While most advice urges that people continue to eat fish regularly - many authorities recommend at least two portions of fish a week - the raised alert to mercury contamination in fish could offer opportunities to companies supplying fish oils, now widely subject to contaminant tests before going on sale in supplements.
With a study to be published next month set to reveal a sharp rise in the presence of chemicals commonly used in flame retardants, or PCBs, in cod liver oil supplements, the industry is under renewed pressure to demonstrate the 'clean' nature of fish oils. The new alert to mercury in fresh fish should prompt the supplements industry to reinforce the safety of encapsulated fish oils, most of which go through molecular distillation to check for contamination with metals.
Consumption of fish oil supplements has grown rapidly in recent years on the back of research that associates the omega-3 fatty acids found in oily fish with reduced risk of heart disease and, increasingly, protection against certain mental disorders such as Alzheimer's.
EFSA's Scientific Panel on Contaminants in the Food Chain (CONTAM) last week published an opinion regarding the possible risks to human health associated with the consumption of foods contaminated with mercury. It has called for further studies on vulnerable population groups, including children and women of childbearing age, where specific intake data are lacking.
Food Standards Australia New Zealand (FSANZ) and the US Food and Drug Administration also released updated advice on mercury in fish last week, extended to provide not only for pregnant women, and women considering pregnancy, but also for young children and the general population.
Mercury is present as an environmental contaminant in foods, notably in fish and seafood in the form of methylmercury. EFSA and other agencies have recommended that vulnerable groups in particular select fish from a wide range of species without consuming too much large predatory fish that tend to contain higher levels of methylmercury, such as swordfish and tuna.
In Europe, the average intake estimates of methylmercury are below but at times rather close to the provisional tolerable weekly intake (PTWI) established by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) (1.6 µg/kg body weight) and some intake estimates exceed the limit established by the US National Research Council (0.7 µg/kg body weight per week), said the CONTAM panel. It has recommended a more complete evaluation of exposures be carried out in Europe.