Dietary iodine is important for thyroid function. In people with prolonged iodine deficiency, not only is the thyroid at risk, but so is brain development. People who do not get enough iodine in their diets can develop intellectual disabilities, and iodine deficiency is the leading preventable cause of intellectual disabilities worldwide. Many nations have required iodine supplementation of food supplies in order to keep their populations healthy.
Natural sources of iodine include fish, seaweed, sea salt, and plants that grow in soil enriched with iodine, such as soil fertilized and mulched with seaweed and fish. People can also receive dietary iodine through supplementation, as seen with salt, and it is also present in some medications. For healthy adults, the daily recommended amount is 150 micrograms. People who eat a balanced diet and have access to iodized salt usually meet this dietary requirement without the need for additional supplementation.
In the body, dietary iodine enters the gut, where it is absorbed. It makes its way to the thyroid and is used in the production of thyroid hormones. Low iodine levels result in the inability to make enough hormones. The body responds to low hormone levels by producing thyroid stimulating hormone. Over time, this causes the thyroid to swell. Meanwhile, the hormone deficiency leads to problems with brain development. Historically, people with intellectual disabilities due to iodine deficiencies were said to have “cretinism,” and this term is still used clinically in some regions.
Getting enough dietary iodine is critical for thyroid health and brain development. While people only need trace amounts of this mineral, if they experience prolonged deficiencies, it can have a permanent impact on their lives. People can also develop health problems as a result of excess iodine consumption, a concern only at very high levels.
The widespread adoption of iodized salt has prevented many cases of iodine deficiency worldwide. Salt was chosen for this supplementation because it is cheap and widely used. Chronic iodine deficiency continues to be a problem in some developing nations where iodized salt is not widely available and where people may not have access to the foods they need in order to eat a balanced diet. Charitable organizations concerned with global health issues are involved in increasing the distribution of dietary supplements and healthy foods to regions in need, including refugee camps, areas with harsh environments, and impoverished communities. These food distributions ensure that people get the dietary iodine they need, along with other key nutrients and minerals.