For the latest study, researchers analyzed data from National Health and Nutrition Examination Survey (NHANES) conducted between the years of 2001 and 2006, which included blood tests that measured vitamin D levels of nearly 5,000 children. By applying the healthy vitamin D level cutoff level of the American Academy of Pediatrics, the researchers found that 6.4 million of the children (about 20 percent) of children in the targeted age group are lacking in vitamin D. By applying a higher cutoff, results revealed that approximately two-thirds of children (24 million) in the age group are deficient in vitamin D. This includes 92 percent of black children, 80 percent of Hispanic children, and 59 percent of white children. The researchers pointed out that children who were taking multivitamins that included vitamin D had higher levels overall. However, less than half of the children were taking a multivitamin.

According to researcher and lead author Dr. Jonathan Mansbach of the Harvard Medical School and Children’s Hospital in Boston, these are “astounding numbers.” He also stated, “If our associations are correct, this is a big problem.” Mansbach says his study supports expert recommendations of children getting a healthy amount of 400 daily units of vitamin D for the prevention of rickets. A child could consume the daily, recommended amount of vitamin D by drinking four cups of fortified milk, or eating large amounts of fish, however, many children do neither. Another great source of vitamin D is natural sunlight. When the skin is exposed to sunlight, the body makes vitamin D. Many children don’t spend enough time outdoors to absorb the sunlight necessary for the body to produce the vitamin. This is especially true for children who live in colder climates. In addition, the bodies of children with darker skin often do not produce enough vitamin D as their skin absorbs less sunlight.

However, much debate remains as to just how much daily vitamin D one should get for the amount to be deemed healthy. While 400 daily units may be enough to prevent rickets, it may not be a large enough quantity to promote general good health and prevent illness. Some experts suggest that newborns should start out getting 400 units of vitamin D a day, and up to 1,000 units per day after the age of 1 year. For teens, the amount suggested is 2,000 units per day, while for adults the various amounts deemed healthy by experts are up to 10,000 units daily. Working to establish standards needs to be a priority.

Few foods contain natural vitamin D. They include fatty fish, egg yolks, certain cheeses and a few meats, such as liver. However, milk and even some cereals are fortified with vitamin D. Mansbach recommends vitamin D supplements, especially for those living in areas where the sun is scarce in the winter. In addition he said, “summer sunlight exposure is the major source of vitamin D for most people, but [too much] sun exposure can cause sunburns and eventually skin cancer. Until more research is performed, we think the safest bet is to take vitamin D supplements.