Why Is Fish Oil No Longer Recommended? What the Research Found

Fish oil is "no longer recommended" in one specific sense: high-dose omega-3 capsules are not advised as a heart preventive for everyone, and in the UK they never were. The NHS advice has not changed: at least two portions of fish a week, one oily. The headline came from a 2024 UK Biobank cohort study: regular fish-oil users without heart disease had 13% more new atrial fibrillation, users with heart disease progressed less, and no dose was recorded.¹ The randomised trials are more precise: at about 1 g a day omega-3 did not reduce major cardiovascular events; at 4 g a day purified EPA cut events by a quarter and EPA plus DHA did nothing; and atrial fibrillation risk rises with dose, about 50% above 1 g a day and about 12% at 1 g or less.^{2, 3, 4, 5, 6, 7}

• What changed: an atrial fibrillation cost above 1 g a day; neutral supplement-dose trials on major events
• What did not change: two portions of fish a week, one oily (NHS); 450 mg a day from food (SACN)
• Who still has a reason: no oily fish, pregnancy, high triglycerides (with a doctor), vegans via algal oil

Is fish oil no longer recommended? What UK bodies say

Nothing was withdrawn, because nothing had been recommended. The NHS says a healthy diet includes at least two portions of fish a week, one oily; it has never advised fish oil capsules for healthy adults.⁸ SACN's 2004 advice set the UK figure at about 450 mg a day of long-chain omega-3, what two portions of fish supply, as a food target with no supplement recommendation.⁹ The GB register still authorises the wording that EPA and DHA contribute to the normal function of the heart, at 250 mg a day: a maintenance statement, not a promise to lower risk.¹⁰ The Wellgard omega-3 guide has the intake picture.

Why do cardiologists say stop fish oil?

For one of three reasons. First, the 2020 STRENGTH trial: 4 g a day of EPA plus DHA in statin-treated heart patients was stopped for futility.⁶ Second, the 2021 meta-analyses of the large trials, which found a dose-related rise in new atrial fibrillation.⁷ Third, the 2024 cohort, widely read as proof of harm although it could not establish cause or dose.¹ All three concern heart patients, high doses, or both. A cardiologist telling a patient with a rhythm disorder to stop a 4 g prescription is following the evidence; it says little about a healthy adult taking 300 mg, so the answer to "why did my doctor tell me to stop" depends on the dose.

What did the big trials find?

Doses are EPA plus DHA a day unless stated.^{2, 3, 5, 6, 11, 12}

At supplement doses the trials were neutral but not empty: VITAL's fall in heart attacks and the Cochrane review's 9% fall in coronary events are small and consistent; deaths and strokes did not move.⁴ The two 4 g trials disagree and nobody has settled why: purified EPA may act differently from EPA plus DHA, or REDUCE-IT's mineral-oil placebo may have flattered the result.^{5, 6} None of that is about a 300 mg capsule.

Does fish oil cause atrial fibrillation, and at what dose?

At high doses it raises the risk; at label doses the signal is small. Across seven cardiovascular trials in 81,210 people, those given omega-3 were about 25% more likely to develop atrial fibrillation; the risk was about 50% higher in trials using more than 1 g a day and about 12% higher at 1 g or less.⁷ The one large trial at a supplement dose, VITAL Rhythm, gave 840 mg a day to 25,119 adults for five years and found 3.7% against 3.4%, not significant.¹² The 2024 cohort's 13% fits that pattern rather than overturning it.¹ Anyone with atrial fibrillation or heart disease should ask their cardiologist before taking more than 1 g a day; is there any danger when taking omega-3 covers who should ask first.

Does fish oil raise bleeding risk?

Not in surgery. A review of 52 publications found fish oil reduced platelet clumping in the laboratory but did not increase surgical bleeding or transfusions, and saw no need to stop it before an operation; VITAL's five years at 840 mg produced no excess bleeding.^{2, 13} At 4 g of prescription EPA, serious bleeding was 2.7% against 2.1%, short of significance.⁵ Tell your surgeon what you take; on warfarin or another anticoagulant, tell your GP or anticoagulant clinic and keep the daily amount steady.

Who still has reason to take omega-3, and how much?

Someone who eats no oily fish gets only tens of milligrams of EPA and DHA a day from food, against the 250 mg behind the register's heart wording and SACN's 450 mg; a supplement at 250 mg to 1 g a day closes that gap.^{9, 10} In pregnancy the register's maternal wording applies at 200 mg of DHA a day on top of the adult 250 mg, omega-3 reduced early preterm birth from 4.6% to 2.7% across 70 trials, and the NHS says avoid fish liver oil for its vitamin A.^{8, 10, 14} High triglycerides are the 2 to 4 g case, under a doctor. Vegans and people with a fish allergy use algal oil; how to get enough omega-3 on a vegan diet has the amounts. General use sits under 1 g a day; EFSA's safety ceiling is 5 g.¹⁵ How much omega 3-6-9 do I need daily turns these figures into label reading.

Does this apply to algae omega-3 and flaxseed oil?

By dose, yes. Algal DHA is the same molecule as fish DHA (600 mg a day raised blood DHA as much as cooked salmon), so the same dose logic applies: an algal product at a label dose sits in the 1 g or less band where VITAL Rhythm found no significant excess.^{12, 16} Flaxseed oil is a different fat, ALA, which the body converts only 5 to 10% to EPA and almost none to DHA, so the fish-oil trials are not about it.⁴ Wellgard Vegan Omega 3 6 9 is a flaxseed-oil capsule supplying 692 mg of ALA per two capsules, against the 2 g a day at which the register's ALA cholesterol wording applies, with 152 mg of linoleic acid, 152 mg of oleic acid and 10 mg of vitamin E, which contributes to the protection of cells from oxidative stress, and no EPA or DHA. For preformed DHA without fish, Wellgard Vegan Omega 3 Gummies supply 50 mg of algal DHA and 50 mg of ALA per two gummies, against the 250 mg of DHA behind the register's brain and vision wording, with vitamin D at 100% of the NRV, which contributes to the maintenance of normal bones and teeth, and vitamins A, C and E; keep to the two-gummy serving, especially for children, because of the vitamin A.

Frequently asked questions

Should I stop taking fish oil, and can I stop suddenly?

At 1 g or less a day with no rhythm condition, nothing in the trials says stop; above 1 g, decide with a doctor; if it was prescribed, stopping is the prescriber's call. There is no withdrawal: blood EPA and DHA drift back towards diet levels over weeks because the body stores little.¹⁷ Should omega-3 be taken daily explains why the trials dosed daily.

Why do doctors not recommend fish oil?

Because trials at about 1 g a day did not reduce major cardiovascular events in healthy adults; the NHS advice is fish on the plate.^{2, 3, 8}

Is fish oil good for you?

At 250 mg a day EPA and DHA carry the register's heart-function wording and DHA the brain and vision wording; in trials, triglycerides fell about 15% and coronary events about 9%.^{4, 10}

Is there a downside to taking fish oil?

Fishy aftertaste and loose stools; atrial fibrillation risk, clear above 1 g a day and small at or below it; no increase in surgical bleeding.^{7, 13}

At what age should you stop taking fish oil?

No age has been identified: the trials ran in adults over 50 and in 70 to 82 year olds.^{2, 11}

Should I stop taking fish oil if I have high cholesterol?

Omega-3 lowers triglycerides, not LDL cholesterol; keep any prescribed statin and ask your GP about the capsule.⁴

Sources

1. Chen G. Regular use of fish oil supplements and course of cardiovascular diseases: prospective cohort study (UK Biobank). 2024. PubMed 38800667.
2. Manson JE. Marine n-3 fatty acids and prevention of cardiovascular disease and cancer (VITAL). 2019. PubMed 30415637.
3. ASCEND Study Collaborative Group. Effects of n-3 fatty acid supplements in diabetes mellitus. 2018. PubMed 30146932.
4. Abdelhamid AS. Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane, 2020. PubMed 32114706.
5. Bhatt DL. Cardiovascular risk reduction with icosapent ethyl for hypertriglyceridemia (REDUCE-IT). 2019. PubMed 30415628.
6. Nicholls SJ. High-dose omega-3 fatty acids vs corn oil and major adverse cardiovascular events (STRENGTH). 2020. PubMed 33190147.
7. Gencer B. Marine omega-3 supplementation and the risk of atrial fibrillation: meta-analysis of cardiovascular outcome trials. 2021. PubMed 34612056.
8. NHS. Fish and shellfish. nhs.uk.
9. SACN. Advice on fish consumption: benefits and risks, 2004. gov.uk.
10. Great Britain nutrition and health claims (NHC) register. gov.uk.
11. Kalstad AA. Effects of n-3 fatty acid supplements in elderly patients after myocardial infarction (OMEMI). 2021. PubMed 33191772.
12. Albert CM. Marine omega-3 fatty acid and vitamin D supplementation and incident atrial fibrillation (VITAL Rhythm). 2021. PubMed 33724323.
13. Begtrup KM, Krag AE, Hvas AM. No impact of fish oil supplements on bleeding risk: a systematic review. 2017. PubMed 28552094.
14. Middleton P. Omega-3 fatty acid addition during pregnancy. Cochrane, 2018. PubMed 30480773.
15. EFSA. EFSA assesses safety of long-chain omega-3 fatty acids, 2012. efsa.europa.eu.
16. Arterburn LM. Algal-oil capsules and cooked salmon: nutritionally equivalent sources of docosahexaenoic acid. 2008. PubMed 18589030.
17. Arterburn LM, Hall EB, Oken H. Distribution, interconversion, and dose response of n-3 fatty acids in humans. 2006. PubMed 16841856.

This article is general information, not medical advice. If you have a heart rhythm condition, take an anticoagulant, have been prescribed an omega-3 medicine or are planning surgery, speak to your GP, cardiologist or pharmacist before starting or stopping an omega-3 supplement.