A new study adds more doubt to the value of fish oil supplementation for heart disease prevention.
A new study adds more doubt to the value of fish oil supplementation for heart disease prevention.
Hello and welcome to the Nutrition Diva podcast. I’m your host, Monica Reinagel, and today I want to share some perspective on a recent study that caught a lot of people by surprise. The study, which was published in the British Medical Journal, suggested that taking fish oil supplements might increase your risk of having a stroke.
Not surprisingly, this has sparked a lot of discussions and raised questions about these popular supplements. If you're wondering whether you should keep taking your fish oil supplements or if it's time to reconsider, stay tuned.
This study utilized data from the UK Biobank project, which followed over 400,000 participants, aged 40 to 69, for fifteen years. And, much to everyone’s surprise, the analysis revealed that for people without heart disease, taking a fish oil supplement was associated with a 13% increased risk of developing atrial fibrillation, and a 5% increased risk of stroke.
Among those who had heart disease, on the other hand, regular use of fish oil supplements appeared to reduce the risk of adverse cardiovascular events or death. So, while taking fish oil appeared to have some benefit for those already with heart disease, healthy people seemed to be worse off when they took fish oil.
But it’s also important to point out that the overall risks of stroke or atrial fibrillation in this cohort were pretty low to begin with. And this is when it’s important to distinguish between a relative risk and an absolute risk. The absolute risk of stroke was 1%, meaning that only 1% of all of the subjects experienced a stroke during the 15 years of the study. Among the fish oil users, the relative risk was 5% higher. That means that their absolute risk of having a stroke increased from 1% to 1.05%.
In other words, while the results were statistically significant, the real-world impact was pretty modest. Moreover, the study had some limitations. First and foremost, this was an observational study. As such, it can show associations (or patterns), but it cannot prove causation. There may have been other factors that weren't fully accounted for, such as differences in participants' diets, lifestyles, and overall health.
Additionally, the study's participant pool was predominantly white, so these observations wouldn’t necessarily be generalizable to other ethnic groups. And, finally, the study did not provide detailed information on the dosage or specific formulations of the fish oil supplements used by participants. Let me explain why that matters.
Surprising findings like this always raise questions about mechanism. Can researchers propose any reasonable explanation for why fish oil, with its decades-long reputation as a heart-healthy nutrient, could possibly increase the risk of cardiovascular disease?
A handful of theories have been put forth but many of them center on the idea that, while fish oil might be beneficial at moderate intake levels, very high concentrations could create imbalances that interfere with heart function. And this is why it’s so problematic that we don’t really know how much fish oil people were taking. It could be that these relatively modest increases in risk were only seen in those taking very high doses of fish oil.
For all these reasons, I’m inclined to think this particular finding is a bit of a red herring. However, this is not the first study to question the benefits of fish oil supplementation to reduce the risk of cardiovascular disease.
Long time listeners may remember an episode I did in 2021, questioning the wisdom of fish oil supplementation as a preventive strategy. A large meta-analysis published in 2018 looked at ten different clinical trials involving individuals with heart disease or at high risk of developing it. The researchers found "no significant association with fatal or nonfatal coronary heart disease or any major vascular events" and concluded there was "no support for current recommendations for the use of such supplements in people with a history of coronary heart disease."
Then, in 2020, there was a large, placebo-controlled trial involving over 13,000 participants from 22 different countries who either had heart disease or were at high risk of developing it.The study found that even high doses of fish oil (4 grams per day) provided no benefit in reducing cardiac events.
As I said back then, I don’t think we’ve overestimated the value of omega-3 fats. But we may have underestimated the benefits of getting our omega-3 from whole foods instead of supplements. In my opinion, this latest finding further supports the advice I offered in 2021: While it’s important for us to get sufficient omega-3 fatty acids, we’re probably better off focusing on getting them from foods rather than supplements.
Two or three servings of fish a week would be enough to meet the recommended intakes for EPA and DHA, the type of fatty acids typically found in fish supplements. And when we eat fish instead of taking a fish oil supplement, we are also getting all of the other nutrients fish provide, including high quality protein, selenium, and vitamin D.
For those who do not eat fish, plant-based sources of omega 3s, such as flaxseed, chia, hemp, and walnuts also provide fiber, lignans and antioxidants that contribute to our health. But because the conversion of these plant-based omega-3s into the more active EPA and DHA forms is fairly low, you’ll need to eat these foods more regularly–one of them every day, if you can manage it.
Finally, while the benefits of fish oil supplements for general heart disease prevention may be questionable, there are other conditions, such as depression or high triglycerides, for which targeted supplementation may be useful. If your doctor has recommended that you take fish oil for one of these specific concerns, check with them before discontinuing. If, on the other hand, they made a more casual recommendation for fish oil for general prevention, it might be worth asking whether any of this new research has altered their view.
Either way, however, I hope this discussion helps to put this new research into perspective for you. If you have a question you'd like me to answer, you can email me at nutrition@quickanddirtytips.com You can also leave me a message at 443-961-6206
I’d also like to invite you to check out my other podcast. It’s called the Change Academy, where we explore the art and science of creating positive behavior change, both in our own lives, and in our workplaces and communities. You can find it on all the major podcast platforms. Just search for Change Academy.
Nutrition Diva is a Quick and Dirty Tips podcast and I couldn’t do it without the support of Brannan Goetschius, Nathan Semes, Davina Tomlin, Holly Hutchings, Morgan Christianson, and Kamryn Lacy.
That's all for this episode. Thanks for listening! I'll see you next week.