If you've paid much attention to health and supplements over the years, chances are you're pretty familiar with Omega-3s. They're commonly advertised in everything from supplements to salmon, and for ages, they've been one of the least controversial nutrients. Omega-3s are good for you, right?
Last month, a concerning study was published. That study involved over 400,000 people, and the results showed that people who took Omega-3 supplements have a 133% higher risk of developing an abnormal heart rhythm called atrial fibrillation.
If that's true, it throws a lot of things into question about the benefits and usefulness of Omega-3 fatty acids, especially in supplement form. Before you panic and throw away your Omega-3s, let's dig deeper because there's more than meets the eye with the current study, past studies, and the truth of fatty acids. There's an important lesson to be found here, and I'll lead you to it, so read on.
Table of Contents
What Are Omega-3s?
First, a brief overview. What even are Omega-3s? Most people today are either taking an Omega-3 supplement or know someone who is. So, let's talk a little about what they are.
Omega-3 fatty acids are a group of, well, fatty acids. Fatty acids might not sound good, but they're an important building block for fat, both in our bodies and in the foods we eat. Fat is one of the most efficient ways the body has to store energy, and fatty acids are a key part of this process. Energy your body doesn't use right away can be stored as fatty acids and called on for use later.
There are three forms of Omega-3 fatty acids: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). ALA is the form of Omega-3 that comes from plant sources like flax seeds and soybeans, while DHA and EPA come from more meat-based sources, particularly fish like salmon and mackerels.
It's important to note here that most Omega-3 supplements you get over the counter, such as fish oil supplements, are generally a mixture of EPA and DHA or are EPA only. You have to find specific supplements to get ALA in the mix.
Omega-3s are also classified as Essential, which means your body needs them but can't make them itself. You have to get your Omega-3s from external sources, like food or supplements.
What Are the Benefits of Omega-3s?
Your body needs a certain amount of Omega-3s to function properly, but "proper function" isn't a particular benefit. Are there more specific benefits to making sure you get more Omega-3s in your diet or through supplements?
Let's go through what common knowledge says and then talk about where these purported benefits come from and what the new study says to throw those results into question.
Cardiovascular Disease
One of the most commonly promoted benefits of Omega-3s is their benefits for heart health. Since heart disease and related cardiovascular issues are the leading cause of death in America and increasingly around the world, a lot of attention is being paid to anything that affects the heart, good or bad.
Currently, the American Heart Association recommends 1-2 weekly servings of seafood to help reduce the risk of heart problems. They also recommend additional EPA and DHA supplements (preferably from fish) for people diagnosed with heart disease.
Infant Development
This one is a little less clear. Some recommendations indicate that additional Omega-3s while pregnant and breastfeeding can benefit the health of a baby.
However, it's not clear whether or not supplements count or if only fish can work, and fish need to be very carefully chosen to avoid mercury contamination, which is extremely dangerous for infants. Many commercial infant formulas already contain some amount of DHA, as well.
Cancer Prevention
As the second leading cause of death for Americans, cancer prevention is also high on the list of things being broadly studied in every way possible.
Some studies have suggested that people who get more Omega-3s in their diets have a lower risk of breast cancer and possibly colorectal cancer. It's far from a miracle preventative, though, and a large clinical trial called the VITAL trial found no supporting evidence of risk reduction.
Other Conditions
Scattered studies, usually small in scope, have indicated some potential benefits of Omega-3s for a handful of other conditions. These include dementia and Alzheimer's disease, rheumatoid arthritis, ADHD, childhood allergies, and cystic fibrosis. However, all of the evidence for these is thin on the ground and requires more study before health authorities will recommend Omega-3s for them.
You may have noticed throughout this section a common refrain: some studies suggest a certain benefit, while others find no supporting evidence. Let's talk more about that.
The Source and Existing Body of Evidence
The most widely-known benefit of Omega-3s is their positive effect on heart health, so let's start there. One of the primary sources for this claim is a study from 2006. That study surveyed people who commonly ate fish and found that among people with diets that had more fish, especially fish with high levels of Omega-3s, there was a 36% lower risk of dying of heart disease. Their data showed a fairly strong correlation; the more Omega-3s consumed from fish, the lower the risk of heart disease death.
Can you spot the issue here?
Surveys show a benefit of a diet rich in fish. An ingredient in those fish is identified and ascribed to have those benefits – Omega-3s. Omega-3 supplements are then created and marketed to have those same benefits. But do they? This is where the controversy begins.
In 2007, an open-label study called the JELIS study took a look at over 18,000 people with high cholesterol levels. The study followed this cohort for 4.6 years on average (with differing lengths of time for different patients). Some of the patients were assigned an EPA Omega-3 supplement to take, while others were not.
The results of this study, too, were moderately promising. They showed the group who took the EPA supplement had a 19% lower risk of heart disease. However, there was one significant drawback with this study: it was open-label, which meant that the patients knew whether or not they were getting the supplement. This is often a confounding factor, which is why the gold standard of medical studies is a double-blind trial, not an open-label trial.
Despite the need for a double-blind trial, one wasn't forthcoming until 2019. We did get that trial, though, in the form of the REDUCE-IT trial. This trial reviewed over 8,100 patients and studied the impact of EPA supplements versus a placebo. It showed promising results, with a significant reduction of heart disease in the EPA group.
Unfortunately, there was one significant issue with this study as well. The placebo was a mineral oil, which can be toxic. The placebo group had higher rates of inflammation and higher cholesterol, so it's just as possible that the mineral oil was responsible rather than the benefits from fish oil in the other group accounting for the differences. It's the kind of potential skewing of results that studies need to keep in mind when they formulate their experiments.
This is a significant enough controversy that entire papers have been written on it, as well, such as 2022's "When Is a Placebo Not a Placebo." Care must be taken to use a placebo that isn't going to have tangible effects itself.
Further confounding information comes from the STRENGTH trial, which was a randomized clinical trial studying the difference between EPA and DHA versus corn oil. It was a proper double-blind study observing some 13,000 patients from 2014 through 2020. Unfortunately, the study was halted prematurely after enough patients experienced an endpoint event (heart attack, myocardial infarction, hospitalization due to angina, and so on) due to no observed difference. In other words, disappointing results for proponents of Omega-3s for heart health.
Finally, we have the VITAL trial, the largest of the clinical trials studying Omega-3s. This one looked at over 25,000 people and showed a 28% reduction in the risk of having a heart attack by taking Omega-3.
Supporting the idea of Omega-3 lowering heart attack risks,, a large Mayo Clinic meta-analysis of over 40 different studies with a total combined number of 135,000 patients found a more significant benefit, stating that supplementation with EPA and DHA "is an effective lifestyle strategy for CVD prevention, and the protective effect probably increases with dosage."
The New Study on Omega-3s
I wouldn't be here today if there wasn't something new to talk about, and indeed, there is. This new study is an observational study from the UK Biobank, stretching from 2006 to 2010, with additional follow-up through 2021. With over 415,000 patients enrolled in the study, it's the largest sampling yet.
What they found is concerning. They found that people taking Omega-3 supplements had a 133% higher risk of developing atrial fibrillation. Atrial fibrillation is a condition where the heart can't pump blood as effectively as it should, which can lead to strokes.
At the same time, the study found that people with diagnosed atrial fibrillation who took Omega-3s had a lower risk of heart disease and cardiovascular death than those who didn't supplement.
Overall, their conclusion was that "Regular use of fish oil supplements might be a risk factor for atrial fibrillation and stroke among the general population but could be beneficial for progression of cardiovascular disease from atrial fibrillation to major adverse cardiovascular events, and from atrial fibrillation to death." In other words, it seems more helpful to people who are diagnosed with atrial fibrillation to slow the progression of the disease, but it might leave the general population more susceptible to atrial fibrillation in the first place.
How does this compare to existing studies? The STRENGTH study showed an increased risk of atrial fibrillation from their Omega-3 group. The VITAL trial, however, didn't. Differences between these studies include, primarily, the dosage; the STRENGTH trial gave patients 4g per day, whereas the VITAL trial was only 840 mg per day.
Lessons and Takeaways
The biggest lesson here comes down to two things.
One: Not everything that has helpful or beneficial effects works the same for every group of people. If Omega-3s are beneficial for people with existing atrial fibrillation but are potentially harmful to those without it, then it's difficult to simply say, "take Omega-3s for a healthy heart".
Two: Beware of megadosing. Megadosing is the act of taking high amounts of a supplement to get more of its effects. Sometimes, megadosing is used to treat a deficiency or to rapidly bring levels into a normal or elevated range for study. Sometimes, people megadose on the idea that something helpful can't have an upper limit. Too much of a good thing, however, isn't always better.
With this news in mind, I plan to continue to take Omega-3s as part of my daily routine alongside MicroVitamin. I follow roughly the same guidelines as the VITAL trial, taking about 1g per day. My goal is to gain the benefits of Omega-3s alongside a healthy diet without risking side effects from megadosing.
As always, remember that just because I take a supplement doesn't mean you should as well. Always talk to your own healthcare professionals and discuss your situation, your options, and the impact Omega-3s might have on your health.
Sources
- Regular use of fish oil supplements and course of cardiovascular diseases: prospective cohort study: https://bmjmedicine.bmj.com/content/3/1/e000451
- Omega-3 Fatty Acids Consumer Factsheet: https://ods.od.nih.gov/factsheets/Omega3FattyAcids-Consumer/
- Fish Intake, Contaminants, and Human Health – Evaluating the Risks and the Benefits: https://jamanetwork.com/journals/jama/fullarticle/203640
- Effects of eicosapentaenoic acid on major coronary events in hypercholesterolaemic patients (JELIS): a randomized open-label, blinded endpoint analysis: https://pubmed.ncbi.nlm.nih.gov/17398308/
- Cardiovascular Risk Reduction with Icosapent Ethyl for Hypertriglyceridemia: https://pubmed.ncbi.nlm.nih.gov/30415628/
- When Is a Placebo Not a Placebo: https://jamanetwork.com/journals/jamacardiology/article-abstract/2797283
- Effect of High-Dose Omega-3 Fatty Acids vs Corn Oil on Major Adverse Cardiovascular Events in Patients at High Cardiovascular Risk: The STRENGTH Randomized Clinical Trial: https://pubmed.ncbi.nlm.nih.gov/33190147/
- Marine n-3 Fatty Acids and Prevention of Cardiovascular Disease and Cancer: https://www.nejm.org/doi/10.1056/NEJMoa1811403
- Effect of Omega-3 Dosage on Cardiovascular Outcomes – An Updated Meta-Analysis and Meta-Regression of Interventional Trials: https://www.mayoclinicproceedings.org/article/S0025-6196(20)30985-X/fulltext
