Patient-Oriented Evidence That Matters
Omega-3 Fatty Acids Do Not Prevent Cancer or Cardiovascular Disease Events
Am Fam Physician. 2019 Sep 15;100(6):374-375.
Do marine n-3 fatty acids (also called omega-3 fatty acids) reduce the risk of cardiovascular events or cancer in patients without known vascular disease or cancer?
This is the second large, well-designed study (the first one included patients with diabetes mellitus; this one included patients without diabetes) that found no benefit from a 1-g daily dosage of marine n-3 fatty acid supplementation for the primary prevention of cardiovascular disease or cancer. This study featured more than 20 comparisons, so the small reduction found in myocardial infarctions may be due to chance alone. (Level of Evidence = 1b)
A recent POEM reported that a U.K. trial of marine n-3 fatty acids in 15,000 patients with diabetes found no evidence of benefit as primary prevention of cardiovascular disease or cancer. The current study is the first adequately powered U.S. trial of marine n-3 (omega-3) fatty acids for primary prevention. The researchers recruited a total of 25,871 men 50 years and older and women 55 years and older who had no history of cardiovascular disease or cancer. The groups were balanced at the start of the study, with a mean age of 67 years, 51% women, and 14% with diabetes. The investigators used a three-month placebo run-in period to exclude patients who were noncompliant, which was approximately one-third of those initially recruited. This could overestimate the potential benefit seen in clinical practice. Participants were randomly assigned to a 1-g daily dosage of marine n-3 fatty acids or placebo. The median follow-up was 5.3 years. There was no reduction in the likelihood of cancer diagnosis or the primary composite cardiovascular outcome (i.e., cardiovascular death, nonfatal myocardial infarction, or ischemic stroke). There was no difference between groups regarding cardiovascular or all-cause mortality. There was a reduction in total myocardial infarctions (hazard ratio = 0.72; 95% CI, 0.59 to 0.90), although the absolute reduction
Editor's Note: Dr. Ebell is Deputy Editor for Evidence-Based Medicine for AFP and cofounder and Editor-in-Chief of Essential Evidence Plus, published by Wiley-Blackwell. Dr. Shaughnessy is an Assistant Medical Editor for AFP.
POEMs (patient-oriented evidence that matters) are provided by Essential Evidence Plus, a point-of-care clinical decision support system published by Wiley-Blackwell. For more information, see http://www.essentialevidenceplus.com. Copyright Wiley-Blackwell. Used with permission.
For definitions of levels of evidence used in POEMs, see http://www.essentialevidenceplus.com/product/ebm_loe.cfm?show=oxford.
To subscribe to a free podcast of these and other POEMs that appear in AFP, search in iTunes for “POEM of the Week” or go to http://goo.gl/3niWXb.
This series is coordinated by Sumi Sexton, MD, Editor-in-Chief.
A collection of POEMs published in AFP is available at https://www.aafp.org/afp/poems.
Want to use this article elsewhere? Get Permissions