Michael F. Jacobson is executive director of the Center for Science in the Public Interest.

How many calories are in that yogurt? How much salt is in that soup? To many people, the nutrition label on packaged food is a given, something that seems always to have been part of the wrapping. But the calorie or sodium or fat content of packaged foods used to be a mystery.

It was only two decades ago, with the Nutrition Labeling and Education Act of 1990, that key nutrition facts were required to be printed on almost all packaged foods. (That law did not cover meat or poultry products, but the Agriculture Department synchronized its regulations for meat and poultry with those of the Food and Drug Administration.) Then-FDA Commissioner David Kessler made sure that the information would be rendered clearly, in contrast to ingredient lists, which are often printed in a tiny, hard-to-read font. The Food and Drug Administration (FDA) issued its final regulations in January 1993. The only substantive change since then has been the addition of a line for trans fat in 2006.

Everyone involved in the passage of the Nutrition Labeling and Education Act knew that the information on, and perhaps the design of, the label would have to be updated as nutrition science evolved and as the public used (or didn’t use) labels. Millions of health-conscious people consider nutrition labels essential when they buy food, but the labels are showing their age. Improving food labels could spur companies to market much healthier foods and encourage consumers to make smarter choices.

One problem is that because of advances in nutrition research since 1993, calories and refined sugars are considered more important today, and concern has shifted from total fat to saturated and trans fats. A bigger problem is that the standard label offers two dozen numbers. But who, other than a nutritionist, might know whether to put back a food that is high in vitamin C and fiber — but also high in sodium and saturated fat?

Some problems could be easily fixed. The labels should display calorie content more prominently. “Sugars” should include only refined sugars added to food and not the naturally occurring sugars in fruits, vegetables and milk. Since — and partly because — trans fat was added to nutrition labels, most artificial trans fat, from partially hydrogenated oil, has been eliminated from foods. The FDA should protect consumers’ health and simply ban partially hydrogenated oil, obviating the need for a “trans fat” line. And consumers would be helped tremendously if the labels highlighted high amounts of saturated fat, sodium and added sugars.

But those changes still would not address label complexity, which can leave many shoppers mystified. What consumers need is easy-to-comprehend information on the front of food packages.

Perhaps the smartest approaches rate foods by giving them credit for the nutrients we should be eating more of and subtracting credit for the bad stuff. The Hannaford Brothers and Food Lion supermarket chains give all foods zero to three gold stars, depending on the balance of nutrients. Everyone can understand these simple ratings, which are printed on shelf tags rather than on labels.

The NuVal system, which is used on shelf tags by Raley’s, Hy-Vee and two dozen other supermarket chains, rates all foods on a scale of 1 to 100. That approach allows people to scan dozens of salad dressings, breakfast cereals or frozen dinners to see which have the highest, or best, numbers.

For several years, the FDA has studied updating food labels to ensure they reflect the latest nutrition science and dietary trends. New regulations might be proposed this year, followed by a period for public comment. The agency has also explored approaches for presenting information on the front of packages.

Let’s hope that, in a few years, food packages will have second-generation labels that really will move our population toward healthier diets. But let’s also hope that Americans eat a lot of foods that don’t have labels and are the healthiest: fresh fruits and vegetables.