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Speaker 1: Welcome to Brainstuff from house Stuff works dot com where

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Speaker 1: smart happens Him Marshall Brain with today's question, why do

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Speaker 1: they add iodine to table salt? I have a box

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Speaker 1: of salt in the kitchen and it says iodide salt,

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Speaker 1: and then at the bottom it says this salt supplies

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Speaker 1: iodine and necessary nutrient on the ingredient label at lists

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Speaker 1: potassium iodine at a concentration of zero point zero zero six.

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Speaker 1: A quarter teaspoon of salt or one point five grams

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Speaker 1: therefore provides sixty seven micrograms of iodine, which is about

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Speaker 1: half of the US recommended daily allowance for iodine. The

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Speaker 1: main reason that you need iodine is because of a

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Speaker 1: gland in your neck called the thyroid gland. The thyroid

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Speaker 1: gland produces two hormones, thyroxine and try iodo thyroneine that

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Speaker 1: your body uses during metabolism. Without these hormones, you start

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Speaker 1: to feel tired, depressed, cold, weak, and so on. Iodine

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Speaker 1: is an important element in these two hormones, so without iodine,

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Speaker 1: your thyroid gland can't produce them. When start for iodine,

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Speaker 1: the thyroid gland also swells up, and when it does

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Speaker 1: it's called a goiter. Groiters can look pretty hideous. Your

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Speaker 1: body doesn't need or contain very much iodine. You might

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Speaker 1: have twenty or twenty five milligrams of iodine in your

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Speaker 1: entire body right now. However, in some parts of the world,

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Speaker 1: the soil contains no iodine at all, so plants contain

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Speaker 1: no iodine, and therefore iodine deficiency is a big problem.

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Speaker 1: In the US, one part of the country that lacks

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Speaker 1: iodine is the Great Lakes region, So companies started adding

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Speaker 1: iodine to salt in the nineteen twenties to eliminate goiter

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Speaker 1: and thyroid problems. If you lived through the Cold War,

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Speaker 1: you may have heard about the practice of taking iodine

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Speaker 1: pills during the threat of a nuclear attack. When a

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Speaker 1: nuclear bomb explodes, one substance it forms is radioactive iodine.

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Speaker 1: If you eat, drink, or inhale, this isotope. Your thyroid

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Speaker 1: gland will concentrate it, and this can lead to a

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Speaker 1: thyroid damage or a cancer. By taking an iodine pill,

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Speaker 1: you saturate your thyroid gland with iodine and prevent it

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Speaker 1: from absorbing any of the radioactive iodine. Do you have

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Speaker 1: any ideas or suggestions for this podcast. If so, please

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Speaker 1: send me an email at podcast at how stuff works

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Speaker 1: dot com. For more on this and thousands of other topics,

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Speaker 1: go to how stuff works dot com and be sure

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Speaker 1: to check out the brain stuff blog on the how

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Speaker 1: stuff works dot com home page