Oct. 26, 2009 -- Millions of children in the U.S. may not get enough vitamin D, and African-American and Hispanic kids are especially at risk, a new study suggests.
Researchers concluded that more than 6 million U.S. children have lower vitamin D levels than the American Academy of Pediatrics recommends. And more than two out of three children, or 24 million, have lower levels than may be optimal for good health, the researchers reported this week in Pediatrics.
"We think kids would probably benefit from getting more vitamin D than most are getting right now," study researcher Jonathan M. Mansbach, MD, of Children's Hospital Boston, Harvard Medical School, tells WebMD.
The problem is no one is sure how much vitamin D children and adults need and what the optimal blood levels of the vitamin should be.
The American Academy of Pediatrics recommends that children get at least 400 international units (IU) of vitamin D a day, and that blood levels not fall below 50 nanomoles per liter (nmol/L).
But studies in adults suggest that blood levels of 75 nmol/L or even higher may be linked to a reduced risk for heart disease, certain cancers, and other diseases.
In the newly published study, researchers analyzed recent data from a nationally representative sample of 5,000 children between the ages of 1 and 11 to estimate vitamin D levels for the nation's children as a whole.
Based on this analysis, they concluded that:
- 6.3 million kids, or nearly 20% of all children ages 1-11 in the U.S., fall below the recommended 50 nmol/L blood levels.
- Slightly more than two out of three had levels below 75 nmol/L, including four out of five Hispanic children and more than nine out of 10 non-Hispanic, black children.
- About 1% of children were clearly deficient in vitamin D (below 25 nmol/L) and at risk for the bone-softening disease rickets.
"If 75 nmol/L really is a more appropriate lowest level of acceptable, there is a lot more vitamin D deficiency in U.S. children that most people realize," Mansbach says.
Vitamin D: The Sunshine Vitamin
Mansbach says studies are needed to determine optimal blood levels of vitamin D in children and how much vitamin D they should be taking to get to those levels.
Most children's multivitamins contain 400 IU of vitamin D, the minimum daily amount recommended by the American Academy of Pediatrics.
But Mansbach says most children probably need more than this, especially darker-skinned children and those who live in colder climates with limited exposure to the sun.
The body converts UV rays from the sun into vitamin D, and all agree that sun exposure is the most efficient way to increase blood levels of the vitamin.
Children with darker skin also need much more exposure to the sun than fair-skinned children to get adequate levels of vitamin D.
Longtime vitamin D research Michael F. Holick, MD, PhD, of Boston University School of Medicine, is a promoter of what he calls "sensible sun exposure."
He says limited sun exposure during the summer -- as little as five minutes a day on the arms and legs -- is more than adequate for producing enough vitamin D.
"This is still a controversial position, but the [medical community] is coming around," Holick tells WebMD.