Iodine: Research Reveals Supplementation Paradox 

Iodine is a powerful element needed for the production of thyroid hormone, that it helps synthesize the hormones that regulate metabolism. Without it, the thyroid can’t function properly. Many of us are also aware that there’s an iodine deficiency problem in certain regions. There are actually estimates that up to 40% of the world’s population is iodine deficient. 

According to Dr David Brownstein, an author, physician and practitioner of holistic medicine, the problem could be far greater than the thyroid function of 40% of the population. “I’ve been interested in the use of iodine for approximately the last 20 years,” said Brownstein in a recent interview. In the first ten years of his practice, he saw so many thyroid problems that it tipped his curiosity. “It always came back to iodine at some point.”  

After finding tests that were clinically reliable, he discovered that the vast majority of his patients were deficient in iodine. His team has tested over 5,000 people and the numbers are frankly shocking. 95% of patients in his US-based clinic were moderately to severely deficient in iodine [1].

“I ask all the practitioners at my lectures ‘what percent of people do they think are walking around with thyroid issues?’ And invariably, the number comes up with usually a minimum of 50 and a maximum of around 75 to 80%. So we have 50-80% of our population with undiagnosed abnormal thyroid function. We’ve got a big problem in this country. We’ve got a problem that’s been driven, I think, in part from iodine deficiency.”

It’s no secret that iodine and thyroid function are inextricably linked. But according to Brownstein, it doesn’t stop there.

“Its not just the thyroid gland that has iodine. All glandular tissue does. The breasts, the ovaries, the uterus, the prostate and other tissues. The skin holds 20% of the body’s iodine. The fats and the muscle cells hold large amounts of iodine. Iodine is concentrated in every cell of the body. Every cell needs and utilises iodine. The white blood cells can’t function without adequate iodine. The list goes on and on.”

When iodine is insufficient, thyroid dysfunction usually follows, even if it’s on a subclinical level. The symptoms include goiter, hypothyroidism, and pregnancy related problems [3]. But Brownstein asserts that when iodine is insufficient, there are wide ramifications in the body. In fact, he speculates that there could be links between iodine deficiency and the increasing number of breast cancer, prostate cancer and chronic illness in the world today [1].

As we are dependant on diet for our supply of iodine, there are a number of possible causes of this deficiency: from soil depletion, to insufficient dietary intake of iodine rich foods, to exacerbated toxicity levels in the environment around us.

To many, the answer is simply to take an iodine supplement but research is now revealing a strange paradox. We have long known that hypothyroidism occurs when the thyroid doesn’t produce enough thyroid hormone. While links between hypothyroidism and iodine deficiency remain true, new research has revealed an irony when people take too much iodine [2].

“Ironically, new research has shown that taking too much iodine may also lead to a subclinical version of the condition [hypothyroidism], which is a milder form that is often missed by laboratory tests. Along with sometimes exhibiting many of the same symptoms of hypothyroidism, such as fatigue and difficulty losing weight, people with subclinical hypothyroidism may have an increased risk of heart disease.

Some, however, may exhibit no symptoms at all.

The new study, published in the American Journal of Clinical Nutrition, revealed that study participants taking relatively higher doses of supplemental iodine — 400 micrograms a day and more – paradoxically began developing subclinical hypothyroidism. The finding highlights precisely why you need to be very careful with taking supplemental iodine, as taking too much can lead to health problems.”

To this end, Dr. Mercola recommends optimising iodine through diet rather than through supplementation. Among these dietary sources, sea vegetables like kelp are known to contain high levels of iodine [4]. According to Brownstein, the purer the source, the better, as toxins can bind to iodine receptor sites and inhibit iodine [5]. Organic cranberries, strawberries, yoghurt, navy beans, and potatoes also feature on the list of iodine sources [4].

So while iodine supplementation may be necessary in some cases, this new research provides an interesting note of caution on a very common condition.



[1] Mercola, (2011), “Dr David Brownstein on Iodine Pt 1/3,” YouTube  retrieved 3 May 2016

[2] Mercola (2012), “Iodine is important but new study shows too much causes problems,” Mercola,  retrieved 3 May 2016

[3] Staff writer (2015), “Iodine Deficiency,” American Thyroid Association, retrieved 3 May 2016

[4] Group, E (2015), “7 Foods Rich in Iodine,” Global Healing Centre,  retrieved 3 May 2016

[5] Mercola (2011), “Dr David Brownstein on Iodine Pt 3/3,YouTube,  retrieved 3 May 2016

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