(NaturalNews) A full one in seven U.S. teenagers are deficient in vitamin D, according to a new analysis conducted by researchers from Cornell University, published in the journal Pediatrics and presented at the annual meeting of the Pediatric Academic Society.
Researchers looked at 2,955 U.S. residents between the ages of 12 and 19 who were included in the National Health and Nutrition Examination Survey III, which was designed to be nationally representative. They used the new definition of vitamin D deficiency — blood levels lowe r than 20 nanograms per milliliter — adopted at the 13th Workshop Consensus for Vitamin D Nutritional Guidelines in 2007.
The researchers found that one in seven teenagers were vitamin D deficient, including 50 percent of black teenagers. Overweight teenagers were twice as likely to be deficient as teenagers of healthy weight, and girls had twice the risk of boys.
Vitamin D deficiency increases the risk of the bone-softening disease rickets in children, and the risk of weak bones and fractures in adults. It has also been linked to higher rates of cancer, cardiovascular disease and autoimmune disorders.
The study authors expressed particular concern over the high rates of deficiency in girls, since teenage girls are physically capable of becoming pregnant. Vitamin D deficiency during pregnancy can increase the risk of gestational high blood pressure and diabetes in mothers, and weakened bones in their children.
Approximately 75.4 of every 1,000 teenage girls in the United States becomes pregnant each year. Eighty percent of these pregnancies are unplanned.
The researchers noted that the link between vitamin D deficiency and obesity poses its own challenges
"Because vitamin D is stored in body fat, simply increasing the dosage of vitamin D may not be effective in overweight adolescents," senior author Linda M. Gerber said. "As the prevalence of childhood obesity increases, vitamin D deficiency may increase as well. In this group, appropriate nutrition could solve both problems."