The story of iodine dates back to 1811, when the French chemist Bernard Courtois was searching for a new way to produce potassium nitrate, the essential ingredient in gunpowder, amid France’s shortage of wood, the traditional source of potassium obtained from ash. Finding an alternative was of paramount importance.
Seaweed, abundant along the Normandy coast, suddenly appeared promising. Courtois used sulfuric acid to clean his tanks, and after using a large quantity, he noticed a purple vapor rising from them. As the vapor condensed, it left behind blackish- purple crystals that glistened on the sides of the tanks. Unbeknownst to him, Courtois had discovered a new element, which he named iodine, meaning “violet” in French. He published his discovery in 1813 in the journal Annales de Chimie.
Within months, two prominent scientists - the English chemist Humphry Davy and the French chemist Joseph Louis Gay-Lussac - independently studied Courtois’s samples. They claimed to have isolated and identified the element. A scientific dispute arose over who had made the discovery, but Courtois was ultimately credited. Iodine was officially listed among the chemical elements in 1813, and its biological importance soon became clear.
Courtois and Coindet jointly received a prize from the French Academy of Sciences in 1831 for their contributions to medicine. This was before anyone fully understood how widespread iodine deficiency was, or how essential iodine is for brain development and overall health. Around the same time, in a groundbreaking study, the Ohio physician David Marine proved that iodine significantly reduced the incidence of goiter in school-aged girls. He also found that iodine was essential not only for preventing goiter, but also for the production of thyroid hormones, which regulate metabolism, support heart and digestive function, and play a vital role in fetal and infant brain development.
Once this was established, attention turned to how iodine could be delivered cheaply and at scale to entire populations. Salt, being inexpensive and widely available, was identified as an ideal solution. Switzerland became the first country to adopt iodized salt in the early 1920s. In the United States, pediatrician David Cowie of the University of Michigan advocated a similar approach, insisting that iodizing table salt could eliminate simple goiter caused by iodine deficiency.
His efforts succeeded, and iodized salt appeared in Michigan stores on May 1, 1924. Although there were some setbacks, including cases of iodine-induced hyperthyroidism in adults with long-standing nodular goiter, the overall benefits were overwhelming. Within a generation, goiter rates declined dramatically in all iodine-deficient regions. However, an estimated two billion people worldwide still suffer from iodine deficiency.
By Ahmad alsarraf
email: [email protected]
