The modern dietary trend that could impact fetal development

The increasing trend of consuming plant-based and gluten-free diets, along with ‘fancy’ salts, is leaving women deficient in iodine, according to new research out of the University of South Australia (UniSA).
 
The small pilot study assessed iodine levels in two groups of participants who were following omnivorous or vegan/plant-based diets, with the findings published in the International Journal of Environmental Research and Public Health.
 
Urine samples taken during the study found neither group had come close to meeting the >100 micrograms per litre (mcg/L) level recommended by the World Health Organization, prompting the researchers to flag the results as a potentially widespread health risk.
 
Iodine deficiency has been linked to impaired fetal development and neurological conditions in newborn babies, leading to the mandatory fortification of non-organic bread with iodised salt in Australia in 2009.
 
‘This research paper throws up some very interesting and important points that all GPs who might have the opportunity to speak to women preconception, and in particular those of us who are working in the antenatal space, need to be aware of,’ Dr Wendy Burton, Chair of RACGP Specific Interests Antenatal and Postnatal Care, told newsGP.
 
Dr Burton said that with Australians embracing dietary trends such as gluten-free and vegan diets, more people are becoming at risk of iodine deficiency – which is particularly concerning for women of childbearing age.
 
‘The threefold impact on iodine levels of the move away from dairy, the move away from breads, and the replacement of traditional iodised table salt with fancy salts such as pink Himalayan is significant,’ she said.
 
‘Australia has become iodine deplete and it’s many years since we started universal supplementation of breads and a recommendation that women who are planning a pregnancy, pregnant or breastfeeding consume 150 micrograms of iodine on a daily basis.’
 
There is a growing preference to opt for Himalayan salt over iodised table salt, despite the former containing an insignificant level of iodine, and around one quarter of the women in the UniSA study reported using the popular alternative.
 
Both groups in the study who chose pink or Himalayan salt instead of iodised salt had ‘severely’ deficient iodine levels, averaging 23 mcg/L. 
 
Urine samples showed iodine readings of 44 mcg/L in the plant-based group, compared to the omnivores’ level of 64 mcg/L.
 
These results are concerning for development to the unborn baby, according to the researchers.

‘Mild-to-moderate iodine deficiency has been shown to affect language development, memory and mental processing speeds [in babies],’ study lead and UniSA research dietitian Jane Whitbread said.
 
‘During pregnancy, the need for iodine is increased and a 150 mcg supplement is recommended prior to conception and throughout pregnancy. It is important to consume adequate iodine, especially during the reproductive years.’
 
But most women do not take iodine supplements before conceiving, Ms Whitbread said.
 
Dietary sources of iodine include fortified bread, iodised salt, seafoods including seaweeds, eggs, and dairy foods.
 
Since the mandatory iodine fortification of bread in 2009, it has been found that women who consume 100 g of iodine-fortified bread every day, approximately three pieces, have a five times greater chance of meeting their iodine intake compared to women who don’t consume that much.
 
Dr Burton says part of the GP’s role in preconception and antenatal care is offering appropriate dietary advice.
 
‘The majority of women do not receive specific preconception counselling, so public health messages that alert women to the need for iodine both through attention to iodine in their diet and as a supplement – the pregnancy and breastfeeding supplements do contain iodine supplementation – are important,’ she said.
 
‘Iodine and folic acid are also available as standalone cheap supplements. And for women who have an otherwise healthy and balanced diet, that would be my recommendation.
 
‘I encourage all individuals to have a healthy and well-balanced diet.’
 
The study also found that for the women on a vegan diet, plant-based milks contain low levels of iodine and are not currently fortified in Australia.
 
Australia has seen a recent increase in the use of plant-based milk, with an average annual increase of 7.2% of almond and soy milk between 2015–20.
 
The average level of iodine in 170 mL of soy milk or almond milk is 0.4–2.3 mcg, compared to 39.1 mcg in the same amount of dairy milk.
 
‘Based on this amount of plant milk intake, if plant milks were fortified with iodine to the average level of dairy milk, consumers of plant milk would increase their daily iodine intake by approximately
37 mcg day,’ the study authors wrote.

The authors recommend that both new types of salts and plant-based milks be fortified with iodine, as well as the implementation of awareness campaigns on the importance of iodine in the diet, particularly for women in their reproductive years.

They also called for a larger study sample to more accurately determine the iodine status of Australian women.

‘I agree with the authors,’ Dr Burton said.
 
‘It’s important for the authorities to consider broadening the mandatory supplementation of iodine so that we can capture incidentally a wider percentage of our population, and therefore reduce the impact of iodine deficiency upon our population.’
 
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antenatal care fetal development iodine preconception pregnancy