Dairy-free milks could leave consumers at risk of iodine deficiency, study finds

The World Health Organisation considers iodine deficiency to be the 'world’s most prevalent, yet easily preventable, cause of brain damage'

Non-dairy milk alternatives, like almond, rice or soya milk, could be more problematic than you think (iStock)

Almond, cashew, hazelnut, coconut, rice, hemp, soya, oat - the dairy-intolerant are spoiled for choice when it comes to milks these days.

And many people who aren’t intolerant often choose dairy-free alternatives for health reasons too.

However, a new study has found that consumers of milk-alternative drinks may be at of risk iodine deficiency.

The World Health Organisation considers iodine deficiency to be the “world’s most prevalent, yet easily preventable, cause of brain damage.”

In the first study of its kind in the United Kingdom, researchers from the University of Surrey examined the iodine content of 47 milk-alternative drinks (including soya, almond, coconut, oat, rice, hazelnut and hemp, but excluding those marketed specifically at infants and children) and compared it with that of cows’ milk.

Of the drinks tested, fourteen were soya, eleven almond, six coconut, six oat, five rice, three hazelnut and two hemp. The cows’ milk tested was semi-skimmed milk and the study was conducted in the winter months.

The researchers found that the majority of dairy-free milks do not have adequate levels of iodine, with concentration levels found to be around two per cent of that found in cows’ milk.

In UK diets, cows’ milk and other dairy products are the main source of iodine. But the study, published in the British Journal of Nutrition, has concluded that most milk-alternative drinks are not an adequate substitute.

Iodine is an essential part of our diets - it’s required to make thyroid hormones and is especially important for pregnant women as it’s crucial for normal foetal brain development.

Previous research in this area by the University of Surrey has shown that low iodine status in pregnant mothers is linked to lower IQ and reading scores in their children (up to the age of nine).

Margaret Rayman, Professor of Nutritional Medicine at the University of Surrey, said: “Many people are unaware of the need for this vital dietary mineral and it is important that people who consume milk-alternative drinks realise that they will not be replacing the iodine from cows’ milk which is the main UK source of iodine. This is particularly important for pregnant women and those planning a pregnancy.

“A glass of a milk-alternative drink would only provide around 2 mcg of iodine which is a very small proportion of the adult recommended iodine intake of 150 mcg/day. In pregnancy, that recommendation goes up to 200 mcg/day.”

Dr Sarah Bath, Lecturer in Public Health Nutrition at the University of Surrey and registered dietitian, added: “Milk-alternative drinks are increasingly being used as a replacement for cows’ milk for a number of reasons that obviously include allergy or intolerance to cows’ milk.

“Worryingly, most milk-alternative drinks are not fortified with iodine and their iodine content is very low. If avoiding milk and dairy products, consumers need to ensure that they have iodine from other dietary sources, where possible.

“If considering taking an iodine supplement, they should avoid kelp which can provide excessive amounts of iodine.”

But should we really be worried about drinking dairy-free milks?

“With regards to iodine deficiency, it is something again that vegetarians and vegans and pregnant women should be a tad more aware of than others but it is more common than people realise,” registered nutritionist and author of Re-Nourish Rhiannon Lambert told The Independent.

“Always check with your GP as they can test for this but be aware than a healthy balanced diet should contain enough.”

She says that good sources of iodine include fish (white fish contains more than oily fish so mix it up), eggs, nuts, meats, bread, dairy products and seaweeds.

“Dairy-free milks should be fortified with essential nutrients usually found in milk such as B12, calcium and vitamin D but iodine is often forgotten,” says Lambert. “This isn’t a big concern if you eat a varied diet, though.

“However, it’s more of a concern if you give up dairy altogether not just the milk as in the UK dairy products are often the most common source. Ensure you are eating a varied diet and always seek help from a health professional for further information.”

More information on good iodine sources such as white fish can be found in the British Dietetic Association Iodine Food Fact Sheet.