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Mother's fish, mercury intake tied to kids' ADHD risk: study

Oct 9 (Reuters) - Children's risk of developingattention-deficit/hyperactivity disorder (ADHD) later in lifemay be tied to how much fish their mothers ate while pregnant,according to a U.S. study.

Researchers writing in the Archives of Pediatrics &Adolescent Medicine found that eating at least two servings offish per week was linked to about a 60 percent lower risk ofkids developing certain ADHD-like symptoms.

But elevated mercury levels, which can also come from eatingmore fish - depending on the fish - were tied to a higher riskof developing the symptoms, such as hyperactivity, impulsivenessand inattentiveness.

Though the study did not prove cause and effect, and did notuse a formal diagnosis of ADHD, it may offer insights into acondition that's estimated to have an impact on one in 10children in the United States, researchers say.

"The really important message is to eat fish," said SharonSagiv, the study's lead author from the Boston University Schoolof Public Health.

"Just stay away from mercury-containing fish, because theseprotective effects are pretty important."

Sagiv said it's best to stay away from "big fishes," such astuna and swordfish, which typically contain the most mercury.Instead, stick to fishes such as haddock and salmon.

Past studies looking at the link between mercury and ADHDhave produced conflicting results.

For the new study, the researchers followed 788 children whowere born near New Bedford, Massachusetts, between 1993 and1998. They used hair samples taken from the mothers right afterdelivery to test their mercury levels, and food diaries to seehow much fish they ate.

Then, once the children were about 8 years old, theresearchers asked their teachers to evaluate the kids' behaviorsto see how many exhibited ADHD-like symptoms.

After taking all of the information into account, theresearchers found 1 microgram of mercury per gram of a mother'shair - about eight times the average levels found in similarwomen's hair in another analysis - was tied to about a 60percent increase in the risk of their child exhibiting ADHD-likebehaviors.

But there was no link below 1 microgram of mercury per gramof a mother's hair.

Sagiv added that the negative effects from lower levels ofmercury may be canceled out by the benefits from eating fish.The children appeared to be 60 percent less likely to exhibitimpulsive or hyperactive behaviors if their mothers ate two ormore servings of fish per week.

That finding conflicts with the U.S. government'srecommendation that says pregnant women should eat no more thantwo six-ounce servings of fish per week to limit their exposureto mercury.

"I think it does call into question those guidelines, butthis is only one study and the results should be confirmed,"Sagiv told Reuters health.

In an editorial that appeared with the study, Bruce Lanphearat Simon Fraser University in Vancouver, echoed Sagiv's adviceon avoiding "big fishes."

In the long term, we have to really find ways to fightcontamination levels in fish so years from now we don't have togive this advice," he added.SOURCE:

(Reporting from New York by Andrew Seaman at Reuters Health;editing by Elaine Lies)

((elaine.lies@thomsonreuters.com;))

Keywords: HEALTH FISH/MERCURY