Fish Oil Supplements: Healthy or Harmful?

I recently came across an article on LinkedIn that suggested fish oil may not be good for one’s health. I disagree with that, and I wanted to share a few reasons why I still incorporate fish oil into my daily routine. 

Fish oil supplements are rich in omega-3 fatty acids like EPA and DHA, which have been studied for their potential benefits for cardiovascular health. Some evidence suggests that fish oil may also help reduce triglycerides, lower blood pressure modestly, improve vascular function, and have anti-inflammatory and anti-arrhythmic effects. The suggested dose is 3000mg of the EPA/DHA daily. To maximize the effectiveness, ensure the fish oil is molecularly distilled to remove heavy metals, store it in the freezer, and take it “frozen.” I take my fish oil daily in addition to eating some occasional fish. 

I came across this prospective cohort study from the UK BioBank, and I must disagree with some of the implied conclusions. The study examined the effects of regular fish oil supplement use on the progression of cardiovascular disease, from healthy status to atrial fibrillation, major adverse cardiovascular events, and death. With a large sample size of over 400,000 participants and a long follow-up period, the study had several strengths. But there were also several problems with this study. 

First, as an observational study, no causal conclusions can be drawn about the effects of fish oil supplements. There may be residual confounding from unmeasured variables that differ between users and non-users of supplements. The study needed more information on the specific dose, formulation, and composition (EPA vs. DHA ratio) of the fish oil supplements used. Prior evidence suggests these factors can significantly impact cardiovascular effects. The exposure was based only on self-reported “regular” fish oil use at baseline. Participants’ use may have changed over the extended follow-up, leading to exposure misclassification bias. Reliance on hospital/death registry data may have missed some atrial fibrillation events triggered acutely.

The study’s generalizability is limited due to the fact that most participants were of white ethnicity, so results may not generalize well to other racial/ethnic groups. Additionally, the study did not fully account for other healthy behaviors the users of fish oil supplements may have in analyses, confounding the results. With many outcome transitions analyzed, there is an increased chance of false positive findings due to diversity. Furthermore, the study did not account for participants’ adherence to fish oil supplements over time, which could impact the observed associations. While the study describes associations, it lacks mechanistic data to explain the divergent effects of fish oil on primary vs secondary prevention of cardiovascular events.

While thought-provoking, this study’s observational nature and several fundamental limitations raise questions about the validity and generalizability of the findings. Randomized controlled trials tracking participant adherence and examining specific fish oil formulations would be needed to better outline their effects across the cardiovascular disease spectrum. The authors rightly acknowledge the need for further research to understand the complex relationships observed. I intend to continue my fish oil daily.

Want to know more about Dr. Purita’s supplement routine?

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