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Scientist respond to modelling study published in the Lancet Planetary Health* looking at plant-based dairy alternatives and iodine and other micronutrient intake.
Prof Ian Givens, Emeritus Professor of Food Chain Nutrition, University of Reading, said:
“This study highlights that the transition from animal-derived foods to those from plants can have substantial risks, particularly if milk consumption is substantially reduced.
“A strength of the study is that it looks at partial replacement rather than only a complete switch, which better reflects how most people actually change their diets. It also breaks the results down by age and sex, which shows clearly who is most at risk. It also highlights the potential value that fortification with key nutrients would provide.
“There are limitations. The findings are based on modelled reduction of dairy intake so they show a risk of inadequacy rather than confirming deficiency but are still valuable data. Plant-based products also vary widely, and change over time, in whether and how much they are fortified, so the size of the effect depends on which products people choose.
“A key concern is that the UK already has a large proportion of teenage girls with very low intakes of the micronutrients that milk and dairy foods are rich in because they have low intakes of milk. Any further transition to plant-derived food among teenage girls is therefore a great concern.”
Dr Pauline Scheelbeek, Associate Professor in Planetary Health & Nutritional Epidemiology, London School of Hygiene & Tropical Medicine, said:
“This study is a welcome contribution to understanding how we can move towards more plant-based diets without compromising nutrition. One of its strengths is that it considers realistic dietary changes and possible future scenarios. What is particularly encouraging is that it shows we already have solutions to address potential nutritional shortfalls. Fortifying plant-based dairy alternatives and bread could help people get the nutrients they need, even when they consume less dairy. We also know from other research, rather than this particular study, that the iodine content of cow’s milk is partly the result of iodine being added to cattle feed, so there is no reason why we shouldn’t take a similar approach with plant-based products.
“However, we need to be careful when interpreting the findings related to risks of deficiencies attributable to dietary shifts. Dietary surveys, such as NDNS, rely on people accurately reporting what they eat: given this forms the input into the models, under-reporting could affect the results. Furthermore, having a dietary intake below recommended levels does not necessarily mean someone has a nutrient deficiency.”
Prof Keith Frayn, Emeritus Professor of Human Metabolism, University of Oxford, said:
“In the move towards net zero, there will need to be a shift away from animal-based products because of their high environmental cost. This is one reason for the current popularity of dairy substitutes based on vegetable products. This is an important paper by experts from the University of Surrey who have used data on more than three thousand people from the National Diet and Nutrition Survey, and modelled outcomes with different replacement strategies. It highlights a potential drawback of the switch from dairy products, namely the reduction in intake of some important micronutrients, of which iodine is the most concerning as iodine deficiency is already widespread, especially amongst young women. The authors found that more than half of teenage girls covered by their study already had inadequate iodine intake.Dairy products have traditionally been a major source of iodine in the UK, and the UK government has resisted iodisation of salt, widely used in much of the world to prevent iodine deficiency, as it conflicts with public health advice to reduce salt consumption. This paper presents credible alternatives, fortification of bread and dairy substitutes, which largely but not completely alleviate the deficiencies that would otherwise occur. We can only hope that this research finds its way into government food policy.”
Prof Jules Griffin, Director of the Rowett Institute, University of Aberdeen, said:
“This modelling study reported by Nicol and colleagues is a well conducted simulation of what might happen if plant-based dairy alternatives began to make up a significant proportion of what the UK population consumes. The authors have identified potential vulnerable groups within the UK population that under such circumstances would be at risk of iodine, calcium, riboflavin and vitamin B12 deficiencies, and they propose some government policy strategies that could address such a situation. The study is well captured in their press release.
“We know from nutrition surveys in the UK certain groups in the population are at greater risk of deficiencies, in part because of their diet, including adolescent girls and women of reproductive age for iodine deficiency and adolescent girls for calcium deficiency, with dairy products being an important source of both micronutrients. This study demonstrates how important the consumption of dairy products is for certain parts of the population. In 2024-2025, about 95% of the milk we consumed was cow’s milk and so while plant-based alternatives are increasingly becoming popular there is not an immediate concern for health from this study outside concerns already raised by the National Diet and Nutrition Survey for iodine and calcium deficiency in adolescent girls and women of childbearing age from the current dietary intakes. This research does demonstrate how important dairy and dairy products are for nutrition of certain parts of the population, particularly children and adolescents, and personally I would opt for policies to make dairy production more sustainable as a better planetary health strategy than the promotion of plant-based dairy alternatives and large-scale fortification.”
Prof Stephen Burgess, Professor in Biostatistics, University of Cambridge, said:
“This is a statistical modelling exercise based on a possible future scenario in which individuals change their diet by replacing dairy products with plant-based alternatives under current fortification practices. This study does not demonstrate any health risks based on these projected reductions in nutrient intake, although we know that several of these nutrients are important for human health. The quantitative impact of these dietary changes will depend on how replacement products are selected and what other accompanying dietary changes are made – modelling assumptions needed to quantify these changes are intrinsically uncertain. But the overall points made by this study are fair and reasonable: changes in consumption away from dairy products could lead to nutrient deficiencies, and this could be overcome by fortification of plant-based foods.”
Prof Tom Sanders, Professor emeritus of Nutrition and Dietetics, King’s College London, said:
“This study is based on further analysis of a large national UK food survey. The statistical analysis has estimated the impact of replacement of dairy milk with plant based dairy alternatives (PBDA) focusing on micronutrient intake. The modelling seems to have been done competently. As expected, micronutrients which are normally supplied by mammalian milk (vitamin B12, riboflavin, calcium, and iodine) were lower in those individuals using plant based dairy alternatives. Riboflavin and calcium can be obtained from other sources but B12 is only supplied by foods of animal origin (particularly meat and fish and to a lesser by eggs and milk). Some plant based dairy alternatives are fortified with B12 and these are useful for vegans, who are at risk of B12 deficiency. Mammalian milk also makes an important contribution to calcium intake and there is a good case for fortifying plant based dairy alternatives with calcium to help promote maximum calcium accumulation in bones in teenagers.
“Much of this paper focuses on the adequacy of iodine intakes and mandatory fortification. The major weakness here is that iodine deficiency cannot be reliably predicted from dietary intake records because the iodine content is dependent on the amount in the soil in which plant foods are grown. Deficiency occurs mainly in isolated mountainous areas that have high rainfall that washes the iodine from the soil (e.g. Tibet). Milk is not naturally high in iodine: the high levels found in milk are because dairy cattle are given “salt licks” that contain supplemental iodine; in the past iodine containing disinfectants were used to clean the cows’ udders in milking parlours and were well known to lead to higher levels of iodine in the milk). Seafood is the best natural source of iodine. Iodine deficiency is rare in the UK (as assessed by urinary iodine excretion) because food is now sourced from many countries.
“The authors suggest mandatory fortification of bread with iodine. However, while iodine fortification has clear benefits in preventing goitre, deaf mutism and severe congenital hypothyroidism when intakes are very low, it can be harmful in populations where intakes are adequate. High intakes of iodine can trigger autoimmune thyroid disorders, particularly in women who have a life-time risk of about 1 in 10. Any argument for mandatory fortification of bread with iodine would require a careful risk benefit analysis.”
* ‘The impact of replacing dairy products with plant-based dairy alternatives on iodine and other micronutrients: a modelling study and evaluation of policy options to support population intake’ by Katie Nicol et al. was published in the Lancet Planetary Health on Wednesday 4 November 2026.
DOI: 10.1016/j.lanplh.2026.101515
Declared interests
Prof Ian Givens: “I have received travel expenses and honoraria in connection with lectures and meetings from the Dairy Council (now Dairy UK), Dutch Dairy Association, European Milk Forum, and the International Dairy Federation. I have also been a consultant to BioCC OÜ the Estonian Bio-Competence Centre of Healthy Dairy Products, to the Dairy Council (now Dairy UK) on fats in dairy products and cardiometabolic diseases and to the School and Nursery Milk Alliance on research evidence on the role of milk in the diets of infants and children. Had previously had research grants from UK Biotechnology and Biological Sciences Research Council (BBSRC), UK Medical Research Council (MRC), Arla Foods UK, AAK-UK (both in kind), The Barham Benevolent Foundation, Volac UK, DSM Switzerland and Global Dairy Platform. Ian contributes to PhD programmes in nutrition at the University of Surrey.”
Dr Pauline Scheelbeek: “I have no competing interests to declare.”
Prof Keith Frayn: “I have no conflicts of interest other than that I write books on metabolism and nutrition.”
Prof Jules Griffin: “I am a consultant for Sitryx, a company specialising in designing drugs to target immunometabolism.
I have received funding from the European Union to investigate endocrine disrupting chemicals and hold a grant from UK Research and Innovation examining the health benefits of a fish diet.
I am a recipient of a travel award from Shimadzu Corporation to present results on their mass spectrometers.
I hold shares in GlaxoSmithKline and Haleon plc.”
Prof Stephen Burgess: “I have no relevant conflict of interest to declare.”
Prof Tom Sanders: “I was Chair of the British Nutrition Foundation Report on Nutrition and Development: Short and Long term consequences for Health.
I have received grant funding for research on vegans in the past. I have been retired for 10 years but during my career at King’s College London, I formerly acted as consultant for companies that made artificial sweeteners and sugar substitutes.
I am a member of the Programme Advisory Committee of the Malaysia Palm Oil Board which involves the review of research projects proposed by the Malaysia government.
I also used to be a member of the Scientific Advisory Committee of the Global Dairy Platform up until 2015.
I did do some consultancy work on GRAS affirmation of high oleic palm oil for Archer Daniel Midland more than ten years ago.
My research group received oils and fats free of charge from Unilever and Archer Daniel Midland for our Food Standards Agency Research.
I was a member of the FAO/WHO Joint Expert Committee that recommended that trans fatty acids be removed from the human food chain.
Member of the Science Committee British Nutrition Foundation. Honorary Nutritional Director HEART UK.
Before my retirement from King’s College London in 2014, I acted as a consultant to many companies and organisations involved in the manufacture of what are now designated ultraprocessed foods.
I used to be a consultant to the Breakfast Cereals Advisory Board of the Food and Drink Federation.
I used to be a consultant for aspartame more than a decade ago.
When I was doing research at King’ College London, the following applied: Tom does not hold any grants or have any consultancies with companies involved in the production or marketing of sugar-sweetened drinks. In reference to previous funding to Tom’s institution: £4.5 million was donated to King’s College London by Tate & Lyle in 2006; this funding finished in 2011. This money was given to the College and was in recognition of the discovery of the artificial sweetener sucralose by Prof Hough at the Queen Elizabeth College (QEC), which merged with King’s College London. The Tate & Lyle grant paid for the Clinical Research Centre at St Thomas’ that is run by the Guy’s & St Thomas’ Trust, it was not used to fund research on sugar. Tate & Lyle sold their sugar interests to American Sugar so the brand Tate & Lyle still exists but it is no longer linked to the company Tate & Lyle PLC, which gave the money to King’s College London in 2006.”