Selenium, Mercury, and Health Benefit Values of Pelagic Ocean Fish of the Central North Pacific

The mercury (Hg) present in ocean fish has caused concern regarding the effects of maternal consumption on child outcomes but it is now recognized that mothers that eat more ocean fish during pregnancy have children with higher social, scholastic, and IQ scores. These findings coincide with the current understanding of the mechanism of Hg toxicity which indicates ocean fish consumption will prevent rather than cause harm. High-Hg exposures sequester selenium (Se) and inhibit Se-dependent enzymes that prevent and reverse oxidative damage in the brain and support fetal brain development. However, aside from certain types of shark and other apex marine predators, seafood contains more Se than Hg and thus counteracts instead of contributing to Hg toxicity. This study evaluates the Hg and Se present in bigeye tuna, yellowfin tuna, albacore tuna, skipjack, swordfish, striped marlin, blue marlin, spearfish, mahimahi, wahoo, monchong, escolar, mako shark, and thresher shark to establish their health benefit values (HBVs). Positive HBVs (0.3–19.6), indicating a molar excess of Se over Hg, were found in 14 of the 15 species studied. Only mako shark uniformly contained Hg in excess of Se to produce a negative HBV (−16.4), indicating its consumption should be minimized during pregnancy.