Iodine is an essential trace element required for the production of thyroid hormones — thyroxine (T4) and triiodothyronine (T3). These hormones regulate metabolism, energy utilization, growth, and development, particularly the development of the brain and nervous system.

The main sources of iodine include iodized salt, marine fish, seafood, dairy products, and eggs. The iodine content of foods may vary depending on their origin and production methods. Both iodine deficiency and excessive iodine intake can disrupt thyroid function.