Methylmercury and long-chain n-3 fatty acids of 88 fish species commonly consumed in Hong Kong

Abstract

Fish is considered by nutritionists as the main source of omega 3 (n-3) polyunsaturated fatty acids which is not available in common edible plant oils. However, methylmercury (MeHg) in fish is considered as the major contributor from food. Risk benefit analysis of MeHg and n-3 fatty acids became a hot topic in the past decade. Different risks and benefit analysis on the consumption of fish have been reported, but most of the analyses were based on the data extracted from different databases. This study provided the levels of n-3 fatty acids, MeHg, and total mercury (tHg) of different fish species commonly consumed in Hong Kong. Among the sampled 88 species of fresh/frozen whole fish, all samples were found to contain quantifiable amount of n-3 fatty acids, MeHg, and tHg. The levels of n-3 fatty acids (EPA plus DHA) in local or imported fish species are ranging from 0.31 to 20.6 mg per g while the highest level was found in Atlantic salmon. For MeHg, the highest content was found for alfonsino at the level of 0.827 μg per g. A modified AOAC 990.08 was single laboratory validated and used for analysis n-3 fatty acids content of fish samples. This paper presents the n-3 fatty acids and MeHg content in 88 fish species. These original results are consistent with overseas findings and are useful in risk/benefit assessment of fish consumption recommendations in general.