Iodine Deficiency: A Thyroid and Metabolism Killer

Without Enough Iodine, Nothing Works Right

There’s a decent chance you have an iodine deficiency. As a result, your metabolism is screwed. Here’s how to know and how to fix it.

An Iodine Deficiency Epidemic?

Are you suffering from an iodine deficiency and an underperforming thyroid? It’s quite possible. There’s a silent epidemic of low iodine levels that may be affecting the health of as many as 74% of U.S. adults.

Consider that when the thyroid is functioning normally, it determines how your body uses energy (i.e., controls your metabolism), manufactures proteins that affect growth and development, plays a part in glucose consumption, helps regulate levels of blood lipids, and even controls body temperature.

When you’re not giving it what it needs – like iodine – it can cause fatigue and rampant weight gain, along with a host of problems, including possibly cancer.

The effects are sometimes subtle or insidious, but consider this statement by Dr. David Brownstein, author of Iodine: Why You Need It and Why You Can’t Live Without It (on Amazon):

“Iodine is the most misunderstood nutrient. After 12 years of practicing medicine, I can say that it is impossible to achieve your optimal health if you do not have adequate iodine levels. I have yet to see any item that is more important for promoting health than iodine.”

The problem lies in the relative scarceness of iodine. It used to be much more available, but due to some epic medical fails, changes in food manufacturing, and plain ol’ geography, it’s become relatively scarce in our diet.

As such, you might have an unhappy thyroid, but not to worry, the problem is oh-so-easy to remedy.

Before we get to the cure, though, let’s look at one of the fascinating stories that make up the medical history of this oft-ignored endocrine gland, one that lends understanding to how it got to be so misunderstood.

Shrink That Sucker with Radiation

Back in the 1920s, doctors started focusing on the problem of sudden infant death syndrome, or SIDS. This is the phenomenon where infants die suddenly in their cribs for no readily apparent reason. Doctors began doing autopsies on the babies and compared the findings with anatomy-book drawings to see if there were any physiological discrepancies.

Lo and behold, the doctors who autopsied the babies diagnosed them as having grossly enlarged thyroid glands. Doctors theorized that these humungous glands put pressure on the infants’ tracheas during sleep, resulting in suffocation.

It was commonly known that radiation could shrink the thyroid gland, so doctors around the country leapt into action and began irradiating the thyroids of every infant they could lure through their clinic door. It was easy because they employed the old guilt game: Parents who ignored the warning were deemed irresponsible.

Enlarged thyroids quickly became a thing of the past! Chalk one up for medical research! SIDS was conquered! No longer would parents lie awake at night fearing the worst. They could rest ea… huh? What’s that, you say? They were wrong?

Corpse Robbers

To find out how they screwed up, we need to take the Hot Tub Time Machine back even further, to Revolutionary War times, when doctors and scientists started establishing medical schools.

Then, as is the case now, medical schools needed bodies for dissection, and there were plenty of bodies almost literally lying around for the picking since poor people were buried close to the surface of the ground. (Rich people had nice waterproof, Tupperware-esque caskets that were buried six feet under.)

These grave robberies and subsequent dissections led to detailed anatomical descriptions and drawings. They, along with body parts stored in actual pickle jars, formed a huge database that served as the basis of medical knowledge for the next couple of hundred years.

Now there’s a particular thing you need to know about the thyroid before we can tie all these links together. Since it’s part of the body’s immune system, the thyroid is especially prone to stress, regardless of whether that stress is caused by financial problems or poor nutrition, both of which are things that pretty much define being poor.

As a result, these cadavers – cadavers that served as the reference point for doctors in the early 20th century – had small, shrunken, stressed-out thyroids.

Are you starting to figure it out yet? When the doctors from the 1920s were looking at the thyroid glands of the autopsied SIDS babies, they weren’t looking at enlarged glands at all! It was the opposite! For the first time, they were looking at normal, healthy thyroid glands! It’s only when they compared them to the Revolutionary War-era cadavers that they looked enlarged.

The atrophied glands of the long-dead cadavers were an anomaly, a direct result of stress and poor nutrition. As a result, doctors made the wrong assumption and began needlessly irradiating healthy thyroid glands in children to shrink them.

So what happened to the children who received radiation treatments? Years later, many of them developed thyroid cancer, most likely due to being irradiated by uranium ions during childhood. Over 30,000 of them died in young adulthood. Meanwhile, SIDS continues to be the major cause of death in infants between one month and one year old.

Around the same time that docs began irradiating healthy thyroid glands, they began treating another thyroid problem, but this time successfully: goiters.

When It Rains, It Pours

The thyroid does its magic through the production of thyroid hormones, the main ones being triiodothyronine (T3) and thyroxine (T4). These hormones are synthesized from the amino acid tyrosine and iodine.

Without iodine, which needs to be provided through the diet, the thyroid freaks out. It cries for help by signaling the pituitary to release Thyroid Stimulating Hormone (TSH), which tells the thyroid gland to get busy making more hormones.

However, if there’s no iodine in the diet, the thyroid gland forms nodules. Alternately, it just gets bigger and bigger, forming a goiter. These growths range from being barely visible to huge bulges that made victims look like some of those bullfrogs that are part of the background on TV’s “Swamp People.”

Luckily, the Morton Salt Company, starting in 1924, got the brilliant idea of adding iodine to its salt. With the birth of iodized table salt, the age of the goiter disappeared almost overnight.

Zip forward to modern times, though, and we’re smack dab in another thyroid crisis brought about again, at least partially, by myopic doctors who no doubt stink at 3D chess.

Iodine’s Got Nothing but Bad Luck

Despite its importance, dietary intake of iodine has decreased by about 50% from 1971 to 2001. Why did that happen?

For one thing, most of the world’s iodine is found in the ocean from seaweeds such as kelp, nori, and kombu, along with saltwater fish and fish heads. Too bad consumption of any of these is relatively rare, at least in the U.S.

Dairy products contain iodine, too, but don’t get excited. Most of it is from iodophor, a cleanser used to sanitize milk tanks. Eggs contain some, but you’d have to eat a coop-full on a regular basis to get enough.

One of the other main sources of dietary iodine (other than iodized salt) used to be wheat flour, as iodine was used in its processing. However, much of wheat is now processed with bromide, a chemical cousin of iodine.

However, bromide doesn’t function like iodine in the thyroid. What’s more, it blocks iodine’s activity. (Add to that the trend of food-phobics fearing all things gluten and you can pretty much scratch bread off as a source of iodine.)

Other chemicals block iodine, too, among them chlorine and fluoride, found in drinking water. Another chemical, perchlorate, which is found in groundwater and food supplies (it’s even used as a flavor enhancer in certain foods), also interferes with iodine absorption.

Then there’s the lack of consistency in the iodized table salt industry itself. A 2008 study found that of 88 samples of iodized table salt, less than half contained enough to thwart off iodine deficiencies.

And then came the doctors. They first advised heart patients to restrict their salt intake, and then, in a classic case of what must be good for the goose with congestive heart failure must be good for the gander with a healthy ticker, they told everyone to cut down on salt.

People took heed of their warnings and saltshakers and their iodine stayed in cupboards and gradually turned into crystallized blocks that could have been mistaken for Lot’s wife.

Then there’s the exercise factor – men and women who exercise a lot excrete precious iodine through their sweat.

What you’re left with is a society where, by some estimates, 74% of its adults are deficient in this vital mineral. You’re also seeing a concomitant rise in benign (and malignant) thyroid growths and nodules, just like in the old days. (Paradoxically, these nodules that arose from low-iodine intake can cause hyperthyroidism, as the nodules that grow overproduce thyroid hormones.)

Many of you no doubt think you’re not included in this dire statistic. You think you’re fine because you don’t restrict your salt intake at all; you eat out at restaurants that have stock in salt mines, eat canned foods without so much as considering the salt content, and you even eat Cheetos.

Well, guess again, my orange-fingered friend, processed foods don’t generally use iodized salt. Neither do restaurants. And that pinkish Himalayan salt that some Whole Foods employee in Birkenstocks told you to use? It’s piss-poor in iodine. So is sea salt because a lot of the iodine is lost during crystallization.

Particularly Susceptible Populations

Vegans are, by and large, in particularly dire straits. They, of course, don’t eat animal products, so they’re often deficient in iodine (along with vitamins B12, A, and D, along with calcium and zinc).

To complicate things, vegans usually eat large quantities of vegetables from the Brassica family, which include broccoli, Swiss chard, Brussels sprouts, and kale. These vegetables contain chemicals known as goitrogens, which, in large enough doses, inhibit the thyroid from taking up iodine.

Paleo dieters might also be in danger, particularly if they’re not eating any dairy products. A study that compared Paleo dieters to Nordic nutrition recommendations found that the Paleo dieters had far less iodine in their systems.

Lastly, pregnant women should be especially mindful of iodine intake as pregnancy increases iodine requirements by about 50%, and the fetus, at least during the first trimester, is completely dependent on the mother’s iodine.

How to Diagnose Low Iodine

Iodine deficiencies are likely to cause a lot of other symptoms before you start looking like you swallowed a mango.

You might have overt symptoms. You may have trouble staying lean, which might be a direct result of thyroid inefficiency. You might have mysterious fatigue. You may suffer from unexplained autoimmune diseases, dry skin, or suffer from constipation or depression.

Other possible symptoms include:

  • Increased sensitivity to cold
  • Weight gain
  • Muscle weakness
  • Elevated cholesterol levels
  • Slowed heart rate
  • Thinning hair
  • Puffy face
  • Pain or stiffness in muscle and joints
  • Bad memory
  • Heavier periods in menstruating women
  • Heart disease
  • Peripheral neuropathy

A malfunctioning thyroid, courtesy of a lack of iodine, might also play a role in various forms of cancer, including breast cancer.

It used to be that taking your temperature first thing in the morning was a semi-reliable way to diagnose thyroid function. If you ran too cool (significantly less than the “normal” 98.6 degrees), there was a good chance you had hypothyroidism.

Unfortunately, the 98.6 degrees number is based on the studies of one guy, a German doctor named Carl Wunderlich. Old Carl stuck a thermometer in the armpits of around 25,000 people and found that the average was 98.6 degrees Fahrenheit. And we’ve been stuck with that number ever since.

The actual number is now closer to 97.5 to 97.9 degrees Fahrenheit, probably because of lower rates of infection and inflammation (Tuberculosis, syphilis, chronic gum disease, and other inflammatory conditions ran rampant in Wunderlich’s day).

More importantly, human body temperature varies among individuals, so taking your body temp to evaluate thyroid function and iodine status is no longer very reliable.

That leaves us with conventional laboratory testing. The following three tests provide a reasonably accurate diagnosis:

  • A 24-hour urine test where you collect your entire urine output over a 24-hour period in jugs and have them analyzed for iodine content.
  • A hair iodine test.
  • A serum thyroglobulin test, which reversely correlates with iodine levels.

If all that’s too daunting, or your doctor is close-minded or, more likely, dismissive, you can just assume you have low iodine and start treating it on your own.

How to Treat Low Iodine

You could simply incorporate iodized salt (on Amazon) into your diet, or, if you’re already using it, increase the amount you use. However, that’s a pretty nonchalant way to go about it.

Luckily, iodine supplements are pretty inexpensive. However, dosages per pill vary widely between manufacturers. Some companies supply the mineral in tiny, RDA-sized dosages of 150 micrograms, whereas others supply it in milligram-sized capsules.

Unfortunately, it’s difficult to say how much you’d need to remedy a deficiency. Simply taking the RDA would be like refilling a bucket with water by adding one drop a day.

However, naturopath Chris Kresser, a thyroid expert, recommends treating suspected iodine deficiencies by starting with a small dose – one 325 mcg. kelp tablet (on Amazon) a day and increasing the dose by one tablet every three weeks, up to 3 tablets a day, unless HYPER-thyroid symptoms occur (nervousness, rapid heartbeat, difficulty sleeping, sensitivity to heat, diarrhea, among others).

This protocol, he stresses, should also be accompanied by 200 mcg. of selenium a day, as selenium is required for the manufacture of the deiodinase enzymes that convert T4 to T3. (Don’t take selenium for a long time, though, as it can lead to mild nerve damage and fatigue. It might be smarter to get it from natural sources like cod, shrimp, halibut, salmon, chicken, chicken eggs, turkey, or Brazil nuts).

For those of us who don’t yet have a deficiency, it might be enough to just go back to filling the saltshaker with iodized salt.




  1. Griffin J et al. Textbook of Endocrine Physiology. Oxford University Press. 3rd edition, 1996.
  2. Kresser C. Is Iodine Deficiency a Bigger Problem Than We Think? Kresser Institute. October 4th, 2017.
  3. Piccone N. The Silent Epidemic of Iodine Deficiency. Life Extension Magazine. October 2011.
  4. Tellebaum J. Iodine Deficiency - An Old Epidemic is Back. Psychology Today. August 17, 2011.

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