While fish oil supplements have been found to help lower triglycerides and blood pressure, there is a lack of scientific evidence supporting their use to prevent heart disease in the general population.

This article will examine what fish oil does, its benefits, side effects, breeds with the highest omega-3s, and what to know about taking and choosing supplements.

Omega-3s are important components of cell membranes and are vital to heart, blood vessel, lung, hormonal, and immune system functions. Research has shown that eating fish and other seafood is beneficial for heart health, especially if these foods are chosen over less-healthy foods.

Eating seafood one to four times a week can lower your risk of dying from heart disease.

Studies on whether taking fish oil supplements can protect against heart disease have produced conflicting results. While some older studies have suggested fish oil could be beneficial, more recent studies have found little or no evidence that fish oil supplements protect against heart disease.

There have also been conflicting research results on whether fish oil supplements are helpful in reducing future cardiovascular events in those with existing heart disease or at high cardiovascular risk.

Alpha-linolenic acid (ALA): Found in plant oils such as flaxseed, soybean, and canola oils; nuts, and seedsEicosapentaenoic acid (EPA):  Found in oily fish like salmon and tuna, and other seafoodDocosahexaenoic acid (DHA): Found in oily fish like salmon and tuna, and other seafood

ALA is an essential omega-3 fatty acid, which means your body can’t make it and you must get it from food. EPA and DHA are not considered essential omega-3s, because they can be produced from ALA. However, the body can only convert ALA into EPA and DHA in small amounts, so proper levels can only be derived from food or supplements.

The reasons for conflicting study results could be because they didn’t account for the greater consumption of seafood and more people taking medications that reduce the risk of heart attacks. The formulation and dosage of fish oil supplements might also play a role in differing study results.

One 2019 study found that taking daily fish oil supplements was effective at lowering the risk of heart disease and death and that greater heart health benefits are achieved with higher doses.

3 Potential Heart Benefits of Fish Oil

Although fish oil supplements haven’t been proven to directly help protect against heart disease, fish oil is considered to be beneficial in lowering certain risk factors for heart disease. These benefits include:

SalmonMackerelTunaHerringSardines

Fish that are lower in fat such as bass, tilapia, cod, and shellfish also contain omega-3s, but at lower levels than fatty fish.

Lowering Triglycerides

Fish oil has been shown to lower blood triglyceride levels. Triglycerides are a type of fat found in the blood that can build up in artery walls. Having high levels of triglycerides is linked to increased risk of heart attack and stroke.  

High-dose (4 grams) EPA fish oil supplements have been found to significantly reduce cardiovascular events in people with high blood triglyceride levels who are at increased risk of heart disease.

Lowering Blood Pressure

High blood pressure is a major risk factor for heart disease. Fish oil has been found to lower blood pressure in people with normal blood pressure and those with high blood pressure.

Consuming 3 grams of EPA and DHA omega-3s per day through seafood or fish oil supplements is recommended as the optimal dose for controlling blood pressure, especially for those with high blood pressure. People with high blood pressure or who are at high risk of heart disease may experience added benefits from consuming more than the recommended 3 grams per day of EPA and DHA.

Lowering Inflammation

Inflammation plays a role in heart disease, heart attacks, and stroke. It increases the growth of plaque (made up of fatty substances) in the blood vessels and loosens plaque, which can lead to blood clots. 

Fish oil supplements have been found to increase anti-inflammatory molecules in the body for up to 24 hours, although it’s not clear if this plays a role in reducing heart disease risk. The use of fish oil to reduce inflammation in those with and without heart disease is still being researched.

How Much Fish Oil Should You Take?

Fish oil supplements should only be taken by those with heart disease under the direction of a healthcare provider. Eating two 3.5-ounce servings of non-fried seafood one to two times a week has been shown to have heart health benefits including reducing the risk of heart disease, stroke, and cardiac death.

Three grams of EPA and DHA fish oil per day consumed through seafood or fish oil supplements has been found to be the optimal dose for blood pressure control.

The Food and Drug Administration (FDA) recommends consuming no more than 5 grams per day of EPA and DHA combined from dietary supplements.

Side Effects

Side effects from taking fish oil are typically mild and can include:

Lovaza: A combination of DHA and EPA with daily recommended dosage of 4 grams per day; can be used along with diet to reduce very high triglycerides, being greater than or equal to 500 milligrams per deciliter (mg/dL) Vascepa: EPA-only supplement with a daily recommended dosage of 4 grams per day; can be used along with diet to reduce very high triglycerides (greater than or equal to 500 mg/dL), or with statins to reduce the risk of cardiovascular events for adults who have high triglycerides (greater than or equal to 150 mg/dL) and heart disease or high risk of heart disease

Unpleasant taste  Bad breath Heartburn, nausea, or stomach discomfort Diarrhea Headache Smelly sweat

Choosing the Best Fish Oil Supplement

Fish oil supplements are available in formulations that include fish oil, krill oil, and cod liver oil. Dosages can vary widely, but a typical supplement will provide approximately 1,000 milligramsof fish oil including 180 milligrams of EPA and 120 milligrams of DHA.

The omega-3s in fish oil generally come in either triglyceride or ethyl ester forms, with the triglyceride form being better absorbed by the body.

It’s important to note that other than the prescription therapies Lovaza and Vascepa, fish oil supplements are not regulated by the FDA, and may contain toxins and additional unhealthy ingredients like saturated fatty acids. Dosage and formulations also can vary widely between products, making it important to check product labels for the types and amounts of omega-3s they contain.

People with high triglyceride levels should also not attempt to treat themselves with nonprescription fish oil supplements. If you are considering using fish oil supplements for any reason, it is best to consult with a healthcare provider first.

Summary

Fish oil supplements are widely marketed as having heart health benefits. However, research is conflicting and fish oil supplementation is not recommended for preventing heart disease in the general population. Fish oil supplements have been found to help lower triglycerides and blood pressure, and fight inflammation, which are all risk factors for heart disease.

Over-the-counter fish oil supplements can vary widely in dosage and formulation and are not overseen by the FDA. It is important to consult with a healthcare provider if you are considering taking fish oil supplements.

A Word From Verywell

Despite the hype, many of the claims about fish oil supplements and heart health have not been backed up by the most current scientific research. If you are considering taking fish oil, it’s best to consult with your healthcare provider to see if taking the supplements could be beneficial based on your individual health concerns.