File Under “Not All Additives Are Bad for You”

(Photo: Adventures of Pam & Frank)

We have all been pretty conditioned these last several years to view food additives of any sort as pure negatives. So it’s interesting to look back to an earlier time and see the effect of an additive that practically no one can argue with. James Feyrer, Dimitra Politi, and David Weil have written a new working paper (abstract; PDF from 2008) about the effect of adding iodine to table salt:

Iodine deficiency is the leading cause of preventable mental retardation in the world today.  The condition, which was common in the developed world until the introduction of iodized salt in the 1920s, is connected to low iodine levels in the soil and water.  We examine the impact of salt iodization on cognitive outcomes in the U.S. by taking advantage of this natural geographic variation.  Salt was iodized over a very short period of time beginning in 1924.  We use military data collected during WWI and WWII to compare outcomes of cohorts born before and after iodization, in localities that were naturally poor and rich in iodine.  We find that for the one-quarter of the population most deficient in iodine this intervention raised IQ by approximately one standard deviation.  Our results can explain roughly one decade’s worth of the upward trend in IQ in the U.S. (the Flynn Effect). We also document a large increase in thyroid related deaths following the countrywide adoption of iodized salt, which affected mostly older individuals in localities with high prevalence of iodine deficiency.

Iodine is hardly the only beneficial additive in our food supply. There’s vitamins A and D in milk. And fluoride in the water? None of these are completely without controversy of course. What other mostly beneficial additives can you think of?

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  1. Shane L says:

    Am I wrong in thinking that additives that slow the process of spoiling in food have also really tangible effects by cutting waste and perhaps also cutting the purchase prices?

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  2. Leon says:

    Wouldn’t there be a decrease in thyroid related deaths?

    “We also document a large increase in thyroid related deaths following the countrywide adoption of iodized salt, which affected mostly older individuals in localities with high prevalence of iodine deficiency.”

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    • Jared N says:

      From footnote 10, page 7:

      10. Thyrotoxicosis might occur as a result of iodization in those individuals that have su?ered from long-term iodine de?ciency and whose goiters have become nodular. In such cases, iodine supplementation causes the output of hormone to jump to toxic levels.

      This could be the cause they’re referring to? Not sure, I was curious myself.

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  3. Enter your name... says:

    Chlorine in tap water. It has probably saved more lives than any other public health measure.

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    • Jaime says:

      …not an additive but part of the purification process. Almost all chlorine is removed from the water afterwards and any traces of it left are actually bad for you (but arguably better than the diseases the water would carry were it not for the chlorine).

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  4. Eric M. Jones says:


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    • Bill McGonigle says:

      Yet it turns out that the cheap form of fluoride, silicofluorides, don’t properly dissociate and can bind to the calcium channel, dragging heavy metals across the blood-brain barrier. There was a big epidemiological study in the 90’s showing a much higher incidence of violent crime in areas where the cheap stuff was used, controlling for other factors. There haven’t been safety studies on silicofluorides, just hand-waving that says it dissociates like sodium fluoride, when it doesn’t. Turns out mass-medicating a population is tricky business. The big Kingston study used to show its effectiveness was run at the same time Kingston got electricity/refrigeration too, and that wasn’t controlled for.

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  5. Bodger says:

    “We also document a large increase in thyroid related deaths following the countrywide adoption of iodized salt, which affected mostly older individuals in localities with high prevalence of iodine deficiency.”

    So the authors are saying that adding iodine caused an INCREASE in thyroid-related deaths? Is this supposed to be a benefit? I had been taught that iodine was critical and that it decreased thyroid disease.

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  6. B. says:

    Folic acid in wheat flour has greatly reduced the rates of spina bifida.

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    • Bill McGonigle says:

      And there’s some new research that suggests that the *cheap form* of folic acid (oxidized) which is what most of the manufacturers chose to use to comply with the regulation, can cause an autoimmune reaction in some genotypes of the population, which causes a reduction of available fetal folic acid and is suspected as the environmental trigger in autism. The timelines match up too. It turns out that mass-medicating the population is tricky business.
      n.b. pregnant women should definitely take a multivitamin that contains the good stuff!

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      • B. says:

        Very interesting, I hadn’t heard that. Sounds like Freakonomics should do a follow-up post.

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      • J1 says:

        Any links to the research? Don’t take it personally, but when somebody mentions links to autism my BS light starts flashing like a strobe.

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  7. Pru says:

    Is that the right link? For starters you say ‘new working paper’ but the link is dated 2008. The abstract in the link is different than that quoted above. The paper in the link also doesn’t seem to go into any discussion about an increase in thyroid related deaths–or use the word ‘death’ at all.

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  8. Patrick says:

    A possible cause of increased mortality, and certainly morbidity, is the Jod- Basedow effect. The long-term iodide deficiency with a resultant goiter followed by an iodide load results in hyperthyroidism, too much T3 & T4 being released. This may result in atrial fibrillation and heart failure. Older people would be at an increased risk since they would not tolerate the effect as well as a young healthy person.

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