Omega-3 fatty acids linked to lower atrial fibrillation risk in U.S. veterans

By Pooja Toshniwal PahariaReviewed by Benedette Cuffari, M.Sc.Jun 22 2023

A recent study published in The American Journal of Clinical Nutrition determined whether marine omega-3 fatty acid (FA) consumption increases atrial fibrillation (AF) risk among United States military veterans.

Study: Dietary ω-3 fatty acids and the incidence of atrial fibrillation in the Million Veteran Program. Image Credit: Natali _ Mis / Shutterstock.com

Background

AF, the most frequently sustained cardiovascular arrhythmia, is highly prevalent in the US and can increase the burden on healthcare facilities. Marine omega-3 FA, such as eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and docosapentaenoic acid (DPA), are primarily consumed among US residents through seafood.

Recent large-scale randomized clinical trials (RCTs) evaluating the impact of DHA and EPA dietary supplementation on the cardiovascular system have documented increased AF risks following DHA and EPA consumption. However, scientific evidence on the link between omega-3 FA intake and AF risk is inconsistent, thus warranting further research.

About the study

The present study assesses the association between omega-3 FA intake and AF among US veterans.

By December 2020, 819,417 veteran individuals participated in the prospective cohort MVP study, provided serum samples, and completed food frequency questionnaires (FFQs). Among the participants, 379,852 individuals completed the Lifestyle Survey to provide data on their dietary habits, among whom those with a positive history of AF were excluded from the present analysis.

AF was determined based on the International Classification of Diseases, ninth and tenth versions (ICD-9, -10) diagnostic codes mentioned in the veterans’ electronic medical records. Positive AF history was based on at least one or two diagnoses in inpatient and outpatient settings before the end of the follow-up period. The mean daily calorie intake of different foods was calculated, following which omega-3 FA consumption was determined using the Harvard University Food Composition Database data.

Multivariate Cox proportional-type hazards regression modeling was performed to determine the hazard ratios (HRs) of AF across quintiles of omega-3 FA intake, adjusting for covariates such as age, gender, body mass index (BMI), ethnicity, race, educational attainment, income, smoking habits, physical exercise, alcohol consumption, nutrient intake, and comorbidities such as coronary artery diseases, heart failure, diabetes, chronic renal disease, and hypertension.

A restricted-type cubic spline analysis was also performed to evaluate the dose-dependent relationships between AF and omega-3 FA. A secondary analysis determined the relationship between dietary omega-3 FA intake and AF risk.

Data were obtained until AF occurrence, death, date of the most recent update in the electronic medical records, or September 30, 2020, in the case of the most recent health visit reported in the electronic medical record on or after October 1, 2020.

Study findings

Among the 301,294 participants, the mean age was 65 years, 91% were male, and 84% were White. The median omega-3 FA consumption was 219 mg daily.

Higher marine omega-3 FA intake was positively associated with physical exercise, hypertension, coronary artery diseases, college-level education, and an annual household income above $60,000 USD. In contrast, higher omega-3 FA intake was negatively associated with alcohol consumption, smoking habits, high school or a lower level of education, and an annual income below $30,000 USD.

Omega-3 FA intake showed a non-linear inverse association with new-onset AF. It was characterized by an initial reduction to 11% after consuming 750 mg daily of marine omega-3 FA, followed by a plateau.

The present study findings contradicted those of the REDUCE-IT and STRENGTH clinical trials, in which the participants consumed 4,000 mg of omega-3 FA daily, which indicates that omega-3 FA may have dose-dependent effects.

Furthermore, the REDUCE-IT trial included individuals with diabetes, cardiovascular diseases, or elevated triglyceride (TG) levels requiring statin therapy. Likewise, the STRENGTH trial included individuals with increased TG and high-density lipoprotein (HDL) levels, elevated risks of cardiovascular disease, and statin use. These inclusion criteria did not apply to the current study cohort.

Conclusions

Marine and dietary omega-3 FA consumption lowered AF risk non-linearly; however, additional studies that include individuals of different ages, races, and ethnicities, more female representation, and multiple FFQs to assess dietary changes over time, are needed to improve the generalizability of the study findings. Future studies may also use objective patient-level information, such as electrocardiograms (ECGs), to capture more atrial fibrillation episodes.