Adding iodine to salt may be the cheapest brain-saving measure in history

The thyroid gland can’t make its hormones without iodine, a trace element the body can get only from food. When iodine runs short, the thyroid strains to keep up and swells into a visible neck lump - a goitre.

The stakes go far beyond appearance. Thyroid hormones steer brain development, so iodine deficiency in pregnancy and infancy can cause lasting intellectual disability. The World Health Organization has called it among the most common preventable causes of brain damage worldwide, once affecting tens of millions.

Prevention is remarkably simple: iodised salt.

Adding iodine to ordinary table salt is considered the most cost-effective fix - a few cents per person per year. Since a global push began around 1990, salt iodisation has sharply cut deficiency across whole populations, quietly protecting the cognitive potential of generations.