Frequently Asked Questions
Iodine for Infants
2.1) What is iodine and what is its function?
Iodine is an essential nutrient used for the production of thyroid hormones. In the body, thyroid hormones are responsible for some metabolic processes and are required for normal growth, bone formation, the development of the brain, and energy metabolism.
2.2) What are the sources of iodine in infants?
Diet is the major source of iodine intake for human. Iodine is present in breast milk. Before the introduction of complementary food (i.e. weaning or transition to solid foods, normally at around 6 months of age), breastmilk is the only food source of dietary iodine for exclusively breast-fed infants. If infant formula has been chosen to partially or wholly replace breastmilk, the iodine content in the infant formula will affect the dietary iodine intake of the infant.
During weaning, the sources of dietary iodine of the infants will depend on the foods taken, including breastmilk (or infant formula) and the complementary foods.
Small amount of iodine is present in local tap water (about 10 μg/L). Certain foods such as marine fish and seaweed are naturally relatively rich in iodine.
2.3) How much iodine is needed for infants?
WHO recommends dietary intakes of iodine for infants aged 0-12 months at 15 μg/kg body weight/day (i.e. 90μg/day, assuming a 6-month infant weighing 6 kg). Nevertheless, when the iodine intake is about one third of this value (i.e. 5μg/kg body weight /day), this may affect the functioning of the thyroid gland. If the thyroid gland's normal functions are significantly affected, there may be potential impact on the brain development of infants.
2.4) What are the health risks of insufficient iodine intake in infants?
Thyroid hormones play a major role in the growth and development of the body and brain in humans. If iodine deficiency exists during this period , it may result in thyroid hormone deficiency (hypothyroidism) . If the thyroid gland's normal functions are significantly affected, there may be potential impact on the brain development of infants.
2.5) How much iodine is in breastmilk?
According to literature, the iodine content of breastmilk varies markedly as a function of the iodine intake of the population, which is affected by the iodine content in the diet being consumed, and whether there is iodine fortification policy. It can vary from tens to thousands of micrograms per liter of breastmilk.
Currently, there is very limited data on the iodine content in breastmilk of Hong Kong lactating women.
2.6) How to choose infant formula?
Breastmilk is the best for infants. However, when it is necessary to feed your baby with infant formula, you may check the nutrition label on the product for its nutritional composition. Codex develops harmonised international food standards to protect the health of the consumers and ensure fair trade practices in the food trade. The goal of Codex in establishing the minimum and maximum values for the essential composition of infant formula is to provide safe and nutritionally adequate infant formula products that meet the normal nutritional requirements of infants. An infant formula product meeting the Codex recommendation should contain nutrients in amount shown in the table below-
You may wish to note that nutrient level below or above Codex standard does not necessarily mean the consumer's health is at risk. When assessing whether a product may pose health risk to the targetted consumer, risk assessment has to be carried out, taking into account of feeding instruction of each product, average body weight of local infants, etc. You should consult your family doctor or paediatrician if in doubt.
2.7) How can I know the iodine content in infant formula?
The iodine content in infant formulae available in the market may vary from brand to brand. Generally, the iodine content of an infant formula is declared on the container. Use the nutrition labelling on the product to find out its iodine content. Refer to Iodine Content Requirements in Infant Formula to check the iodine content of an infant formula and help you choose one which suits your baby. Centre for Food Safety has also uploaded the Iodine Level in Selected Infant Formulae available in Hong Kong to it's website for public enquiries.
2.8) Would there be any difference in the iodine content in the prepared liquid infant formula milk if I use bottled distilled water or boiled tap water when preparing it?
It has been revealed from laboratory analysis that s mall amount of iodine (about 10 μg/L) is present in local boiled tap water whereas iodine is not detected in bottled distilled water. As such, using boiled tap water to prepare infant formula will add extra iodine in the prepared liquid infant formula milk.
2.9) Where can I find more information about nutrition for infants and lactating women?
Visit the Department of Health (DH)'s Family Health Services website on infant nutrition, on nutritional advice to pregnant and lactating mothers, or consult your family doctors or paediatricians . For foods rich in iodine, visit the CFS website on the Risk Assessment Report of the Dietary Iodine Intake in Hong Kong Adults.