It could be time to FoodSwitch

Nutritional information is then provided, including the fat, sugar and salt content of each food item. The information is presented in a ‘traffic-light’ format, with ‘red’ indicating a less healthy choice, ‘amber’ representing a reasonable choice and ‘green’ being the healthiest of choices within a food category.

Cost: Free

Compatibility: iPhone, iPad2

Requirements: iOS 4.2 or later