There has been debate of late about fortifying our bread with iodine. David Roberts, Programme Manager for Nutrition at the New Zealand Food Safety Authority, answers a few key questions:
“Why is it an issue in New Zealand?
“• Iodine is an essential nutrient for growth and development. Iodine occurs naturally in most foods, but usually in small amounts. Because iodine can’t be made in the body we need to get it from the food we eat.
• Iodine is important for our thyroid hormones. These hormones support normal growth and development in children and help to maintain the body’s metabolic rate. As iodine is essential for brain development, it is particularly important that unborn babies (foetus), infants and young children have enough iodine.
• Recent studies have indicated that the iodine status of New Zealanders is declining to the point where the New Zealand Government has decided to replace non-iodised salt with iodised salt in most bread. This will contribute to helping to reduce the risk of iodine deficiency disorders affecting the New Zealand population.
Low iodine status may be due to:
• people eating more commercially prepared foods (which tend to be made with non-iodised salt)
• a reduction in the use of iodine-containing sanitisers by the dairy industry. Cows’ milk and foods made from cows’ milk had higher levels of iodine when the dairy industry used disinfectants containing iodine during milk processing
• less salt being used in home prepared foods because of health messages encouraging consumers to reduce their salt intake
“What are the symptoms/health implications of such deficiency?
“• Low iodine levels in our diet may lead to health issues often referred to as iodine deficiency disorders. This might include poor growth and development in infants and children, including reduced intellectual quotient (IQ), thyroid diseases, and goitre (swelling of the thyroid gland in the neck).
“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?
• In the general population aged 15 years and older, the proposed fortification is predicted to reduce the prevalence of inadequate iodine intakes from 51% to less than 1% overall. In children aged 5-14 years, a large improvement in status would also be achieved. In all age groups, those who do not use iodised table salt are more likely to have inadequate intakes than those who do use iodised table salt.
• The absence of New Zealand dietary survey data for young children (< 5 years) makes estimating current and post fortification intakes difficult. However, it is apparent that the proposed fortification would increase the iodine intakes of young children.
• 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. The Ministry of Health 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.
“• One of the reasons bread was chosen is because it is eaten widely by New Zealanders. Bread manufacturers will replace non-iodised salt with iodised salt in most bread.
• Replacing non-iodised salt with iodised salt, to most bread, is a simple and low cost way of helping to increase the iodine intake of most New Zealanders, and reduce the number of people who aren’t getting enough iodine.”