Omega-3 and Cardiovascular Health: What the Evidence Really Says About Atrial Fibrillation

Hello, I am Dr. Isabel Viña Bas, physician and Scientific Director at IVB Wellness Lab. Relatively recently, a news story generated quite a stir among those who take omega-3 dietary supplements: can omega-3 increase the risk of atrial fibrillation? Following a study published in British Medical Journal, several headlines suggested that taking omega-3s could be harmful to the heart, even for healthy individuals.

But in science, sticking to the headline means only getting half the story. A study is just one piece of a much larger puzzle, and to interpret it correctly, you have to look at how it was conducted, who was studied, what was actually measured, and what its limitations were. In this case, moreover, there is much more evidence regarding the Omega-3 and Cardiovascular Health than fits in a headline.

The idea I want you to take away from the start is the same one I always repeat in consultations: more is not better, better is better. With the Omega-3 this applies

What did the study that linked fish oil consumption to atrial fibrillation say?

The study that sparked the controversy was published in British Medical Journal fish oil supplements with four different scenarios: prevention in healthy individuals, established cardiovascular disease (including atrial fibrillation), major events such as heart attack or stroke, and mortality.

And here comes the first important nuance, the one that almost no headline picked up on: the study did not conclude that omega-3 increased the risk of heart attack, stroke, or cardiovascular death in healthy people. In those who they already had cardiovascular disease, omega-3 appeared to be associated with certain benefits; in healthy individuals, the effect on stroke, heart attack, angina, or cardiovascular death was neutral.

What did make headlines was something else: in healthy individuals, an association was observed with a higher risk of atrial fibrillation. And this is where it pays to sweep under the rug and look at how that supposed omega-3 consumption had been measured.

How was omega-3 intake actually measured in this study?

This is, for me, one of the most eye-opening parts of the entire analysis. Upon entering the study, participants were only asked if took omega-3 supplements. La respuesta era sí o no, sin más matiz.

They did not record which type of omega-3 they took, whether it came from fish oil or algae, the total amount consumed, how much EPA and DHA the product provided, or whether they maintained that intake throughout the 10–12 years of follow-up. And this last point is especially important: someone who reported taking omega-3 at the baseline could have stopped years later, and someone who started without taking it could have added it later on.

Therefore, we cannot assume that the behavior declared at the beginning remained the same throughout the entire follow-up. This is one of the limitations that, for me, carries the most weight when drawing general conclusions about omega-3 consumption.

We also didn't know how much EPA and DHA each person was taking, and this is key because EPA and DHA are the two active omega-3s

So, does omega-3 increase the risk of atrial fibrillation?

the dose. El omega-3 participa en la conducción del impulso eléctrico del corazón. El EPA y el DHA favorecen el funcionamiento de la bomba sodio-potasio ATPasa, presente en las células cardíacas, necesaria para generar y mantener el gradiente eléctrico que permite que el corazón se contraiga.

too fast electrical conduction.

According to the episode's explanation, dose-response studies suggest that up to 1.5 grams of omega-3 daily

This explains why some results seem contradictory at first glance. We are not dealing with a molecule that is simply good or bad for the heart; we are dealing with a substance whose effect it also depends on the quantity, like a curve where increasing the dose helps up to a point, after which it stops adding value and can even work against you.

Omega-3 in people with cardiovascular disease: a different effect than in healthy people

Here, for me, is one of the most interesting parts of the study. In people with cardiovascular disease, omega-3 consumption was associated with a protective effect against certain events. It may seem contradictory to the association with atrial fibrillation observed in healthy individuals, but that is precisely why we cannot analyze an isolated result without considering the person's context and the amount of omega-3 involved.

The study showed that, in people with cardiovascular disease, omega-3 could be beneficial, while in healthy people the effect on stroke, heart attack, or cardiovascular death was neutral, with that added association to atrial fibrillation. Subsequent evidence helps put more pieces of this puzzle together.

What do other studies say about omega-3 and cardiovascular health?

The episode also analyzes another study published in British Medical Journal in 2020, conducted in nearly half a million people, which evaluated the relationship between the regular consumption of omega-3 and cardiovascular events.

Here, regular consumption of omega-3 was associated with lower cardiovascular risk, a lower risk of all-cause mortality and a small benefit against myocardial infarction, stroke, and other cardiovascular events. And, unlike the study that made headlines, that increased risk of atrial fibrillation was not observed in healthy individuals.

This does not mean that one study invalidates the other. What it allows us to understand is that the scientific evidence is more complex than a headline, and that the various studies, their characteristics, and their limitations must be evaluated together. It is also the underlying reason why I place so much emphasis on not focusing solely on major events and reviewing markers such as the lipoprotein(a), a frequently overlooked cardiovascular risk factor.

What amount of omega-3 (EPA and DHA) actually protects cardiovascular health?

Another of the studies mentioned in the episode is the VITAL study, which analyzed supplementation with 840 mg of EPA and DHA

These results add another piece to the body of evidence and help to understand that the moderate doses of EPA and DHA may have a different profile than that of very high doses.

Why Omega-3 Can Protect the Heart, Beyond Heart Rhythm

Omega-3 may offer beneficial effects against certain cardiovascular events.

This idea is also supported by a meta-analysis involving more than 80,000 people and various studies with different amounts of omega-3. The general conclusion is that omega-3 fatty acids have a cardiovascular protective role, aunque existe una relación entre dosis y riesgo de fibrilación auricular. Volvemos, de nuevo, al mismo punto: no se trata de tomar más omega-3, sino de encontrar la cantidad adecuada.

How much omega-3 should we take per day?

If you want to benefit from omega-3 without resorting to excessive amounts, the first step is to distinguish between a necessary minimum and higher quantities that may make sense in specific situations. At a minimum, an intake of approximately 250 mg daily of EPA + DHA, the recommended amount by the EFSA and the World Health Organization as explained in the episode.

From there, intake can be increased according to individual needs. As a general strategy, I stay between 250 mg and 1.5-2 grams daily, avoiding reaching 3-4 grams per day unless there is a specific recommendation from a healthcare professional.

This does not mean that everyone needs to take a food supplement. Omega-3 is also obtained through your diet, and if your diet already allows you to achieve an adequate intake, that can perfectly be your strategy. The supplementation should be understood as a tool to supplement the diet, not to replace it.

How to know if we are getting enough omega-3?

There is a way to find out your omega-3 level: the Omega-3 Erythrocyte Index, which measures the amount of omega-3 present on the surface of erythrocytes. According to the data from the episode, an index between approximately 8 and 12% is considered adequate.

Below 8% there is a higher cardiovascular risk

This measurement is not essential for everyone, but it can be useful if you want to know if your diet provides enough omega-3 or check how your body responds to a specific strategy.

Can we get enough omega-3 from diet alone?

Yes, and in fact this should always be one of the first strategies to consider. If you eat fish regularly, you can get EPA and DHA directly through diet.

With a vegan diet, the situation is somewhat more complex. Plant-based foods mainly provide ALA (alpha-linolenic acid), which the body can convert into EPA and DHA, but with limited conversion. Those following a vegan diet need to be especially consistent with chia and flax seeds, or flaxseed oil, to achieve the necessary ALA intake, although this conversion remains limited and also depends on individual capacity.

That is why, in this context, supplementation can be an option to ensure at least the minimum intake. But the underlying idea remains the same: the supplementation should not substitute

¿Qué pescado azul aporta más omega-3?

Find out what fish are highest in omega-3 helps you make better choices every day. Among the options with the highest content, we find mackerel (about 1,446 mg of omega-3 per 85 g), herring (about 1,000 mg per 85 g), pink salmon and wild sockeye salmon (around 1,094 mg per 85 g), farmed Atlantic salmon (around 1,000 mg per 85 g), sardinas (unos 835 mg de EPA + DHA

oily fish can cover an important part of your EPA and DHA needs. If you want to go further and choose the most suitable omega-3 form based on your health goal, tienes un análisis más detallado en el blog.

And what if, in addition to eating fish, we take an omega-3 supplement?

Here we return to the principle that runs throughout this article: more is not better, better is better. If one day you eat a generous portion of fish rich in omega-3, it doesn't make much sense to also add a supplement with several grams of EPA and DHA.

The strategy I propose is simple: cover the necessary minimum and let the rest come from your diet. As a reference, that minimum is around 250 mg daily of EPA + DHA. From there, if you want to increase the amount you can, without needing to reach excessively high doses. If you're looking for a EPA-rich omega-3 supplement to cover that minimum without going overboard—that is the reference I use with my patients. This way, you achieve something important: using supplementation as a support, without it replacing a proper diet.

Omega-3 and Your Heart: What I’d Like You to Know

After reviewing the study that sparked the controversy and putting it in the context of the rest of the evidence, I'm taking away several ideas.

Primero: a single study does not change everything we know about a nutrient on its own; science works like a puzzle where each piece of research adds a new piece. Second: the study that generated the headlines found an association between omega-3 and a higher risk of atrial fibrillation in healthy individuals, but with significant limitations in how it measured that intake. Third: in people with cardiovascular disease, omega-3 showed beneficial associations against certain events. Fourth: doses matter: moderate amounts seem to provide benefits, while very high doses, around 3-4 grams daily, can increase the risk of atrial fibrillation. And fifth: You don't need to take large amounts to benefit from omega-3; as a minimum guideline, 250 mg daily of EPA + DHA is recommended, generally not exceeding 1.5–2 grams daily without a specific reason.

Lastly, you can obtain omega-3 through your diet, especially from fatty fish, and when your diet falls short, supplementation can help you round out that intake. Because, once again, in nutrition and in everything related to your cardiovascular health, more is not better. Better is better. It is not about accumulating omega-3 at any cost, but about reaching an adequate amount and maintaining it with a strategy consistent with your needs.

Transforming your health is a matter of applying science consistently, day by day.

Hope you like it :)

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