Dr. M. Zulf Mughal and colleagues warn "Vitamin D deficiency during childhood and adolescence might impair the acquisition of peak bone mass at the end of skeletal growth and maturation, thereby increasing the risk of osteoporotic fractures later in life."
Mughal and his team measured Vitamin D levels in 14 white and 37 non-white 14-16-year-old girls attending an inner city multi-ethnic girls' school in the UK.
They found that 73 percent of the girls were vitamin D deficient with 17 percent were severely deficient. Average vitamin D levels were, however, higher in white girls than in non-white girls.
The researchers correlated the deficiency of vitamins to the estimated duration of daily sunlight exposure and percentage of body surface area exposed. The dietary intake of vitamins was not considered.
"This is in keeping with the fact that the main source of vitamin D is that produced by the action of solar ultraviolet B radiation acting on 7-dehydrocholesterol in skin," the team explains. "Only small amounts are obtained from dietary sources."
The researchers pointed out that "religious and cultural beliefs that encourage wearing of concealing clothing and restriction of outdoor activities" might have a role in the difference, as reported by previous studies "in Saudi Arabian adolescents."
In an editorial, Dr. N. J. Bishop, from the University of Sheffield, UK, expresses concern that "failure to supply an essential nutrient during a period of rapid growth and development is likely to result in problems across the population as a whole."
Bishop suggests that needs of older children and adolescents from cultures that avoid sunlight should be taken care of. "Perhaps more exercise outdoors would help deal with this problem," he writes.
The study has been reported in the Archives of Disease in Childhood.
