SWITCHED TO PLANT MILK? WHY WOMEN COULD BE MISSING OUT ON A VITAL NUTRIENT
If you have swapped cow's milk for plant milk in your morning latte or cereal, new research suggests it is worth checking you are still getting enough iodine.
A study published in The Lancet Planetary Health has found that replacing dairy with plant-based alternatives could leave many women and teenage girls short of this quiet but essential nutrient.
Iodine helps the thyroid make hormones that keep our metabolism ticking along, and it is vital for a baby's brain development during pregnancy and infancy.
What the plant milk study found
Researchers used food diaries from more than 3,500 people in the UK National Diet and Nutrition Survey, collected between 2016 and 2019.
They then modelled what would happen if people swapped some or all of their milk, cheese and yoghurt for plant-based versions, gram for gram.
At the time of the survey, only about 12 per cent of plant-based dairy alternatives on UK supermarket shelves contained added iodine.
Iodine turned out to be the nutrient most affected by the swap.
Even before any changes, 32 per cent of women aged 19 to 49 and 54 per cent of girls aged 14 to 18 were already below the average daily requirement.
If just over a third of dairy was replaced, those figures rose to 42 per cent of women and 65 per cent of teenage girls.
With a complete switch, 80 per cent of girls aged 14 to 18 fell short.
The findings were reported by News-Medical on November 13, and you can read the full study here.
Why women are most at risk
In the modelling, dairy was a key source of iodine, so swapping it out left a gap.
Plant-based drinks are made from oats, nuts, soy or rice, which naturally contain very little iodine unless it is added.
Women of childbearing age and teenage girls came out as the most vulnerable groups in the modelling.
That matters because pregnancy and breastfeeding increase our need for iodine, and mild deficiency has been documented in adolescent girls and pregnant women.
The researchers modelled two fixes: making iodine fortification of plant-based dairy compulsory, and using iodised salt in commercial bread.
Combining both worked best, and the authors described them as "effective, evidence-based strategies".
What it means for plant milk fans in Australia
The good news for Australians is that we already have one of those safety nets in place.
According to Food Standards Australia New Zealand, bread in Australia and New Zealand has had to be made with iodised salt since 2009, except for organic bread.
FSANZ says this provides enough iodine for most of the population.
However, if you mainly buy organic or homemade bread, or you have cut back on bread altogether, you may be missing out on that boost.
It is also worth remembering that this was a UK study, so the exact numbers will not translate directly to Australian kitchens.
Simple ways to keep your iodine up
You do not have to give up your favourite oat flat white to stay on track.
Check the nutrition panel on your carton, as some plant-based drinks are fortified with iodine and others are not.
Enjoy seafood regularly, which FSANZ lists as a good source of iodine.
Choose iodised salt if you add salt at home, while keeping your overall salt intake in check.
If you are pregnant, breastfeeding or planning a pregnancy, the NHMRC recommends a daily iodine supplement of 150 micrograms.
Women with an existing thyroid condition should speak to their GP before taking one.
Kelp and seaweed supplements are not recommended, as the amount of iodine they contain can vary widely.
The bottom line
The researchers point out that their work estimates the risk of falling short rather than measuring actual deficiency, as no blood or urine tests were involved.
Still, the message is a useful one as more of us embrace plant-based eating for our health and the planet.
Plant milk can absolutely be part of a healthy diet, as long as you make sure the nutrients dairy used to provide are coming from somewhere else.
If you are unsure whether you are getting enough iodine, have a chat with your GP or an accredited practising dietitian.
