If you’ve ever stood in the supplement aisle staring at 20 different fish oil bottles, wondering which one is actually worth it, you’re not alone.
Omega-3s are one of the most talked-about “heart health” supplements, but the research doesn’t always match the marketing.
Omega-3 fatty acids, found in fatty fish, algae, seeds, and nuts, have been promoted for decades as “heart-healthy” nutrients. But when it comes to what research truly supports about their role in preventing or treating heart disease, the picture is nuanced, evidence-based, and sometimes surprising.
Omega-3s are known to:
- Reduce triglyceride levels
- Exhibit anti-inflammatory and antioxidant effects1
-
Support nervous system and cell membrane function2
Let’s unpack the latest research, including benefits, limitations, and what it means for everyday health decisions.
Not All Omega-3s Are the Same
There are three primary forms of omega-3 fatty acids:
- EPA (eicosapentaenoic acid) – mainly in marine sources
- DHA (docosahexaenoic acid) – also from marine sources
- ALA (alpha-linolenic acid) – from plant sources (example: flaxseed, walnuts)
Most cardiovascular research has focused on EPA and DHA, as these forms directly influence lipid metabolism, inflammation, and vascular biology. ALA may offer modest benefits, but its effects depend on conversion to EPA and DHA in the body, a process that is fairly inefficient in many individuals.
This matters because many people assume “an omega-3 is an omega-3,” but the type you choose can change the outcome. In other words, the supplement you’re taking (or the foods you’re eating) may not be doing what you think it’s doing.
Do Omega-3s Reduce Heart Attacks and Cardiac Events?
Studies show that omega-3s can benefit the following conditions via supplementation:
- Cardiovascular events3
- Myocardial infarction (heart attack)4
- Coronary Heart Disease4
- Heart Failure5
- Cardiovascular death3
The heart health benefits of omega-3 supplements depend on the type and amount used. Some studies suggest that supplements with only EPA may be more effective for heart health than those that combine EPA and DHA, but research results are mixed.4,6 Other studies show that supplements containing both EPA and DHA can also support heart health.4 Because there is no clear conclusion, the most suitable omega-3 supplement depends on your personal health needs, the type of omega-3, and the dose used.
Safety
Generally, omega-3 supplements have been shown to have:
- No increase in cancer risk
- No increase in gastrointestinal side effects
- No overall increase in major bleeding events (unless on high doses and blood-thinning medication)
For many people, omega-3 supplements feel like a “safe bet,” especially compared to more aggressive medications. And while they’re generally well tolerated, it’s still important to treat them like a real therapeutic tool.
Potential Risks: Atrial Fibrillation and Bleeding
Omega-3 supplements may carry risks:
- Research on omega-3s and atrial fibrillation (AFib) has been mixed. Some high-dose trials suggested a slightly increased risk, while others did not. However, when looking further into the research:
- Individuals with existing AFib may experience no increase in recurrence, and in some cases a delay in recurrence, when supplementing with omega-3s7,8,9
- A large study of over 25,000 participants without AFib followed for a median of 5.3 years found no difference in AFib risk between those who supplemented and those who did not.10
- This suggests AFib risk is likely influenced by dose, formulation, and baseline cardiovascular status, rather than omega-3s.
- Bleeding risk:
- Mild bleeding risk may occur at higher doses, especially in individuals on anticoagulant or antiplatelet therapy.
- For most people, omega-3s remain well-tolerated when used appropriately.
What Does This Mean in Practice?
Diet Comes First
The evidence discussed here applies to supplements, not dietary omega-3 intake. Dietary omega-3s consistently support cardiovascular health with minimal risk:
- Aim to eat fatty fish (e.g., salmon, sardines, trout) 2-3 times per week.
- Include plant sources of ALA, such as flaxseed, chia seeds, and walnuts.
The good news is you don’t need a perfect supplement routine to support your heart. Food-based omega-3s remain the foundation of heart-healthy nutrition. Small, realistic habits like adding salmon once or twice a week or tossing chia seeds into a smoothie can add up over time.
Who Might Benefit from Supplements?
- Individuals with cardiovascular disease or elevated risk.
- People with very high triglycerides.
- Individuals with low habitual fish intake, including those following plant-based diets.
Who Should Speak with Their Health Care Team First?
Omega-3 supplementation should be individualized, particularly for:
- Individuals with atrial fibrillation
- Those with bleeding disorders
- People taking blood-thinning medications
Heart health is best approached holistically, through nutrition, movement, sleep, stress management, and evidence-based medical care, with omega-3s as one supportive piece of a larger strategy.
If you’re considering omega-3 supplementation or want a personalized approach to cardiovascular health, working with a qualified health professional, such as a Naturopathic Doctor, can help ensure your plan is both safe and scientifically grounded.
References
1. Omega-3 fatty acids supplementation and oxidative stress parameters: A systematic review and meta-analysis of clinical trials. Pharmacological Research. 2019;149:104462.
2. Monahan KD, Wilson TE, Ray CA. Omega-3 Fatty Acid Supplementation Augments Sympathetic Nerve Activity Responses to Physiological Stressors in Humans. Hypertension. Published online November 1, 2004.
3. Yan J, Liu M, Yang D, Zhang Y, An F. Efficacy and Safety of Omega-3 Fatty Acids in the Prevention of Cardiovascular Disease: A Systematic Review and Meta-analysis. Cardiovascular drugs and therapy. 2024;38(4).
4. Bernasconi AA, Wiest MM, Lavie CJ, Milani RV, Laukkanen JA. Effect of Omega-3 Dosage on Cardiovascular Outcomes: An Updated Meta-Analysis and Meta-Regression of Interventional Trials. Mayo Clinic proceedings. 2021;96(2).
5. Seth J, Sharma S, Leong CJ, Rabkin SW. Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA) Ameliorate Heart Failure through Reductions in Oxidative Stress: A Systematic Review and Meta-Analysis. Antioxidants. 2024;13(8):955.
6. Dinu M, Sofi F, Lotti S, et al. Effects of omega-3 fatty acids on coronary revascularization and cardiovascular events: a meta-analysis. European journal of preventive cardiology. 2024;31(15).
7. Kumar S, Sutherland F, Morton JB, et al. Long-term omega-3 polyunsaturated fatty acid supplementation reduces the recurrence of persistent atrial fibrillation after electrical cardioversion. Heart rhythm. 2012;9(4).
8. Kowey PR, Reiffel JA, Ellenbogen KA, Naccarelli GV, Pratt CM. Efficacy and safety of prescription omega-3 fatty acids for the prevention of recurrent symptomatic atrial fibrillation: a randomized controlled trial. JAMA. 2010;304(21).
9. Macchia A, Grancelli H, Varini S, et al. Omega-3 fatty acids for the prevention of recurrent symptomatic atrial fibrillation: results of the FORWARD (Randomized Trial to Assess Efficacy of PUFA for the Maintenance of Sinus Rhythm in Persistent Atrial Fibrillation) trial. Journal of the American College of Cardiology. 2013;61(4).
10. Albert CM, Cook NR, Pester J, et al. Effect of Marine Omega-3 Fatty Acid and Vitamin D Supplementation on Incident Atrial Fibrillation: A Randomized Clinical Trial. JAMA. 2021;325(11):1061-1073.
