Iodine is a nutrient found in every organ and tissue, but iodine deficiency may affect as many as 74% of all adults. That’s not good because iodine is vital to healthy thyroid function and the thyroid plays a huge role in metabolism.

The thyroid does its thing through the production of thyroid hormones, the main ones being triiodothyronine (T3) and thyroxine (T4). These hormones are synthesized from the amino acid tyrosine and iodine. Without iodine, which needs to be provided through diet, the thyroid freaks out, sending a message to the pituitary to release thyroid-stimulating hormone (TSH), which instructs the thyroid to get busy making hormones.

However, if there’s no iodine in the diet, the thyroid gland either forms nodules or it just gets bigger and bigger, forming what’s known as a goiter. Most people don’t get to the goiter stage, but plenty develop nodules. They also develop symptoms like dry mouth, dry skin, lack of sweating, reduced alertness, muscle pain, and difficulty maintaining low body fat. Furthermore, it’s probably impossible to reach your optimum health level without having adequate iodine levels.

The trouble is, iodine isn’t as common as other minerals. The farther you get away from the sea (the source of most earthly iodine) and the foods contained therein, the more likely you’re deficient. This is why the Morton Salt Company started adding iodine to its salt in 1924. Thyroid problems disappeared almost overnight. However, despite its dietary importance, iodine intake has decreased by about 50% from 1971 to 2001, the latest dates for which I could find statistics.

A number of things happened to bring this on. For one thing, well-meaning doctors told people to stop eating as much salt for fear it would get their diastolics all pumped up into dangerous zones. People, by and large, listened. People used to get a lot of iodine through wheat flour, too. Manufacturers used iodine in its processing, but nowadays they use bromide instead, which blocks iodine’s activity. Soy products, too, block iodine absorption, as does the fluoride and chlorine in your drinking water. Furthermore, restaurants pretty much don’t use iodized salt. Neither do the manufacturers of salty snacks, so that cuts out a couple of other iodine avenues.

There’s also a movement towards “designer salts,” like that pink Himalayan stuff you see on every wanna-be chef’s kitchen countertop. While it’s pretty, it doesn’t have much iodine in it, and the Sherpa that hiked it out of the mountains for you to use probably has a massive Everesque goiter on his neck.

Lastly, you, as an athlete, lose a lot of precious iodine through your sweat. Supplementation is clearly in order. Luckily, iodine, in the form of supplements, is pretty inexpensive. However, dosages per pill vary widely between manufacturers. Some companies supply the mineral in tiny, RDA-sized dosages of 150 micrograms, whereas others supply it in milligram-sized capsules. (The largest I found was 12.5 mg. per capsule.)

Unfortunately, it’s difficult to say how much you’d need to remedy a deficiency. Simply taking the RDA would be like refilling a bucket with water by adding one drop a day. A more functional approach would be to take between 6 mg. and 12 mg. for a period of weeks or months (up to three). As always, play it smart if you try the supplement approach. If you don’t think you have a deficiency, you might simply want to start keeping a shaker of iodized salt on the table.