First it was calories, then it was fat and sodium. Now, the latest health concern is high-fructose corn syrup.

As the country deals with obesity issues, ingredients in food have come under increasing scrutiny, bringing some confusion to the marketplace but also opportunities for companies as they try to differentiate themselves in a competitive grocery store.

Consumer concern has been getting a quick response from food companies, as many remove high-fructose corn syrup from well-known products, replacing it with cane or beet sugar. Sara Lee Corp. is the latest to jump on board, removing the sweetener from its two best-selling breads. Among the big-name products that already have undergone recipe overhauls are Hunt's ketchup, Gatorade, and everything in Starbucks' pastry case.

High-fructose corn syrup, the widely used and historically inexpensive sweetener, has been getting a critical look from food scientists and many American families, due at least in part to books, movies, and studies looking at why Americans continue to gain weight. First lady Michelle Obama has said that she won't feed her daughters products containing the ingredient.

Many medical and nutritional experts, as well as the Corn Refiners Association, say that all sweeteners are metabolized in the same way.

A Princeton University study, on the other hand, has found that long-term consumption of high-fructose corn syrup does lead to abnormal increases in body fat, especially around the belly. Books such as The Omnivore's Dilemma have added to the debate, asserting that widespread use of high-fructose corn syrup is part of what's wrong with the American diet. And movies such as Food, Inc. have heightened many consumers' skepticism.

Last week, Sara Lee, the maker of Jimmy Dean sausages and frozen cheesecake, announced it would remove high-fructose corn syrup from its Soft & Smooth and 100 percent Whole Wheat bread lines because their consumers - mothers in particular - had asked them to. "We're seeing more and more consumers asking for products without high-fructose corn syrup," said Sara Lee spokesman Jeff Dryfhout.

Over the last few years, Kraft Foods Inc. has removed high-fructose corn syrup from its Capri Sun juice drinks, Wheat Thins, Premium crackers, Nabisco 100-calorie packs, and the majority of its salad dressings.

A danger, according to nutritionists, is that a label reading "HFCS-free" could become synonymous with "healthy." Keri Gans, of the American Dietetic Association, said both high-fructose corn syrup and sugar provide a lot of extra calories and no nutritional value. "The message should be that people should limit their baked goods intake and eat less-processed foods with nothing added to it," she said. "And eat more whole foods, fruits, vegetables, and whole grains."

Audrae Erickson, president of the Corn Refiners Association, cited a survey that said only 3.6 percent of consumers are concerned about high-fructose corn syrup: "A sugar is a sugar, whether it's corn sugar or cane sugar." Production of high-fructose corn syrup has been on the decline over the last few years, and that's putting pressure on the corn-growing industry.

For decades, corn syrup reigned as the industrial food-sweetener of choice. Trade barriers made sugar more costly to U.S. consumers, and corn subsidies made the grain-derived sweetener extremely cheap. However, increased ethanol production in recent years has boosted the price of corn and, consequently, of corn sweeteners. The average price of high-fructose corn syrup during fiscal 2009 was 31 cents a pound, compared with 36 cents a pound for sugar, according to the U.S. Department of Agriculture.

"It's clear that food and beverage manufacturers are listening to their customers, who are asking for all-natural sugar," Andy Briscoe, president of the Sugar Association, said in a statement. He added that the association is "excited that Sara Lee has joined with other major brands in making sugar its sweetener of choice, and based on what we've heard, we are confident grocery shoppers will welcome this move."