Vitamin D recommendations for teens may be too low

NEW YORK (Reuters Health) - Adolescents can safely take, and may need, vitamin D doses that are up to 10 times what is generally recommended, a small study suggests.

In a trial that followed 340, 10- to 17-year-olds for one year, Lebanese researchers found that vitamin D doses equivalent to 2,000 IU per day were not only safe, but also achieved more-desirable blood levels of the vitamin.

The dose used in the study was 10 times the official "adequate intake" level set for vitamin D in the United States -- 200 IU per day for children and adults younger than 50.

An adequate intake, or AI, is set when health officials believe there is insufficient evidence to lay down a recommended dietary allowance, or RDA.

But some researchers have argued that the 200 IU standard is too low. This year, the American Academy of Pediatrics began recommending that children and teenagers get 400 IU of vitamin D each day.

In the current study, reported in the Journal of Clinical Endocrinology & Metabolism, researchers looked at whether adolescents can take doses equivalent to 2,000 IU per day without risking side effects -- like nausea, vomiting, constipation and weight loss.

Dr. Ghada El-Hajj Fuleihan and colleagues at the American University of Beirut first conducted an 8-week safety study in which 25 adolescents were given either a weekly dose of 14,000 IU of vitamin D3 -- also known as cholecalciferol -- or a placebo.

They found that the high vitamin dose caused no toxic effects.

Then, in a longer-term study, the researchers randomly assigned 340 10- to 17-year-olds to take either 14,000 IU or 1,400 IU of vitamin D3 per week for one year.