Because
iodine deficiency (ID) during infancy can irreversibly impair neurodevelopment and increase mortality, it is critical that dietary
iodine is adequate in this vulnerable group. Lactating mothers consuming
iodized salt can transfer adequate
iodine to the infant via breast milk, but during the weaning period, infants are at risk for ID for several reasons: (1) requirements per kg bodyweight for
iodine and
thyroid hormone during infancy are higher than at any other time in the life cycle; (2) experts recommend no extra
salt (iodized or not) be given to infants during the first year; (3) cow's milk (a major source of dietary
iodine in many countries) is also not recommended for infants during the first year; and (4)
iron deficiency, a common disorder during infancy, can impair
iodine metabolism and reduce
thyroid hormone production. For many weaning infants in industrialized countries,
iodine fortified into commercial infant foods becomes important. This has recently been demonstrated in Switzerland, where a long-standing
iodized salt program provides adequate
iodine to pregnant women and school-age children, but new national data suggest weaning infants not receiving
iodine-containing commercial baby foods have inadequate
iodine intakes. Thus, even in countries with effective
iodized salt programs, infants may be at risk of ID during weaning and may need additional dietary and/or supplemental sources of
iodine.