How can fish oil help my heart? What the research shows

There seems to be something about foods that are good for your heart and bad for your breath. Fish oil and garlic, two of the foods with a sterling reputation when it comes to heart health are also, well, notorious for their signature scents. But even the more indulgent heart-healthy foods, like dark chocolate and red wine, aren’t quite conducive to fresh breath. There’s still a lot we need to figure out about fish oil (we’ll get to that), but if you read on and decide it’s worth taking, you may want to consider keeping mints handy.

When we talk about fish oil, we're of course interested in the omega-3 fatty acids that you can get from supplements or just eating a meal with the right fish. Omega-3s are one of two primary types of polyunsaturated fatty acids (or PUFAs), the other being omega-6 fatty acids. There are multiple omega-3 fatty acids, as well, but the major ones are eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and alpha-linolenic acid (ALA).

Fish oil boasts EPA and DHA but often also contains other fats as well as some vitamin A and vitamin D. You can get these fatty acids by eating oil fish such as mackerel, salmon, sardines, herring, tuna, and cod liver, though most people opt for supplements in the form of capsules.

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Fish oil has a reputation for improving heart health and lowering your risk of heart disease, but the science isn’t as cut and dry. Several different aspects of heart health are risk factors for cardiovascular disease, including heart conditions that affect blood vessels, the structure of the heart, or create blood clots. Some of those conditions include hypertension (abnormally high blood pressure), high LDL (“bad”) and low HDL (“good”) cholesterol levels, and high triglyceride levels. Fish oil may improve heart health by acting on your risk of several of these conditions.

But not all research has found a beneficial effect of fish oil. Multiple studies found that fish oil supplementation had no effect on risk of cardiovascular disease. One meta-analysis of 10 different studies involving a total of 77,917 people actually found no evidence that omega-3 fatty acid supplements are protective against heart disease in people with a high risk (Aung, 2018). But clinicians have pushed back against this analysis, claiming the studies looked at are flawed enough to call into question the overall findings. Another study found that while the risk of CVD didn’t decrease in its participants, the risk of dying from a cardiovascular event did (Bowman, 2018).

But other researchers have found ways fish oil impacts overall heart health. Fish oil may lower blood pressure in patients with systolic hypertension (Minihane, 2016). And one review of studies that looked at how blood vessels dilate found that fish oil supplementation may improve blood flow (Wang, 2012). Fish oil may help lower high triglyceride levels in patients who have high triglycerides (Oelrich, 2013). But the relationship between fatty acids and triglyceride levels has also been hotly debated for years. Two researchers looked at multiple disagreements about fish oil and triglyceride levels within the research community and suggested the disagreement had a lot to do with factors that complicate measuring triglyceride levels and categorizing study participants (Singh, 2016).

That’s not to say that high triglyceride levels aren’t worth watching. What we do seem to know is that high triglyceride levels are associated with a higher risk of cardiovascular disease. But we don’t yet know whether it’s the triglycerides themselves that are an independent risk factor or whether these levels are a sign of something else that may influence risk of heart disease such as obesity, diabetes, or other metabolic issues (Navar, 2019). And studies done to look at the effects of lowering triglyceride levels with drugs have all used fibrates, a type of medication derived from fibric acid that speeds up the removal of triglycerides from our blood. While the studies don’t show much impact on CVD risk, it may be because fibroids simply aren’t the best treatment for high triglyceride levels (Singh, 2016).

If you’re a fan of fish, getting enough omega-3s through your fish consumption will probably be easy. Just make sure you’re adding fatty fish such as mackerel, salmon, sardines, herring, and fatty tuna to your diet a couple of times a week. For people following an eating pattern similar to the Mediterranean Diet or fans of oily fish, this shouldn’t be a big change from how they’re already eating. But if you’re not a huge fan of fish, supplements are another solid option. If you're following a vegan or vegetarian diet, you'll want to supplement with alpha linolenic acid, a type of omega-3 fatty acid found in plants, or with algae oil, which can contain DHA and EPA. Flaxseed oil is a good option for meeting your daily needs, and you can get more ALA by adding walnuts and chia seeds to your diet.

Guidelines for recommended dosage differ from group to group, but the World Health Organization (WHO) advises 200–500 mg of combined EPA and DHA (WHO, n.d.). You may see this in grams on the packaging, in which case, choose dietary supplements that offer between 0.2 and 0.5 g of the two fatty acids. High doses should only be taken under the supervision of a medical professional.

The most infamous side effect of fish oil supplements is the fishy breath or burps that may follow shortly after downing the capsules. This effect hasn’t really been studied, and so the potential fixes are anecdotal. But many people report that the fishy burps are diminished if you store your fish oil in the fridge. Some brands that make fish oil pills side-step this potential side effect by adding essential oils for flavoring to their pills, such as peppermint or orange. That way, if you do end up burping anyway, it’s minty and not fishy. Other side effects of omega-3 supplements may include bloody nose, heartburn, nausea, loose stools, and belching.

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Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

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Current version

February 09, 2020

Written by

Linnea Zielinski

Fact checked by

Mike Bohl, MD, MPH, ALM

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About the medical reviewer

Mike Bohl, MD, MPH, ALM

Dr. Mike is a licensed physician and a former Director, Medical Content & Education at Ro.