Iodine is a trace element essential for human health, serving as a fundamental component of the thyroid hormone thyroxine (T4). This hormone, produced by the thyroid gland, plays a central role in regulating metabolism—the body’s process of converting food into energy. Through its influence on growth, temperature regulation, and energy levels, iodine is indispensable for maintaining normal physiological function. When the body lacks sufficient iodine, the thyroid gland cannot produce enough thyroxine, leading to hypothyroidism. This condition slows metabolic activity and can cause fatigue, weight gain, and in severe cases, goiter, an enlargement of the thyroid gland that visibly swells the neck.
For adults, the recommended daily intake of iodine is around 150 micrograms (0.15 mg). The richest dietary sources include seafood, seaweed, saltwater fish, and dairy products, as well as foods grown in iodine-rich soils. However, in many inland or mountainous regions, natural iodine levels in soil and water are low, increasing the risk of deficiency.
Iodine is especially critical during pregnancy and early childhood, when the brain and nervous system are rapidly developing. Insufficient iodine at these stages can lead to irreversible intellectual disabilities, stunted growth, and in severe cases, cretinism, a disorder marked by profound mental and physical impairment. Even mild iodine deficiency during pregnancy can reduce a child’s cognitive performance later in life.
To combat this global problem, the World Health Organization (WHO) advocates the universal use of iodized salt—ordinary table salt fortified with small amounts of iodine. WHO recommends that iodized salt contain roughly one iodine molecule per 100,000 salt molecules, while the United States employs a higher ratio of about one per 10,000, offering a greater safeguard against deficiency.
Despite major progress in salt iodization programs, WHO estimates that more than two billion people worldwide still consume too little iodine. Sustaining public health initiatives, expanding access to iodized salt, and raising awareness of iodine’s importance remain essential steps toward eradicating iodine deficiency disorders and supporting healthy brain development across the globe.
Iodine: A Vital Element for Metabolism and Brain Development
