LAS VEGAS — The increasing number of front-of-pack labeling systems for foods and beverages has led some to wonder if one universal system might be better. The First Amendment might keep that from happening, however, said Sarah Roller, a Washington-based partner for Kelley Drye, during a session June 28 at the Institute of Food Technologists’ annual meeting and food exposition in Las Vegas.

An Institute of Medicine report released last October said federal agencies should develop a new nutrition rating system with symbols to display on the front of food and beverage packaging. The system should replace any other symbols being used on the front of packaging, the report added.

One universal system, even if it is voluntary, would present issues, Ms. Roller said. From a First Amendment standpoint, it might be argued one system bans the speech of other labeling systems, such as Guiding Stars or NuVal, she said.

Ms. Roller said labeling systems that are false or misleading will not last long anyway.

The number of labeling systems may not confuse consumers either, said Annette Maggi, president of Annette Maggi & Associates, Inc. in the Minneapolis area. Retail chains generally use only one labeling system. Consumers generally shop at only one or two stores and thus need to figure out only one or two labeling systems.

Front-of-pack labeling systems fall into three categories, said Ms. Maggi, who worked for NuVal for three years.

First, a factual system involves facts, such as low in fat or high in fiber. Second, a seal-of-approval system has baseline criteria that a product must meet to carry a front-of-pack symbol. The “Great For You” symbol from Wal-Mart Stores, Inc., Bentonville, Ark., is one example. Finally, a nutrient density system involves mathematical equations to determine a score or ranking for a product’s health rating. Guiding Stars and NuVal are examples.

Proving how effective front-of-pack labels are is difficult because retail chains often do not share sales data, Ms. Maggi said. A study appearing in the February 2010 issue of The American Journal of Clinical Nutrition examined Guiding Stars, she said, and a study appearing in the May 2011 issue of the American Journal of Preventive Medicine examined NuVal.

The American Heart Association has examined which consumers may notice its Heart-Check on the front of packaging, said Dennis Milne, director of business relations in Nutrition and Obesity Strategies Development at the Dallas-based association.

The A.H.A. divided consumers into four categories: pro-actives, who are diligent in healthy eating and look at labels; struggling dieters, who may be 10 to 15 lbs overweight but look at labels; the overweight who do not check labels; and the lucky, who are not concerned about nutrition, but they do not have to be because of their high metabolism. The pro-actives and the struggling dieters are most likely to look for the A.H.A.’s Heart-Check mark, Mr. Milne said.

Consumers do not enter retail stores with the strategy of looking for the Heart-Check, he said. If they see the symbol, however, it may be a “tipping point.” It may cause the consumer to choose the product with a Heart-Check over a similar product without one, Mr. Milne said.