Fish Intake Associated with Brain Shrinkage

Fish Intake Associated with Brain Shrinkage
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Exposure to mercury during pregnancy appears to influence fetal brain development, as detected by decreased size of a newborn’s brain.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

“All fish contain small amounts of [methylmercury], the most toxic form of mercury, [and] fish consumption represents the main source.” We’ve seen that mercury exposure through fish consumption, even within the governmental safety limits, can have adverse neurological and behavioral effects on child development. And, severe exposure can cause overt structural brain abnormalities like microcephaly, which is a shrunken brain disorder. But we didn’t know whether low exposure could also affect brain size, until this new study.

Autopsy studies suggest mercury preferentially affects the developing cerebellum, and so researchers used ultrasound to measure the brain size in newborns of mothers who had high body levels of mercury, compared to a control group of women who had low levels of mercury. Let’s put that into practical terms. 

Compared to the low-level control group, here’s where the high-level mercury women were. How much canned tuna consumption is that equivalent to? Here’s what your body mercury burden is if you eat one serving of canned tuna a day—about half a can. Here’s what two cans a week will do to you. And, this is just one can a week.

So, the bodies of the women suffering high mercury contamination in the ultrasound brain study were considered heavily contaminated, but even just a little canned tuna once in a while could bump your levels even higher. So, the high really wasn’t that high. But still, what did they find?

They demonstrated that newborns born to mothers with higher mercury hair levels had cerebellums up to 14% shorter than those born to mothers with lower mercury hair levels. They conclude that “prenatal exposure to” what may be considered “low-levels of methylmercury does [indeed] influence fetal brain development,” as detected by “decreased size” of a newborn’s brain.

Please consider volunteering to help out on the site.

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

“All fish contain small amounts of [methylmercury], the most toxic form of mercury, [and] fish consumption represents the main source.” We’ve seen that mercury exposure through fish consumption, even within the governmental safety limits, can have adverse neurological and behavioral effects on child development. And, severe exposure can cause overt structural brain abnormalities like microcephaly, which is a shrunken brain disorder. But we didn’t know whether low exposure could also affect brain size, until this new study.

Autopsy studies suggest mercury preferentially affects the developing cerebellum, and so researchers used ultrasound to measure the brain size in newborns of mothers who had high body levels of mercury, compared to a control group of women who had low levels of mercury. Let’s put that into practical terms. 

Compared to the low-level control group, here’s where the high-level mercury women were. How much canned tuna consumption is that equivalent to? Here’s what your body mercury burden is if you eat one serving of canned tuna a day—about half a can. Here’s what two cans a week will do to you. And, this is just one can a week.

So, the bodies of the women suffering high mercury contamination in the ultrasound brain study were considered heavily contaminated, but even just a little canned tuna once in a while could bump your levels even higher. So, the high really wasn’t that high. But still, what did they find?

They demonstrated that newborns born to mothers with higher mercury hair levels had cerebellums up to 14% shorter than those born to mothers with lower mercury hair levels. They conclude that “prenatal exposure to” what may be considered “low-levels of methylmercury does [indeed] influence fetal brain development,” as detected by “decreased size” of a newborn’s brain.

Please consider volunteering to help out on the site.

Images thanks to redjar, Allison Stillwell, Fenderloving, redjar, matthetube and _paVan_ via flickr

 

Doctor's Note

I’ve covered mercury in fish before, in videos such as Nerves of MercuryHair Testing for Mercury before Considering Pregnancy, and Fish Fog. For more on canned tuna in particular, check out:

What else can we do to protect our newborns? See:

But what about the long chain omega-3 DHA in fish—isn’t that necessary for healthy brain development? That’s the topic of my next video, Mercury vs. Omega-3s for Brain Development.

For more context, check out my blog post: Top 10 Most Popular Videos of 2013

If you haven’t yet, you can subscribe to my videos for free by clicking here.

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