Research from the University of Adelaide shows that iodized salt used in bread is not enough to provide healthy levels of iodine for pregnant women and their unborn children.
The study-- led by researchers from the University's Robinson Institute - has prompted calls for pregnant women to keep taking iodine supplements.
Iodine deficiency is recognized by the World Health Organization (WHO) as the most common preventable cause of brain damage in the world.
"Iodine is an essential element which is important for human brain development and thyroid function," says one of the lead authors of the study, Associate Professor Vicki Clifton from the University's Robinson Institute and the Lyell McEwin Hospital.
"In 2009, Australian bread producers began a mandatory program of iodine supplementation in bread to help provide a boost to iodine levels in the community. Our study was aimed at determining whether or not that was having a positive impact on iodine levels for pregnant women."
In the study, almost 200 South Australian women were tested throughout their pregnancy and six months after giving birth.
"We found that South Australian women are mildly iodine deficient. Despite the inclusion of iodized salt in bread, women who were not taking an iodine supplement during pregnancy were still suffering from iodine deficiency," Associate Professor Clifton says.
"Those women who were taking a supplement in addition to eating bread with iodized salt were receiving healthy levels of iodine, well within WHO guidelines."
This is the latest study to follow on from the pioneering work of the University's Emeritus Professor Basil Hetzel AC, who began researching iodine deficiency more than 50 years ago at the Queen Elizabeth Hospital, in collaboration with the Papua New Guinea Public Health Department.
His work revealed very low urine iodine levels and high rates of goitre were associated with a form of brain damage called 'cretinism'. Professor Hetzel showed that this brain damage could be prevented by correcting the severe iodine deficiency before pregnancy.
"There's a lot of work going on around the world to ensure that pregnant women are receiving enough iodine for the healthy development of their unborn babies," says Professor Hetzel, who is also a lead author on this current study.
"The message is simple: by taking iodine supplements, pregnant women will be able to prevent brain and organ development problems in their babies, and also maintain a healthy level of iodine for themselves."
Professor Hetzel says Australia continues to be a world leader in this field, "but there is still very little public understanding about the dangers of iodine deficiency".
The results of this study were published in the Nutrition Journal.
Associate Professor Vicki Clifton
NHMRC Senior Research Fellow Robinson Institute
The University of Adelaide
Phone: +61 8 8133 2133
Emeritus Professor Basil Hetzel AC
School of Medicine
The University of Adelaide and Women's and Children's Hospital
Phone: +61 8 8161 7021