Omega-3s and mercury: fishing for the truth?
New developments in epidemiological studies have indicated that n-3 long-chain polyunsaturated fatty acids in fish may counteract the negative effects of methylmercury exposure
On 7 December 2012, the European Commission (EC) asked EFSA’s Scientific Panel on Contaminants in the Food Chain (CONTAM) to do an analysis regarding the risks and benefits to human health of fish/seafood consumption related to methylmercury.
At first glance, what appeared to be yet another attack on the omega-3 industry is nothing more than the last of several exercises to determine whether the harmonised maximum levels for mercury in fish and seafood laid down in Commission Regulation (EC) No. 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs should be revised.1
As part of this exercise, an external scientific report, as well as a scientific opinion, was published in December of last year. Because the previous risk assessments on mercury and methylmercury needed to be updated, the scientific literature not considered in the Joint FAO/WHO Expert Committee on Food Additives (JECFA) evaluations on methylmercury in 2003 and inorganic mercury in 2010 was collected, compiled and summarised.2,3 The scientific literature on studies in experimental animals and humans from 2002 to 2011 and found to be relevant to assess mercury toxicity in food is documented in this 360 page report.4
Following a request from the EC, the CONTAM Panel was asked to deliver a scientific opinion on the risks to human health related to the presence of inorganic mercury and methylmercury in food. The Panel was asked to consider new developments regarding the toxicity of inorganic mercury and methylmercury since EFSA’s opinion on 24 February 2004 and to evaluate whether the provisional tolerable weekly intakes (PTWIs) established by JECFA for methylmercury and inorganic mercury were appropriate.5
Of interest is that this report included the statement: 'For methylmercury, new developments in epidemiological studies from the Seychelles Child Development Study Nutrition Cohort have indicated that n-3 long-chain polyunsaturated fatty acids in fish may counteract the negative effects of methylmercury exposure.'
In its evaluation, the CONTAM Panel took into consideration the Report of the Joint FAO/WHO Expert Consultation on the Risks and Benefits of Fish Consumption published in 2011.6 The following statements come from that report, providing further reason not to be concerned about the pending final scientific opinion:
- 'There is an absence of probable or convincing evidence of risk of coronary heart disease associated with methylmercury.'
- 'When comparing the benefits of LCn3PUFAs with the risks of methylmercury among women of childbearing age, maternal fish consumption lowers the risk of suboptimal neurodevelopment in their offspring compared with the offspring of women not eating fish in most circumstances evaluated.'7
Similar exercises have been done by other governments and organizations with favourable results.
- In 2009, the US Food and Drug Administration (FDA) made available a draft risk assessment and benefit report, titled ‘‘Report of Quantitative Risk and Benefit Assessment of Commercial Fish Consumption, Focusing on Fetal Neurodevelopmental Effects (Measured by Verbal Development in Children) and on Coronary Heart Disease and Stroke in the General Population.'8 According to the report: 'The results of our quantitative risk and benefit assessment are generally consistent with research reported in recent years in the scientific literature.' In other words, the benefits outweigh the risks. Although this report is still in draft form, GOED has been told by the FDA that is shouldn’t be too much longer until it is finalised.
- According to the 2010 Dietary Guidelines for Americans: 'Moderate, consistent evidence shows that the health benefits from consuming a variety of seafood in the amounts recommended outweigh the health risks associated with methylmercury, a heavy metal found in seafood in varying levels.'9
- According to the Food Standards Australia New Zealand: 'People can safely eat 2–3 servings a week of most types of fish. However, because of the presence of higher levels of mercury in some fish, there are a few types you should limit in your diet, especially if you are pregnant.'10
References
1. http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2006:364:0005:0024:EN:PDF.
2. ftp://ftp.fao.org/es/esn/jecfa/jecfa61sc.pdf.
3. www.who.int/foodsafety/chem/summary72_rev.pdf.
4. www.efsa.europa.eu/en/supporting/pub/297e.htm.
5. www.efsa.europa.eu/de/efsajournal/pub/34.htm.
6. http://whqlibdoc.who.int/publications/2011/9789241564311_eng.pdf.
7. http://www.efsa.europa.eu/de/efsajournal/pub/2985.htm.
8. www.fda.gov/Food/FoodSafety/Product-SpecificInformation/Seafood/FoodbornePathogensContaminants/Methylmercury/ucm088758.htm.
9. www.cnpp.usda.gov/Publications/DietaryGuidelines/2010/PolicyDoc/PolicyDoc.pdf.
10. www.foodstandards.gov.au/consumerinformation/mercuryinfish.cfm.