A UK study estimates that replacing dairy products with plant-based alternatives could reduce iodine intake by up to 28 per cent

This study addresses a very interesting issue in the current field of nutrition, particularly in relation to sustainability: does replacing animal-based foods with plant-based alternatives mean maintaining the same nutrient intake? The researchers used dietary data from over 3,000 people in the UK to simulate how partially or completely replacing milk, yoghurt and cheese with their plant-based alternatives would affect the intake of essential micronutrients, such as iodine, calcium, vitamin B12 and riboflavin.

The authors found that, for a range of dairy products sold in the UK, replacing approximately one-third of dairy products could reduce average iodine intake by between 9 per cent and 21 per cent. This is particularly relevant because iodine is essential for the synthesis of thyroid hormones and for proper neurological development, particularly during pregnancy and the early stages of life. One of the most vulnerable groups is adolescent girls aged between 14 and 18, an age group in which iodine intake is often below recommended levels. 

An interesting aspect of the study is that it does not merely identify a potential nutritional problem, but also evaluates strategies to prevent it. For example, the authors note that fortifying plant-based alternatives with iodine and other micronutrients would help to significantly reduce the nutritional losses associated with this shift, and that combining this measure with the use of iodised salt in bread-making could improve iodine intake even among groups that already have insufficient levels in their usual diet.

However, the results must be interpreted whilst bearing in mind certain limitations. This is a modelling study – that is, a mathematical simulation based on various hypothetical scenarios – rather than a nutritional intervention involving people. In this case, the researchers simulated food substitutions on a gram-for-gram basis, using dietary data collected between 2016 and 2019 and nutritional information on plant-based products available on the market in 2020; consequently, they may not have taken into account any nutritional adjustments people might make to the rest of their diet, changes in nutritional status, or the onset of diseases related to deficiencies in these nutrients.

Another point to consider is that an estimated intake below requirements does not necessarily imply a clinical deficiency, and that the results pertain to the British population; therefore, they cannot be directly extrapolated to Spain, where there are significant differences in dietary patterns, sources of iodine and the use of iodised salt. It would be interesting to carry out similar studies in the Spanish population, particularly among children, adolescents and women of childbearing age.

The message I would like to convey is that plant-based alternatives are not necessarily harmful, nor is it necessary to maintain a high intake of dairy products; rather, the substitution of foods should be planned with their nutritional composition in mind, and not solely based on the food’s origin. In this regard, improving the fortification, labelling and nutritional information of these products could help ensure that the transition towards more sustainable diets is also healthy and safe.

This is a modelling study; however, the sample size should be larger for this type of analysis, which means that it does not establish any kind of causality. It highlights what other studies have already confirmed, although in this case the study was conducted solely on oats, as in other studies that have already been published. The study focuses on several micronutrients: iodine, calcium, riboflavin (vitamin B2) and cyanocobalamin (vitamin B12), which are often deficient in this type of food product, but they should also have analysed others such as: vitamins A, D, K and E, or selenium, zinc or even phosphorus, given the importance of the calcium-to-phosphorus ratio (2 - 1.5:1) for calcium absorption.

The study is well designed, although the title might initially give the impression that it covers all plant-based food products, when in fact it only covers those containing or made from oats; in other words, products made from soya, rice, almonds, etc., are not compared. This implies that the title should mention oats, as well as the country or territory in which the study was conducted – the United Kingdom – as has been the case with other similar studies published in scientific journals, such as that by Khalil and Herter-Aeberli in 2023 for Switzerland or that by Lawrence et al. in 2025 for Australia. The title should specify the territory for which the sample was analysed.

Furthermore, for all studies of this type carried out on plant-based food products analogous to milk and dairy products, the terminology used deviates from what is envisaged under risk management within the concept of risk analysis in the context of food safety. For plant-based drinks, the term ‘alternative’ should not be used; instead, ‘analogue’ or ‘equivalent’ should be used. The study should use the term Plant-based analogue or Plant-based equivalent, but should not be titled: Plant-based alternative. Therefore, the study should have been titled: Replacing dairy with plant-based analogues could reduce iodine intake, but fortification would prevent this, modelling study suggests.

This study clearly demonstrates that these food products, whilst they may have significant nutritional value, do not have the same composition. Although the timing of consumption may be equivalent to that of milk or dairy products, if they are not fortified – particularly with calcium, iodine, vitamin B2 and vitamin B12 – according to these findings, they could lead to nutritional deficiencies, which in turn could result in nutritional deficits.