Iodine deficiency is the most common cause of preventable Mental Retardation

According to the International Council for the Control of Iodine Deficiency Disorders, "Iodine deficiency is the single most common cause of preventable mental retardation and brain damage in the world. It also decreases child survival, causes goiters, and impairs growth and development." Iodine deficiency can cause miscarriages, stillbirths, and complications in pregnancy.

Supplementation must be done carefull because excessive iodine can trigger autoimmune thyroid disease and hypothyroidism.