Mercury, omega-3 fatty acids, and seafood intake are not associated with heart rate variability or QT interval

Abstract

Mercury (Hg), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) concentrations differ across seafood types. Our aim was to investigate the association of Hg, EPA, and DHA, as well as avid consumption of diverse seafood types, with cardiovascular variables heart rate variability (HRV) and QT interval duration (QTc) in a contemporary population. We measured HRV and QTc by Holter monitor, EPA and DHA in plasma, total Hg in whole blood, and possible confounders in 94 avid seafood consumers from Long Island, NY. Participants had mean Hg of 8.4 mcg/L, mean EPA of 1.2%, and mean DHA of 3.7% of total fatty acids. Adjusted for possible confounders, EPA+DHA, Hg, and total seafood consumption were not associated with HRV or QTc. Associations with consumption of specific seafood types were suggested (eg, tuna steak with QTc and anchovies with HRV) but require verification.

Assessment of Cardiac Autonomic Function in Relation to Methylmercury Neurotoxicity

“…In Inuit adults, blood mercury was significantly correlated with CV RR and LF ( r = −0.18 and r = −0.18, respectively), but these significant associations disappeared after adjusting for potential confounders [ 10 ]. In avid fish consumers, either blood total mercury or serum docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) level was not significantly associated with any HRV parameter in a multiple regression analysis [ 19 ]. Gump et al [ 18 ] measured LF, HF, and LF/HF ratio at rest and during stress in children aged 9–11 years to assess parasympathetic responses to acute stress, but neither blood mercury nor lead was significantly related to baseline HRV parameters (HRV data not shown).…”

“…HRV has been analyzed using a Holter monitoring system [ 10 , 14 , 15 , 16 , 19 ], an ECG analyzer with analog-to-digital converter [ 7 , 8 , 9 , 12 ], or other ECG measuring instruments [ 11 , 13 , 17 , 18 ]. ECG signals for R‒R intervals were digitalized at 128 Hz [ 10 , 14 , 15 , 16 ], 200 Hz [ 17 ], 250 Hz [ 7 ], 500 Hz [ 18 ], and 1000 Hz [ 8 , 9 , 12 ].…”

“…ECG signals for R‒R intervals were digitalized at 128 Hz [ 10 , 14 , 15 , 16 ], 200 Hz [ 17 ], 250 Hz [ 7 ], 500 Hz [ 18 ], and 1000 Hz [ 8 , 9 , 12 ]. Three reports did not mention the sampling frequency [ 11 , 13 , 19 ]. Most of the study subjects were examined in a supine position [ 7 , 8 , 9 , 11 , 12 , 17 ] after subjects lay quietly for two min or longer, but the subjects examined by Lim et al [ 13 ] were sitting in a quiet and dark room.…”

“…Most of the study subjects were examined in a supine position [ 7 , 8 , 9 , 11 , 12 , 17 ] after subjects lay quietly for two min or longer, but the subjects examined by Lim et al [ 13 ] were sitting in a quiet and dark room. The remaining reports did not provide any detailed information [ 10 , 14 , 15 , 16 , 18 , 19 ].…”

“…We excluded review papers ( n = 6), case series ( n = 3), studies addressing occupational mercury exposure ( n = 2) or studies in which data for either HRV ( n = 3) or mercury biomarkers ( n = 6) were not described. Finally, included were 13 studies of methylmercury exposure and HRV: ten studies [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ] that were included in a previous systematic review by Gribble et al [ 6 ] and three new studies [ 17 , 18 , 19 ]. In all of the identified studies, the statistical significance was set at p < 0.05.…”