- Iodine deficiency is estimated to affect over 800 million people worldwide. Over 40
million people are affected by some degree of iodine deficiency-related brain damage
(16). In later infancy and childhood, iodine deficiency causes mental retardation,
delayed motor development, growth failure, stunting, speech and hearing defects (17).
Iodine deficiency is the single most common preventable cause of mental
retardation and brain damage in children (8;16).