SMC Alert
15/09/09
IMMEDIATE RELEASE
Contact:
Peter Griffin
Science Media Centre
Why are we fortifying our bread 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. The iodisation of bread means that
people will not have to increase their salt intake in order to improve their iodine intake.
The move follows a decision by the Government to delay mandatory fortification of folic acid in bread until at least May
2012. Across the Tasman, Australian bakers were required to add folate to bread from this week in a bid to cut spina
bifida rates.
Food Standards Australia New Zealand has concluded that any risk from iodine fortification is very small across all
groups. A fact sheet containing more information can be found here.
The Science Media Centre gathered comment from local experts on the mandatory fortification.
The comments shown are excerpts: full comments can be found on the SMC website.
Professor Christine Thomson, of the Department of Human Nutrition at the University of Otago, comments:
Researchers in the Department of Human Nutrition at University of Otago identified the re-emergence of mild iodine
deficiency in New Zealand in the early 1990s, in spite of adequate iodine status reported during the 1960s-1980s.
Subsequent research by us indicated that the low iodine status is being reflected in disturbances in thyroid hormone
metabolism, enlarged thyroid glands (goitre) and more recently a possible impairment in cognitive function of children.
This situation is likely to worsen unless measures are taken to increase our iodine status. The most vulnerable groups
in the population are pregnant and lactating women, as vital foetal mental and physical development occurs during
pregnancy and during early infancy. Young children are also vulnerable to iodine deficiency in terms of cognitive and
physical development.
Lyn Gillanders, Senior Clinical Dietitian at the NZ Dietetic Association comments:
Worldwide iodine deficiency is the biggest single cause of preventable brain damage and mental retardation. In NZ
evidence from the 2002 National Children's Nutrition Survey was that NZ children had urinary iodine excretion rates
consistent with mild iodine deficiency (this is best way of measuring iodine status). It's an issue in NZ because the
consequences might be that children do not learn and develop as well as they might do. The effects of deficiency are
seen at all stages of development but the other vulnerable time would be foetal development and when being breast fed.
It's really not all that different from folic acid fortification but maybe New Zealanders have had almost 100 years to
get used to the idea that we need a little extra iodine because they are familiar with seeing iodised salt on the
supermarket shelves. Maybe people think salt is more "natural". It is perhaps worth mentioning that it would be a bad
idea to encourage New Zealanders to have more iodised salt as table salt because salt intake is one of the biggest
factors driving up our collective blood pressure and consequent strokes and heart disease. So we hope that this is a
win/win situation.
Dr Sheila Skeaff, Senior Lecturer at the Department of Human Nutrition, University of Otago, comments:
There are low levels of iodine in New Zealand soils, and it common in New Zealand for our diets to be lacking in iodine.
In the past most of our iodine came from dairy foods such as milk and cheese, and iodised salt used at the table or in
cooking. But today people are adding less salt to food or are replacing iodised salt with rock or sea salt that contains
virtually no iodine. Changes in the dairy industry has meant that the amount of iodine in dairy foods is much lower than
it used to be. Many people are not aware that the salt used to make foods bought in the supermarket (i.e. processed
foods), is not iodised. And although fish and seafoods are rich in iodine, most New Zealanders do not eat enough of
these foods to get much iodine from them. At present, most children and adults, especially pregnant and lactating women,
are iodine deficient. Iodine is an essential element needed for normal growth and development, particularly of the
brain. Growing brains need iodine and that is why pregnant women and children need a good supply of iodine in their
diets.
People who do not eat commercial breads should ensure that they obtain additional iodine from consuming more iodine-rich
foods or taking an iodine-containing supplement. The use of kelp tablets, however, is not recommended as these tablets
often contain variable and very high amounts of iodine. In contrast to folic acid, which is recommended for one group of
the population (i.e. pregnant women), iodine is needed for all groups of the population and the replacement of
non-iodised salt with iodised salt is relatively simple for food manufacturers; this may explain why the mandatory
fortification of bread with iodised salt is less controversial than mandatory folic acid fortification. Nonetheless, the
lack of iodine in the New Zealand diet for almost two decades has received little attention in the media, despite the
possible implications this may have on brain development, both for individuals and society.
In 2008 the Copenhagen Consensus, a panel of 8 top-economists including 5 Nobel Laureates, identified the iodisation of
salt as the world's third best investment to improve the state of the planet.
David Roberts, Programme Manager for Nutrition at the New Zealand Food Safety Authority, comments:
Who is the most vulnerable?
· Iodine deficiency is associated with a wide range of adverse health effects; with the most detrimental involving the
developing brain, especially during foetal growth and infancy periods. Hence the iodine status of pregnant and
breastfeeding women is of particular importance. As substantial brain and nervous system development continues into the
first two to three years of life, this period is also critical with respect to iodine nutrition. In adults, long periods
of iodine deficiency increase the risk of thyroid dysfunction, predominantly hyperthyroidism and associated serious
health consequences in later life. Further, both adults and children are at risk of developing goitre from iodine
deficiency. Thus, iodine deficiency represents a significant threat to the health and wellbeing of the New Zealand
community now and in the future.
What will the impact of fortification be?
· Although the proposed mandatory fortification will increase the iodine intakes of pregnant and lactating women by an
important and useful amount, it is likely that a high proportion of these groups will still have inadequate intakes. For
these women, it is recommended to regularly choose foods that are naturally important sources of iodine, such as low-fat
milk and milk products, eggs and seafood. Iodised salt will provide some iodine in their diet, if used instead of
non-iodised salt in cooking or at the table.
· The Ministry of Health has been working to secure a subsidised iodine-only tablet to help pregnant and breastfeeding
women meet their extra iodine requirements [and] has indicated that a daily 150 microgram iodine-only tablet will be
available later this year. Once the iodine-only tablet has been assessed and approved for supply it will be available to
all pregnant and breastfeeding women as an over-the-counter pharmacy product.
ends