by Monica Mollica ~ trainergize.com
Fish oil is a popular supplement, and for good reasons (I will soon post a long article about all the beneficial health effects of fish oil)! But what about fish? After all, fish is a good protein source…Yes, fish is an excellent source of both protein and the omega-3 fatty acids EPA and DHA (in case of fatty fish like salmon and mackerel).
Unfortunately, concerns have been raised against high fish consumption for several reasons. First, fish is a relatively expensive food with restricted availability in certain areas. Second, fish also has a characteristic taste that many people do not like. And last but not least, fish (especially fatty fish that is a good source of EPA and DHA) contains a high level of environmental toxins, among all mercury (also called methylmercury) and PCBs (polychlorinated biphenyls) 1-6. It is the contaminants in fish that have raised the most concerns.
Fish absorb environmental toxins as they grow, and so it builds up in them. It builds up more in some types of fish and shellfish than others, depending on what the fish eat and in which waters they live, which is why the levels vary 2, 7-9. So while the omega-3 fats EPA and DHA in fish protect against cardiovascular disease, contaminants in fish (especially mercury) increase the risk for cardiovascular disease and mortality 6, 10-13. While some believe the benefits of consuming fish outweigh the dangers 14, other scientists counter that the fish contamination issue warrants a serious considerations and warn against increasing fish consumption 3, 4, 15, 16. This warning is substantiated by the finding that high-fish consumers often have blood mercury levels exceeding the maximum level recommended by the U.S. Environmental Protection Agency and National Academy of Sciences 17.
High levels of environmental toxins not only increase the risk for cardiovascular disease, but also cause neurologic damage to developing fetuses and young children 1, 2. In response to these concerns, the Food and Drug Administration and the Environmental Protection Agency issued a joint advisory in 2004 for women who are pregnant or might become pregnant, nursing mothers, and young children 2:
1.) Do not eat shark, swordfish, king mackerel, or tilefish because they contain high levels of mercury.
2.) Eat up to 340 g (12 oz)/wk (2 average meals) of a variety of fish and shellfish that are lower in mercury, such as shrimp, canned light tuna, salmon, pollock, and catfish. Furthermore, albacore (white) tuna has more mercury than canned light tuna. So, when choosing your 2 weekly meals of fish and shellfish, you may eat up to 170 g (6oz)/wk (1 average meal) of albacore tuna.
3.) Check local advisories about the safety of fish caught by family and friends in your local lakes, rivers, and coastal areas. If no advice is available, eat up to 170 g (6 oz)/wk (one average meal) of fish you catch from local waters, but do not consume any other fish during that week.
A high intake of mercury can also cause endocrine disruptions; among all it has been shown that high mercury levels in the body decreases levels of thyroid hormones and testosterone 18, 19. Since thyroid hormones increases energy expenditure 20-22, while testosterone increases muscle mass 23, this is especially negative for people who are trying to built muscle and/or loose excess body fat to get in shape.
Because of the varying amounts of mercury and PCBs in fish, consumption of a variety of fish species, both wild and farmed, is recommended to minimize exposure to environmental toxins while maximizing health benefits. However, while it is safe for most people to consume 2-3 servings of fish per week 10, 24, 25, this amount is not enough to provide the health promoting and fat loss effects of EPA and DHA.
About the Author:
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Monica Mollica has a Bachelor’s and Master’s degree in Nutrition from the University of Stockholm, Sweden, and is an ISSA Certified Personal Trainer. She works a dietary consultant, health journalist and writer for www.BrinkZone.com, and is also a web designer and videographer.
Monica has admired and been fascinated by muscular and sculptured strong athletic bodies since childhood, and discovered bodybuilding as an young teenager. Realizing the importance of nutrition for maximal results in the gym, she went for a BSc and MSc with a major in Nutrition at the University.
During her years at the University she was a regular contributor to the Swedish bodybuilding magazine BODY, and she has published the book (in Swedish) “Functional Foods for Health and Energy Balance”, and authored several book chapters in Swedish publications.
It was her insatiable thirst for knowledge and scientific research in the area of bodybuilding and health that brought her to the US. She has completed one semester at the PhD-program “Exercise, Nutrition and Preventive Health” at Baylor University Texas, at the department of Health Human Performance and Recreation, and worked as an ISSA certified personal trainer. Today, Monica is sharing her solid experience by doing dietary consultations and writing about topics related to health, fitness, bodybuilding, anti-aging and longevity.
References:
1. ARHP/PSR. Fish consumption to promote good health and minimize contaminants: a quick reference guide for clinicians: Association of Reproductive Health Professionals; 2004.
2. FDA. What You Need to Know About Mercury in Fish and Shellfish 2004. EPA-823-R-04-005.
3. Gochfeld M, Burger J. Good fish/bad fish: a composite benefit-risk by dose curve. Neurotoxicology. Aug 2005;26(4):511-520.
4. Stern AH. Public health guidance on cardiovascular benefits and risks related to fish consumption. Environ Health. 2007;6:31.
5. Domingo JL. Omega-3 fatty acids and the benefits of fish consumption: is all that glitters gold? Environ Int. Oct 2007;33(7):993-998.
6. Guallar E, Sanz-Gallardo MI, van’t Veer P, et al. Mercury, fish oils, and the risk of myocardial infarction. N Engl J Med. Nov 28 2002;347(22):1747-1754.
7. Domingo JL, Bocio A, Falco G, Llobet JM. Benefits and risks of fish consumption Part I. A quantitative analysis of the intake of omega-3 fatty acids and chemical contaminants. Toxicology. Feb 12 2007;230(2-3):219-226.
8. Domingo JL, Bocio A. Levels of PCDD/PCDFs and PCBs in edible marine species and human intake: a literature review. Environ Int. Apr 2007;33(3):397-405.
9. Mahaffey KR. Fish and shellfish as dietary sources of methylmercury and the omega-3 fatty acids, eicosahexaenoic acid and docosahexaenoic acid: risks and benefits. Environ Res. Jul 2004;95(3):414-428.
10. Smith KM, Sahyoun NR. Fish consumption: recommendations versus advisories, can they be reconciled? Nutr Rev. Feb 2005;63(2):39-46.
11. Rissanen T, Voutilainen S, Nyyssonen K, Lakka TA, Salonen JT. Fish oil-derived fatty acids, docosahexaenoic acid and docosapentaenoic acid, and the risk of acute coronary events: the Kuopio ischaemic heart disease risk factor study. Circulation. Nov 28 2000;102(22):2677-2679.
12. Salonen JT, Seppanen K, Nyyssonen K, et al. Intake of mercury from fish, lipid peroxidation, and the risk of myocardial infarction and coronary, cardiovascular, and any death in eastern Finnish men. Circulation. Feb 1 1995;91(3):645-655.
13. Virtanen JK, Voutilainen S, Rissanen TH, et al. Mercury, fish oils, and risk of acute coronary events and cardiovascular disease, coronary heart disease, and all-cause mortality in men in eastern Finland. Arterioscler Thromb Vasc Biol. Jan 2005;25(1):228-233.
14. Mozaffarian D, Rimm EB. Fish intake, contaminants, and human health: evaluating the risks and the benefits. Jama. Oct 18 2006;296(15):1885-1899.
15. Hites RA, Foran JA, Carpenter DO, Hamilton MC, Knuth BA, Schwager SJ. Global assessment of organic contaminants in farmed salmon. Science. Jan 9 2004;303(5655):226-229.
16. Hites RA, Foran JA, Schwager SJ, Knuth BA, Hamilton MC, Carpenter DO. Global assessment of polybrominated diphenyl ethers in farmed and wild salmon. Environ Sci Technol. Oct 1 2004;38(19):4945-4949.
17. Hightower JM, Moore D. Mercury levels in high-end consumers of fish. Environ Health Perspect. Apr 2003;111(4):604-608.
18. Barregard L, Lindstedt G, Schutz A, Sallsten G. Endocrine function in mercury exposed chloralkali workers. Occup Environ Med. Aug 1994;51(8):536-540.
19. Vachhrajani KD, Chowdhury AR. Distribution of mercury and evaluation of testicular steroidogenesis in mercuric chloride and methylmercury administered rats. Indian J Exp Biol. Aug 1990;28(8):746-751.
20. Bianco AC, Maia AL, da Silva WS, Christoffolete MA. Adaptive activation of thyroid hormone and energy expenditure. Biosci Rep. Jun-Aug 2005;25(3-4):191-208.
21. Kim B. Thyroid hormone as a determinant of energy expenditure and the basal metabolic rate. Thyroid. Feb 2008;18(2):141-144.
22. Ranneries C, Buemann B, Toubro S, Raben A, Astrup AV. [Low energy metabolism in persons predisposed to obesity: significance of the thyroid status]. Ugeskr Laeger. Jan 26 1998;160(5):644-647.
23. Rooyackers OE, Nair KS. Hormonal regulation of human muscle protein metabolism. Annu Rev Nutr. 1997;17:457-485.
24. Holub BJ. Clinical nutrition: 4. Omega-3 fatty acids in cardiovascular care. Cmaj. Mar 5 2002;166(5):608-615.
25. US Department of Agriculture. National nutrient database. Release 20 [2008].
