Swapping 35% of Dairy for Plant Milks Raises Iodine Shortfall
A UK computer model in Lancet Planetary Health found plant-based dairy swaps cut iodine, calcium, riboflavin and B12 intake. Fortification could limit the drop.
Replacing 35 percent of dairy with plant-based alternatives would raise the share of UK girls aged 14 to 18 with too little iodine from 54 percent to 65 percent, according to a computer simulation published in the September issue of the journal Lancet Planetary Health, as reported by Smithsonian Magazine. The model also found lower intake of calcium, riboflavin and vitamin B12, but iodine fell the most.
The same simulations suggested that adding nutrients to plant-based dairy products and to bread could reduce the shortfall.
How the researchers ran the simulation
The team used data from the UK’s National Diet and Nutrition Survey, which covered more than 3,500 people aged 1.5 to 100. They fed the data into a computer model that swapped regular milk, yogurt and cheese for commercially available plant-based versions. They then tracked intake of four micronutrients: iodine, calcium, riboflavin and vitamin B12.
Even a modest replacement of dairy lowered intake of all four. For women aged 19 to 49, the share with low iodine intake at baseline was 32 percent, and it would rise to 42 percent after the 35 percent dairy swap. If dairy were replaced entirely, the model projected that 80 percent of teenage girls and 72 percent of teenage boys would fall short on iodine.
The body uses iodine to make thyroid hormones, and it matters for brain development, particularly in infants, adolescents and pregnant people.
What fortification changed in the model
The researchers then modeled adding iodine to plant-based dairy products and to bread. With 20 percent dairy replacement, iodine shortfall among teenage girls dropped to 37 percent. With a complete swap, it was projected at 43 percent among adolescent girls.
Limits of the findings
The results come from a model, not from measuring people’s health. Ian Givens, director of the Institute for Food, Nutrition and Health at the University of Reading, who was not involved in the study, said in comments compiled by the Science Media Centre that the findings show a risk of inadequacy rather than confirmed deficiency. He called the study’s look at partial replacement, rather than only a full switch, a strength, and said the breakdown by age and sex shows who is most at risk.
Why it matters
Plant-based milks, yogurts and cheeses are increasingly popular for health and environmental reasons, and many lack nutrients found in dairy. Study co-author Katie Nicol of the University of Surrey said government policy would be needed to make fortification happen, and that more sustainable diets should not compromise public health.
Smithsonian also notes that some people have switched from table salt, which is often iodine-fortified, to Himalayan, sea or kosher salt, which it says is contributing to a rise in iodine deficiency.
Some products already carry added nutrients. Caroline Orfila Jenkins, vice president for science and technology at Oatly, told the Guardian that all of the company’s unflavored, non-organic oat drinks contain added iodine, calcium, riboflavin and vitamin B12. Nichola Ludlam-Raine, a dietitian and spokesperson for the British Dietetic Association who was not part of the study, noted to the Guardian that organic drinks do not contain added nutrients.
Source: Smithsonian Magazine
