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the health risks of mercury exposure are well documented, and harm to even fetal development are of particular concern. Now, the latest study found that children who were exposed to more mercury in the womb were more likely to have attention problems and hyperactivity and other symptoms of ADHD to 8 years
to complicate the matter, however, is that the same study found that children whose mothers ate more fish during pregnancy - fish is known to be the main source of mercury exposure for many people - had a significantly lower risk of ADHD symptoms than children whose mothers ate less fish. The finding raises the possibility that the health benefits of eating fish, which is rich in omega-3 fatty acids that are good for brain development, could outweigh the harms of mercury exposure low level. in utero - as measured by samples of their cord blood - showed more errors and lower scores on neurocognitive tests. But another study found that children exposed to higher levels of mercury were actually less likely to have behavioral problems such as hyperactivity or chronic inattention.
( PLUS Consumer Reports Warns pregnant women against canned tuna)
So, Dr. Susan Korrick and colleagues at Brigham and Women's Hospital Boston studied data on 788 children born between 1993 and 1998 in New Bedford, Mass., area. The researchers measured mercury in hair samples of mothers of children 10 days postpartum, and used a questionnaire of 59 point for assessing the behavior of children at the age of 8.
the researchers found that higher mercury levels in hair samples were associated with an increased risk of ADHD symptoms or deficit-hyperactivity disorder in children (the researchers confirmed the diagnosis of ADHD, but only to determine if the children had symptoms that were typical of the disease). Even after adjusting for potential factors that could affect the risk of ADHD symptoms, including education or depression of the mother, or her diet during pregnancy, the correlation with the mercury remained.
Studies suggest that mercury affects the development of the central nervous system by disrupting the important neurochemical levels as dopamine.
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"The message that prenatal mercury exposure is not healthy the fetus is not changed by this study, "said Korrick. But because these studies were conflicting, Korrick said the results should "demonstrate fairly consistent results related to ADHD behaviors."
Based on the new data, Korrick said the higher risk ADHD symptoms begin to appear mercury levels of 1 microgram per gram: rate of inattention and hyperactivity in children whose mothers showed exposure levels above this threshold ranged from 40% to 70% higher than for those whose mothers had lower levels of mercury
.But this study does not suggest that pregnant women should avoid eating fish altogether. the data also showed that children of women who ate more fish during pregnancy - more than two servings per week. - were 60% less likely to have symptoms of ADHD than children whose mothers ate less Although it sounds contradictory, Korrick stresses that fish not everything is rich in mercury and eating more fish could have other benefits for the brain and the development of behavior that should be considered. The current study did not determine which types of fish women in the study ate, however.
( PLUS New Dietary Guidelines: Cut salt and sugar, eat more fish)
This balance between the pros and cons of fish consumption may also help explain the conflicting results of previous studies of mercury. In those with no increased risk of ADHD or other behavioral symptoms, participants could be heavy consumers of global fish, so that the benefits of their diet for neurocognitive development of children may have offset the misdeeds mercury. However, in these studies showing harmful effect of mercury at low levels, the adverse effects of mercury may have overwhelmed the potential benefits of fish, if participants had used cash primarily fish that were rich in mercury and may be low omega-3.
The Agency US Environmental Protection urges pregnant women to limit their fish intake to two 6 oz. servings per week, to protect developing babies. Large deep-water species such as tuna, swordfish and mackerel, which are among the most popular options on restaurant menus, also tend to be higher in mercury than small, oily fish, such as salmon, herring and sardines. Learning that the fish are nutritious, but low in mercury - others include catfish, tilapia, and whitefish - takes some work, but organizations such as the Food and Drug Administration and the National Resources Defense Council have useful lists
."It is not necessarily contradictory," says Korrick advice to eat fish while avoiding mercury exposure. "It would be a regrettable message of public health if people stopped eating fish due of the concern over mercury. to understand and appreciate the avoidance mercury is a prudent thing to do during pregnancy is important, but understanding and appreciation that fish consumption is important is good to remember too. Eating fish is not getting exposed to mercury "
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