Chicago ? About a third of U.S. children and teens take vitamins, even though most of those taking the pills are healthy, active kids who probably don’t need them, a new study suggests.

Youngsters who could benefit the most from vitamins — kids in fair or poor health with the worst eating habits — were the least likely to take them, researchers reported.

The study was released Monday in the February issue of Archives of Pediatrics & Adolescent Medicine.

The American Academy of Pediatrics recommends supplements for these kids:

• Breast-fed babies: 400 international units of vitamin D drops daily, until they start drinking at least four cups a day of vitamin D-fortified formula or milk.

• Children who don’t drink at least four cups of fortified milk, juice or other vitamin D-fortified foods: 400 IU vitamin D supplements daily.

• Children with iron-deficiency anemia: iron supplements.

• Children with eating disorders, obese kids in weight-loss programs and those with certain chronic illnesses including cystic fibrosis, inflammatory bowel disease and liver disease: various vitamin and/or mineral supplements.

Doctors should always be consulted before starting children on vitamins.