The software, known as the Snackwise Nutrition Rating System, assigns points to snack foods using 10 values posted on the nutritional label of food packaging, such as fat, sugar, fiber and vitamins. Each food is then color-coded red, yellow or green with increasing nutritional value.

As a result, school officials may be able to separate snack foods by color, or devote entire vending machines to "green" snacks.

Kristi Houser, a dietitian with Columbus Children's Hospital's Borden Center for Nutrition and Wellness in Ohio, which designed and sells the software product, explained that kids may make different choices about snacks if they know more about what's healthy to eat on a regular basis.

"It's not that you can't eat chocolate chip cookies," she said. "It's just that you need to be aware that you can't buy chocolate chip cookies every time."

Some students may initially grumble and groan if schools provide only "green" snacks, but research shows that they will eventually give in, Houser said.

"If kids are given vending machines filled with healthy snacks, they'll buy it," she said in an interview.

School officials may want to consider setting up tasting tables, so kids can try some of the newer, healthier options before turning their noses up, Houser suggested.

She added that she and her colleagues decided to design the software when they realized that schools have fallen under pressure to modify the snacks they sell to kids, and many nutritional guidelines focus only on fat and sugar, ignoring nutrients.

"Something could get cut out because it just had a little too much fat or sugar," she said.

The Snackwise tool, in contrast, rates snacks using what the researchers consider to be major nutritional concerns for young children: calories, total and saturated fats, fiber, sugar, protein, calcium, iron and vitamins A and C.

Houser said that students might be surprised to learn that baked potato chips receive a yellow, not a green, rating. Although they are low in fat and calories, they do not add anything to a kid's diet, such as fiber or nutrients, making them a less than ideal choice, she said.

The program also gives a yellow rating to regular-sized chocolate bars, because they are "moderately okay" when not sold in the king-sized versions, Houser said.

She and her colleagues introduced the Snackwise program during the American Academy of Pediatrics' Annual Meeting in San Francisco. The program costs $100 for each school district, and is available at www.snackwise.org.