Maternal Seafood Consumption May Damage Child's Heart Function
A Vegan Health Article from All-Creatures.org

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From by Michael Greger, M.D.
http://www.DrGreger.org

In the May 2004 issue of "Latest in Human Nutrition" (archived on my website at http://www.DrGreger.org/newsletters.html ), I documented why the Environmental Protection Agency estimates that every year in the U.S. 300,000 children are born at risk for lower intelligence and learning problems due to mercury exposure because their mothers ate fish.[1] New research from Harvard, published in the Journal of Pediatrics, suggests children born to fish-eating moms may suffer from irreversible heart damage as well.[2]

Mercury is considered the most dangerous environmental poison of all the toxic heavy metals.[3] Mercury fallout from industrial smokestacks worldwide (particularly coal-burning power plants) settles in our waterways and drains into the ocean where it works its way up the food chain. Except for one sample of chicken which exceeded even the levels in fish, FDA analyses indicate that "fish and shellfish are almost exclusively the source of mercury in the U.S. diet."[4]

People eating fish, particularly the most contaminated species like tuna, place themselves not only at risk for the "fish fog" syndrome I described in the May 2004 issue, but may shorten their lifespan due to mercury's cardiotoxic effect. Mercury contamination has been blamed for why many studies, including Harvard's Physicians' Health Study, have failed to show overall decreased cardiac mortality from fish consumption.[5],[6],[7] Yes, fish have heart-healthy omega-3's, but at the same time may be so filled with mercury that they cancel each other out. In fact, a few studies have shown increased cardiac mortality among fish-eaters.

A study published in the journal of the American Heart Association, for example, found that the half of the population studied that ate the most fish had over twice the risk of having a heart attack, and over twice the risk of dying from a heart attack.[8] "Fish is not merely a source of n-3 fatty acids," the investigators warn, "but also of methyl mercury,"[9] a fact with potentially "enormous" public health implications. [10] Methyl-mercury is considered the most toxic form.

In fact just last month, February 2005, researchers published a study which followed over a thousand middle-aged men for over a decade, and indeed found that those who seemed to eat the most fish may be shaving years off their lives. Mercury is thought to damage the heart by not only acting as a pro-oxidant itself, but depleting the body of critical antioxidants like glutathione and selenium.[11] Because our bodies have no mechanism for getting rid of mercury, it continues to accumulate in our bodies throughout our lives.

If mercury is this toxic to the hearts of adults, what is it doing to the hearts of children exposed in the wombs of fish-eating mothers? In a joint collaboration between Harvard and the University of Copenhagen, researchers measured the levels of mercury in umbilical cord blood of over a thousand fish-eating pregnant women to find out how much mercury their new infants had been getting. They then followed these children from birth through adolescence. And much of the cardiac dysfunction found through age 7 was still apparent at age 14. The heart rhythm abnormalities were subtle, but, the researchers fear, could lead to increase risk of serious cardiac dysfunction later in life. [12] Interestingly, the researchers think the abnormality is probably due not to damage to the heart muscle itself, but to irreversible damage to the children's brainstem, the area of the brain that controls the beating of the heart.[13]

As reported in Environmental Health Perspectives, this research "suggests that when expectant women consume fish containing high levels of the toxicant, their children's future cardiovascular health may be jeopardized."[14] The mercury-free source of omega 3's for our families should be two tablespoons a day of ground organic flax seeds.

References:

[1] Mahaffey KR, Clickner RP and CC Bodurow. "Blood Organic Mercury and Dietary Mercury Intake." Environmental Health Perspectives 112(2004):562.

[2] Grandjean P, Murata K, Budtz-Jørgensen E, et al. "Cardiac Autonomic Activity In Methylmercury Neurotoxicity: 14-Year Follow-Up Of A Faroese Birth Cohort" Journal of Pediatrics 144(2004):169.

[3] Harriss RC and Hohenemser C. Mercury-measuring and managing the risk. Environment. 20(1987):25.

[4] "Total Diet Study Statistics on Elements." Washington, DC: U.S. Food and Drug Administration. 25 April 2000.

[5] Curb JD, Reed DM. Fish Consumption and Mortality from Cardiovascular Disease. New England Journal of Medicine. 313(1985):821.

[6] Vollset SE, Heuch I, Bjelke E. Fish Consumption and Mortality from Cardiovascular Disease. New England Journal of Medicine. 313(1985):820.

[7] Morris MC, Manson JE, Rosner B, Buring JE, Willett WC, Hennekens CH. A prospective study of fish consumption on cardiovascular disease. Circulation 86(1992):I-463..

[8] Salonen JT, Seppänen K, Nyyssönen 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 91(1995):645.

[9] Salonen JT, Nyyssonen K, Salonen R, et al. "Fish Intake and the Risk of Coronary Disease." New England Journal of Medicine 333(1995):937.

[10] Salonen JT, Seppänen K, Nyyssönen 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 91(1995):645.

[11] 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." Arteriosclerosclerosis, Thrombosis and Vascular Biology 25(2005):228.

[12] Grandjean P, Murata K, Budtz-Jørgensen E, et al. "Cardiac Autonomic Activity In Methylmercury Neurotoxicity: 14-Year Follow-Up Of A Faroese Birth Cohort" Journal of Pediatrics 144(2004):169.

[13] Murata K, Weihe L, Budtz-Jørgensen E, et al. "Delayed Brainstem Auditory Evoked Potential Latencies In 14-Year-Old Children Exposed To Methylmercury." Journal of Pediatrics 144(2004):177.

[14] Tibbets J. "Methylmercury and Children's Heart Function." Environmental Health Perspectives 112(2004):A870.

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We began this archive as a means of assisting our visitors in answering many of their health and diet questions, and in encouraging them to take a pro-active part in their own health. We believe the articles and information contained herein are true, but are not presenting them as advice. We, personally, have found that a whole food vegan diet has helped our own health, and simply wish to share with others the things we have found. Each of us must make our own decisions, for it's our own body. If you have a health problem, see your own physician.