Are Fish Oil Supplements a Good Idea? It is Complicated

At the Kahn Center it is routine to measure and Omega Index and a large percentage of patients are very low in Omega-3. This is true of those following a vegan diet and those on omnivore diets. Many patients are seen already taking some kind of Omega-3 supplements, usually fish or krill oil, but often algal oil.

Prior studies with high dose prescription fish oil have reported an increase in atrial fibrillation

A new study examined relationships between taking Omega-3 supplments in a large population. The findings are "complicated". 


A prospective cohort study drawing data from the UK Biobank with entry from 2006 to 2010 and follow-up to 31 March 2021 (median follow-up 11.9 years) was performed. 415 737 participants, aged 40-69 years, enrolled in the UK Biobank study.

Incident cases of atrial fibrillation, major adverse cardiovascular events, and death, identified by linkage to hospital inpatient records and death registries.

The role of fish oil supplements in different progressive stages of cardiovascular diseases, from healthy status (primary stage), to atrial fibrillation (secondary stage), major adverse cardiovascular events (tertiary stage), and death (end stage) was measured. This was NOT a randomized study.


 Among 415 737 participants free of cardiovascular diseases, 18,367 patients with atrial fibrillation, 22,636 with major adverse cardiovascular events, and 22,140 deaths during follow-up were identified.

Regular use of fish oil supplements had different roles in the transitions from healthy status to atrial fibrillation, to major adverse cardiovascular events, and then to death.

For people without cardiovascular disease there was a 13% increase for the transition from healthy status to atrial fibrillation and a 5% increase from healthy status to stroke. 

For participants with a diagnosis of a known cardiovascular disease, regular use of fish oil supplements was beneficial for transitions from atrial fibrillation to major adverse cardiovascular events (8% lower), atrial fibrillation to myocardial infarction (15% lower), and heart failure to death (9% lower).


Regular use of fish oil supplements might be a risk factor for atrial fibrillation and stroke among the general population but could be beneficial for progression of cardiovascular disease from atrial fibrillation to major adverse cardiovascular events, and from atrial fibrillation to death.

Further studies are needed to determine the precise mechanisms for the development and prognosis of cardiovascular disease events with regular use of fish oil supplements.

Natural sources of Omega-3 (flax, chia and hemp seeds, walnuts, greens, algae like chlorella and cold water fish if selected) should be emphasized. At the Kahn Center we will continue to check Omega-3 blood levels and emphasize higher levels in those found to be deficient. 

Dr. Joel Kahn

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