Prof Jennie Brand-Miller answers your questions.
I read an article in the Sydney Morning Herald suggesting iodine deficiency could be why Australian children lag behind at school. Can you tell me more about iodine and how much we need and where we can get it naturally.
Iodine is a naturally occurring mineral that is needed by the thyroid gland in order to synthesize thyroxine, an important hormone that regulates metabolism. In babies and young children, thyroid hormones play a key role in physical and mental development. A deficiency of iodine can lead to learning difficulties and affect physical development and hearing. The recommended dietary intake a day for iodine is 150 micrograms for most adults, but this increases to 220 micrograms during pregnancy and 270 micrograms while breast-feeding, as your baby will take the iodine it needs from you.
Iodine deficiency Because Australian and New Zealand soils are low in iodine, the National Health and Medical Research Council and the New Zealand Ministry of Health recommend that all women who are pregnant, breastfeeding or considering pregnancy, take an iodine supplement. However, it’s best to speak with your doctor before taking a supplement, especially if you have a pre-existing thyroid condition.
Though iodine deficiency is not typically a problem in the United States, as most table salt is enriched with iodine, the American Thyroid Association recommends that all women who are pregnant, breast-feeding, or considering pregnancy take an iodine supplement of 150 micrograms each day. Kelp and seaweed supplements are not recommended as they contain varying amounts of iodine and can even cause toxicity (too much iodine). Again, speak with your doctor first.
Best natural sources of iodine The best source of iodine in our diet is seafood. We also get iodine from other foods including milk and vegetables, but the amount varies depending on how these foods are grown and processed. In Australia and New Zealand, all salt used for making bread (apart from organic breads) must now be iodised, so bread has become a source of iodine. While we don’t recommend that you add salt to your food, if you use it in cooking (for example, when boiling rice or pasta), it’s best to buy iodized salt and use sparingly, particularly if you don’t regularly consume other iodine-rich foods. Another tip I learned lately was that iodized salt has a use-by date because it loses the iodine gradually to the air (vaporisation). If you use the large SAXA containers as I do, but only a little, it might be years before it’s empty. So check the use-by date … you may need to bin it if you have had it in the cupboard for a long while!
Four tips for increasing your iodine intake
1. Include a few meals of fish or seafood each week (there are two fish recipes in this issue of GI News for starters to try).
2. A glass of milk or container of yogurt with cereal or as a snack will provide iodine as well as calcium and other nutrients.
3. If you use salt in cooking or on your meals, choose iodized salt rather than other types.
4. Sushi is a good way to get iodine, but for food safety reasons needs to be homemade (without raw fish) and eaten fresh. Nori (sushi wrappers) can also be chopped into salads and stir-fries for vegetarians or non-fish eaters, but avoid kelp, which can contain very large amounts of iodine.
This is an edited extract from my latest book (with Dr Kate Marsh and Prof Robert Moses), The Bump to Baby Low GI Eating Plan for Conception, Pregnancy and Beyond (Hachette Australia) which is available from good bookshops and online. You can also visit us HERE.
We are delighted to let GI News readers know that a US edition is well on the way (we have just checked the page proofs). The publisher is Matthew Lore of The Experiment. Matthew has published many of our books in the past and we are absolutely delighted to be working with him on this. We will keep you posted re the publication date.
GI testing by an accredited laboratory
Dr Alexandra Jenkins
Glycemic Index Laboratories
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Toronto, Ontario M5C 298 Canada
Phone +1 416 861 0506
Research Manager, Sydney University Glycemic Index Research Service (SUGiRS)
Human Nutrition Unit, School of Molecular and Microbial Biosciences
NSW 2006 Australia
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