Breastfeeding provides babies with iodine

WHO recommends that breastfeeding mothers without access to iodised salt should take an iodine supplement capsule to provide a year’s worth of iodine for them and their infant. ETH Zurich researchers tested the effectiveness of this method for the first time.

Iodine is essential for the human body. This trace element is especially crucial for infants in order to ensure healthy development. Iodine deficiency can disrupt growth and damage the nervous system. In iodine-poor regions, such as Switzerland with its iodine-deficient soils, iodised salt is recommended for use in cooking and the food industry. So newborns generally receive enough of the trace element through breast milk and baby food containing added iodine. However, iodised salt or supplemented baby food are not available everywhere, particularly in remote areas of developing countries, and do not always reach vulnerable segments of the population.

To ensure newborns receive enough of the trace element, the World Health Organisation (WHO) recommends that new mothers take one iodine capsule to provide a year’s dose of iodine for the mother and child by way of breastfeeding. If breastfeeding is not possible, physicians give a lower concentration pill directly to the infant. The effectiveness of these two methods, however, had never been tested. For the first time, a team of researchers from ETH compared the direct administration of iodine with indirect nourishment through breast milk in newborns and monitored the iodine status of mothers and their babies over a one-year period. In the course of the study, they found that giving an iodine capsule to the mother is more effective than administering it to the child directly. However, both methods are insufficient to ensure that both mother and child receive enough of the trace element.

All reserves put into breast milk

Raschida Bouhouch, a PhD student in the Laboratory of Human Nutrition at ETH, and her colleagues conducted a blind study of 241 mother-and-child pairings in Morocco. Half the mothers were given an iodine capsule and the baby a placebo. The parameters were reversed for the other half of participants. The pills were administered along with the first vaccination given during the first eight weeks following birth. Over the next nine months, Bouhouch and her colleagues measured the iodine concentration in breast milk and urine of the mother and her child to determine their iodine status.

Although administration of iodine to the mother passed an astonishing amount of the trace element from the mother’s breast milk to the child, the iodine concentration in the urine of the baby was well below the critical threshold just nine months after birth. In the case of the mother herself, the one-time dose was unable to remedy the iodine deficiency at any point in time. “The mother’s body is apparently programmed to put all its iodine reserves into nourishing the child and does not keep sufficient reserves for itself,” explains Bouhouch. Shortly after birth, the infants had a much better iodine status than their mothers; however, the values were still under the minimum threshold needed by the body.