Plant-based diets for sustainability and health - but are we ignoring vital micronutrients?

Plant-based diets, with limited quantities of animal foods, are increasingly promoted for sustainability and health. In many countries, animal-source foods provide the majority of several micronutrients at a population level; in the UK, milk and dairy products contribute around one third of total calcium, vitamin B₁₂ and iodine intake in adults. Recommendations for a predominantly plant-based diet may have the unintended consequence of reducing intake of micronutrients, particularly in groups with an already-low intake of these nutrients, such as women of reproductive age. Furthermore, young women are the group most likely to replace dairy products with plant-based alternatives. Milk alternatives are often fortified to match the nutrient content of cows' milk for some micronutrients (e.g. calcium), but not of others (e.g. iodine or vitamin B₂). Unfortified alternatives have an iodine concentration that is just 2 % of that of UK cows' milk, and the rise in popularity of these products may increase iodine-deficiency risk in consumers. Low nutrient intake is of concern prior to, and during, pregnancy, when many of the micronutrients at risk (iron/calcium/iodine) are essential for foetal development. While there may be awareness of some at-risk nutrients on a plant-based diet, this may not be the case for all. At-risk nutrients should be considered in nutrition guidelines and advice given by healthcare professionals to ensure that the diets are well planned and supplemented when necessary. This review focuses on the provision of micronutrients (particularly iodine) from plant-based diets in the UK.