There was an interesting interview about dietary iodine and health on Life Matters on Radio National (RN) and here is the link to the podcast:
http://www.abc.net.au/radionational/programs/lifematters/iodine-deficiency-and-diet/8546078.
The guests were Prof Creswell Eastman and Karen Charlton, here is their background provided on the website:
- Creswell Eastman Professor of Medicine Sydney Medical School, Principal at the Sydney Thyroid Clinic, Consultant Emeritus, Westmead Hospital
- Karen Charltona nutritional epidemiologist at the University of Wollongong’s School of Medicine.
A couple of reasons for sharing this:
1) Some further dietary info on iodine
2) To really highlight the impact of low iodine for women planning a pregnancy or pregnant.
Diet and iodine
The dietary side was noting that Australians are eating less bread and are thus missing the iodine fortification in bread. My feeling is that not everyone likes bread, can tolerate bread, or has it as part of their culture and diet, and that is fine, we just need to know where else to get it! Iodised salt is an easy source, but obviously no-one is encouraging excessive dietary salt intake, just a smidge. Dairy is another good source, but dairy may not be part of your diet due to religious, cultural, taste or digestive issues with dairy (esp if you are Asian or African, you may not be able to tolerate the lactose). Iodine is in seaweed and seafood, dairy, eggs and plants, however there are variable levels of iodine in the soil, and the amount varies depending on the seasons, so whilst plant sources are good, they can be a little less consistent. Lastly, iodine absorption can be inhibited by goitrogens such as soy and plants on the cabbage family (the brassicaceae family); so be mindful of how much soy you are having and lightly steaming/cooking your veges reduces this effect.
So, here are some good sources of iodine that are not limited to bread:
- seaweed
- seafood – two to three times a week ideally; fresh, tinned, fish, oysters….
- dairy
- bread – note that organic bread does not have to be fortified with iodine
- eggs
- legumes such as navy beans.
If pregnant, then supplementation is recommended, see below.
Pregnancy and brain development in the baby
Many people already know that low iodine is associated with low thyroid function and in severe cases may cause a goitre. Low iodine is can also interfere with fertility, is associated with miscarriage risk, and cause breast pain. In severe cases of low iodine in the pregnant mother, a condition called cretinism can occur, and this nearly always only happens in developing countries of mountainous inland regions such as Nepal.
The risk to the unborn baby can range from irreversible mild to fatal damage and the risk is greatest in the first 8 weeks of gestation – when some women may not know they are pregnant yet or may not have been supplementing. Potential risks for the unborn child include impaired neurocognitive development, lower IQ, hypothyroidism, motor skill and hearing problems. Obviously this occurs on a range of very mild to severe (as above).
As discussed on the interview, a couple of studies that came out in 2014 both showed that even mild iodine deficiency in women can lead to lowered IQ (up to 10 points) in the baby. These studies were landmark studies in that they followed up at 9 years (a Tassie study) and 10 years (Europe) and both studies found that this effect was not reversible. That is, the neurological development in utero has a lasting effect and could not be corrected by supplementing or diet changes in the baby/child. Interestingly, on testing both groups showed marked reduction in performance in language, visual and comprehensive tests, not maths. Another meta-analysis in China showed similar results.
So, the moral of the story is: eat a balanced diet with loads of fresh foods, include fish and other iodine-rich foods if you can. If not, supplement appropriate to your age, gender and if you are pregnant or breast feeding, and always seek professional advice before supplementing because too much iodine is also an issue!
