While new research suggests more than one of three of children in the United States take dietary supplements -- mainly in the form of multivitamins and multiminerals -- some doctors question the perceived benefits of these supplements.
The new study, published in the journal Archives of Pediatrics and Adolescent Medicine, suggests that many parents may believe that multivitamins provide children with extra nutrients they might not be getting in their everyday diets.
However, there is no solid evidence that taking a multivitamin improves a child's health.
Dr. David Katz, associate professor of Public Health at Yale University School of Medicine, notes that a recent consensus conference held by the National Institutes of Health (NIH) "concluded that we don't know if multivitamins or minerals do any good."
In the current research, NIH scientists analyzed data from the 1999 to 2002 National Health and Nutrition Examination Survey, which includes information on more than 10,000 children ages 18 or younger.
They found that over 30 percent of children take dietary supplements regularly. Most children only take one supplement, most likely containing some combination of vitamins A, C or D, as well as calcium and iron.
Most medical experts agree that there is no evidence to suggest that children who take multivitamins encounter any negative consequences from ingesting high levels of nutrients.
"In general, I have a favorable view of judicious nutrient supplementation because our ancestors, eating a natural diet of nutrient-rich, calorie-dilute foods, consumed much higher levels of many nutrients than we do today," said Katz. "A supplement can help make up the difference."
However, there are no proven benefits either for the average child. Katz explains that most studies on supplement use have been disappointing.
"On a strictly evidence-based platform, we can't say what [nutrients] are too much, too little, or just right, since we don't know what health effects these supplements are having," he said.
It is important that children get the right amounts of nutrients for growth and development, but taking multivitamin pills may not be the best way.
"How nutrients act in foods, in concert with other nutrients, may differ markedly from how they behave in isolation," said Katz. "Some supplements have tried to address this by keeping nutrients in their native combinations -- a product called Juice Plus, made from fruits and vegetables, is an example."
Researchers found that supplement use was lowest among infants, increased in young children and then declined again in adolescents. Children aged 4 to 6 were most likely to take supplements.
And although dietary supplement use has increased among adults over the years, it has remained relatively constant among teenagers, and it has declined in children. About 50 percent of children took supplements in the 1970s, compared to about 30 percent today.
Part of the reason for this decline among children is due to improved infant formulas, which are now fortified with nutrients such as iron and vitamin D.
"The most common supplement user since 1970 were infants, but with the Infant Formula Act providing needed nutrients, it appears this practice is in decline," said Dr. George Blackburn, associate professor of surgery and nutrition at Harvard Medical School.