A new food-labeling campaign called Smart Choices, backed by most of the nation's largest food manufacturers, is designed to help shoppers easily identify smarter food and beverage choices." The green checkmark label that is starting to show up on store shelves will appear on hundreds of packages, including - to the surprise of many nutritionists - sugar-laden cereals like Cocoa Krispies and Froot Loops. "These are horrible choices," said Walter C. Willett, chairman of the nutrition department of the Harvard School of Public Health. He said the criteria used by the Smart Choices Program were seriously flawed, allowing less healthy products, like sweet cereals and heavily salted packaged meals, to win its seal of approval. "It's a blatant failure of this system and it makes it, I'm afraid, not credible," Mr. Willett said. Froot Loops qualifies for the label because it meets standards set by the Smart Choices Program for fiber and Vitamins A and C, and because it does not exceed limits on fat, sodium and sugar. It contains the maximum amount of sugar allowed under the program for cereals, 12 grams per serving, which in the case of Froot Loops is 41 percent of the product. That is more sugar than in many popular brands of cookies. "Froot Loops is an excellent source of many essential vitamins and minerals and it is also a good source of fiber with only 12 grams of sugar," said Celeste A. Clark, senior vice president of global nutrition for Kellogg's, which makes Froot Loops. Dr. Clark, who is a member of the Smart Choices board, said that the program's standard for sugar in cereals was consistent with federal dietary guidelines.