Anecdotally, adolescent vegetarianism seems to be rising, thanks in part to YouTube animal slaughter videos that shock the developing sensibilities of many U.S. children.
But there isn't enough long-term data to prove that, according to government researchers.
The new estimate of young vegetarians comes from a recent federal Centers for Disease Control and Prevention study of alternative medicine based on a survey of thousands of Americans in 2007.
Information on children's diet habits was gleaned from about 9,000 parents and other adults speaking on the behalf of those under 18.
Vegetarians are most often female, from higher-income families and living on the East or West coasts, according to previous studies.