If your parents ever told you to go play outside for the sake of a vitamin or insisted you drank a glass of milk to grow strong bones, they were talking (at least in part) about vitamin D. Though humans have only known of its existence for about a century, the nutrient’s ability to stave off physical development problems has made it a big part of public health conversation and explains why cereal boxes advertise that their product delivers a dose.
“Fortification has been successful in preventing vitamin D deficiency in most people in the U.S.,” says Daniel Roth, a pediatrician at the Hospital for Sick Children in Toronto. Though our bodies make the nutrient after ultraviolet B (UVB) exposure, we don’t always make enough, and adding the vitamin to food staples has helped a majority of the residents in the U.S. and Canada. But the solution isn’t perfect, and decades after fortification practices began, medical experts are wondering how to adapt the public health measure to fit everyone’s needs.
