A growing number of nutrition experts believe the federal government should develop a single national standard for rating the nutritional content of a food item. So far, however, the Land of the Free is relying on the wide variety of industry- and retailer-sponsored nutrition rating programs — Guiding Stars, NuVal and Smart Choices, to name a few. Supporters are now pointing to a new study from Great Britain's Food Standards Agency — the U.K. version of the Food and Drug Administration — to bolster their argument. Extensive consumer research there found that a traffic light format that rates nutrients by amount per serving and overall healthfulness is the most widely comprehended option. The study found consumers easily understood a red circle means stop, yellow means caution and green means go for it.