Switching from dairy to plant-based alternatives could lead to deficiencies of vital micronutrients, especially among young people and women, a study suggests.
Even partially switching to vegan alternatives to milk, cheese and yogurt could result in lower iodine, calcium, riboflavin and vitamin B12 if the substitutes, often based on soy, almonds or oats, are not fortified, the scientists said.
The biggest concerns involve iodine, a trace mineral used by the thyroid gland to produce hormones that regulate metabolism and promote healthy growth and brain development. More than half of British teenage girls already have insufficient iodine intake, researchers say.
Replacing one-fifth to one-third of dairy consumption with plant-based alternatives would result in the prevalence of iodine deficiency increasing from 54% to 65% among adolescent girls and from 32% to 42% among women aged 19 to 49, according to modeling based on typical market fortification levels.
“Iodine deficiency has known health effects and that is why we want to raise awareness about it,” said Dr Sarah Bath, associate professor in public health nutrition at the University of Surrey. “The population groups that appear to be at risk and have the lowest intakes are young women and women of childbearing age, and this is the key stage of life where iodine is particularly important.”
Plant-based alternatives to milk, cheese and yogurt are growing in popularity, although there are signs that some consumers are turning back.
In the UK, children consume around half and adults around a third of their total iodine intake from dairy products, but there are no formal requirements for vegan alternatives to be fortified with micronutrients.
Researchers looked at the impact of replacing dairy with plant-based alternatives on the UK market, including 146 non-dairy milks, 76 yoghurts and 67 cheeses. While 61% had added calcium and 46% had vitamin B12, only 19% were enriched with riboflavin and 12% with iodine.
At these levels, the scientists’ modeling showed that replacing a third of dairy consumption with vegan alternatives led to a 9 to 21 percent drop in iodine intake, as well as a drop in calcium, riboflavin and vitamin B12. The shift to 100% non-dairy alternatives has led to insufficient iodine levels reaching 80% in adolescent girls and 72% in adolescent boys.
Requiring all non-dairy alternatives to be fortified with iodine would prevent an average drop, according to the study. Adding iodized salt to bread helped reduce the proportion of adolescent girls with insufficient iodine intake in modeled scenarios. The study is published in the Lancet Planetary Health.
Some companies are already fortifying their dairy alternatives. Niamh Brannelly, head of nutrition and science communications at Danone in the UK, said its core range of Alpro products were enriched with calcium, iodine and vitamins B2 and B12.
Caroline Orfila Jenkins, vice president for science and technology at Oatly, said all of its unflavored, non-organic oat drinks are fortified with nutrients including iodine, calcium, riboflavin and vitamins B12 and D. “This research highlights the importance of appropriate fortification as diets become more plant-based,” she said.
Nichola Ludlam-Raine, a dietitian and spokesperson for the British Dietetic Association, said the work raised a significant concern at a population level, but did not mean everyone who changed would become nutrient deficient, as overall diet was also important.
“To anyone choosing plant-based milk, I would recommend checking the label and choosing one fortified with iodine, like Alpro,” she said. “Organic drinks are not fortified with added nutrients, so they are unlikely to provide iodine. White fish like cod or haddock, as well as eggs, yogurt and kefir for those who consume them, can also provide iodine. I would not recommend relying on seaweed or kelp supplements as a source of iodine, as the iodine content can vary greatly and may be excessive.”
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