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.
Harmless...but Possibly Useless?
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."
A Downward Trend
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.
Researchers also found that supplement use is much more common in health-conscious households. White children in higher-income families are more likely to use supplements compared to black children in lower-income families without health insurance.
And children who watch a lot of television or who live in households where people smoke are less likely to take multivitamins.
"What it means is educated, empowered parents believe nutritional supplements will enhance the health of their children," said Katz. "Of course, we have no real evidence this is so."
Better Safe Than Sorry?
So why do large numbers of parents continue to give their children supplements?
"This is clearly a case where the public has decided that an absence of evidence is not the same as evidence of absence," said Katz. "The view prevails that nutrients in pill form can be good for us.
"This paper shows that parents are willing to put that conviction where their children's mouths are."
For some children, however, taking a multivitamin pill is recommended. Researchers found that children who are skinny are more likely to be given supplements than their chubbier peers. For these children, a multivitamin can improve their health, suggests Katz.
"The one thing that I can most readily endorse is that the lightest children get supplements," he said. "That is logical, if not of proven benefit."
But authors of the article note that even if this is no proven benefit, it is still important for pediatricians and dieticians to take the extra nutrients into account -- especially since individual and national-level estimates of nutrient intake rarely account for them.
"To truly assess the nutrient status and estimate the potential health risks of U.S. children, we must include nutrient intakes from dietary supplements as well as from food," the authors write.
Selecting the Right Supplement
For parents considering a multivitamin for their child, the best advice is to talk to your pediatrician.
"The Pediatric Society says get your nutrients from food, including fortified food/functional food, leaving supplements to special needs children determined by pediatricians," Blackburn said. "Parent advice varies between infant, child and teenager. It would not be good for supplement to replace healthy food as the focus of nutrition among infant, children and adolescents."
Katz agrees. "The real issue here is that nutrient fortification does not make junk food wholesome. A vitamin is a supplement to a healthful diet, and should never be seen as a substitute for it."
If parents feel the need to give their children supplements, Katz recommends only a multivitamin. "Do not supplement single nutrients, with the possible exceptions of fish oil and calcium in girls around puberty," he said. "A multi is fine, but make sure it is in addition to an emphasis on a healthful dietary pattern, not an alternative to it.
"I would not recommend any revisions to basic dietary guidelines because of multivitamin use in children."