Iodine in biology
The U.S. Food and Nutrition Board and Institute of Medicine recommended daily allowance of iodine ranges from 150 micrograms per day for adult humans to 290 micrograms per day for lactating mothers. However, the thyroid gland needs no more than 70 micrograms per day to synthesize the requisite daily amounts of T4 and T3. The higher recommended daily allowance levels of iodine seem necessary for optimal function of a number of other body systems, including lactating breasts, gastric mucosa, salivary glands, oral mucosa, arterial walls, thymus, epidermis, choroid plexus and cerebrospinal fluid, among others.
Child health and nutrition in Africa
Inadequacies in iodine intake on the other hand impair the synthesis of thyroid hormones, which are critical for normal development and proper functioning of the brain and nervous system as well as the conservation of body heat and energy. Iodine deficiency causes endemic goitre and cretinism as well as stunting of mental and physical development. Globally, 1.6 million people are at risk of iodine deficiency disorders and 50 million children affected by them. About 100,000 children are born each year with mental retardation, most of them in Africa. This is due to the low consumption of iodine-rich foodstuffs (e.g. marine products) and the over-consumption of foodstuffs causing goitre, particularly bitter cassava, which is a staple in Central Africa.