Iodine supplementation for breastfeeding mothers and iodine intake in babies
The iodine intake of breastfeeding mothers directly influences the iodine content of breast milk and therefore the intake of babies. A study funded by the FSVO is examining how much iodine a breastfeeding mother needs in order to meet her baby’s requirements.
Background
Representative studies show that certain population groups are deficient in iodine. This particularly affects women of childbearing age, pregnant and breastfeeding women, and young children. Mothers’ iodine intake directly influences the iodine content of breast milk.
Although the WHO recommends an iodine supplementation of 250 micrograms (µg) per day, the scientific evidence for this recommendation is weak. However, an iodine deficiency in mothers can have an adverse effect on their babies’ development.
Aims of the study
The study had the following aims:
- To determine an estimated average daily requirement (EAR) of iodine during the breastfeeding period.
- To assess the effect of a postnatal iodine supplementation on the iodine concentration in breast milk.
- To estimate how much iodine mothers need to consume to ensure an adequate iodine intake for breastfed babies.
Results
The preliminary results indicate that determining recommendations on the basis of the balance between intake and excretion alone may be insufficient. The results are therefore also interpreted with regard to maintaining healthy thyroid function. The findings are due to be published in a journal in 2026.
The preliminary results show that recommendations may be insufficient if they are only based on the balance between iodine intake and iodine excretion. The researchers therefore also include thyroid function in their analysis.
In view of the results, the FSVO recommends that mothers should continue taking iodine supplements started during pregnancy while they are breastfeeding.
Study design
Between 2021 and 2024, the researchers conducted a randomised crossover trial with 17 breastfeeding mothers and their babies. This involved the same mothers receiving different quantities of iodine at different times, so that the effects of iodine intake could be directly compared within the same people. The study participants took between 0 and 300 micrograms (µg) of iodine per day. The researchers then recorded the iodine intake and excretion of mothers and babies using samples of food, breast milk, urine and nappies.
Stakeholders
The study was conducted by the Children’s Hospital Zurich (Eleonore Foundation) in collaboration with the Laboratory of Human Nutrition at ETH Zurich.