benefit and many unproven ones

Assorted fruits, nuts and seeds in bowls and on table
August 23, 2024/Diabetes & Endocrinology
Thyroid Issue? Here’s What To Eat and What To Avoid

No diet can cure hypothyroidism or hyperthyroidism, but some foods and supplements can cause trouble

Assorted foods with selenium on plates and in bowls, with chalkboard with SE on it
August 19, 2024/Diabetes & Endocrinology
Should You Take Supplements for Hyperthyroidism?

Only take supplements recommended by your healthcare provider — others can worsen your condition

Trending Topics

Person sitting on floor at night next to bed in deep thought, with partner sleeping in bed
Understanding Mental Load: What It Is and How It Affects You

When you get bogged down with mental tasks, you can experience mood changes, sleeplessness and more

Hands holding two different kinds of pain medications separated by a white line
Can You Take Acetaminophen and Ibuprofen Together?

You can alternate these OTCs to help with pain management and fever reduction

Smiling person with headphones on, sweeping floor in living room
Understanding Non-Exercise Activity Thermogenesis (NEAT Exercise)

Non-exercise activity thermogenesis is all the activity we do that’s not technically exercise but is still important to your health and well-being

Ad