Researchers at the University of Rochester Medical Center in New York looked at the levels of anti-oxidants vs. the amount of smoke exposure in more than 2,000 children and teens ages 6 and 18 in the 2003-2004 National Health and Nutrition Examination Survey.
The study, presented at the Pediatric Academic Society Meeting in Baltimore, showed that secondhand smoke exposure is associated with lower levels of anti-oxidants in children.
"We don't know enough yet to say that this group of children need supplements to make up for the anti-oxidants they're losing, but it's always wise to feed children an abundance of fruits and vegetables high in anti-oxidants and other healthy nutrients," Dr. Karen Wilson said in a statement.
Anti-oxidants are believed to play an important role in protecting the body's cells against free radicals, which can damage cells, Wilson said.
The higher the level of cotinine -- a byproduct of metabolizing tobacco smoke -- in a child's blood, the lower the anti-oxidant level, after controlling for diet and supplements, the researchers said.