One in seven US teens is vitamin D deficient, according to a new study. In children, vitamin D deficiency can interfere with bone mineralisation, leading to rickets. In adults, it is linked to cardiovascular disease, cancer, diabetes, immune dysfunction and hypertension.
The study employs a new definition of vitamin D deficiency recommended by a group of scientists attending the 13th Workshop Consensus for Vitamin D Nutritional Guidelines in 2007.
These experts collectively proposed that the minimum acceptable serum vitamin D level be raised from 11 nanograms per milliliter (ng/mL) to at least 20 ng/mL.
Using the newer criteria, the study finds more than half of African-American teens are vitamin D deficient. Girls had more than twice the risk of deficiency compared with boys. And overweight teens had nearly double the risk of their normal-weight counterparts.
"These are alarming findings... To meet minimum nutritional requirements, teens would need to consume at least four glasses of fortified milk daily or its dietary equivalent," said Sandy Saintonge.
Saintonge is assistant professor of clinical pediatrics and assistant professor of clinical public health at Weill Cornell Medical College (WCMC) and a paediatric emergency physician at New York Hospital Queens.
"Other foods rich in vitamin D include salmon, tuna, eggs and fortified cereals. A vitamin supplement containing 400 IU of vitamin D is another alternative," said Saintonge.
"We should also consider a national fortification strategy, perhaps including routine supplementation and monitoring of serum levels, but more research is needed to determine optimal vitamin D levels."
Of the specific findings, the authors were particularly concerned about the role of weight in deficiency. "Because vitamin D is stored in body fat, simply increasing the dosage of vitamin D may not be effective in overweight adolescents," noted senior author Linda M. Gerber, professor of public health at WCMC.
Data was obtained from National Health and Nutrition Examination Survey III, a cross-sectional survey administered to a nationally representative sample of persons aged two months and older. Analyses were restricted to 2,955 participants aged 12 to 19, said a WCMC release.
The findings were published in the March issue of Paediatrics.