WASHINGTON (AP) — Wal-Mart, the largest U.S. grocer, says it will reformulate thousands of products to make them healthier and push its suppliers to do the same, joining first lady Michelle Obama's effort to combat childhood obesity.

The first lady accompanied Wal-Mart executives Thursday as they announced the effort in Washington. The company plans to reduce sodium and added sugars in some items, build stores in poor areas that don't already have grocery stores, reduce prices on produce and develop a logo for healthier items.

"No family should have to choose between food that is healthier for them and food they can afford," said Bill Simon, president and CEO of Wal-Mart's U.S. division.

As the country's largest grocer, Wal-Mart's size gives it unique power to shape what people eat. The grocery business is nearly twice the size of No. 2 competitor Kroger. The company also has massive influence on products made by other manufacturers and sold at the store.

Mrs. Obama said the announcement has "the potential to transform the marketplace and help Americans put healthier foods on their tables every single day."

"We are really gaining some momentum on this issue, we're beginning to see things move," she said.

Wal-Mart plans to reduce sodium by a quarter and cut added sugars in some of its private label products by 2015. It also plans to remove remaining industrially produced trans fats.

A number of food makers have made similar moves, lowering sodium in their products based on shopper demand and increasing scrutiny by health groups. Bumble Bee Foods, General Mills Inc., Campbell Soup Co., PepsiCo Inc. and Kraft Foods Inc. all announced sodium reductions to their products in this spring alone.

Food makers say they are trying to reduce sodium gradually, making it a more palatable change to its customers and giving the industry time to reformulate products. Most said they support efforts to curb sodium in American's diets but are waiting to see if the Food and Drug Administration decides to mandate a reduction.