For years, health advocates have urged the public to read the ingredients and ignore the marketing. For years, consumers have ignored the health advocates.

But lo! It looks as if they’re finally listening.

Food purchases are less driven these days by what’s written on the front of the box than what’s listed as ingredients, said Andrew Mandzy, director of strategic insights at Nielsen. Some consumers aren’t even reading so much as they are counting: About 61 percent said that the shorter the ingredients’ list, the healthier the product. Many are looking beyond the boxes themselves. In 2014, 48 percent of consumers went online for health information. In 2016, 68 percent did. Use of technology such as calorie-tracking apps is also up, Mandzy said.

“There’s a shift in how people are thinking about ‘better for you,’ ” he said. “People are looking for back-to-basics, simpler ingredients.”

Health professionals are happy to see the shift. “The overall trend of a more-educated consumer is excellent,” said Sharon Allison-Ottey, doctor, health educator, and author of “Is That Fried Chicken Worth It?” “Just being aware of what you’re eating leads you to eating less.”

Front-of-package claims such as “low-fat” and “excellent source of vitamin C” are starting to lose their magical powers, Nielsen data show. Sales of items marked for their lower fat content are down 1.2 percent in dollar value over the past five years. For “fat-free,” sales are down 2.7 percent. Items marked for their “vitamins and minerals” have seen a 0.8 percent decline in that period.

One claim, at least, seems to still work: “natural,” an essentially unregulated and therefore meaningless term. So-called natural foods have included chicken nuggets, Cheetos and Gatorade. Sales for products bearing the label are up 4.2 percent.

But Nielsen also created a separate category with its own, narrower criteria. For that category, the market researchers took a closer look at ingredients, store placement (for example, is it in the “Natural” aisle?), and the rest of the brand. Anything USDA-certified organic, for example, was in, and anything with genetically modified organisms or artificial or synthetic ingredients was out. The growth in that narrower category was nearly triple the growth in the broader one, at 11.2 percent.

As consumers pay closer attention to ingredients, they may be getting a little too zealous, avoiding some that are largely harmless. Sales of products blaring that they are gluten-free are up 11.8 percent over the past five years, and soy-free sales are up 29.8 percent. But health professionals don’t recommend that average Americans make a point of cutting out either of these ingredients

Unless you are diagnosed with celiac disease or gluten intolerance, “‘gluten-free’ has nothing to do with the actual health benefits of the food,” Allison-Ottey said. While she hopes that attention to gluten translates into more-conscious eating overall, that’s not guaranteed. “Can a manufacturer take advantage of a consumer by slapping ‘gluten-free’ on a food that never had it? Yes,” she said.

As for soy, unless you have breast cancer, in which case soy’s estrogen content is a concern, you don’t need to avoid it, Allison-Ottey said. “In an average diet, you wouldn’t have to worry about too much soy,” she said. “You’re not going to over-indulge.”

Food manufacturers are giving customers what they want. “The trend is towards products that have more ‘free from’ labels on them than a NASCAR driver has auto parts endorsements on his jacket,” a Packaged Facts market research report from April said. Gluten-free and soy-free are just the beginning. No artificial ingredients, no trans fats, no high-fructose corn syrup, and no GMOs are also popular.

Of course, not all of it is hype. Artificial trans fats are so unhealthy that the Food and Drug Administration is requiring manufacturers to remove partially hydrogenated oils, the main source of them, from foods by June 2018. High-fructose corn syrup, like all sugar, can contribute to weight gain, diabetes, and other chronic diseases.

Among the very healthiest foods are those that have no labels at all: fresh fruits and vegetables. Consumers seem to be learning this lesson, too. Growth in sales of these items from the perimeter of the supermarket is outpacing those from the center of the store, Mandzy said.

“The fresher the product, typically, the better the product,” Allison-Ottey said. “As close to the ground as you can get.”