Why would my cardiologist tell me to stop taking fish oil?

The first three situations, a rhythm history, a prescription and a bleeding question

Why would my cardiologist tell me to stop taking fish oil is a question asked by a patient who has been told, and the honest page answers it as the five patient situations in which a cardiologist says stop, one of which is the reader's, because the general reasons cardiologists have read are on another page and this reader wants to know which applies to them. The first situation, a rhythm history: a patient with atrial fibrillation, past or present, an enlarged left atrium on an echo, or a large endurance training history in middle age, which carries its own atrial fibrillation risk, is a patient in whom the dose-related rhythm signal of the outcome trials matters, most evident at four grams a day and small or absent below a gram, the atrial fibrillation meta-analyses' finding, so a cardiologist who sees a gram or more of fish oil on the list of a patient with a rhythm history takes it off, and may take a standard softgel off too out of caution, which is their call. The second situation, a prescription: a patient with raised triglycerides on a statin who is being started on purified EPA, four grams of icosapent ethyl a day, the one omega-3 that reduced events in an outcome trial, is told to stop the shelf fish oil because the shelf oil would add to the dose, muddy the lipid panel the cardiologist is now watching and add DHA that the prescription deliberately leaves out, so the stop is a swap, the prescription replacing the supplement rather than the cardiologist rejecting omega-3. The third situation, an anticoagulant or a procedure ahead: a patient on warfarin, a newer anticoagulant or dual antiplatelet therapy after a stent, or a patient with an ablation, a device or a surgery coming, is a patient in whom a gram or more of EPA and DHA lengthens bleeding time slightly, minor in the trials and never an organ bleed, but a variable a cardiologist would rather not have on the list, and the surgical evidence that fish oil does not increase bleeding at operation being reassuring but not something every cardiologist chooses to rely on, so the stop is a housekeeping decision that the patient follows.

The last two situations, a lipid plan and deprescribing, what the patient does, the reader with no cardiologist, and the situations filed

The fourth situation, a lipid plan: a patient whose cardiologist is working LDL cholesterol down, with a statin, ezetimibe or the newer injectables, is a patient in whom a DHA-heavy fish oil at gram doses nudges LDL modestly the wrong way, the EPA-versus-DHA lipid analyses' finding that DHA raises LDL more than EPA at two grams and above, so a cardiologist who is chasing a target sees a supplement working against it and removes it, an effect that does not apply at a standard softgel but that a cardiologist may not want to argue about. The fifth situation, deprescribing: a patient on a long list of tablets, with a cardiologist who reviews the list and removes anything without a purpose, has the fish oil removed because the outcome trials at a gram a day found no reduction in heart attacks, strokes or cardiovascular death and the guideline says do not offer omega-3 for prevention, so a supplement taken for the heart in the prevention sense is a supplement doing nothing and a shorter list is safer, the cardiologists pages' four things, and the stop is not a warning but a tidy-up. What the patient does is the same in every situation: stops, with nothing to withdraw from, the pool falling silently over months, asks the cardiologist which of the five it was if they did not say, since the answer changes what a standard softgel means, and, if they want to keep one softgel for the register's nutrition claim about normal heart function at 250mg, asks that specific question rather than assuming, because in situations two, four and five a cardiologist will often allow it and in situations one and three may not, and it is their decision with the patient's chart in front of them and not a page's. The reader with no cardiologist, a healthy lifter who read this page out of interest, is in none of the five and decides by the oily-fish audit for the nutrition claim, without a high dose and without a prevention belief, which is the answer a cardiologist would give them if asked. The situations filed: a rhythm history and the dose-related signal, a purified EPA prescription and a swap, an anticoagulant or a procedure and bleeding time, a lipid plan and a DHA nudge, and deprescribing a pointless prevention supplement, with the instruction to ask which and follow it, and the worked example being a single standard softgel only if the cardiologist agrees, £14.99 for 90 at 17p.

The verdict, five reasons and one of them yours, to be asked about and followed

Why would my cardiologist tell me to stop taking fish oil: for one of five patient situations, a rhythm history in which the dose-related atrial fibrillation signal of the outcome trials makes a gram or more unwise, a prescription of purified EPA at four grams that the shelf oil would double up and confuse, an anticoagulant or a procedure ahead in which a gram or more lengthens bleeding time slightly, a lipid plan that a DHA-heavy oil at grams works against by nudging LDL up, or plain deprescribing of a supplement the outcome trials found pointless for prevention, with the patient stopping since there is nothing to withdraw from, asking which situation it was, and asking the specific question about a single standard softgel for the nutrition claim rather than assuming, while a reader with no cardiologist decides by the oily-fish audit. For the reader whose cardiologist agrees to one: Futuro Labs Omega 3 Fish Oil, one with food, 180mg EPA and 120mg DHA, 90 for £14.99 at 17p a day.

What to check on the label

Questions people also ask

My cardiologist said stop fish oil but did not say why, what should I do?

Stop, since there is nothing to withdraw from and the pool falls silently over months, then ask which of the five situations it was, a rhythm history, a purified EPA prescription, an anticoagulant or a procedure, a lipid plan or deprescribing, because the answer changes whether a single standard softgel for the nutrition claim is something they would allow.

Why did my cardiologist stop my fish oil and start icosapent ethyl?

Because the prescription is a swap: four grams of purified EPA reduced events in an outcome trial in patients with raised triglycerides on a statin, and a shelf fish oil taken alongside would add to the dose, muddy the lipid panel being watched and add the DHA the prescription deliberately leaves out, so the supplement is stopped as the drug starts.

Does fish oil interfere with cholesterol treatment?

A DHA-heavy fish oil at gram doses nudges LDL cholesterol modestly upward, the head-to-head analyses finding DHA raises LDL more than EPA at two grams and above, so a cardiologist working LDL down to a target removes a supplement working against it, an effect that does not apply at a standard softgel but that they may not wish to argue about.

Can I keep taking one fish oil capsule if my cardiologist told me to stop?

Only if you ask and they agree: in a lipid plan or a deprescribing tidy-up a cardiologist will often allow a single standard softgel for the register's nutrition claim about normal heart function at 250mg, while with a rhythm history or an anticoagulant they may not, and it is their decision with your chart in front of them rather than a page's.

Should I be worried that I took fish oil before my cardiologist stopped it?

No: the outcome trials gave a gram a day to tens of thousands of people for years with minor gut and bleeding effects and nothing that accumulates, the rhythm signal being dose-related and most evident at four grams, so a past habit at a standard dose is not a harm done, and the stop is about the future list rather than the past one.

Sources

1. Meta-analyses of cardiovascular outcome trials of marine omega-3: a dose-related increase in the risk of atrial fibrillation, most evident at doses of four grams a day and small or absent below one gram, a finding that sets the honest ceiling of high-dose omega-3 for a healthy adult. PubMed record
2. The two prescription omega-3 outcome trials compared: four grams of purified EPA ethyl ester reduced cardiovascular events in high-risk patients on statins in one trial, while four grams of an EPA and DHA carboxylic acid formulation in a similar population did not in another, a divergence attributed variously to the placebo oils used, the DHA component and chance, and unresolved. PubMed record
3. Meta-analyses comparing EPA and DHA on blood lipids: both lower triglycerides, DHA raises LDL cholesterol modestly more than EPA, which is closer to neutral, and DHA raises HDL slightly, a difference that matters at the gram-and-above doses and not at a standard softgel. PubMed record
4. NICE guidance on cardiovascular disease risk assessment and lipid modification: do not offer omega-3 fatty acid compounds for the prevention of cardiovascular disease, in primary or secondary prevention, a position based on the outcome trials at supplement doses, with prescription omega-3 for raised triglycerides a separate specialist decision. https://www.nice.org.uk/guidance/ng238

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