A University of Surrey study published in The Lancet Planetary Health quantifies the micronutrient cost of the UK's shift from dairy to plant-based alternatives. The numbers are stark: replacing just a third of dairy intake with vegan milks, cheeses, and yoghurts — at current fortification rates — drops iodine intake by 9% to 21% across age groups. A full switch pushes iodine deficiency to 80% among adolescent girls, up from an already alarming 54% baseline. The core problem is not that plant-based products cannot carry the nutrients. It is that nobody requires them to. Of 146 non-dairy milks, 76 yoghurts, and 67 cheeses surveyed, 61% had added calcium and 46% had vitamin B12, but only 12% included iodine. Fortification is voluntary, and the market has collectively decided iodine is not a priority. Iodine matters because the thyroid gland uses it to produce hormones that regulate metabolism, growth, and brain development. Deficiency during pregnancy and adolescence has documented downstream effects. UK children currently get about half their iodine from dairy; adults get about a third. Remove that source without replacing the nutrient, and the arithmetic is simple. The study's modelling shows the fix is equally straightforward. Mandatory iodine fortification of all non-dairy alternatives would prevent average declines. Adding iodised salt to bread — a measure already used in other countries — further reduces the prevalence of inadequacy among teenage girls. These are not novel interventions; they are policy choices other nations have already made. Some companies are ahead of the regulation. Danone's Alpro range and Oatly's unflavoured, non-organic oat drinks already include iodine alongside calcium, riboflavin, and vitamins B12 and D. But voluntary action by a few brands does not cover a population-level transition. Organic plant-based drinks, notably, are not fortified with added nutrients. Registered dietitian Nichola Ludlam-Raine of the British Dietetic Association adds necessary nuance: overall diet matters, and not everyone who switches will become deficient. White fish, eggs, yoghurt, and kefir can contribute iodine for those who consume them. She warns against seaweed or kelp supplements, where iodine content varies widely and can be excessive. The structural question is whether the UK will regulate fortification before the dietary shift outpaces voluntary compliance. The gap between consumer behaviour and nutritional infrastructure is widening, and the population bearing the cost — young women and adolescent girls — is precisely the group for whom iodine deficiency carries the highest stakes.
