The fact is that nothing affects the health of your thyroid more than your iodine intake. Today, I want to talk to you about another reason why avoiding vitamins with iodine is the right idea for your health.

There are three different ways in which your iodine intake can become a serious problem:

1. Too Little

Iodine deficiencies of under 50 micrograms (mcg), per day, can lead to higher rates of goitrous thyroid enlargement long term. The most severe deficiencies, under 20 mcg per day, can also lead to hypothyroidism. (Read:  How much iodine do you need?)

2. Too Much

Even a brief high dose (over 1100 mcg), or an ongoing intake above 300 mcg, can slow the activity of the thyroid gland.  This is through a mechanism called the Wolffe-Chaikoff effect (Read: Iodine not too much not too little).

The full range of iodine varies only from 90 mcg in pediatric populations to 290 mcg in pregnancy.1 For those who are susceptible, this can also cause autoimmune thyroid disease (Hashimoto’s Thyroiditis and Graves’ Disease).

Key Insight: Goiters and nodules are also more common among those with higher iodine intakes when compared to control groups free of nodules and goiters (Read: Thyroid nodules the full story and how to treat them naturally). These issues are even more pronounced among adults and the elderly.2

Excessive iodine may also play its own role in thyroid cancer. People with thyroid cancer are also shown to have a higher iodine intake than controlled populations who are free of thyroid cancer.3

3. Fluctuating Intake

A substantial increase in iodine intake can unmask latent autoimmune thyroid disease.  This is true even if the change stays within safe levels.

You read that right. Let’s consider a safe level of iodine between 100 – 300 mcg.  If a group of people went from a typical intake on the low end and raised it by 100 mcg per day, they would expect to see an increase in autoimmune thyroid disease.

This exact instance happened in Denmark. In 1998, they became one of the most recent modern countries to start fortifying their salt intake with iodine.

For the following 16 years, they have shown an increased rate of:

  • Hypothyroidism
  • Hashimoto’s Thyroiditis
  • Graves’ Disease
  • Thyroid surgery4

In the graph below, you can plainly see that 1998 was the year of iodine fortification:

The average intake of iodine went up by only 66 – 70 mcg, yet the rate of autoimmune thyroid disease elevated by 53% in the initial years.5

The Danish study clearly shows the dangers of even minor changes in iodine intake.  Because their iodine fortification occurred with adherence to the latest guidelines. They did it carefully, and yet it still caused a skyrocketing of thyroid disease.

The Presence of Iodine in Vitamins

The problem with iodine in vitamins starts with the issue of excessive iodine intake. Americans consume an average of 150 mcg of iodine daily (despite a wide range of dietary habits).6

When supplemental iodine enters the mix, the amount can readily exceed safe limits. Furthermore, supplements that contain iodine may have higher amounts and more variable amounts than labels indicate.

In a recent study, 114 of the top brand of multivitamins were evaluated for their iodine content. Some were prescription prenatal supplements, and some were over the counter supplements.

All of them had added iodine and had a labeled amount of iodine per serving. Some had iodine from kelp, some had iodine from potassium iodine.

Key Insight: The most typically-labeled dose of iodine in multivitamins was 150 mcg, but they often ranged from 25 mcg to 300 mcg.

Researchers randomly selected 60 out of the 114 products and purchased them from retail locations as consumers would. They then took these purchased products and did lab analysis to find the actual iodine content.

Fluctuating Amounts of Iodine in Vitamins

They suspected that the increases in thyroid disease could be due in part to higher than expected and fluctuating amounts of iodine in vitamins.

The results absolutely shocked the scientists when they found:

  • Not one single product contained the amount of iodine claimed on the label. Not one.
  • The iodine in prescription vitamins was not better controlled than that of non-prescription vitamins.
  • Kelp products were worse than those with potassium iodine.
  • Some products had three times as much iodine as reported.
  • Several products had 400 – 600 mcg of iodine when measured.

When I ask thyroid patients to avoid all supplements with iodine, including multivitamins, some argue that their multi does not have all that much in it.

Sadly, when it comes to iodine, just a little extra might be all that it takes to trigger thyroid disease. Even if you think it is not all that much, the actual amount present may be very different.

Bottom Line: Multivitamins are a good idea. A carefully constructed diet will not supply all the recommended amounts of essential vitamins and minerals.

Dialing In Your Intake

When I taught in medical school, I had young doctors log their diets and calculate their intake of vitamins and minerals. They were often always surprised to see that even healthy diets fall short in many common nutrients.

This is true even before considering variables in:

  • Absorption
  • Personal requirements
  • Depletion from illness and medication
  • Differences between adequate and optimal levels of nutrients

Key Insight: Even getting the basic recommended dietary allowance rarely happens from healthy diets.

If anyone wishes to run this experiment for themselves, Cronometer is a great app that can help. Sadly, it does not include iodine.

Some of the top nutrients people with thyroid disease tend to run low in include:

  • Selenium
  • Magnesium
  • Vitamin D
  • Zinc
  • Vitamin C
  • DHA
  • Calcium
  • Vitamin K
  • Molybdenum

In closing, getting your iodine intake right is easy. If you have thyroid disease and are on thyroid medication, here’s what you should avoid:

  • Iodized salt
  • Sea vegetables
  • Iodine supplements
  • Supplements that contain iodine
  • Commercial bread and baked goods
  • Dairy foods (avoid or reduce)

Heal Your Thyroid Today

Now that you know a bit more about iodine and why you should be avoiding it in vitamins, isn’t it time to get a better read on your overall health? Take the Thyroid Quiz today (Click Here), and unlock the action steps you can take to improve your overall health.


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P.S. Whenever you are ready, here is how I can help you now:

1. Schedule a Thyroid Second Opinion with me, Dr. C, Click Here for Details
2. Download and use my Favorite Recipes Cookbook Here
3. Check out my podcast Medical Myths, Legends, and Fairytales Here

Dr. Alan Glen Christianson (Dr. C) is a Naturopathic Endocrinologist and the author of The NY Times bestselling Adrenal Reset Diet, The Metabolism Reset Diet and The Thyroid Reset Diet.

Dr. C’s gift for figuring out what really works has helped hundreds of thousands of people reverse thyroid disease, lose weight, diabetes, and regain energy. Learn more about the surprising story that started his quest.