Plant-based milk warning as study finds swaps could leave people short of key nutrients
Switching from dairy to plant-based milk, yoghurt and cheese could reduce intake of iodine, calcium and key vitamins, with teenage girls and younger women most affected, researchers say.
Swapping cow’s milk, yoghurt and cheese for plant-based alternatives could leave some people short of key vitamins and minerals, new research suggests.
Teenage girls and younger women may be particularly at risk, with researchers warning that even a partial switch could reduce intake of iodine, calcium and vitamins B2 and B12.
The study, published in The Lancet Planetary Health, examined 289 plant-based products, including 146 milks, 76 yoghurts and 67 cheeses.
Researchers found wide differences in how many products were fortified with nutrients. Just 12% contained added iodine, while 61% had calcium, 46% vitamin B12 and 19% vitamin B2.
Using dietary data from more than 3,500 people, the team modelled what would happen if dairy products were partly or fully replaced with plant-based alternatives.
Among girls aged 14 to 18, replacing around 20% to 35% of dairy increased the proportion with inadequate iodine intake from 54% to 65%.
If dairy was replaced completely, the figure rose to 80% for teenage girls and 72% for boys.
Calcium intake was also affected. Among girls aged 14 to 18, inadequate intake rose from 54% to 70% when all dairy was replaced, while among boys it increased from 30% to 47%.
Dr Sarah Bath, associate professor at the University of Surrey and lead author of the study, said many people may not realise dairy is a major source of iodine in the UK.
She said: “People are also unaware that dairy products are a major source of iodine, particularly in the UK, and that plant-based alternatives, unless fortified, have a very low iodine content.”
Iodine is needed to produce thyroid hormones and is particularly important during pregnancy and for brain development.
The researchers said mandatory fortification of plant-based products could help, although their modelling suggested iodine intake would remain too low for some groups.
Dr Katie Nicol, from the University of Surrey, said dietary moves towards more sustainable foods should not come at the expense of public health.
However, other experts questioned how far the findings could be applied.
Professor Tom Sanders, emeritus professor of nutrition and dietetics at King’s College London, said iodine deficiency could not be reliably predicted from food records alone and pointed out that seafood is another important source.
The Vegan Society also disputed the suggestion that switching from dairy was inherently a problem.
Senior dietitian Emily Angus said many plant-based milk alternatives were already fortified and said people following vegan diets should choose fortified products.
The NHS says a well-planned vegan diet can provide the nutrients the body needs, while calcium, iodine and vitamins B2 and B12 can also be obtained from a range of fortified foods and supplements.