The Myth of Iodine Deficiency: An Interview with Dr. Ray Peat

Is iodine supplementation safe and, if not, is there a safe amount of supplemental iodine?

Dr. Peat: “A dosage of 150 mcg (micrograms, not milligrams, e.g., ug not mg) is a safe amount of iodine. There are excellent references describing the effect of a moderate iodine excess (even below a milligram per day) on the thyroid. An iodine deficiency can cause hypothyroidism (rare now), but so can an excess. Iodine deficiency is an unusual cause of hypothyroidism, except in a few places, like the mountains of Mexico and China, and the Andes.

“Most goiters now are from estrogen-like effects, but they used to be from iodine deficiency. Chronic excess iodine tends to cause thyroiditis, regardless of the gland’s size. The amounts used by Abraham and Flechas are much larger than this — very toxic doses, enough to cause severe thyroid problems.”

Is the Iodine Test Kit (from Dr. Abraham) valid and does it reveal thyroid deficiency?

“Guy Abraham and some of his followers claim that an iodine deficiency can be shown by the quick disappearance of a spot of iodine painted on the skin. The skin test of iodine deficiency is completely unscientific. Iodine is converted to colorless iodide by reductants, including vitamin C, glutathione, and thiosulphate. “G. Abraham’s Iodine Test Kit contains iodine overdose pills. The test is completely irrational. It implies that the body should be saturated with iodine.”

Is there a rational way to determine iodine deficiency or excess?

“It’s easy to recognize a chronic iodine deficiency, because it causes the thyroid gland to enlarge. Goiters can be caused in various ways, for example by being exposed to various goitrogens, including excess iodine, or by excessive estrogen and deficient progesterone, as well as by an iodine deficiency. “However, a chronic excess of iodine is harder to recognize, because it can produce a variety of degenerative changes. Measurement of the average daily iodine intake or excretion in the urine would be needed to confirm an excess. High iodine intake can suppress TSH, and since high TSH is pro-inflammatory, the iodine can have some protective anti-inflammatory actions, but in the long run, the thyroid suppression becomes a problem.”

Note: I have a list of references on iodine toxicity that are too lengthy for this newsletter. If you are interested in these references, please email me at, and I will send them to you.


To Your Health – July 2008 by Lita Lee



Mary Shomon: Do you think the majority of people with hypothyroidism get too much or too little iodine? Should people with hypothyroidism add more iodine, like kelp, seaweeds, etc.?

Dr. Ray Peat: 30 years ago, it was found that people in the US were getting about ten times more iodine than they needed. In the mountains of Mexico and in the Andes, and in a few other remote places, iodine deficiency still exists. Kelp and other sources of excess iodine can suppress the thyroid, so they definitely shouldn’t be used to treat hypothyroidism.


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  1. Changes | Against The Grain linked to this post on October 19, 2013

    [...] supplementation.  A little research on this suggests that indeed this is the case.  Apparently in an interview, Dr. Peat stated the following in response to the question, “Is iodine supplementation safe [...]

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