Over a year ago, I questioned my daily supplementation of omega-3 fatty acid (triglyceride-reducing agents found in fish oil) by looking at some evidence for and against its health benefits. After this mini-literature review
, I decided to continue taking fish oil tabs despite the lackluster evidence for improved cardiovascular health including prevention of heart attacks and stroke.
Lately I've been experiencing (get ready for it) a change of heart.
It all went down after perusing the American College of Physicians' Journal Club
, a collection of journal reviews dedicated to highlighting important findings of a collection of high-impact medical journals. I couldn't help but notice that study after study demonstrated a lack of evidence for supporting fish oil supplementation in the prevention of major cardiac events (heart attacks, strokes) in patients at high risk or with known heart disease.
Below are a few of the major articles that I found most remarkably unremarkable.
The (lack of) Evidence
Evangelos et al made a big splash (I'll stop) in the fish oil world after publishing a meta-analysis
demonstrating no significant beneficial effects of daily omega-3 supplementation use on major cardiac events. They did this by analyzing 18 well-designed studies that, when combined, encompassed over 60,000 adult participants. They found no association between omega-3 polyunsaturated fatty acids (PUFA) supplementation and a lower risk of all-cause death, heart attack-related deaths or strokes. These results were consistent despite omega-3 doses, and all participants were enrolled in these studies for at least one year.
Limitations of this meta-analysis include homogeneity of participants (mostly made up of European heritage), heterogeneity of omega-3 compounds (made up of varying ratios of EPA/DHA fatty acids) and publication date of the analyzed studies (some dated back to the 1980s).
Kwak and colleagues conducted their own meta-anaylsis
that examined heart-health benefits of omega-3 fatty acid supplementation in adults with a history of heart disease. Here they found no association between omega-3 supplementation and the prevention of heart-related events in patients with known past events (also known as secondary prevention). These findings were consistent despite variations in geographic area, dosage of EPA or DHA or concomitant medication use.
Limitations of this meta-analysis include the small number of participants for most studies examined and the relatively short duration of fish oil use.
Kowey et al took a different angle in their study
by examining the effects of omega-3 fatty acids on prevention of abnormal heart rhythms (arrhythmias) in individuals with a history of such arrhythmias. They did this by starting one group of participants on high-dose daily omega-3 pills and one group on placebo pills made up corn oil. They then compared the number of abnormal heart rhythm events over a 6-week period and found no significant difference in the number of events.
A notable limitation of this study involves the narrow demographics of the included participants (adult individuals with previous documented arrhythmias who were never treated with specific medications and had no heart valve dysfunction, etc.). By making the selection criteria so stringent, it makes it harder for clinicians to generalize these findings when making treatment decisions on their panel of patients.
Take Home Point
I want to be excited about fish oil. I really do.
Although these omega-3 fatty acid supplements are incredibly safe and easy to use, I continue to struggle proving their effectiveness in many important health-related conditions that relate to my own health profile.
Until I see some solid consistent evidence showing the effectiveness of fish oil on heart-related conditions, I'm tossing my fish oil supplements back to where they belong... the bottom of the sea.
*Ask your doctor if you have any individualized questions regarding fish oil, especially prior to starting or stopping this supplementation
**This blog was originally written for The American Resident Project.