Plant-based dairy alternatives linked to nutrient deficiencies
This modelling study matters because it highlights a common gap in public discussion of plant-based eating: swapping foods with similar culinary roles does not guarantee similar nutrient intake. The key point is not that plant-based diets are inherently deficient, but that commercially available alternatives vary widely in fortification, and dairy contributes several micronutrients in the UK diet that are not automatically replaced.
It is also important to read these findings as a projection, not proof that every individual who chooses plant-based products will become deficient. The researchers modelled replacement scenarios using current intake data and current market fortification patterns. That makes the results highly relevant for policy and food supply, but still different from measuring clinical deficiency outcomes in people over time. Individual risk will depend on the rest of the diet, supplement use, product choice and life stage.
The strongest practical signal is around iodine. Unlike calcium or vitamin B12, iodine often gets less attention from consumers comparing labels, yet the study suggests it may be the hardest nutrient to maintain when dairy intake falls. That is especially relevant for groups with higher vulnerability to low intake, including adolescents and women of reproductive age.
For readers, the takeaway is less about avoiding plant-based alternatives and more about recognising that “plant-based” and “nutritionally equivalent” are not the same thing. In real life, adequacy may depend on deliberately choosing fortified products and paying attention to the broader diet, rather than assuming the swap is neutral. The policy discussion around mandatory fortification is therefore not just technical; it shapes whether sustainable eating patterns are realistically achievable without widening nutritional risk.
Researchers from Surrey University, in collaboration with colleagues from Queen’s University Belfast, investigated the impact of replacing milk, yoghurt and cheese with commercially available plant-based alternatives on micronutrient intake.
It found that children, teenagers and women were most impacted by the shift to plant-based. Researchers have suggested that mandatory fortification of plant-based products and other foods, such as bread, could lessen the risk of nutrient deficiencies.
The team analysed data from the National Diet and Nutrition Survey, from over 3,500 individuals, aged between 18 months and 100 years old.
Using a novel modelling technique, they assessed the impact of replacing dairy products with plant-based alternatives on four essential micronutrients found in dairy products – iodine, calcium, riboflavin and vitamin B12.
The findings showed that even modest replacements of dairy intake with plant-based dairy alternatives resulted in marked declines in all four micronutrients. Iodine was found to be particularly sensitive to dairy replacement.
The study revealed that replacing just 20% to 35% of dairy products with plant-based dietary alternatives, under current market fortification levels, increased iodine inadequacy among adolescent females from 54% to 65% and from 32% to 42% in women aged 19-49 years old.
At full replacement, the prevalence of iodine inadequacy rose to 80% among adolescent females and 72% in adolescent males.
They said the findings indicate that current voluntary fortification practices are insufficient to support a healthy and equitable transition towards Net Zero and EAT-Lancet dietary targets.
Researchers examined whether the impact of mandatory fortification of plant-based dairy alternatives with micronutrients was a potential way to prevent deficiencies.
It found that fortification prevented declines in micronutrient intake when dairy products were replaced, although levels of iodine remained inadequate in 59% of adolescent females. However, iodine-fortified bread was found to improve iodine intake, reducing inadequacy in adolescent females to 37%.
According to the researchers the most effective strategy for reducing iodine inadequacy is to combine mandatory fortification of plant-based dairy alternatives with iodine-fortified bread, the researchers said.
Dr Katie Nicol, University of Surrey, said: “Nutrition policy must evolve in tandem with environmental targets however it is important that shifts towards more sustainable diets do not compromise on public health. Fortification of foods is one way that this could be achieved however government policy is needed to make this happen.”
Dr Sarah Bath, Associate Professor in Public Health Nutrition, said that the UK is particularly vulnerable to iodine insufficiency due to the lack of iodine fortification policy.
“People may also be unaware of the importance of iodine, which is needed to make thyroid hormones to regulate our metabolism, support healthy growth and brain development.”
Dr Anne Nugent from the School of Biological Sciences at Queen’s University Belfast said that as the nutrient composition of dairy alternatives available on supermarket shelves can vary, the research also applied a condition to make sure that every dairy alternative identified had an equal chance of selection.
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