Influence of n-3 fatty acids on cardiac autonomic activity among Nunavik Inuit adults

OBJECTIVES: Inuit from Nunavik (northern Quebec) consume large amounts of fish and marine mammals, which are important sources of n-3 polyunsaturated fatty acids (n-3 PUFAs). These substances have a beneficial impact on heart rate (HR) and heart rate variability (HRV). However, it is unknown if this beneficial impact remains significant in populations with high mercury exposure. The study assessed the impact of n-3 PUFAs (Docosahexaenoic [DHA] and Eicosapentaenoic acid [EPA]) on resting HR and HRV among Nunavik Inuit adults considering mercury and other potential confounders. STUDY DESIGN: Cross-sectional study employing clinical measurements. METHODS: Complete data were collected among 181 adults ≥ 40 years old (109 women and 72 men) living in the 14 coastal villages of Nunavik. Several indices of HRV were derived from a 2-hour Holter monitoring assessment. n-3 PUFAs levels were measured in membrane erythrocytes. Simple linear regression was used to analyse the relationship between n-3 PUFAs levels and resting HR and HRV parameters while multiple linear regressions were carried out to control for confounders. RESULTS: In the overall analyses, EPA was associated with SDANN (β = 0.07, p = 0.04) and LF norm (β = -1.84, p = 0.03) after adjusting for confounders. Among women, DHA was associated with resting HR (β =-1.40, p = 0.03) while EPA was associated with SDNN (β = 0.08, p = 0.03), SDANN (β = 0.09, p = 0.02) and resting HR (β = -2.61, p = 0.002). No significant association was observed in men. CONCLUSIONS: These results suggest a beneficial impact of n-3 PUFAs on resting HR and HRV among Nunavik Inuit women.