In 1811, Courtois noted a violet vapor arising from burning seaweed ash and Gay-Lussac subsequently identified the vapor as iodine, a new element. The Swiss physician Coindet, in 1813, hypothesized the traditional treatment of goiter with seaweed was effective because of its iodine content and successfully treated goitrous patients with iodine. Two decades later, the French chemist Boussingault, working in the Andes Mountains, was the first to advocate prophylaxis with iodine-rich salt to prevent goiter. The French chemist Chatin was the first to publish, in 1851, the hypothesis that iodine deficiency was the cause of goiter. In 1883, Semon suggested myxedema was due to thyroid insufficiency and the link between goiter, myxedema, and iodine was established when, in 1896, Baumann and Roos discovered iodine in the thyroid. In the first 2 decades of the 20th century, pioneering studies by Swiss and American physicians demonstrated the efficacy of iodine prophylaxis in the prevention of goiter and cretinism. Switzerland's iodized salt program has been operating uninterrupted since 1922. Today, control of the iodine deficiency disorders is an integral part of most national nutrition strategies.