How Long to Detox from Fish Before Pregnancy?

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How many months does it take to clear 99% of the mercury and other industrial toxins from one’s body, and what role might our fat stores play in holding on to fat-soluble pollutants?

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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.

“[I]ncreased fish consumption of mothers before and during pregnancy leads to increased [exposure to both mercury and the long-chain omega 3 DHA].” Mercury “may negatively affect…brain development [in one’s unborn baby], whereas DHA may…stimulate brain development.” As we saw, though, the results of this study showed that the negative effect of mercury outweighs the beneficial effect of DHA for most species of fish. Unfortunately, in the last two national surveys of “women of childbearing age, [they] were less aware and knowledgeable about this [problem] than other women,” despite FDA and EPA campaigns to inform every OB/GYN and pediatrician in the United States about the potential risks of mercury in fish. But I wanted to highlight the “before.” Not just during pregnancy, but even before one gets pregnant.

Since mercury sticks around, women may want to “avoid polluted fish consumption” for a year before they get pregnant, in addition to just during pregnancy. The reason they suggest a year before getting pregnant is because the half-life of mercury in the body is estimated to be about two months. They fed folks two servings a week of tuna, and other high-mercury fish, to push their mercury levels up, and then stopped the fish at week 14. And, slowly but surely, their levels came back down. I know a lot of moms are concerned about exposing their children to mercury-containing vaccines, but if they just ate a single serving a week, or less, of fish during pregnancy, the latest data shows their infants end up with substantially more mercury in their bodies than getting injected with up to six mercury-containing vaccines.

But, with a two-month half-life, within a year of stopping fish consumption, your body can detox nearly 99% of the mercury. Unfortunately, the other industrial pollutants in fish can take longer for our body to get rid of—a half life as long as ten years for certain dioxins, and PBCs, and DDT metabolites found in fish. So, to get that same 99% drop could take 120 years, which is a long time to delay one’s first child.

What do these other pollutants do? Well, high concentrations of industrial contaminants are associated with 38 times the odds of diabetes. That’s as strong as the relationship between smoking and lung cancer! Isn’t diabetes mostly about obesity, though? Well, these are fat-soluble pollutants, and so, “[a]s people get fatter, the retention and toxicity of [persistent organic pollutants] related to the risk of diabetes may increase,” suggesting the “shocking” possibility that “obesity [may only be] a vehicle for such chemicals.” We may be storing pollutants in our spare tire, like a hazardous waste dump.

Now, the pollutants could just be a marker of animal product consumption. Maybe that’s why there’s such higher diabetes risk, since more than 90% of the persistent organic pollutants comes from animal foods—unless you work in a chemical factory, or stumble across some toxic waste. And, indeed, in the U.S., every serving of fish a week is associated with a 5% increased risk of diabetes—which makes fish consumption about 80% worse than red meat.

Please consider volunteering to help out on the site.

Images thanks to harinaivoteza via flickr. Thanks to Ellen Reid for her image-finding expertise, and Jeff Thomas for his Keynote help.

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.

“[I]ncreased fish consumption of mothers before and during pregnancy leads to increased [exposure to both mercury and the long-chain omega 3 DHA].” Mercury “may negatively affect…brain development [in one’s unborn baby], whereas DHA may…stimulate brain development.” As we saw, though, the results of this study showed that the negative effect of mercury outweighs the beneficial effect of DHA for most species of fish. Unfortunately, in the last two national surveys of “women of childbearing age, [they] were less aware and knowledgeable about this [problem] than other women,” despite FDA and EPA campaigns to inform every OB/GYN and pediatrician in the United States about the potential risks of mercury in fish. But I wanted to highlight the “before.” Not just during pregnancy, but even before one gets pregnant.

Since mercury sticks around, women may want to “avoid polluted fish consumption” for a year before they get pregnant, in addition to just during pregnancy. The reason they suggest a year before getting pregnant is because the half-life of mercury in the body is estimated to be about two months. They fed folks two servings a week of tuna, and other high-mercury fish, to push their mercury levels up, and then stopped the fish at week 14. And, slowly but surely, their levels came back down. I know a lot of moms are concerned about exposing their children to mercury-containing vaccines, but if they just ate a single serving a week, or less, of fish during pregnancy, the latest data shows their infants end up with substantially more mercury in their bodies than getting injected with up to six mercury-containing vaccines.

But, with a two-month half-life, within a year of stopping fish consumption, your body can detox nearly 99% of the mercury. Unfortunately, the other industrial pollutants in fish can take longer for our body to get rid of—a half life as long as ten years for certain dioxins, and PBCs, and DDT metabolites found in fish. So, to get that same 99% drop could take 120 years, which is a long time to delay one’s first child.

What do these other pollutants do? Well, high concentrations of industrial contaminants are associated with 38 times the odds of diabetes. That’s as strong as the relationship between smoking and lung cancer! Isn’t diabetes mostly about obesity, though? Well, these are fat-soluble pollutants, and so, “[a]s people get fatter, the retention and toxicity of [persistent organic pollutants] related to the risk of diabetes may increase,” suggesting the “shocking” possibility that “obesity [may only be] a vehicle for such chemicals.” We may be storing pollutants in our spare tire, like a hazardous waste dump.

Now, the pollutants could just be a marker of animal product consumption. Maybe that’s why there’s such higher diabetes risk, since more than 90% of the persistent organic pollutants comes from animal foods—unless you work in a chemical factory, or stumble across some toxic waste. And, indeed, in the U.S., every serving of fish a week is associated with a 5% increased risk of diabetes—which makes fish consumption about 80% worse than red meat.

Please consider volunteering to help out on the site.

Images thanks to harinaivoteza via flickr. Thanks to Ellen Reid for her image-finding expertise, and Jeff Thomas for his Keynote help.

Doctor's Note

Mercury vs. Omega-3s for Brain Development is the study about balancing risks and benefits.

Update: In 2019, I did a new video on fish and pregnancy: Avoiding Fish for 5 Years Before Pregnancy.

I explored how long it takes to get rid of some of the other pollutants in How Fast Can Children Detoxify from PCBs? PCBs are found most concentrated in fish and eggs (see Food Sources of PCB Chemical Pollutants). This may also help explain the remarkable findings in Eggs & Diabetes.

The fact that we can still find DDT in Umbilical Cord Blood decades after the pesticide was banned speaks to the persistence of some pollutants. There’s a shortcut for moms, but it’s The Wrong Way to Detox.

More on the risks of mercury can be found in these videos:

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

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