( Health.com ) -- Mercury exposure from eating fish does n't appear to raise the risk of heart disease and stroke , as some research has suggested , according to a new study in the New England Journal of Medicine . The study -- the largest of its kind to date -- should help settle long-standing uncertainty about whether mercury from fish , which in high doses is believed to cause developmental delays in fetuses and infants , might also impact the heart health of adults . `` This research provides really robust evidence that mercury exposure from fish consumption at levels commonly seen in [ the ] U.S. and similar countries is not linked to an increased risk of cardiovascular disease , '' says Dariush Mozaffarian , M.D. , the lead author of the study and an associate professor of cardiovascular medicine at Brigham and Women 's Hospital and Harvard Medical School , in Boston . `` For the average consumer who 's worried about mercury in fish , our study suggests that cardiovascular toxicity should not be a concern . '' Health.com : 10 best foods for your heart . Not only is eating fish safe , but it 's also good for your heart , thanks to its low levels of saturated fat and abundant omega-3 fatty acids . In the study , in fact , the participants with the highest mercury exposure appeared to be at slightly less risk of heart attack and stroke than those with the lowest exposure , a trend that is probably due to the benefits of fish consumption rather than the mercury itself , the researchers say . Fish ingest mercury , an industrial by-product , when it collects in rivers and oceans . Mercury levels tend to be more concentrated toward the top of the underwater food chain , as smaller fish ( such as sardines and shrimp ) are eaten by larger fish ( such as swordfish and tuna ) . Fish-oil supplements , which many people take to promote heart health , have not been found to contain mercury , says Stephen Kopecky , M.D. , a cardiologist and professor of medicine at the Mayo Clinic , in Rochester , Minn. Health.com : Supplements for cholesterol : what works ? For years , health officials have warned pregnant women , nursing mothers , and young children to limit their fish consumption due to concerns about the apparent link between mercury exposure and subtle delays in the brain development of infants and children . Neurological problems stemming from mercury-laden fish do not appear to be a concern for adults , but doctors have been less certain about the effects of mercury on heart health . Some experts have suggested , for instance , that mercury could affect heart health by interfering with heart function , promoting blood clots , or neutralizing antioxidants . To test this theory , Mozaffarian and his colleagues measured mercury levels in the stored toenail clippings of 3,427 people with a history of heart disease , heart attack , or stroke , and compared them with an equal number of demographically similar people without heart problems . ( Toenail clippings are a common way of measuring mercury exposure . ) Health.com : 10 healthy fish recipes . The participants , who were part of two long-running government studies known as the Nurses ' Health Study and the Health Professionals Follow-Up Study , also answered detailed questions about their dietary habits . The average mercury concentrations were about the same in both groups , 0.23 versus 0.25 micrograms per gram . ( By comparison , 0.4 micrograms per gram is considered the upper limit of safety for pregnant moms and infants . ) The researchers found no relationship between mercury exposure and the risk of heart attack and stroke , even in people with mercury concentrations of up to 1 microgram per gram . `` Any way we looked at it , we found no evidence for higher risk , '' says Mozaffarian , who is also an associate professor of epidemiology at the Harvard School of Public Health . In short , there is no reason to change the current dietary recommendations regarding fish and mercury , Kopecky adds . Health.com : Healthy fish choices . The American Heart Association generally recommends that people eat fish at least twice a week , limiting their consumption of large , predatory fish that might have higher mercury levels . The Food and Drug Administration , meanwhile , urges pregnant women and young children to eat no more than two servings of fish per week . These groups should stick with salmon , catfish , canned light tuna , and other low-mercury species , and should avoid high-mercury species altogether , the agency says . Copyright Health Magazine 2010 .
The study should settle whether mercury from fish , might also impact the heart health of adults . It 's also good for your heart , thanks to its low levels of saturated fat . Comment: