CHICAGO, June 30 (Xinhua) -- Researchers at the Northwestern University have developed a novel app, FoodSwitch, which can act as a nutritionist at the shopper's side in the grocery store.

With a tap of the screen, users can scan a packaged food's barcode, quickly see its nutritional rating and identify similar foods that are healthier.

The app provides a simple Health Star Rating that scores each food between 0.5 stars of unhealthy to 5 stars of the healthiest. The scoring is based on a scientific algorithm that weighs the impact of different nutrients on health.

The app also provides a breakdown of the food's fat, saturated fat, sugars and salt in grams and gives a percentage of an adult's daily intake for each, which is shown as red, yellow and green traffic lights.

When a food gets few stars or multiple red lights, consumers can see it's high in fat, saturated fat, sugars and salt.

Users also can compare multiple products in the same category, such as regular and fat-free salad dressing, to quickly determine which product is healthier.

Unlike other nutrition apps, FoodSwitch asks users to crowdsource information on new and changing foods within the U.S. food supply to update the app's 268,000-product database in real time, given that 20 percent of the packaged foods in the U.S. turn over every year.

FoodSwitch has already launched successfully in Australia, New Zealand, the United Kingdom, India, China, South Africa and Hong Kong. It officially became available in the United States on June 28.

The United States has the largest food supply, about 400,000 foods, in the world.