Does soy infant formula cause thyroid disease in healthy infants?
Prior to the 1960’s soy formula was made from soy flour and was deficient in iodine12. Iodine deficiency is known to cause goiter (an enlarged thyroid gland). Worldwide, however, there were only a small number of case reports (comprising 12 individuals) linking thyroid abnormalities in infants to this early type of soy-based infant formula13,14,15,16. Since iodine supplementation was introduced in 1959, only one case has been reported in the medical literature, associating the consumption of soy protein with thyroid abnormality17. All modern infant formulas, including soy-based infant formula, are designed to provide a nutritionally balanced diet when used as the sole source of nutrition for an infant. While experts agree that breast milk is the best choice of food for infants, soy infant formulas are a suitable alternative to breast milk or cow’s milk formula for healthy term infants. The New Zealand Ministry of Health recommends that clinicians who are treating infants with hypothyro
