Lead author Dr. Ghada El-Haff Fuleihan of the American University of Beirut-Medical Center, in Lebanon, said that in his short- and long-term trials of relatively high doses of vitamin D3 none of the children ages 10 to 17 showed any evidence of vitamin D intoxication.

"Our research reveals that vitamin D, at doses equivalent to 2,000 IUs a day, is not only safe for adolescents, but it is actually necessary for achieving desirable vitamin D levels," Fuleihan said in a statement.

Due to rapid skeletal growth, children are more likely to be vitamin D deficient and less likely to reach vitamin D levels considered toxic, the researchers said.

For the short-term study -- conducted during the summer and early fall when highest natural levels are reached -- 15 boys and 10 girls received weekly 14,000 IU doses of vitamin D for eight weeks. For the one-year study 172 boys and 168 girls received either 1,400 IUs each week or 14,000 IUs of vitamin D each week.

The findings are scheduled for publication in the Journal of Clinical Endocrinology & Metabolism.