“Human studies consistently show two things: First, if you give people extra iodine, many of them develop thyroid disease. Second, if people with thyroid disease reduce their iodine intake, the disease often goes away.” Dr. Alan Christianson in his book The Thyroid Reset Diet
The common perception is that a lack of iodine causes hypothyroidism. But numerous studies have shown that excessive iodine is the culprit and not iodine deficiency.
Dr. Christianson talks about this in detail in his book on the thyroid. He says that by reducing iodine consumption, 80% of hypothyroid patients reverse thyroid. Not 100%, but 80%, which by no means is a small number. Especially for a disease that is supposed to be chronic. And the modern medical system does not even believe that the thyroid can be reversed.
Thyroid has risen exponentially after fortifying salt with iodine globally!
Till 1990, the world was largely deficient in iodine. And WHO categorised 112 countries as “severely iodine deficient”
With the help of the fortification of salt, this problem was completely eliminated. By end of 2014, there was not even a single country with iodine deficiency. But unfortunately, there are now over 50 countries which have more than adequate or excessive iodine. And though the problem of goitre vanished from the world, the problem of hypothyroidism and thyroid cancer grew exponentially. In fact, thyroid cancer has grown sevenfold since then.
Population studies have concluded that global iodine fortification has increased the risks of hypothyroidism.
Australia fortified salt in 1998 and cases of thyroid increased by 64%. In Hungary, the increase was 950%. In Poland and Zimbabwe, the increase was 300%. 
The US was amongst the first countries to fortify their salt with iodine. Mayo Clinic tracked the rate of Hashimoto’s disease in patients from 1935 to 1967. They documented a 4800% increase in Hashimoto’s disease i.e. from 2.1 per 100,000 persons, it was up to 94.1 for those over 40. 
Iodine is a very special nutrient. Usually, all nutrients are used by multiple parts of the body but iodine is largely used in the thyroid gland and only for the purpose of producing thyroid hormones. Usually, for all nutrients, the range that the body can tolerate is quite wide, but in the case of the thyroid, the range is quite narrower. Also, unlike other nutrients, iodine can vary vastly from batch to batch; hence it’s difficult to predict how much iodine you are consuming.
Iodine is essential for life. However, just as too little iodine can cause thyroid problems, excessive iodine also causes thyroid disorders.
Each day, our thyroid gland will need 50-200mcg of iodine to make the thyroid hormones. It’s an extremely small amount. Just to put things in perspective, your lifetime supply of iodine can be fitted in a teaspoon. That’s it. 
Not just Dr Richardson recommends lower iodine levels, even WHO recommends the same. Here is a recommended level of iodine consumption as per WHO. 
|WHO Level||Types of Illness||Dietary Iodine Intake|
|1||Endemic goitre, Congenital hypothyroidism||<20 mcg|
|2||Pediatric goitre, low rate of adult disease||20-49 mcg|
|3||Lowest disease rate + reversal of autoimmune thyroid, hypothyroidism||50-99 mcg|
|4||Low disease rate||100-199 mcg|
|5||Iodine-induced hyperthyroidism, autoimmune thyroid disease, goitre, hypothyroidism||200-299 mcg|
|6||Hypothyroidism, goitre, autoimmune thyroid disease||>300 mcg|
Almost all of us are consuming a lot more than the recommended levels.
“Iodine is dangerous stuff, and it is rarely found in nature. When iodine does occur in food, water, cosmetics, and nearly all other sources, it is in its less reactive form called iodide.” The Thyroid Reset Diet” book.
With excess iodine in the body, thyroid cells may become inflamed and the immune system may start attacking it. And that causes autoimmunity and then thyroid disorder.
Test Tube Trials
Test tube studies have shown that too much iodine slows down the thyroid and causes the immune system to attack it. 
A recent study has shown that of people who were given 2000mcg of iodine, 31% developed thyroid disease.
Another study showed that in people who took 200mcg of iodine, over 10% of them developed thyroid disease. 
Wolff Chaikoff Effect: Excessive iodine is the most effective way to stop thyroid overload
Dr. Christianson explains that similar to a circuit breaker in our houses, our body also has a circuit breaker to protect us against excessive iodine. It is called the Wolff-Chaikoff effect. One of the most dangerous situations in thyroid disorder is a hyperthyroid storm: a condition in which thyroid hormones are so high that they can be lethal. The strongest way to stop overactive thyroid is to give a megadose of iodine, thanks to the Wolff Chaikoff effect.
It’s quite clear that excess iodine slows down thyroid function.
A study has shown that people suffering from Hashimoto’s disease were assigned a low-iodine diet. And 78.3% of them were cured of Hashimoto’s within 3 months. The group’s TSH average came down from 14 to 3.18.
Another study was done on patients who suffered from hypothyroidism but not Hashimoto’s. Even for these people, 63.6% of participants returned to normal thyroid function. 
Iodized salt is the first thing that should be ruled out. Each gm of iodized salt contains 45mcg of salt. A typical person eats anywhere between 5-10 gms daily. Which is 200-400mcg of iodine just from salt. Whereas our body needs much lower.
Even sendha namak/rock salt, Himalayan pink salt contains iodine. Dr. Christianson recommends Kosher Salt, which is easily available on Amazon.
Here is a list of some daily-use food items with a high dosage of iodine:  
|Food||Maximum Iodine per serving|
|White Bread, enriched||610 mcg|
|Whole Wheat Bread||530 mcg|
|Multigrain Bread||440 mcg|
|Skim Milk||360 mcg|
|Milk, low fat (2%)||150 mcg|
|Sugar cookie||750 mcg|
|Cake with icing||1300 mcg|
|Boiled whole eggs||230 mcg|
|Cod (fish)||315 mcg|
|Pollock (fish)||280 mcg|
Not just foods, but even cosmetics may have high doses of iodine. Human studies have shown that long-term exposure to topical iodine products can cause thyroid disorders. It was found that of the medical staff using iodine-based products, 39% had unsafe iodine levels. Hence, FDA has thankfully banned all iodine-containing antiseptics. But it has still not been done for cosmetics, which is a cause of concern for us. 
Several ingredients in personal care products contain iodine and the most common one is PVP. PVP is 12% iodine and many moisturisers, conditioners contain .5-5% PVP. One single application of moisturiser can lead to 2430 mcg of iodine being absorbed by the body. That’s more than 10 times the daily requirement.
Apart from PVP, look for the following ingredients:
Products like mascara, hair sprays, and eyeliners are not of concern. But we should be careful with shampoos, conditioners, sunscreen, and skin moisturisers.
Dr. Christianson has created an iodine-balancing diet, which is divided into 2 phases: The Reset Phase and Maintenance Phase.
In Reset Phase, the doctor recommends 50-99 mcg of iodine. In the maintenance phase, the recommendation is 100-199 mcg.
Some key points of the Iodine Balancing Diet are:
Dr. Christianson mentions that the only effective and reliable test is the iodine-to-creatinine ratio. Unfortunately, Indian labs are not conducting this simple test.
It’s very difficult to become deficient in iodine given the amount of iodine in so many products. And as you can see in the table above, even if you get iodine>20mcg per day, you are largely safe if you are an adult. Only for a kid, that low iodine is a bigger problem. Most of us are consuming way higher than desired 50-200 mcg range, hence it’s difficult to be deficient in iodine. Try cutting down on iodine for a few months to see how your body reacts and whether you feel better.
This book presents a very different approach to thyroid management. It presents facts and research papers to substantiate its suggestions. It’s worthwhile to lower our iodine intake to manage thyroid disorders better. If you want to know more about the subject, I would highly recommend the book.
Appendix: (Technical Stuff: Additional reading for nerdy ones)
TSH: Thyroid stimulating hormone. It is the signal from the pituitary gland to the thyroid gland to produce more thyroid hormones. So when the thyroid gland is producing less thyroid hormone, the pituitary gland produces more TSH. Hence, in the case of hypothyroidism, the body has elevated levels of TSH.
Thyroglobulin (Tg): It is the main protein from which thyroid hormones are made. Dr Christianson says if thyroid hormone is a car, then thyroglobulin is the chassis and iodine atoms are the wheels that are fitted at the final stages of assembly.
TPO: Thyroid Peroxidase is an enzyme which makes iodine stick to the thyroglobulin faster. When there is excess iodine in the system, then body functions start behaving abnormally. A healthy person may have 8-10 iodine atoms on each molecule of thyroglobulin. But when there is excess iodine, then this number can go up to 60. In such cases, the immune system can start attacking the TPO or Tg. And that’s the start of autoimmune thyroid disease. That’s why it is extremely crucial to do an antibody test for TPO and Tg. 
T4: T4 is a piece of Tg molecule with 4 iodine atoms.
T3: T3 has 3 iodine atoms and is the active hormone.
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