EPA/DHA improves heart rate variability at rest and during acute stress

Omega‐3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) reduce cardiovascular disease (CVD) by affecting many pathways influencing autonomic tone. Heart rate variability (HRV) is a non‐invasive method used to index autonomic influence on the heart. Lower levels of HRV are associated with an increased risk of CVD. This study examined whether HRV could be influenced by EPA/DHA supplementation and whether this relationship existed in a dose‐response manner. We enrolled 26 adults with elevated trigylcerides (150–500 mg/dl) in a placebo‐controlled, double‐blind, randomized crossover trial (8 wk treatment, 6 wk washout) that tested a nutritional dose of EPA/DHA (0.85 g/d; LOW) and a pharmaceutical dose (3.4 g/d; HIGH). We compared HRV at rest and during a simulated public speech and cold pressor test. Total HRV was 8% greater following the HIGH treatment compared to the placebo and LOW treatments (p<0.05). The square root of the mean square of successive differences in R‐R interval (RMSSD) was 14% greater following the HIGH treatment compared to the placebo and LOW treatments (p<0.05). There were no differences between the LOW and placebo treatments for any HRV measures (p>0.05). These results support prior evidence that EPA and DHA improve autonomic function and indicate that there is a threshold for above which omega‐3 fatty acids must be consumed to have a beneficial effect on autonomic function. Grant Funding Source : National Fisheries Institute, GlaxoSmithKline