Bakers will begin using iodized salt in bread this month in both Australia and New Zealand. The Science Media Centre explains why bread is being fortified with iodine.

"Iodine is one of the essential nutrients which our bodies need in order to function properly. It’s most well-known for being an important constituent of our thyroid hormones, which regulate metabolism and, in children, normal growth and development.
It’s also very important for brain development in unborn, and young, children. Indeed, researchers from Otago have shown that correcting mild iodine deficiency in children improves their intelligence.

"Iodine is also something in which most New Zealanders, not just our children, are increasingly deficient. There are a number of reasons for this, including changing diet over the last few years and changing practices in the dairy industry. In addition, the iodine content of New Zealand soils is low, meaning that our fruits, vegetables and grains have low iodine content.

"To combat this deficiency, the salt used to make bread in New Zealand (excepting organic and salt-free breads, and some home-bake bread mixes) will be replaced with iodised salt from early next month."