The multifarious symbols, icons and exclamatory nutrition claims that adorn food packaging may sell products, but a group of independent experts in nutrition and communication acknowledged Wednesday that a patchwork of "front-of-package" nutrition ratings has failed dismally to improve Americans' eating habits. And they outlined guidelines to make future labeling more helpful.

panel of the National Academy of Sciences concluded Wednesday that if these prominent labels are to be useful guides to eating right, they should give consumers a minumum of consistent, basic facts about a food item: the calorie content of a portion size that is easily understood, as well as its sodium, saturated-fat and trans-fat levels.

"This is information that is unlikely to currently appear on the front of a package," said Alice Lichtenstein, director of the Tufts University cardiovascular nutrition lab.

The bold nutrition claims more commonly touted on the front of food products -- claims such as "low-carb!" "high in fiber!" "rich in Vitamin C!" "a good source of calcium!" or "no added sugar!" -- offer little information of value to a consumer trying to manage her weight and avoid chronic diseases linked to obesity, the group said. Indeed, the authors added, such labels often distract consumers' attention from evidence of a product's nutritional deficits. A report still to come is expected to explore how such packaging "clutter," as Lichtenstein called these ancillary claims, influences consumers' choices.

The panel dismissed prominent nutritional claims that focus on a product's overall fat content as distinctly unhelpful. Such claims fail to reflect growing evidence that consuming moderate amounts of polyunsaturated fats and monounsaturated fats can help protect against heart disease, the report notes. Drawing attention to fat content also may lead consumers to conclude there is a direct relationship between consumption of dietary fat and obesity, in spite of the fact that no such link has been established.

"There is some evidence that consumers continue to be confused about the various types of fats, and that many continue to avoid even beneficial fats," the report states. The authors recalled the unintended consequences of a time when nutritionists seemed to label all fats as bad: food manufacturers quickly responded by reformulating products to be "fat-free" -- often adding high levels of sodium and sugars in fat's place.

The report, which was released Wednesday by the National Academy's Institute of Medicine,  zeroed in on how "front-of-package" nutrition ratings and symbols -- 20 of which they reviewed in the report -- can best serve consumers. Rather than hornswaggle shoppers with information that a dietitian might find perplexing, ratings systems should communicate in simple shorthand information that helps consumers maintain or reach a healthy weight. Doing so, in turn, will drive down the rate of diseases that are linked to obesity, including Type 2 diabetes, cardiovascular disease and certain cancers, they said.

-- Melissa Healy/The Los Angeles Times