Advice On The Safety and Nutritional Contribution of Wild and Farmed Fish
Food Safety Fish
The European Food Safety Authority (EFSA) has published an opinion on the health risks related to the consumption of wild and farmed fish. EFSA's Opinion says that there are no consistent differences between wild and farmed fish both in terms of safety and nutritional value. Consumption of fish, and in particular fatty fish due to its richness in long chain n-3 polyunsaturated fatty acids, is beneficial to cardiovascular health and also to foetal development. In general, dietary recommendations suggest weekly consumption of one to two portions of fatty fish.
The greatest susceptibility to the critical contaminants, methylmercury and dioxin-like compounds, occurs during early human development. Scientific experts therefore advise that - in particular for vulnerable groups such as the unborn child, pregnant women and women of child-bearing age - the nutritional benefits of fish should be weighed against the potential risks related to the presence of contaminants in certain types of fish. Overall, nutritional guidelines concerning fish consumption will not lead to intakes of dioxins and dioxin-like PCBs which cause safety concern, with the exception of fatty fish caught from the Baltic sea (e.g. herring and salmon) where the available data concerning contaminant levels support the more specific recommendations established by Swedish and Finnish food safety authorities. The Panel notes however that advice regarding fish consumption should also take into account other sources of these contaminants in the diet. With respect to methylmercury, women eating up to two portions of fish per week are unlikely to exceed tolerable intake levels provided that certain types of top predatory fish are avoided. Additional guidance regarding the types and quantities of fish most suited to consumers' diets is provided by national food safety authorities in Member States. Finally, the EFSA Panel on Contaminants in the Food Chain recommends the development of a consistent and agreed methodology for carrying out quantitative assessments of risks and benefits related to food consumption.
EFSA was asked by the European Parliament to assess the health risks related to human consumption of wild and farmed fish and to include an overall impact and risk assessment related to the consumption of Baltic herring. EFSA's advice concentrates on the most relevant heavy metals and persistent organic contaminants, namely methylmercury, dioxins and dioxin-like PCBs and also reviews the nutritional value and benefits from consuming fish. In order to carry out this assessment requiring multi-disciplinary expertise, EFSA established an Inter-panel working group consisting of members from the following Scientific Panels: Contaminants in the Food Chain (CONTAM); Dietetic Products, Nutrition and Allergies (NDA); Additives and Products or Substances used in Animal Feed (FEEDAP); and Animal Health and Animal Welfare (AHAW).
Fish makes an important nutritional contribution to the diet, providing proteins, fatty acids (such as long-chain n-3 polyunsaturated fatty acids - LC n-3 PUFAs) and certain vitamins and minerals. Consumption of fish is beneficial to cardiovascular health and may also benefit development of the unborn child. Dietary recommendations often advise one to 2 portions (130g per portion) of "fatty fish" (such as herring and salmon) per week, or greater amounts of lean fish, in order to achieve intake levels of LC n-3 PUFA favourable to the cardiovascular system.
In assessing the safety of wild and farmed fish, EFSA's CONTAM Panel reviewed a wide range of contaminants and concluded that the two contaminants for which high consumers of fish might exceed the provisional tolerable weekly intake (PTWI) are:
(i) methylmercury which is found at elevated concentrations in tuna and other top predatory fish which are mostly caught in the wild, and
(ii) dioxins and dioxin-like PCBs for which higher levels are found in fatty fish, e.g. herring and salmon.
Methylmercury is particularly toxic to the nervous system and the developing brain. Exposure during pregnancy and early infancy is therefore of particular concern. Pregnant women eating up to two portions of fish per week are unlikely to exceed provisional tolerable weekly intake (PTWI) levels for methylmercury, as long as they do not consume blue fin or albacore tuna. (These species are not likely to be found in canned tuna in Europe). Other top predatory fish, such as marlin, pike, swordfish, and shark also frequently contain high levels of methylmercury. EFSA already recommended in March 2004 that women of childbearing age (in particular, those intending to become pregnant), pregnant and breastfeeding women, as well as young children, select fish from a wide range of species without giving undue preference to top predatory fish, such as swordfish and tuna.
For dioxins and dioxin-like PCBs, it would take several years to reduce levels in the human body. It is therefore not possible for women wishing to become pregnant to reduce these levels without excluding fish (as well as other possible food sources of dioxins and dioxin-like PCBs) from their diets completely for several years before conception. However, women consuming up to two portions per week of fatty fish will not exceed the provisional tolerable weekly intake for dioxins and dioxin-like PCBs provided that they take into account other possible sources in the diet so as not to exceed the PTWI.
According to EFSA's Opinion frequent consumers of fatty fish coming from the Baltic Sea, i.e. Baltic herring and wild Baltic salmon are more likely to exceed the PTWI for dioxins and dioxin-like PCBs than other consumers of fatty fish. On average, Baltic herring and wild Baltic salmon are respectively 3.5 and 5 times more contaminated with dioxin and dioxin-like PCBs in comparison with non-Baltic herring and farmed salmon. Specific advice concerning Baltic fish consumption, taking into account these higher contamination levels, is given by national food safety authorities in Sweden and Finland2.
Advice on fish consumption needs to take into account total dietary exposure of relevant contaminants, based on national consumption patterns. Guidance regarding the types and quantities of fish most suited to consumers' diets is provided by national food safety authorities in Member States. Factors which affect the levels of contaminants found in fish include: species; life stage and fish's diet; season; and location of catch. These levels vary broadly within species and between species in both wild and farmed fish. Based on the data available, there are no consistent differences between nutrient and contamination levels of wild and farmed fish. In farmed fish, fish oil and fish meal are the most important sources of organic contaminants and possibilities for reducing contaminants levels in fish feed should be further explored. For wild fish the only action possible is the long-term control of emissions of pollutants to the environment.
Fish, whether wild or farmed, has its place in a well balanced diet and overall there is no consistent difference between wild and farmed fish with respect to their safety for the consumer.