"One of the most sensitive indicators of an adequate diet is growth curve," Bier says. "If children are growing well and in their [range of expected growth] that is an extraordinarily good indicator that they have an adequate diet."
McDuff says that, fortunately, providing that adequate diet is much easier today, thanks to the increasing number of health food stores and the fact that regular supermarkets offer an array of products to meet vegetarian needs.
"The sheer availability of these foods makes veganism less of an issue than in the past," says Melanie Wilson, editor of Vegetarian Baby and Toddler magazine. Indeed, the well-priced selection of veggie burgers, veggie chicken fingers, tofu dogs and rice-milk desserts is tempting even non-vegetarians to stock up.
And as Americans become less meat-oriented, parents are becoming more accepting when their teens adopt a meatless diet.
"Twenty years ago, my parents freaked out when I told them I didn't want to eat animals," recalled Jeannie McStay, a spokeswoman for the Baltimore-based Vegetarian Resource Group. "Today's parents grew up in the '60s and '70s so are not as shocked."
Back then, teens became vegetarians to defy their meat-eating parents. Today, the reverse also happens: The teens of vegetarian parents rebel by eating meat.
"I get letters from parents on both sides," Hermann says.
Regardless, her advice is the same: Keep offering healthy food at home, then let your children find their own way.