Walmart, the largest retailer of U.S.-grown rice, announced a new initiative today to "make food healthier and healthier food more affordable." First Lady Michelle Obama joined Walmart for the program announcement, which builds on the administration's "Let's Move" campaign.

Key elements of the program include working with food manufacturers to reduce sodium levels by 25 percent before 2015 on a broad range of grocery items, including grain products. A front-of-package seal will be developed to identify "better-for-you" items, such as whole-grain foods. Walmart will also reduce prices on healthier products that feature reduced sodium, sugar or fat.

"The largest corporation in America is launching a program that has the potential to change the marketplace and help families put nutritious food on their table every single day," Obama said.

Walmart promotes U.S. rice during September National Rice Month through in-store sampling, price reductions and promotional displays. Walmart accounts for an estimated 20 percent of domestic market rice sales.