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In my kitchen, I have a box of salt labeled 'Iodized Salt*,' with a note at the bottom stating, '*This salt provides iodine, an essential nutrient.' The ingredient list includes Potassium Iodide at a 0.006% concentration. A quarter teaspoon (1.5 grams) of this salt contains 67 micrograms of iodine, covering roughly half of the U.S. Recommended Daily Allowance for iodine.
Iodine is crucial primarily because of the thyroid gland located in your neck. This gland produces two hormones, thyroxine and triiodothyronine, which play a vital role in metabolism (refer to this article for more information). A lack of these hormones can lead to symptoms like fatigue, depression, cold sensitivity, and weakness. Iodine is a key component of these hormones, and without it, the thyroid gland cannot produce them. Iodine deficiency can also cause the thyroid gland to swell, a condition known as goiter (see this page for an illustration).
Your body requires only a small amount of iodine, typically holding about 20 to 25 milligrams at any given time. However, in regions where the soil lacks iodine, plants do not absorb it, leading to iodine deficiency. In the U.S., areas like the Great Lakes region historically faced this issue. To combat goiter and thyroid-related problems, iodine was added to salt starting in the 1920s.
During the Cold War, you might recall the recommendation to take iodine pills in the event of a nuclear attack. When a nuclear bomb detonates, it produces radioactive iodine. If ingested or inhaled, this isotope can accumulate in the thyroid gland, potentially causing thyroid damage or cancer. Taking iodine pills saturates the thyroid with non-radioactive iodine, preventing the absorption of the harmful radioactive variant.
Check out these fascinating resources:
- How Your Brain Works
- How Food Works
- How Food Preservation Works
- Endocrine System
- Iodine
- Thyroid Function
- Fortification of Salt
- Thyroid Disorders
- Thyroid Goiter
