Micronutrient Monday: What Is Iodine?

By: Amanda Schroeder

Of all of the minerals we readily consume, I’m sure I think about iodine the least. (And, weirdly, I think about minerals a lot!) The media hasn’t gone into a frenzy over it, like it has for other minerals (e.g. calcium). And since it isn’t the topic of too many of our everyday conversations, it’s easy to overlook. Iodine is a trace mineral, meaning we need it in very small quantities, but it packs a punch! It is a vital component of certain thyroid hormones (T3 and T4, if you’re curious). These hormones are responsible for several chemical reactions inside your body that essentially decide your metabolism! In addition, they are absolutely paramount to the development of well-functioning skeletal and central nervous systems in fetuses and infants. I think it’s time we think a little bit more about iodine!

Thanks to iodized table salt, iodine deficiency is relatively uncommon in this country, though it does happen. When your iodine levels are too low, your body cannot make thyroid hormones. It hates this, of course, and will expand your thyroid gland as much as it can manage in order to absorb the maximum amount of iodine from your blood. This condition is called goiter. It can be quite obvious when it occurs because your thyroid gland, which is in your neck, can become fairly big! A widespread prevalence of goiter is actually the reason that the U.S. began adding iodine to table salt in the 1920s. (Aww. Thanks, guys!) In addition to goiter, iodine deficiency in pregnant women can result in major damage to the unborn fetus, often causing deficits in brain development and growth retardation. It can even lead to miscarriage and stillbirth. Extreme iodine deficiency in pregnant women can cause cretinism, which is a disorder characterized by several physical and neurological abnormalities, including mental retardation, stunted growth, and deaf mutism, just to name a few. Based on this information, iodine is very, very important for women of childbearing age. The minute that a woman becomes pregnant, her body must not only supply adequate vitamins and minerals for herself, but also for her baby. Even iodine levels that are less than desired, but not low enough to actually cause goiter, can cause a woman to give birth to a baby with a lower-than-average IQ. Ladies, do you want smart babies? Make sure you’re getting enough iodine! Take a look at this table to see how much you should be consuming.

Recommended Dietary Allowances (RDAs) for Iodine
Age Male Female Pregnancy Lactation
Birth to 6 months 110 mcg* 110 mcg*
7–12 months 130 mcg* 130 mcg*
1–3 years 90 mcg 90 mcg
4–8 years 90 mcg 90 mcg
9–13 years 120 mcg 120 mcg
14–18 years 150 mcg 150 mcg 220 mcg 290 mcg
19+ years 150 mcg 150 mcg 220 mcg 290 mcg


Despite the scary consequences of iodine deficiency, it is not advisable to begin any sort of iodine supplementation without help from your doctor. It can affect the absorption and functions of other medications and can be quite dangerous. Symptoms of excessive iodine levels are actually very similar to those of deficiency. Too much iodine will cause your thyroid to shut down the production of thyroid hormones, which can also result in goiter. Long term excess has even been linked to the development of thyroid cancer! And consuming a sizable amount of iodine at once can cause symptoms such as fever, stomach pain, burning of the mouth, throat, and stomach, vomiting, weak pulse, and coma. Yikes!

So, where can you find this trace mineral? Well, for starters, in iodized salt! Remember to limit your sodium to under 2,300 mg per day, but choosing iodized table salt at the grocery store is an easy and inexpensive way to help you reach proper levels. (Unsure how much sodium you’re eating? Track your daily intakes here!) Iodine is also found in several foods, particularly sea vegetables, seafood, dairy, grain products, and eggs. The amount of iodine found in any food is highly variable; milk from one cow might be a great source, while milk from another cow might have little to none. This is because iodine is found first in the soil, so plant foods grown in low-iodine soil will not acquire as much of the mineral. And, in turn, the animals who eat those plant foods will have lower iodine levels in their flesh, milk, or eggs. Seaweed tends to have the most iodine of all foods; just 1 g can offer anywhere from 11 – 1,989% of your daily value! (You see what I mean about highly variable?!)

Looking to add a little more iodine to your life? Take a peek at these simple recipes!


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