Millions of children in the U.S. under the age of 11 may suffer from suboptimal levels of vitamin D, according to the results of a large study.
The study is the most up-to-date analysis of vitamin D levels in U.S. children. It builds on the growing evidence that levels have fallen below what's considered healthy.
The researchers looked at vitamin D levels in a nationally representative sample of roughly 5,000 children between 2001 and 2006. Extrapolating to the entire U.S. population, the study suggests that roughly 20 percent of all children have blood vitamin D levels below 50 nmol/L, and more than two-thirds of all children have levels below 75 nmol/L.