Fish is an important source of energy, high-quality proteins, fat, vitamins and minerals. Within lipids, n-3 long-chain PUFA (n-3 LC PUFA), mainly EPA and DHA, play an important role in health promotion and disease prevention. In contrast to the potential health benefits of dietary fish intake, certain chemical pollutants, namely heavy metals and some organic compounds, contained in seafood have emerged as an issue of concern, particularly for frequent fish consumers and sensitive groups of populations. The present review summarises the health benefits and risks of fish consumption. n-3 LC-PUFA are key compounds of cell membranes and play an important role in human health from conception through every stage of human development, maturation and ageing. DHA has a major role in the development of brain and retina during fetal development and the first 2 years of life and positively influences neurodevelopment, mainly visual acuity and cognitive functions. n-3 LC-PUFA are also effective in preventing cardiovascular events (mainly stroke and acute myocardial infarction) especially in persons with high cardiovascular risk. By contrast, there is convincing evidence of adverse neurological/neurodevelopmental outcomes in infants and young children associated with methylmercury exposure during fetal development due to maternal fish consumption during pregnancy. Dioxins and polychlorinated biphenyls present in contaminated fish may also develop a risk for both infants and adults. However, for major health outcomes among adults, the vast majority of epidemiological studies have proven that the benefits of fish intake exceed the potential risks with the exception of a few selected species in sensitive populations.

The health benefits of seafood are well documented and based on the unique supply of n-3 highly unsaturated fatty acids (HUFA). Aquaculture now contributes about 50 % of food-grade seafood globally and Atlantic salmon (Salmo salar) is a rich source of n-3 HUFA. However, salmon and other oily fish can accumulate lipophilic persistent organic pollutants (POP), including dioxins (PCDD/F), polychlorinated biphenyls (PCB) and polybrominated diphenyl ethers (PBDE), derived largely from feed. In the present study, triplicate groups of salmon, of initial weight 0·78 kg, were fed one of three experimental diets for 11 weeks. The diets were coated with either a northern fish oil (FO) with a high POP content (cNFO), the same oil that had been decontaminated (deNFO) or a blend of southern fish oil, rapeseed and soyabean oils (SFO/RO/SO). Dietary PCDD/F+dioxin-like PCB (DL-PCB) concentrations were 17·36, 0·45 and 0·53 ng toxic equivalents (TEQ)/kg, respectively. After 11 weeks, the flesh concentrations in fish fed the cNFO, deNFO and SFO/RO/SO diets were 6·42, 0·34 and 0·41 ng TEQ/kg, respectively. There were no differences in flesh EPA and DHA between fish fed the cNFO or deNFO diets although EPA and DHA were reduced by 50 and 30 %, respectively, in fish fed the SFO/RO/SO diet. Thus, decontaminated FO can be used to produce salmon high in n-3 HUFA and low in POP. Salmon produced using deNFO would be of high nutritional value and very low in POP and would utilise valuable fish oils that would otherwise be destroyed due to their high pollutant concentrations.