Balancing the benefits of n-3 polyunsaturated fatty acids and the risks of methylmercury exposure from fish consumption

Abstract

Fish and shellfish are widely available foods that provide important nutrients, particularly n-3 polyunsaturated fatty acids (n-3 PUFAs), to many populations globally. These nutrients, especially docosahexaenoic acid, confer benefits to brain and visual system development in infants and reduce risks of certain forms of heart disease in adults. However, fish and shellfish can also be a major source of methylmercury (MeHg), a known neurotoxicant that is particularly harmful to fetal brain development. This review documents the latest knowledge on the risks and benefits of seafood consumption for perinatal development of infants. It is possible to choose fish species that are both high in n-3 PUFAs and low in MeHg. A framework for providing dietary advice for women of childbearing age on how to maximize the dietary intake of n-3 PUFAs while minimizing MeHg exposures is suggested.

Figure 1. Examples of fish species that, when consumed, allow an individual to meet the daily recommended intake for DHA while not exceeding the US EPA RfD, prepared according to the methodology described by Tsuchiya et al.

Fish species are divided into three categories: species that provide levels below and above a de minimus intake ratio of 17 mg DHA for every 1 μg Hg and species that exceed this ratio while also providing for a Hg intake of less than 6 μg of Hg exposure per day. Values are based on intakes equivalent to the RfD by an individual weighing 60 kg and consuming 60 g/day.