Effect of Omega-3 Fatty Acid in Cardiovascular Risk

Family Practice Recertification, October 2013, Volume 31, Issue 1

Does consumption of omega-3 (n−3) fatty acids reduce cardiovascular outcomes in patients without myocardial infarction who have multiple cardiac risk factors?

Frank J. Domino, MD

Review

Roncaglioni MC, et al. N−3 fatty acids in patients with multiple cardiovascular risk factors. N Engl J Med. 2013 May 9;368(19):1800-8. http://www.nejm.org/doi/full/10.1056/NEJMoa1205409.

Study Methods

This was a double-blind, placebo-controlled randomized clinical trial of 12,500 patients in Italy.

Patient Demographics

Patients who were included in the study had at least one of the following features: Multiple cardiovascular (CV) risk factors, including an age of 65 years or older, male sex, hypertension, hypercholesterolemia, current smoking, obesity, or a family history of premature CV disease (CV at <55 years for the patient’s father or brother, or CV at <65 years for the patient’s mother or a sister); clinical evidence of atherosclerotic vascular disease; or “any other condition putting the patient at high cardiovascular risk in the opinion of the patient’s general practitioner.”

Intervention and Control

Patients were randomized to receive daily either 1 g of n−3 fatty acids or an olive oil capsule placebo.

Results and Outcomes

The initial primary endpoint was a combined rate of death, nonfatal myocardial infarction, and nonfatal stroke. At 1 year, the event rate was found to be lower than expected, so the primary endpoint was revised to “time to death from cardiovascular causes or admission to the hospital for cardiovascular causes.”

Secondary endpoints were a composite of time to death, nonfatal myocardial infarction, or nonfatal stroke, as well as a composite of time to death from cardiovascular causes, nonfatal myocardial infarction, or nonfatal stroke; death from coronary heart disease; and sudden death from cardiac causes.

At a median of 5 years follow-up, the primary endpoint occurred in 11.8% of the entire study population, 11.7% of those who received n−3 fatty acids, and 11.9% of those who had received placebo, which was a non-significant difference. Additionally, there was no difference across all secondary endpoints.

Conclusion

Use of n−3 fatty acids in patients at risk of heart disease doesn’t provide any protective benefit compared to olive oil capsules over a median of 5 years.

Commentary

Wouldn’t it be great if taking a pill lowered your heart risk? This review reminds us that very few over-the-counter medications can be used for primary prevention benefits. In the US, multivitamins provide no improved outcomes, vitamin C doesn’t prevent urinary tract infections, and vitamin E may actually increase prostate cancer risk. On the plus side, vitamin D lowers the risk of falls in patients over 65 years old, and it may also lower colorectal cancer risk. But aside from aspirin for those at high risk, there’s nothing much else available for heart disease.

So, when do n−3 fatty acid supplements offer benefits? There is conflicting data in regard to their use in secondary prevention of cardiovascular disease, unless the patient has congestive heart failure. Some patients have said that n−3 fatty acid helps treat their constipation, but this hasn’t been clinically proven. There is also some data on the supplements lowering triglyceride levels in patients with very high triglycerides, but patient-oriented outcomes are not yet known.

Now, what do we tell our patients? Save your money and spend it at the fish counter. Eat oily fish at least twice a week and use olive or sunflower oil for cooking and eating, as a cohort study from Spain found that frying foods with those oils doesn’t increase cardiovascular risk.1 However, the best thing to recommend for patients is exercise. For the primary prevention of cardiovascular disease, 30 to 50 minutes of exercise per day for 5 days per week is needed.2

References

1. Guallar-Castillón P, et al. Consumption of fried foods and risk of coronary heart disease: Spanish cohort of the European Prospective Investigation into Cancer and Nutrition study. BMJ. 2012 Jan 23; 334:E363. http://www.bmj.com/content/344/bmj.e363.

2. Hordern, MD, et al. Exercise prescription for patients with type 2 diabetes and pre-diabetes: A position statement from Exercise and Sport Science Australia. J Sci Med Sport. 2012 Jan 15; 15(1): 25-31. http://www.sciencedirect.com/science/article/pii/S1440244011000806.

About the Author

Frank J. Domino, MD, is Professor and Pre-Doctoral Education Director for the Department of Family Medicine and Community Health at the University of Massachusetts Medical School in Worcester, MA. Domino is Editor-in-Chief of the 5-Minute Clinical Consult series (Lippincott Williams & Wilkins). Additionally, he is Co-Author and Editor of the Epocrates LAB database, and author and editor to the MedPearls smartphone app. He presents nationally for the American Academy of Family Medicine and serves as the Family Physician Representative to the Harvard Medical School’s Continuing Education Committee.