Iodine

Iodine is a trace mineral required for the synthesis of thyroid hormones T3 (triiodothyronine) and T4 (thyroxine), which regulate metabolism, growth, and development. Iodine deficiency is the most common preventable cause of cognitive impairment worldwide. Thyroid dysfunction (both hypo- and hyperthyroidism) is a well-established cause of hair loss. The recommended daily intake is 150 mcg for adults, with the UL at 1,100 mcg. Iodine sources include iodized salt, seaweed, dairy products, and fish. Excessive iodine intake can paradoxically cause thyroid dysfunction.