February 2 (HealthDay News) -- Many healthy U.S. children and teenagers may be popping vitamins and mineral supplements they don't need, researchers report.

The experts note that vitamin and mineral supplements are not considered necessary when a person eats a varied diet.

On the other hand, children who actually need these supplements -- those with poorer nutrition, less physical activity, and from low-income households -- may not be getting the dosage of vitamins and minerals they require, according to researchers reporting in the February issue of the Archives of Pediatric & Adolescent Medicine.

For its part, the supplements industry views the findings as a "call to action" to get vitamin and mineral supplements to this underserved population, said Duffy MacKay, vice president of scientific and regulatory affairs at the Center for Responsible Nutrition, in Washington, D.C.

The American Academy of Pediatrics does not recommend supplemental vitamins for most children over the age of 1. The supplements are recommended for children with chronic diseases, eating disorders and certain other conditions.

In fact, supplement overdose or poisoning can be an issue, especially in younger (2-to-4-year-olds) children; overdoses can lead to vomiting, or to more serious problems such as kidney or liver damage.

"We were curious about why certain parents may choose to use over-the-counter multivitamin supplements for children, and some might not," said study author Dr. Ulfat Shaikh, an assistant professor of pediatrics at the University of California Davis School of Medicine and pediatrician at UC Davis Children's Hospital. "We hypothesized that supplements might be used to reduce adverse effects if parents thought their child wasn't eating right or were wondering where their next meal was coming from."

The authors reviewed data on vitamin and mineral supplementation as well as diet, exercise and health insurance factors on almost 11,000 children and adolescents aged 2 to 17 from the 1999-2004 National Health and Nutrition Examination Survey.

About a third (34 percent) of young people had used vitamin and mineral supplements in the month before being interviewed.

As expected, underweight children used vitamins and minerals the most.

Surprisingly, however, these supplements were more likely to be consumed by children who did not need them as much, i.e. white children from families with higher incomes, more food security and, overall, better nutrition and physical activity levels. Thirty-seven percent of these children (who were also less likely to be obese) took vitamins, compared to 28 percent of those in less privileged situations.

Cost seems to be the biggest obstacle to lower-income households adding supplements to their children's diet, the team found.

"One of the things that we thought was responsible for this was the possibility that income and parental education status might override other factors," Shaikh said.

And, indeed, the data showed that 22 percent of children in households below the federal poverty line used vitamins, compared with 43 percent in households above the poverty line.

Thirty-eight percent of children in households without food stamps used vitamins, compared with 18 percent of youngsters in households that did use food stamps.

The Center for Responsible Nutrition has been lobbying to get vitamins and mineral supplementation covered by the food stamp program and WIC (Women Infants Children), Duffy said.

SOURCES: Ulfat Shaikh, M.D., assistant professor, pediatrics, University of California Davis School of Medicine and pediatrician, UC Davis Children's Hospital; Duffy MacKay, vice president, scientific and regulatory affairs, Center for Responsible Nutrition, Washington, D.C.; February 2009 Archives of Pediatric & Adolescent Medicine