Effects of omega-3 fatty acid supplementation on heart rate variability

BACKGROUND Obesity and overweight are major public health challenges and are associated with autonomic imbalance and decreased heart rate variability (HRV), a non-invasive indicator of cardiovascular risk. Omega-3 polyunsaturated fatty acids have shown cardioprotective effects and may modulate autonomic function. Nevertheless, the effect of omega-3 supplementation on HRV in individuals who are overweight or obese remains unclear. AIM To study the effect of omega-3 supplementation on HRV in overweight and obese individuals and to explore the heterogeneity across different study designs. METHODS In accordance with PRISMA guidelines, a systematic review and meta-analysis were conducted. PubMed, Science Citation Index, and Scopus were searched for randomized controlled trials (RCTs) assessing the impact of oral omega-3 supplementation on HRV in overweight or obese participants. Primary outcomes were the impacts of omega-3 supplementation on time-domain HRV indices [root mean square of successive differences (RMSSD), standard deviation of normal-to-normal intervals (SDNN), and percentage of successive normal-to-normal intervals differing by more than 50 milliseconds (pNN50%)], and frequency-domain indices [high-frequency (HF) power, low-frequency (LF) power, and LF/HF ratio]. RESULTS Four RCTs (n = 134 participants) met the inclusion criteria. Two trials compared pre- vs post- omega-3 supplementation, and two compared omega-3 with placebo on HRV in overweight and obese children and adults. In the within-subject analyses, omega-3 supplementation was associated with a significant increase in RMSSD [mean difference (MD) = -11.69 milliseconds, 95%CI: -18.50 to -4.87, P = 0.0008), SDNN (MD = -26.13 milliseconds, 95%CI: -35.84 to -16.42, P < 0.00001), and pNN50% (MD = -9.45, 95%CI: -14.27 to -4.64, P = 0.0001). Between-group comparisons showed that omega-3 supplementation had no significant effect on HF power, LF power, or the LF/HF ratio. CONCLUSION Omega-3 supplementation represents a promising and low-cost strategy for enhancing autonomic balance and potentially reducing cardiovascular risk in overweight and obese populations, as it improves time-domain HRV measures.