Does fish oil prevent heart disease?
Short answer
Little or no effect in most trials.
The largest review found little or no effect on deaths, strokes or overall heart events, and a slight drop in coronary events. Purified EPA cut events in one large trial; most other pills did not.
This page says what the research shows. It does not say whether you should take fish oil.
Where the evidence stands
Each dot is one on-topic paper. Steps near the top answer the question more directly. Select a dot to see the study.
↑ Stronger evidence
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Trials in people: heart attacks, strokes and heart deaths
Trials that measured heart attacks, strokes and heart deaths directly.
11 -
Trials in people: other measures
Trials that measured other health or performance measures.
3 -
Trials in people: lab tests or safety
Trials that measured lab tests, side effects or safety.
0None among the papers we read.
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Population studies
Studies that followed or surveyed groups of people. They show links, not causes.
0None among the papers we read.
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Blood levels and genes
Studies that link blood levels or genes to health.
0None among the papers we read.
↓ Weaker evidence
- Points to benefit
- Mixed
- No difference
- No direction
- Points to harm
Not on the ladder: 3 reviews of many studies (shown below), 4 opinion or narrative papers. Counts are papers, not people. Some studies appear in more than one paper.
See every studyWhat we found
- A 2020 review of 86 trials (162,796 people) found little or no effect on death from any cause (RR 0.97) or on heart and stroke events (RR 0.96). Abdelhamid 2020
- In 8179 high-risk people on statins, purified EPA (icosapent ethyl) 4 g a day cut heart events from 22.0% to 17.2% over a median 4.9 years. Bhatt 2019
- A mixed EPA and DHA pill at 4 g a day, tested in 13 078 high-risk people, did not lower heart events: 12.0% versus 12.2% with corn oil. Nicholls 2020
- Purified EPA raised hospital stays for atrial fibrillation (irregular heartbeat), 3.1% versus 2.1%, and new atrial fibrillation in a Japanese trial, 3.1% versus 1.6%. Bhatt 2019, Miyauchi 2024
What the research says
Big reviews find little or no overall effect
The 2020 Cochrane review pooled 86 trials with 162,796 people. It found little or no effect on death from any cause, strokes or overall heart and stroke events. Coronary heart disease events dropped slightly (RR 0.91), on low-certainty evidence. The 2018 version linked earlier benefit claims to less reliable trials.
A 2022 review of 884 trials of 27 supplements found omega-3 lowered heart deaths (RR 0.93) and heart attacks (RR 0.85). So the reviews disagree on size, and two single trials, REDUCE-IT and PISCES, found bigger drops than either review.
Studies: Abdelhamid 2020, Abdelhamid 2018, An 2022, Bhatt 2019, Lok 2026
Purified EPA versus mixed EPA and DHA
REDUCE-IT gave purified EPA (icosapent ethyl) 4 g a day to 8179 people on statins with high triglycerides. Heart events fell from 22.0% to 17.2% (hazard ratio 0.75). Amarin Pharma funded it. A 2025 guideline suggested EPA, but not EPA plus DHA.
STRENGTH gave a mixed EPA and DHA pill, also 4 g a day, to 13 078 high-risk people on statins. Heart events did not differ from corn oil (hazard ratio 0.99). In Japan, open-label RESPECT-EPA found fewer events with purified EPA, but within chance (P=0.055).
Studies: Bhatt 2019, Nicholls 2020, Miyauchi 2024, Patel 2025
1 g daily pills showed no clear heart benefit
VITAL gave 1 g a day to 25,871 US adults without heart disease. Major heart events were 386 versus 419 with placebo (hazard ratio 0.92), not a clear difference. Total heart attacks were lower (hazard ratio 0.72), a secondary result.
ASCEND, in 15,480 people with diabetes, found serious vascular events in 8.9% versus 9.2% over 7.4 years. DO-HEALTH, in 2157 Europeans aged 70 and older, found no change (hazard ratio 1.00). A re-analysis of VITAL that folded in earlier trials estimated fewer heart attacks.
Studies: Manson 2019, ASCEND Study Collaborative Group 2018, Gaengler 2024, Hamaya 2025
Dialysis patients had fewer heart events
PISCES gave 4 g a day of fish oil (1.6 g EPA, 0.8 g DHA) or corn-oil placebo to 1228 people on kidney dialysis. Serious heart events were 0.31 versus 0.61 per 1000 patient-days (hazard ratio 0.57), about half the rate.
Strokes were also lower (hazard ratio 0.37). Side effects did not differ meaningfully. Everyone in this trial was on dialysis, so the result may not hold for other people.
Studies: Lok 2026
Irregular heartbeat and bleeding showed up as harms
In REDUCE-IT, purified EPA raised hospital stays for atrial fibrillation (3.1% versus 2.1%), and serious bleeding was 2.7% versus 2.1%, within chance (P=0.06). In people who already had atrial fibrillation, these stays were 12.5% versus 6.3%.
RESPECT-EPA also found more new atrial fibrillation with purified EPA (3.1% versus 1.6%). VITAL saw no extra bleeding with 1 g a day. STRENGTH's 4 g mixed pill had more stomach side effects (24.7% versus 14.7%). The 2020 Cochrane review found little or no effect on arrhythmia.
Studies: Bhatt 2019, Olshansky 2023, Miyauchi 2024, Manson 2019, Nicholls 2020, Abdelhamid 2020
What reviews of many studies found
Reviews pool or sum up earlier studies. They are not on the ladder, because they repeat studies already counted there.
Pooled review (meta-analysis) · Abdelhamid 2020
Pooled 86 trials with 162,796 people. Found little or no effect of fish omega-3 on deaths, strokes or overall heart events, and a slight drop in coronary heart disease events and deaths, on low-certainty evidence.
Pooled review (meta-analysis) · An 2022
Pooled 884 trials of 27 vitamins, minerals and other supplements in 883,627 people. Omega-3 pills lowered heart deaths (RR 0.93), heart attacks (RR 0.85) and coronary events (RR 0.86). The omega-3 trial count is not given.
Pooled review (meta-analysis) · Abdelhamid 2018
The 2018 version pooled 79 trials with 112,059 people. It found little or no effect on deaths or heart events, and said earlier signs of benefit came from trials with higher risk of bias.
How the research grew
The papers we read span 2011 to 2026. 7 of the 21 on-topic papers came out in 2024 to 2026. The earliest trial in people here is from 2018.
- 2011
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
Each dot is one on-topic paper, colored by what it found. Rings mark key papers:
- 2019. REDUCE-IT: purified EPA cuts heart events. Bhatt 2019
- 2019. VITAL: largest trial, no clear effect. Manson 2019
- 2020. STRENGTH: mixed EPA and DHA shows no benefit. Nicholls 2020
- 2020. Biggest review: 86 trials, small coronary drop. Abdelhamid 2020
- 2026. Dialysis trial finds fewer heart events. Lok 2026
Doses tested
12 trial papers gave a set daily amount in mg a day, from 840 to 4,000. Each dot shows the dose and what the trial found.
- mg a day01,0002,0003,0004,0005,000
- Points to benefit
- Mixed
- No difference
- No direction
- Points to harm
One row per paper, so a trial reported in two papers appears twice.
Not shown: 2 trial papers with no single daily dose in the abstract, or a different unit.
Who funds this research
7 of 14 trial papers have a company stake: Amarin (REDUCE-IT, two re-analyses), AstraZeneca (STRENGTH), DSM (DO-HEALTH), drug firms (RESPECT-EPA), Nordic Naturals and Pronova BioPharma/BASF (VITAL depression). Six have no disclosure details in PubMed. Not every supporting trial has a stake, so confidence stands.
- Company stake 7
- No disclosure in PubMed 6
- No stake declared 1
- Bhatt 2019Company stake
- Nicholls 2020Company stake
- Szarek 2024Company stake
- Gaengler 2024Company stake
- Miyauchi 2024Company stake
- Okereke 2021Company stake
- Miller 2023Company stake
- Lok 2026No disclosure in PubMed
- ASCEND Study Collaborative Group 2018No disclosure in PubMed
- Manson 2019No disclosure in PubMed
- Verma 2021No disclosure in PubMed
- Olshansky 2023No disclosure in PubMed
- Aggarwal 2025No disclosure in PubMed
- Hamaya 2025No stake declared
Funding rule. A stake is always shown. Confidence is lowered only when every supporting study comes from a party with a stake. "No disclosure in PubMed" means the PubMed record has no conflict-of-interest statement. It does not mean there is no conflict.
All 21 on-topic papers
Each paper shows what it tested, what it found, and who has a stake. Every paper also has its own page that explains how much it counts and how it fits. See every study as a list.
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Randomized trial · measured the question itselfLok et al., 2026The New England journal of medicine · PubMed
Fish-Oil Supplementation and Cardiovascular Events in Patients Receiving Hemodialysis.
1,228 people · adults on long-term kidney dialysis, in 26 sites in Canada and Australia
Tested4 g a day of omega-3 fish oil (1.6 g EPA, 0.8 g DHA) versus corn-oil placebo, about 3.5 years
Serious heart events were 0.31 vs. 0.61 per 1000 patient-days (hazard ratio, 0.57; 95% CI, 0.47 to 0.70). Fatal and nonfatal stroke: 0.37. Side effects did not differ meaningfully between groups.
Points to benefitNo disclosure in PubMedAbstract onlyNo disclosure in PubMed. Supported by the Heart and Stroke Foundation of Canada and others.
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Trial, not randomized · measured the question itselfHamaya et al., 2025The American journal of clinical nutrition · PubMed
A Bayesian analysis of the VITAL trial: effects of ω-3 fatty acid supplementation on cardiovascular events.
25,871 people · older US adults in the VITAL trial, with no heart disease at the start
Tested840 mg a day of EPA and DHA versus placebo, reanalyzed using earlier trial results, median 5.3 years
With earlier trial results added, hazard ratios for coronary artery disease were 0.88 to 0.93 and for heart attack 0.82 to 0.90. Stroke risk was unchanged.
Points to benefitNo stake declaredAbstract onlyFinancial support from the National Institutes of Health.
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Trial, not randomized · measured the question itselfAggarwal et al., 2025Journal of the American Heart Association · PubMed
Cardiovascular Outcomes With Icosapent Ethyl by Baseline Low-Density Lipoprotein Cholesterol: A Secondary Analysis of the REDUCE-IT Randomized Trial.
8,175 people · adults on statins with high triglycerides and high heart risk, split by baseline LDL (bad) cholesterol
TestedIcosapent ethyl 2 g twice a day versus placebo, split by LDL below or at/above 55 mg/dL
With LDL below 55 mg/dL, main heart events were 16.2% vs 22.8% (hazard ratio [HR], 0.66 [95% CI, 0.50-0.87]). With LDL at or above 55: 17.4% vs 21.9% (HR, 0.76 [95% CI, 0.69-0.85]).
Points to benefitNo disclosure in PubMedAbstract onlyNo disclosure in PubMed. The parent trial was funded by Amarin.
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Trial, not randomized · measured the question itselfSzarek et al., 2024Journal of the American College of Cardiology · PubMed
Lipoprotein(a) Blood Levels and Cardiovascular Risk Reduction With Icosapent Ethyl.
7,026 people · adults on statins with high triglycerides and heart disease, or diabetes with other risk factors, with a lipoprotein(a) blood test
TestedIcosapent ethyl 2 g twice a day versus placebo, looking at results by lipoprotein(a) blood level
Heart event reductions with icosapent ethyl did not vary across lipoprotein(a) levels (interaction P > 0.10). Icosapent ethyl cut first major heart events in groups with levels at or above 50 mg/dL and below 50 mg/dL.
Points to benefitCompany stakeAbstract onlySupported by Amarin, which sells icosapent ethyl; three authors are Amarin employees and stockholders.
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Randomized Trial for Evaluation in Secondary Prevention Efficacy of Combination Therapy-Statin and Eicosapentaenoic Acid (RESPECT-EPA).
2,460 people · adults in Japan with stable heart artery disease, low blood EPA, and on statins
TestedIcosapent ethyl 1800 a day (the abstract gives no unit) versus no EPA, open-label, median 5 years
Main heart events: 112 of 1225 (9.1%) vs 155 of 1235 (12.6%) (hazard ratio, 0.79 [95% CI, 0.62-1.00]; P=0.055). New atrial fibrillation: 3.1% vs 1.6% (P=0.017).
No differenceCompany stakeAbstract onlyAuthors report lecture fees or grants from many drug firms, including Mochida, Kowa, Daiichi-Sankyo and Bayer.
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Trial, not randomized · measured the question itselfMiller et al., 2023European heart journal. Cardiovascular pharmacotherapy · PubMed
Potential effects of icosapent ethyl on cardiovascular outcomes in cigarette smokers: REDUCE-IT smoking.
8,179 people · adults on statins with high triglycerides and high heart risk, split by smoking history
TestedIcosapent ethyl versus placebo (dose not given in the abstract), by current, former and never smokers, median 4.9 years
In current and former smokers (n = 4913), main heart events were lower (hazard ratio: 0.77 [95% CI: 0.68-0.87]). Benefit was also seen in non-smokers.
Points to benefitCompany stakeAbstract onlyGrants listed include Amarin Pharma, which sells icosapent ethyl.
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Icosapent Ethyl Reduces Ischemic Events in Patients With a History of Previous Coronary Artery Bypass Grafting: REDUCE-IT CABG.
1,837 people · adults on statins with high triglycerides who had earlier heart bypass surgery
TestedIcosapent ethyl 4 g a day versus placebo, median 4.8 years (a subgroup of REDUCE-IT)
Main heart events fell (hazard ratio [HR], 0.76 [95% CI, 0.63-0.92]). Hospital stays for atrial fibrillation or flutter were higher: 5.0% vs 3.1% (P=0.03). Bleeding rose slightly, within chance.
Points to benefitNo disclosure in PubMedAbstract onlyNo disclosure in PubMed. The parent trial was funded by Amarin.
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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.
13,078 people · adults on statins at high heart risk, with high triglycerides and low HDL cholesterol
Tested4 g a day of an EPA and DHA omega-3 pill versus corn oil, on top of usual care
Heart events: 785 patients (12.0%) with omega-3 vs 795 (12.2%) with corn oil (hazard ratio, 0.99 [95% CI, 0.90-1.09]). Stomach side effects: 24.7% vs 14.7%. The trial stopped early.
No differenceCompany stakeAbstract onlyAuthors report AstraZeneca grants, fees, shares or jobs; AstraZeneca made the omega-3 pill tested (Epanova).
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Randomized trial · measured the question itselfBhatt et al., 2019The New England journal of medicine · PubMed
Cardiovascular Risk Reduction with Icosapent Ethyl for Hypertriglyceridemia.
8,179 people · adults on statins with high triglycerides and heart disease, or diabetes with other risk factors
Tested2 g icosapent ethyl (purified EPA) twice a day (4 g/day) versus placebo, median 4.9 years
Heart events: 17.2% vs 22.0% (hazard ratio, 0.75; 95% CI, 0.68 to 0.83). Heart death: 4.3% vs 5.2%. Hospital stays for atrial fibrillation: 3.1% vs 2.1% (P=0.004). Serious bleeding: 2.7% vs 2.1% (P=0.06).
Points to benefitCompany stakeAbstract onlyFunded by Amarin Pharma, which makes icosapent ethyl.
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Randomized trial · measured the question itselfManson et al., 2019The New England journal of medicine · PubMed
Marine n-3 Fatty Acids and Prevention of Cardiovascular Disease and Cancer.
25,871 people · men 50 and older and women 55 and older in the US, with no heart disease or cancer at the start
Tested1 g a day of fish-oil omega-3 versus placebo, median 5.3 years
Major heart events: 386 with omega-3 vs 419 with placebo (hazard ratio, 0.92; 95% CI, 0.80 to 1.06). Total heart attacks: 0.72 (95% CI, 0.59 to 0.90). Total stroke: 1.04. No extra bleeding was seen.
No differenceNo disclosure in PubMedAbstract onlyAuthors filed disclosure forms but no details in PubMed. Funded by the National Institutes of Health and others.
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Randomized trial · measured the question itselfASCEND Study Collaborative Group et al., 2018The New England journal of medicine · PubMed
Effects of n-3 Fatty Acid Supplements in Diabetes Mellitus.
15,480 people · adults with diabetes but no known heart or artery disease
Tested1 g a day of omega-3 capsules versus olive oil placebo, mean 7.4 years
Serious vascular events: 689 (8.9%) with omega-3 vs 712 (9.2%) with placebo (rate ratio, 0.97; 95% CI, 0.87 to 1.08). Death from any cause: rate ratio, 0.95. Serious side effects did not differ.
No differenceNo disclosure in PubMedAbstract onlyNo disclosure in PubMed. Funded by the British Heart Foundation and others.
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Randomized trial · other health measuresGaengler et al., 2024The journal of nutrition, health & aging · PubMed
Effects of vitamin D, omega-3 and a simple strength exercise programme in cardiovascular disease prevention: The DO-HEALTH randomized controlled trial.
2,157 people · healthy Europeans aged 70 and older
Tested1 g a day of omega-3 versus placebo, plus vitamin D and home exercise in a mix of groups, 3 years
Omega-3 did not change the risk of major heart events (adjusted HR 1.00, 95% CI 0.64-1.56). It lowered triglycerides (-0.08 mmol/L) but raised LDL cholesterol (0.11 mmol/L).
No differenceCompany stakeAbstract onlyOne author reports funding from DSM, Pfizer, Nestec, Roche and others; the trial's omega-3 supplier is not named in the abstract.
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Trial, not randomized · other health measuresOlshansky et al., 2023Journal of the American Heart Association · PubMed
Cardiovascular Benefits of Icosapent Ethyl in Patients With and Without Atrial Fibrillation in REDUCE-IT.
8,179 people · adults on statins with high triglycerides and heart risk, split by whether they had atrial fibrillation (irregular heartbeat) before the trial
TestedIcosapent ethyl versus placebo (dose not given in the abstract), in people with and without earlier atrial fibrillation
Atrial fibrillation hospital stays: 3.1% vs 2.1% (P=0.004) overall; 12.5% vs 6.3% with earlier AF. Serious bleeding trended higher on drug (7.3% vs 6.0%; 2.3% vs 1.7%). Heart benefit was similar with or without prior AF.
Points to benefitNo disclosure in PubMedAbstract onlyNo disclosure in PubMed. Grants listed are from the US Veterans Affairs and NIH.
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Effect of Long-term Supplementation With Marine Omega-3 Fatty Acids vs Placebo on Risk of Depression or Clinically Relevant Depressive Symptoms and on Change in Mood Scores: A Randomized Clinical Trial.
18,353 people · US adults aged 50 and older in the VITAL trial, checked for depression
Tested1 g a day of fish oil versus placebo, median 5.3 years
Depression risk was higher with fish oil (hazard ratio [HR], 1.13; 95% CI, 1.01-1.26). Major heart events as a side-effect check: 2.7% vs 2.9%. Gastrointestinal bleeding: 2.6% vs 2.7%.
No differenceCompany stakeAbstract onlyOne author got free product from Pronova BioPharma/BASF; another got free product from Nordic Naturals.
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Micronutrient Supplementation to Reduce Cardiovascular Risk.
884 studies, 883,627 people · Adults in 884 trials of 27 vitamins, minerals and other supplements, including omega-3 fats
TestedOmega-3 fatty acid supplements versus control, among many supplements tested
Omega-3 supplements lowered heart deaths (RR: 0.93; 95% CI: 0.88-0.97), heart attacks (RR: 0.85; 95% CI: 0.78-0.92) and coronary heart disease events (RR: 0.86; 95% CI: 0.80-0.93).
Points to benefitCompany stakeAbstract onlyOne author got lecture fees from Abbott Nutrition; another sits on a Novo Nordisk trial safety board. No fish oil maker named.
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Pooled review (meta-analysis)Abdelhamid et al., 2020The Cochrane database of systematic reviews · PubMed
Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease.
86 studies, 162,796 people · adults at varying heart risk, in 86 trials lasting 12 to 88 months
TestedFish-oil omega-3 (EPA and DHA) from 0.5 g a day to over 5 g a day, versus placebo or usual intake
Little or no effect on all-cause death (RR 0.97, 95% CI 0.93 to 1.01), heart events (RR 0.96, 95% CI 0.92 to 1.01), stroke (RR 1.02) or arrhythmia (RR 0.99). Heart-disease events fell slightly (RR 0.91, 95% CI 0.85 to 0.97).
MixedNo stake declaredAbstract onlyAll authors: none known. Funded by the UK Medical Research Council.
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Pooled review (meta-analysis)Abdelhamid et al., 2018The Cochrane database of systematic reviews · PubMed
Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease.
79 studies, 112,059 people · adults at varying heart risk, in 79 trials lasting 12 to 72 months
TestedFish-oil omega-3 (EPA and DHA) supplements or advice, versus placebo or usual intake
Little or no effect on all-cause death (RR 0.98, 95% CI 0.90 to 1.03), heart events (RR 0.99, 95% CI 0.94 to 1.04), stroke (RR 1.06) or arrhythmia (RR 0.97). The small drop in heart-disease events (RR 0.93) did not hold in sensitivity analyses.
No differenceNo stake declaredAbstract onlyAll authors: none known. Funded by the UK Medical Research Council.
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OtherPatel et al., 2025Endocrine practice : official journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists · PubMed
American Association of Clinical Endocrinology Clinical Practice Guideline on Pharmacologic Management of Adults With Dyslipidemia.
adults with high blood fats at risk of heart disease, as covered by past trials
TestedGuideline on blood-fat drugs; for high triglycerides it covers EPA alone and EPA plus DHA
For adults with high triglycerides and heart disease or higher risk, the task force suggested EPA but not EPA plus DHA. It strongly recommended against niacin.
No weight on the ladderNo disclosure in PubMedAbstract onlyDisclosures are in an appendix not shown in PubMed.
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Opinion or narrative reviewDjuricic et al., 2023Annual review of pharmacology and toxicology · PubMed
Pros and Cons of Long-Chain Omega-3 Polyunsaturated Fatty Acids in Cardiovascular Health.
general adults and high-risk heart patients, as covered by past studies
TestedEPA and DHA from fish, supplements and drugs, as covered by past studies
Long-term studies link higher EPA and DHA to lower heart disease risk. Some large trials support use in high-risk patients, but the evidence is inconsistent. Possible harms are discussed.
No weight on the ladderNo disclosure in PubMedAbstract onlyNo disclosure in PubMed.
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Update on Omega-3 Polyunsaturated Fatty Acids on Cardiovascular Health.
People with high blood fats and heart disease risk, as covered by past trials
TestedFish oil (omega-3) supplements, as described in past trials
The authors say fish oil lowers very high triglycerides and, in their own earlier pooled analysis, lowered fatal and total heart attacks. No new numbers are given in the abstract.
No weight on the ladderNo stake declaredAbstract onlyThe authors declare no conflict of interest.
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Opinion or narrative reviewMozaffarian et al., 2011Journal of the American College of Cardiology · PubMed
Omega-3 fatty acids and cardiovascular disease: effects on risk factors, molecular pathways, and clinical events.
general adults and heart patients, as covered by studies up to 2011
TestedLong-chain omega-3 fats (EPA and DHA) from seafood and fish oil, as covered by studies
The authors say benefits look most consistent for heart disease death and sudden cardiac death. Evidence on non-fatal heart attack, stroke and atrial fibrillation conflicts. Guidelines suggest at least 250 mg/day or 2 fish servings a week.
No weight on the ladderNo disclosure in PubMedAbstract onlyNo disclosure in PubMed. Funded by NHLBI.
21 papers we read and set aside as off topic
- Zhang et al., 2022. Omega-3 Polyunsaturated Fatty Acids Intake and Blood Pressure: A Dose-Response Meta-Analysis of Randomized Controlled Trials. (pooled review (meta-analysis))
- Wang et al., 2023. Association Between Omega-3 Fatty Acid Intake and Dyslipidemia: A Continuous Dose-Response Meta-Analysis of Randomized Controlled Trials. (pooled review (meta-analysis))
- Torres-Acosta et al., 2020. Cardiovascular Effects of ADHD Therapies: JACC Review Topic of the Week. (systematic review)
- Wylenzek et al., 2024. A systematic review on the impact of nutrition and possible supplementation on the deficiency of vitamin complexes, iron, omega-3-fatty acids, and lycopene in relation to increased morbidity in women after menopause. (systematic review)
- O'Keefe et al., 2021. Prevention and Treatment of Atrial Fibrillation via Risk Factor Modification. (systematic review)
- Marklund et al., 2019. Biomarkers of Dietary Omega-6 Fatty Acids and Incident Cardiovascular Disease and Mortality. (blood level study)
- Manson et al., 2019. Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease. (randomized trial)
- Budoff et al., 2020. Effect of icosapent ethyl on progression of coronary atherosclerosis in patients with elevated triglycerides on statin therapy: final results of the EVAPORATE trial. (randomized trial)
- Qian et al., 2024. Biomarkers of glucose-insulin homeostasis and incident type 2 diabetes and cardiovascular disease: results from the Vitamin D and Omega-3 trial. (population study: cases vs controls)
- Harris et al., 2004. The Omega-3 Index: a new risk factor for death from coronary heart disease? (blood level study)
- AREDS2 Research Group et al., 2012. The Age-Related Eye Disease Study 2 (AREDS2): study design and baseline characteristics (AREDS2 report number 1). (trial plan, no results yet)
- Sammons et al., 2024. ASCEND-Eye: Effects of Omega-3 Fatty Acids on Diabetic Retinopathy. (randomized trial)
- Bakbak et al., 2024. Icosapent ethyl modulates circulating vascular regenerative cell content: The IPE-PREVENTION CardioLink-14 trial. (randomized trial)
- Ahmad et al., 2026. Omega-3 fatty acids and oral and systemic inflammation: A secondary analysis of a randomized trial in patients with coronary artery disease. (randomized trial)
- Jackson et al., 2024. Beneficial effects of linoleic acid on cardiometabolic health: an update. (opinion or narrative review)
- Djuricic et al., 2021. Beneficial Outcomes of Omega-6 and Omega-3 Polyunsaturated Fatty Acids on Human Health: An Update for 2021. (opinion or narrative review)
- O'Keefe et al., 2024. Omega-3 Blood Levels and Stroke Risk: A Pooled and Harmonized Analysis of 183 291 Participants From 29 Prospective Studies. (blood level study)
- Román et al., 2019. Mediterranean diet: The role of long-chain ω-3 fatty acids in fish; polyphenols in fruits, vegetables, cereals, coffee, tea, cacao and wine; probiotics and vitamins in prevention of stroke, age-related cognitive decline, and Alzheimer disease. (opinion or narrative review)
- Holmes et al., 2018. Lipids, Lipoproteins, and Metabolites and Risk of Myocardial Infarction and Stroke. (population study: cases vs controls)
- Randall et al., 2025. Blood omega-3 fatty acids and coronary artery stenosis: a postmortem study. (blood level study)
- Sha et al., 2025. Sarcopenia and Risk of Cognitive Impairment: Cohort Study and Mendelian Randomization Analysis. (population study: followed a group)
Words on this page
- Hazard ratio (HR)
- Compares how often something happened in two groups over time. 1 means no difference. 0.80 means 20% lower risk; 1.20 means 20% higher.
- Relative risk (RR)
- Compares the risk in two groups. 1 means no difference. 0.85 means 15% lower risk.
- 95% CI (confidence interval)
- The range where the true result likely lies. If the range includes no effect (1 for ratios, 0 for differences), the result is not clear.
- p-value (p =)
- How likely a result this large would be by chance if there were no real effect. Below 0.05 is usually called a clear result.
- Placebo
- A dummy pill or fake treatment, so people do not know which group they are in.
- Pooled review (meta-analysis)
- A study that combines the results of many earlier studies to get one overall answer.
How the short answer is set
Fixed rules turn the studies into the short answer, so the same studies always give the same answer. The rules start from GRADE, a standard system for rating evidence, in plain language.
| Confidence | What it means |
|---|---|
| High | We are confident the answer is right. |
| Moderate (this page) | The answer is probably right, but it could change. |
| Low | The answer may well change. |
| Very low | Any answer is very uncertain. |
| Not tested in people | Only cell or animal studies exist. |
Why moderate here
- Large trials in people counted heart attacks, strokes and heart deaths directly.
- Lowered once: trial results disagree, most clearly purified EPA versus mixed EPA and DHA.
- Reviews pooling up to 86 trials find small drops at most.
- Purified EPA benefit rests mostly on one company-funded trial and its re-analyses.
How this page was made
Label
- Search
- PubMed, Nov 14, 2026. Searches written by Claude Opus 5.5; papers ranked by PubMed
- First read of all 42 papers
- Claude Sonnet
- Independent second read
- Claude Haiku
- Disagreements settled by
- Claude Opus 5.5
- Page text written by
- Claude Opus 5.5
- Charts
- Drawn by code from the study records
- Source check by a person
- Not yet. Required before search engines may list this page.
- Expert review
- No
- Papers read in full
- 0 of 42; all from PubMed abstracts
- Method
- v0.2, created Nov 14, 2026
Search. We ran four PubMed searches for fish oil and omega-3 supplements and heart attacks, strokes and heart deaths: pooled and systematic reviews since 2012 (10 of 251), trials in people (22 of 954), population studies (10 of 720). The first number is how many papers we read; the second is how many PubMed found. We took the ones PubMed ranks as most relevant. See the full PubMed search. Of the 42 papers read, 21 were on topic.
Limits. Digestery reads at most about 60 papers per question, so large fields are sampled, not covered in full. Abstracts can leave out key details, such as side effects and funding.
Review queue
These items wait for a person. Search engines are asked not to list the page until the first one is done.
- OpenThe short answer is new. It waits for a source check by a person.
- OpenREDUCE-IT appears six times (Bhatt 2019; re-analyses Szarek 2024, Verma 2021, Olshansky 2023, Aggarwal 2025, Miller 2023). Count it as one trial.
- OpenVITAL appears three times (Manson 2019; re-analysis Hamaya 2025; depression study Okereke 2021). Okereke 2021 is relevant only for its side-effect heart counts.
- OpenVITAL dose shows as 1 g/day (Manson 2019) and 840 mg/day EPA+DHA (Hamaya 2025); same pill, two figures on the dose chart.
- OpenRESPECT-EPA (Miyauchi 2024) gives the dose as 1800 with no unit; mg/day assumed for the dose chart. Please confirm.
- OpenBlood-level studies O'Keefe 2024 (stroke, 183 291 people) and Harris 2004 kept off-topic: they measure blood omega-3, not supplements. Reader B included them.
- OpenAn 2022 pools 27 micronutrients; its 884 trials and 883,627 people are not omega-3 only. Stake rests on one author's Abbott Nutrition fees.
- OpenNo abstract here questions the placebo oils. STRENGTH says corn oil was meant as an inert comparator; PISCES also used corn oil.
- OpenNo COI statement in PubMed for PISCES (Lok 2026), ASCEND (ASCEND Study Collaborative Group 2018) and three REDUCE-IT re-analyses; VITAL (Manson 2019) gives no details.
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| Date | Change | Reason |
|---|---|---|
| Nov 14, 2026 | Page created from 42 papers. | First version of the page. |
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