New research suggests that 7 out of 10 children in the US have low levels of vitamin, nudging millions of them toward higher risk of bone disease, high blood pressure and other risk factors for heart disease.

The study was led by Dr Michal L. Melamed, assistant professor of medicine and of epidemiology and population health at Albert Einstein College of Medicine at Yeshiva University, Bronx, New York, and is published in the 3 August online issue of Pediatrics.

Melamed, who has written a lot of scientific papers on the importance of vitamin D, told the media that:

"Several small studies had found a high prevalence of vitamin D deficiency in specific populations, but no one had examined this issue nationwide."

For the study, he and his team analyzed data on more than 6,000 children aged from 1 to 21. The data came from the 2001-2004 National Health and Nutrition Examination Survey (NHANES) which is considered unique because it combines interviews and physical examinations. The data is also representative of the US population as a whole.

They found that 9 per cent were deficient in vitamin D while another 61 per cent were insufficient. Deficient in vitamin D was defined as having less that 15 nanograms of vitamin D per millilitre (ng/mL) of blood, while insufficient was defined as having between 15 and 28 ng/mL.

In terms of demographics and behaviour, low levels of vitamin D were more common in children who were: older, female, obese, African-American, Mexican-American, drank milk less than once a week, or spent more than 4 hours a day playing videogames, using computers or watching TV.

In terms of health, low levels of vitamin D deficiency were linked to poor bone health, lower levels of calcium, higher systolic blood pressure, and lower levels of HDL (good) cholesterol. These last three are key risk factors for heart disease.

First author Dr Juhi Kumar, a fellow in pediatrics at Children's Hospital at Montefiore Medical Center, The University Hospital and Academic Medical Center for Albert Einstein College of Medicine, said they had expected to find a high prevalence of vitamin D deficiency, but:

"The magnitude of the problem nationwide was shocking."

The authors recommend routine screening for children at high risk of vitamin D deficiency. They also suggest parents need to make sure their children get their vitamin D through an appropriate combination of diet, supplements and exposure to sunlight.

Melamed said parents should:

"Turn off the TV and send their kids outside."

He said just 15 to 20 minutes of being outside every day is enough, and unless your child burns easily leave the sunscreen off for the first 10 minutes because this is long enough for he or she to get the benefit without the damage that sunlight can cause.

"Prevalence and Associations of 25-Hydroxyvitamin D Deficiency in US Children: NHANES 2001-2004."
Juhi Kumar, Paul Muntner, Frederick J. Kaskel, Susan M. Hailpern, and Michal L. Melamed.
Pediatrics, published online August 3, 2009.
DOI: 10.1542/peds.2009-0051

Source: Albert Einstein College of Medicine, via PRnewswire.

: Catharine Paddock, PhD