Mercury May Counteract DHA Benefits From Fish 40530

Mercury May Counteract DHA Benefits From Fish

BALTIMORE--The mercury content of fish maycounteract the heart-healthy properties of docosahexaenoic acid (DHA), anomega-3, according to a case-control study in the Nov. 28 issue of The NewEngland Journal of Medicine (347, 22:1747-54, 2002) (www.nejm.org).Researchers from the Johns Hopkins Medical Institutions noted that while DHAlevels were inversely related to myocardial infarction, patients with thehighest mercury levels exhibited the highest risk of myocardial infarction.

Researchers started their case-control study based on theevidence that mercury increases the risk of cardiovascular disease. They statedthat the mercury content of fish may counteract the beneficial effects of itsomega-3 fatty acids, including DHA.

Researchers compared the joint association of mercury levels intoenail clippings and DHA levels in adipose tissue with the risk of a firstmyocardial infarction in men. There were 684 men with a first diagnosis ofmyocardial infarction and 724 male controls. After researchers adjusted data forDHA levels and coronary risk factors, it was found that mercury levels in themen who suffered a first myocardial infarction were 15-percent higher than inthe controls. And, after researchers adjusted for mercury levels, DHA levelswere inversely related to the risk of myocardial infarction. Researchersconcluded that while DHA seems to have a protective effect, mercury levels mightdiminish the protective effects of fish intake.

"There is a general consensus of concern not only amongscientists but also health authorities around the world regarding intake ofmercury through fish," said Morten Bryhn, M.D., Ph.D., director of R&Dat Lysaker, Norway-based Pronova Biocare. "The industry devoted to workingwith marine omega-3 fatty acids as food supplements and pharmaceuticals has hadremoval of mercury from their products as a primary objective together withother man-made pollutants. ... Marine omega-3 fatty acids are essential fattyacids important for a series of organ functions, and a regular intake hasrecently been identified as protective against cardiovascular diseases by theAmerican Heart Association (AHA)." He added that new guidelines issued byAHA present an equal choice between eating fish or taking omega-3 supplements,and consumers uncertain of the mercury content in fish sold locally can opt touse omega-3 concentrates instead.