The New (Food) Math

Whole Foods

Its "Health Starts Here" program, started in January, encourages employees and shoppers to follow a 28-day whole-foods, low-fat plan, complete with an online personal nutrient assessment.

Safeway

FoodFlex mines data about shoppers' typical grocery purchases from their loyalty cards. The online program then suggests healthy alternatives.

Hannaford Bros.

"Guiding Stars," this grocery chain's nutrition-rating system, started in 2006 and has been a big hit among shoppers who don't know the difference between peanut and olive oils, whole-grain crackers and saltines. But only 28% of analyzed foods merit any stars.