An iodine primer

What if your diet is perfect--no wheat, no junk carbohydrates like that from corn or sugars, you are physically active--yet you fail to lose weight? Or you hit a plateau after an initial loss?

First think iodine.

Iodine is an essential nutrient. It is no more optional than, say, celebrating your wedding anniversary or obtaining vitamin C. If you forget to do something nice for your wife on your wedding anniversary, I would fear for your life. If you develop open sores all over your body and your joints fall apart, you could undergo extensive plastic surgery reconstruction and joint replacement . . . or you could just treat the scurvy causing it from lack of vitamin C.

Likewise iodine: If you have an iodine deficiency, you experience lower thyroid hormone production, since T3 and T4 thyroid hormones require iodine (the "3" and "4" refer to the number of iodine atoms per thyroid hormone molecule). This leads to lower energy (since the thyroid controls metabolic rate), cold hands and feet (since the thyroid is thermoregulatory, i.e., temperature regulating), and failed weight loss. So iodine deficiency is one of the items on the list of issues to consider if you eliminate wheat with its appetite-stimulating opiate, gliadin, and high-glycemic carbohydrate, amylopectin A, and limit other carbohydrates, yet still fail to lose weight. A perfect diet will not fully overcome the metabolism-limiting effects of an underactive thyroid.

Given sufficient time, an enlarged thyroid gland, or goiter, develops, signaling longstanding iodine deficiency. (The treatment? Iodine, of course, not thyroid removal, as many endocrinologists advocate.) Your risk for heart attack, by the way, in the presence of a goiter is increased several-fold. Goiters are becoming increasingly common and I see several each week in my office.

Iodine is found in the ocean and thereby anything that comes from the ocean, such as seafood and seaweed. Iodine also leaches into the soil but only does so coastally. It means that crops and livestock grown along the coasts have some quantity of iodine. Humans hunting and foraging along the coast will be sufficient in iodine, while populations migrating inland will not.

It also means that foods grown inland do not have iodine. This odd distribution for us land dwelling primates means that goiters are exceptionally common unless iodine is supplemented. Up to 25% of the population can develop goiters without iodine supplementation, a larger percentage experiencing lesser degrees of iodine deficiency without goiter.

In 1924, the FDA became aware of the studies that linked goiters to lack of iodine, reversed with iodine supplementation. That's why they passed a regulation encouraging salt manufacturers to add iodine, thought to be an easy and effective means for an uneducated, rural populace to obtain this essential nutrient. Their message: "Use more iodized salt. Keep your family goiter free!" That was actually the slogan on the Morton's iodized salt label, too.

It worked. The rampant goiters of the first half of the 20th century disappeared. Iodized salt was declared an incredible public health success story. Use more salt, use more salt.

You know the rest. Overuse of salt led to other issues, such as hypertension in genetically susceptible people, water retention, and other conditions of sodium overexposure. The FDA then advises Americans to slash their intake of sodium and salt . . . but make no mention of iodine.

So what recurs? Iodine deficiency and goiters. Sure, you eat seafood once or twice per week, maybe even have the nori (sheet seaweed) on your sushi once in a while . . . but that won't do it for most. Maybe you even sneak some iodized salt into your diet, but occasional use is insufficient, especially since the canister of iodized salt only contains iodine for around 4 weeks, given iodine's volatile nature. (Iodized salt did work when everybody in the house salted their food liberally and Mom had to buy a new canister every few weeks.)

Iodine deficiency is common and increasing in prevalence, given the widespread avoidance of iodized salt. So what happens when you become iodine deficient? Here's a partial list:

--Weight loss is stalled or you gain weight despite your efforts.
--Heart disease risk is escalated
--Total and LDL cholesterol and triglyceride values increase
--Risk of fibrocystic breast disease and possibly breast cancer increase (breast tissue concentrates iodine)
--Gingivitis and poor oral health increase (salivary glands concentrate iodine)

(Naturopathic doctor Lyn Patrick, ND, has written a very nice summary available here.)

So how do you ensure that you obtain sufficient iodine every day? You could, of course, eat something from the ocean every day, such as coastal populations such as the Japanese do. Or you could take an inexpensive iodine supplement. You can get iodine in a multivitamin, multimineral, or iodine drops, tablets, or capsules.

What is the dose? Here's where we get very iffy. We know that the Recommended Daily Allowance (RDA), the intake to not have a goiter, is 150 mcg per day for adults (220 mcg for pregnant females, 290 mcg for lactating females). Most supplements therefore contain this quantity.

But what if our question is what is the quantity of iodine required for ideal thyroid function and overall health? Ah, that's where the data are sketchy. We know, for instance, that the Japanese obtain somewhere between 3,500 and 13,000 mcg per day (varying widely due to different habits and locations). Are they healthier than us? Yes, quite a bit healthier, though there may be other effects to account for this, such as a culture of less sweet foods and more salty, less wheat consumption, etc. There are advocates in the U.S., such as Dr. David Brownstein in Michigan, who argues that some people benefit by taking doses in the 30,000 to 50,000 mcg per day range (monitored with urinary iodine levels).

As is often the case with nutrients, we lack data to help us decide where the truly ideal level of intake lies. So I have been using and advocating intakes of 500 to 1000 mcg per day from iodine capsules, tablets, or drops. A very easy way to get this dose of iodine is in the form of kelp tablets, i.e., dried seaweed, essentially mimicking the natural means of intake that also provides iodine in all its varied forms (iodide, sodium iodate, potassium iodide, potassium iodate, iodinated proteins, etc.) This has worked out well with no ill effects.

The only concern with iodine is in people with Hashimoto's thyroiditis or (rarely) an overactive thyroid nodule. Anyone with these conditions should only undertake iodine replacement carefully and under supervision (monitoring thyroid hormone levels).

Iodine is inexpensive, safe, and essential to health and weight management. If it were a drug, it would enjoy repeated expensive marketing and a price tag around $150 per month. But it is an essential nutrient that enjoys none of the attention-getting advantages of drugs, and therefore is unlikely to be mentioned by your doctor, yet carries great advantage for helping to maintain overall health.

Comments (7) -

  • Javeux

    7/10/2012 2:52:14 PM |

    Do you think the excessive iodine intake in Japan is connected to the prevalence of Hashimoto's disease? Isn't it possible to "trigger" the disease by ingesting massive amounts of iodine? There seems to be a lot of poor digestive health in Japan though, so perhaps it's simply that combined with wheat, which isn't uncommon in their diet (soy sauce, ramen, soba, gyouza, karaage & tempura, many common desserts and snacks etc).

    Aren't the toxins (bromine, mercury, radioactive iodine etc) in kelp troublesome for the thyroid? Anecdotally at least, I've heard of people responding quite poorly to kelp compared to potassium iodide. One tablet (150mcg) was enough to give me some uncomfortable symptoms, but I'm in the process of having my thyroid tested, so who knows what's wrong with it? For the same reason, I'm quite interested in iodine and all things thyroid, so thanks for the posts.

  • Corey

    7/10/2012 7:55:24 PM |

    Very interesting. I'm currently reading "The Art & Science of Low Carbohydrate Living" by Volek & Phinney, and they recommend drinking chicken or beef broth to replace the sodium that's lost on a low carb diet.

    Dr. Davis, how does this relate to your iodine recommendations? I ask because after eating perfectly for several months, a Spectracell report showed that my LDL-C & -P were still far too high, and no better than when I wasn't watching my diet. Particle size did increase, for what that's worth.

    Any thoughts you might have are truly appreciated.


  • Joanna

    7/11/2012 7:36:21 PM |

    Thanks for more information on iodine - particularly the history lesson!  I developed a goiter several years ago and yes, an endocrinologist last year wanted to remove my thyroid because of it.  I politely declined and asked what were my other options; a biopsy was done (which was negative) and I have to return for monitoring every 6 months (and so far have gotten the same advice each time to have it removed) but I have retained my thyroid gland.  After researching it here and on other sites, I began supplementing my diet with kelp tablets - since I was doing this on my own I have kept the dose on the low side (I think it's 225 mcg per day).  It's hard for me to be certain but I do think the goiter is slowly shrinking.  And when my regular doctor did a thyroid panel recently my TSH (which had been a little out of range) had returned to normal. (My T3 and T4 values were never a problem.)

    I am far happier with this approach than having surgery and then taking a synthetic supplement for the rest of my life.  My only question is whether or not I should up my dosage to closer to the 500 to 1,000 mcg you recommend?  Dr. Davis do you do any special monitoring or tests on your patients who are supplementing to make certain they are not getting too much?

    Thanks again for all the great info.

  • Dr. Davis

    7/21/2012 2:07:19 PM |

    Very nice!

    Nobody knows what the ideal dose of iodine is, Joanna. But I believe the 500 mcg range, perhaps a bit higher, is in the ballpark of the ideal range.

    I only monitor conventional thyroid measures every 6 months. Iodine toxicity is signaled by a rise in TSH, but I have NEVER seen this happen.

  • Joanna

    7/23/2012 8:21:34 PM |

    Good to know - and thank you!  I was pleasantly surprised when the TSH went back to normal after about six months on the iodine.

  • fred

    10/8/2012 10:05:38 PM |

    I've started taking 1/2 tab of Iodoral (~6 mg) again after stopping for a while and getting around 1 mg /day from kelp.
    Started originally by taking one tab at 12.5 mg per day but it was too much....too wired up.  The insert that comes with the Iodoral talks about possibly taking more than 12.5 mg...bit I wouldn't try it.
    At 6 mg it seems to up metabolism some...increases immunity...boosts mental clarity.  At least those are my impressions.
    The 1 mg from kelp seems to have little effect.

  • antidrugrep

    6/27/2013 7:43:29 AM |

    Personal/clinical notes and speculation from a family doc:

    At the very least, I briefly outline iodine repletion therapy for my hypothyroid patients who haven't had theirs surgically removed. I've stopping being surprised they weren't told about it before by previous providers. I have stuck with recommending 1000 mcg daily - preferably potassium iodide (KI) - for 3-6 months. I've had few try it, with equivocal results.

    However, I checked my own TSH awhile back and it was "high normal" at 2.1 (I adhere to the NACB recommendation of a 2.5 cutoff value). I've never felt particularly unhealthy, though I've often wondered if my health is anywhere close to optimal. And I knew my iodine intake was low: not much seafood and didn't supplement any iodine.

    So I took 900 mcg of KI daily for the better part of a year, and finally got around to rechecking the TSH: 1.6. Not a BIG change, but (I think) a substantive one. Not sure if I feel any better as a result, but it spurred me to double my dose to 1800 mcg daily and plan a TSH recheck in about 3 months. Might even check a 24-hr urine iodine around then, too. Here's hoping.

    Of course, my understanding is that KI is one of the least bioavailable forms, and though the potential for heavy metals from the seawood forms is daunting, I'm considering switching at some point. Just depends on if I continue to get encouraging results with the KI.