By SHERYL GAY STOLBERG
Published: January 20, 2011

WASHINGTON — Wal-Mart, the nation’s largest retailer, will announce a five-year plan on Thursday to make thousands of its packaged foods lower in unhealthy salts, fats and sugars, and to drop prices on fruits and vegetables.

The initiative came out of discussions the company has been having with Michelle Obama, the first lady, who will attend the announcement in Washington and has made healthy eating and reducing childhood obesity the centerpiece of her agenda. Aides say it is the first time Mrs. Obama has thrown her support behind the work of a single company.

The plan, similar to efforts by other companies and to public health initiatives by New York City, sets specific targets for lowering sodium, trans fats and added sugars in a broad array of foods — including rice, soups, canned beans, salad dressings and snacks like potato chips — packaged under the company’s house brand, Great Value.

In interviews previewing the announcement, Wal-Mart and White House officials said the company was also pledging to press its major food suppliers, like Kraft, to follow its example. Wal-Mart does not disclose how much of its sales come from its house brand. But Kraft says about 16 percent of its global sales are through Wal-Mart.

In addition, Wal-Mart will work to eliminate any extra cost to customers for healthy foods made with whole grains, said Leslie Dach, Wal-Mart’s executive vice president for corporate affairs. By lowering prices on fresh fruits and vegetables, Wal-Mart says it will cut into its own profits but hopes to make up for it in sales volume. “This is not about asking the farmers to accept less for their crops,” he said.

The changes will be introduced slowly, over a period of five years, to give the company time to overcome technical hurdles and to give consumers time to adjust to foods’ new taste, Mr. Dach said. “It doesn’t do you any good to have healthy food if people don’t eat it.”

Wal-Mart is hardly the first company to take such steps; ConAgra Foods, for example, has promised to reduce sodium content in its foods by 20 percent by 2015.

But because Wal-Mart sells more groceries than any other company in the country, and because it is such a large purchaser of foods produced by national suppliers, nutrition experts say the changes could have a big impact on the affordability of healthy food and the health of American families and children.

Some say the company has almost as much power as federal regulators to shape the marketplace.

“A number of companies have said they are going to make voluntary reductions in sodium over the next several years, and numerous companies have said they are going to try to get trans fat out of their food,” said Michael Jacobson, executive director of Center for Science in the Public Interest. “But Wal-Mart is in a position almost like the Food and Drug Administration. I think it really pushes the food industry in the right direction.”

But Wal-Mart is pushing only so far. The company’s proposed sugar reductions are “much less aggressive” than they could be, Mr. Jacobson said, noting that Wal-Mart is not proposing to tackle the problem of added sugars in soft drinks, which experts regard as a major contributor to childhood obesity. And he said it would be “nice if Wal-Mart’s timeline were speedier” than five years.

Wal-Mart has been planning the initiative for more than a year; the effort was in its early stages when Ms. Obama joined it. The first lady’s appearance with Mr. Dach and other Wal-Mart executives when they make the announcement at a community center in Washington’s Anacostia neighborhood on Thursday morning is out of the ordinary and a prominent effort by the administration to spur further moves toward healthier food.

“We’re not just aligning ourselves with one company; we’re aligning ourselves with people who are stepping up as leaders to take this country to a healthier place,” said Sam Kass, the White House chef who doubles as Mrs. Obama’s top adviser on matters of nutrition.

“There’s no qualms about that,” Mr. Kass said. “The only question that we have is do we think this is a significant step in that direction, and do we think there is a method in place to track progress, and do we think this will have the impact we are pushing for.”

Over the last year, Mr. Kass and other aides to the first lady have spent countless hours in meetings with company officials; both Mr. Kass and Mr. Dach said Mrs. Obama pushed the company to hold itself accountable by issuing public progress reports. The Partnership for a Healthier America, a nonprofit organization that works with the first lady on her Let’s Move initiative to reduce childhood obesity, will monitor the company’s progress.

The changes will not happen overnight. Wal-Mart is pledging to reduce sodium by 25 percent, eliminate industrially added trans fats and reduce added sugars by 10 percent by 2015. Its other plans are less specific. In addition to proposing to lower prices on healthy foods, Wal-Mart is planning to develop criteria, and ultimately a seal, that will go on truly healthier foods, as measured by their sodium, fat and sugar content.

The company says it will also address the problem of “food deserts” — a dearth of grocery stores selling fresh produce in rural and underserved urban areas like Anacostia — by building more stores. And it will increase charitable contributions for nutrition programs.

A range of studies has shown that low-income people, especially those who receive food stamps, face special dietary challenges because eating healthy costs more and healthier food is harder to get in their neighborhoods. James D. Weill, president of Food Research and Action Center, an organization that has discussed the problem with Wal-Mart, said the company recognized “how much hunger and food insecurity there is in the country.”

Mr. Dach said the lower prices and food reformulations were motivated by the demands of Wal-Mart’s own customers. He said the company believed that, if it was successful, the price reductions would save Americans who shop at Wal-Mart approximately $1 billion a year on fresh fruits and vegetables alone.

“Our customers have always told us, ’We don’t understand why whole wheat macaroni and cheese costs more than regular macaroni and cheese,’ ” Mr. Dach said, adding, “We’ve always said that we don’t think the Wal-Mart shopper should have to choose between a product that is healthier for them and what they can afford.”

Mr. Jacobson, of the Center for Science in the Public Interest, said that reducing sodium was the trickiest of the food reformulation challenges. Sodium is in every food category, and it is more difficult to replace than the partly hydrogenated oil that composes trans fats, or than sugars, because there are easy substitutes for oils and sugars. But sodium, which contributes to hypertension and raises the risk of heart disease, must simply be reduced, which can greatly alter taste.

Mr. Dach said the company had yet to conquer its reformulation challenges, and described the goals as both aspirational and realistic. “We think it’s a realistic target, but it’s aspirational in the sense that we can’t tell you today how it’s all going to get done,” he said.