Salvation from halogenation

Iodine is a halogen.

On the periodic table of elements (remember the big chart of the elements in science class?), the ingenious table that lays out all known atomic elements, elements with similar characteristics are listed in the same column. The elegant genius of the periodic table has even allowed prediction of new, undiscovered elements that conform to the "laws" of atomic behavior.

Column 17 (also called "group VIIa") contains all the halogens, of which iodine is one member. Other halogens include fluorine, chlorine, and bromine.

Odd phenomenon in biologic systems: One halogen can often not be distinguished from another. Thus, a chlorinated compound can cleverly disguise itself as an iodinated compound, a brominated compound can mimic an iodinated compound, etc.

What this means in thyroid health is that, should sufficient iodine be lacking in the body, i.e., iodine deficiency, other halogens can gain entry into the thyroid gland.

While a polychlorinated biphenyl (PCB) molecule may be recognized as an iodinated compound, it certainly doesn't act like an iodinated compound once it's in the thyroid's cells and can disrupt thyroid function (Porterfield 1998). Another group of chlorine-containing compounds, perchlorates, that contaminate groundwater and are found as pesticide residues in produce, are extremely potent thyroid-blockers (Greer 2002). Likewise, bromine-containing compounds, such as polybrominated diphenyl ethers (PBDEs), widely used as flame retardants, also disrupt thyroid function (Zhou 2001). Perfluorooctanoic acid (PFOA), found in Teflon non-stick cookware and stain-resistant products,  has been associated with thyroid dysfunction (Melzer 2010). PFOA, incidentally, can disrupt thyroid dysfunction that will not show up in the TSH test used by primary care physicians and endocrinologists to screen for thyroid dysfunction. (In fact, the presumed champions of thyroid health, the endocrinology community, have proven a miserable failure in translating and implementing the findings from  toxicological science findings to that of preserving or restoring thyroid health. They have largely chosen to ignore it.)

We therefore navigate through a world teeming with halogenated thyroid blocking compounds. We should all therefore avoid such exposures as perchlorates in produce by rinsing thoroughly or purchasing organic, avoid non-stick cookware, avoid use or exposure to pesticides and herbicides.

Another crucial means to block the entry of various halogenated compounds into your vulnerable thyroid: Be sure you are getting sufficient iodine. While it doesn't make your thyroid impervious to injury, iodine circulating in the blood in sufficient quantities and residing in sufficient stores in the thyroid gland provides at least partial protection from the halogenated impostors in your life.

I make this point in the context of heart disease prevention, since even the most subtle degrees of thyroid dysfunction can easily double, triple, or quadruple heart disease risk. See related posts, Is normal TSH too high? and Thyroid perspective update.

Comments (26) -

  • Anonymous

    9/24/2010 2:52:02 PM |

    What is the mechanism by which the thyroid problems lead to heart disease? I have typically had a tsh of 4-5, my doc always said that was OK, but more recently it is down to 2, not sure what caused the chang, but we have started using iodized salt again instead of the "Kosher salt" Coudld this alone be the difference?

  • Anna

    9/24/2010 3:54:17 PM |

    It's my understanding that everyday PFOA exposure isn't so much a result of daily *use* of products with Teflon/non-stick coatings,  but rather is due to the contamination of the environment during a mid-stage manufacturing process.  PFOA contamination is now essentially global and shows up even where the end-products are not in widespread use.

    So even if one doesn't have any or use any Teflon/stain-resistant items in daily life  one can still be exposed to PFOA in the environment (even unborn children show evidence of exposure though fetal cord testing) because it is extremely persistent and doesn't break down (one if the characteristics that has made non-stick/stain-resistance so popular and "desirable").  

    There is a completely different issue with non-stick cookware surfaces; toxic gas that is emitted if the item is overheated (esp without enough food contents to moderate the temperature).  Birds are esp susceptible to those toxic fumes and many pet birds have been harmed by non-stick pans overheated on ranges.  But that's not the same as the PFOA contamination during manufacturing.

    So it is not enough to not personally own and not use Teflon/non-stick and stain-resistant fabrics/textiles (though that's a great step in the right direction).  The environmental exposure still continues.  Even persons in remote areas can't completely avoid contact with PFOA contamination at this point.

    If the items are still in production for the market, more PFOA is still being released into the environment during manufacturing.  

    There are new non-stick coatings now on the market, but how long will be it be before we discover an unintended consequence to their production?  

    I try to reduce my own demand for such products.  Whenever I can, I choose products without non-stick and stain-resistant finishes.  The short-term benefits aren't worth it in the long run if we are exposing our children while still in the womb and subjecting them at critical developmental stages to such powerful endocrine-disruptors.  Kids shouldn't be the "canaries in the coal mine".

  • Ed Terry

    9/24/2010 4:33:06 PM |

    Many drugs also contain fluorine molecules in order to slow down metabolism and excretion.

    All semi- and synthetic statins have fluorine atoms in the molecule.  While the main metabolic pathways are known, there could also be lesser alternate metabolic products formed.  

    I've been unable to find free research papers describing all possible metabolic pathways of drugs.  Once the main products are known, no one pays additional attention.

  • Kevin

    9/24/2010 4:57:24 PM |

    Could this be the result of our national salt phobia?  I have low blood pressure so I add iodized salt to everything.  I also run 50+ miles a week and eat salt during long runs.  


  • Anonymous

    9/24/2010 6:11:38 PM |

    I have a question completely off subject.  My cardiologist just prescribed Livalo and when I tried to research it online there is not much reported.  Have you heard much about it and what is your opinion of it?  I have had a bad reaction to all the statins I have tried to date and am a little afraid to try it.  Any information on this drug would be appreciated.

  • Dr. William Davis

    9/24/2010 6:18:42 PM |

    Anonymous about TSH 4-5--

    Please enter "iodine" in the site-specific search for past posts about iodine use.

    Iodine restoration could indeed explain your improved TSH, though there is great variation in both thyroid status and in thyroid testing to consider, as well. However, if your TSH is again in the 4-5 range, I would get another opinion from someone more up-to-date or at least open minded.

  • Laura

    9/24/2010 7:42:37 PM |

    Thank you for sharing, very informative.

  • kellgy

    9/25/2010 2:50:33 PM |

    Interesting perspective on halogens Dr. Davis. I suppose drinking water from plastic bottles even from the ubiquitous "water coolers" puts us at risk with halogens and/or petrochemicals. I think we have forgotten about the beauty and safety of glass as a useful product.

  • Dr. William Davis

    9/25/2010 4:31:14 PM |

    Hi, Kell--

    Yes, indeed.

    We got rid of the polycarbonate water cooler in our office a while back and replaced it with a glass one. Polycarbonate is the standout problem, leaching out bisphenol A.

  • Anonymous

    9/25/2010 9:50:39 PM |

    Geez "Ed TerrY" ...
    I guess I am wondering where the fluorine atom is located in
    (1S,3R,7S,8S,8aR)-8-{2-[(2R,4R)-4-hydroxy-6-oxooxan-2-yl]ethyl}-3,7-dimethyl-1,2,3,7,8,8a-hexahydronaphthalen-1-yl 2,2-dimethylbutanoate; otherwise known as simvastatin (Zocor). All statins (not just simvastatin) act by competitively inhibiting 3-hydroxy-3-methylglutaryl coenzyme A HMG-CoA reductase, the rate-limiting enzyme of the HMG-CoA reductase pathway, the metabolic pathway responsible for the endogenous production of cholesterol. The presence of a fluorine atom in a statin molecule would most likely destroy this inhibitory activity. Lets at least try to have a basic understanding of what we say in our comments, or keep them to ourselves.

  • Peter

    9/26/2010 2:26:44 PM |

    The levels of BPA on two fifths of all supermarket receipts is apparently as much as a thousand times higher than that in can linings, for example.

  • Saddam

    9/27/2010 12:33:55 PM |

    Heart  disease is one of the most  dangerous disease which takes thousands of life every years all over the world. If we know its symptoms and Treatment for heart disease>. We can prevent is to large extent.

  • Anonymous

    9/27/2010 1:48:23 PM |

    Anonymous said, “I guess I am wondering where the fluorine atom is located in”

    Your Zocor example belongs to a hydrophilic statin of the type 1 class. You must research lipophilic statins of the type 2 class, for instance Lipitor: by far the most extensively prescribed blockbuster drug in the history of medical science.

    3-phenyl-4-(phenylcarbamoyl)-5-(propan-2-yl)- 1H-pyrrol-1-yl]-3,5-dihydroxyheptanoic acid

    Examine the chemical structure of all synthesized statins: Crestor, Baycol, Vytorin, Zetia/Ezetimibehave, they contain para-fluorophenyl groups. Generally, organofluorines in pharmaceuticals are meant to protect breakdown by metabolic enzymes and strengthen bonds to target proteins.

    In regards to type 2 statins, the fluorophenyl group replaces the butyryl group in order to strengthen binding to the HMGR enzyme. Lithopholic statins are especially insidious due to their ability to cross the blood brain barrier and easily penetrate cell membranes.

  • julianne

    9/28/2010 2:16:51 AM |

    Just discovered there is a the polycarbonate water container in our coffee espresso machine at home.

    When I took iodine with my Hashimotos, it flared up badly? In my case (and other Hashis sufferers) what is the answer, besides avoiding other halogens?

  • steve

    9/28/2010 5:16:41 PM |

    any thoughts on Bill Clinton's new near vegan Ornish/Esselstyne diet?

  • Anonymous

    9/28/2010 7:23:15 PM |

    "Your Zocor example..."

    Well said, and thank you for the update.

  • Anand Srivastava

    9/28/2010 7:31:39 PM |


    My brother has the same problem. Hashi, which he detected when he tried to supplement iodine.

    Do you have an idea regarding possible remedies or good websites?


  • Anonymous

    9/28/2010 7:35:33 PM |

    Polycarbonate bottles are a minor problem compared with the thermal credit card receipts that are everywhere.  Many of these have BPA levels that are off the charts, and a lot of people touch their mouths after handling them.

  • Dr. William Davis

    9/28/2010 8:42:22 PM |

    Julianne and Anand--

    Hashimoto's can indeed be flared by iodine.

    What I've been doing is to start with minimal doses, e.g., 100 mcg per day--not much more than a few shakes of the salt shaker--and build up over time. This has worked well, so far.

    It may also be important to supplement selentium, 200 mcg per day, since this tends quiet Hashimoto's inflammation.

  • Dr. William Davis

    9/28/2010 8:51:31 PM |

    Hi, Anna--

    Thanks for the great clarification.

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  • Anonymous

    10/3/2010 9:56:22 PM |

    I expect this comment to get struck off the blog because it suggests the BPA scare is overblown........

    The European Food Safety Authority (EFSA; Brussels) has concluded  it
    could not identify any new evidence that would lead it to revise the
    current Tolerable Daily Intake (TDI) for bisphenol A (BPA) of 0.05
    mg/kg body weight, which EFSA set in 2006. The EFSA advisory panel
    also says data currently available “do not provide convincing evidence
    of neurobehavioural toxicity of BPA.”


  • Anonymous

    10/5/2010 8:50:33 PM |

    This is all so unproductive.  

    You cannot micromanage your chemical exposure in America in 2010.  If our environment is  thoroughly suffused with "toxins" (in insidious micro-amounts or in great big chunks as per comments on thermal credit card receipts and grocery store shelves) there is nothing you can do about it.  

    This is all a big distraction from what is important for your health (eat approximately right, exercise enough) and for your life (love, work, use your brain, and play. And vote, thoughtfully).

    Just my two cents.

  • Ross4Teflon

    10/19/2010 3:10:34 PM |

    Hi -- Because there's so much misinformation out there about Teflon, I'm not surprised that you are concerned. I'm a representative of DuPont though, and hope you'll let me share some information with you and your readers, so that everyone can make truly informed decisions.

    The recent Exeter study tried to determine whether there is a potential relationship between PFOA and thyroid changes.  The study’s authors state that the observed association is a correlation, which may or may not be causal.  This is inconsistent with other studies, including studies of workers who have had much higher levels of PFOA exposure than the general public.  These workers have not shown any changes that would indicate impact on the thyroid.  The weight of evidence gathered from a number of significant health studies continues to indicate to us that there is no health risk to the general public from exposure to PFOA.  Please take a look at for more info.

  • qualia

    10/28/2010 3:26:58 PM |

    with regard to hashimoto: ALWAYS go 100% off gluten when having hashimoto, as it is 90% of the time an autoimmune disease which is almost always triggered and maintained by gluten and leaky gut. secondly, as with all autoimmune diseases - be sure to be in a high-optimal range of your vitamin d (like 60-80ng/L).

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