WASHINGTON — Executives from some of the largest mass-market retailers vowed at a White House ceremony to open or expand 1,500 stores in communities designated as “food deserts” because of limited access to nutritious food.

Appearing with first lady Michelle Obama, whose Partnership for a Healthier America is working to combat obesity by improving Americans’ diets, executives from Walgreen Co., Walmart, Supervalu Inc. and a handful of smaller companies pledged to open or remodel stores in the hope of reaching 9.5 million of the 23.5 million Americans who live in areas where finding affordable, healthy food can be difficult.

Walgreens plans to open 1,000 so-called “food oasis” stores over the next five years and said it’s in an ideal position to help solve the problem, in which people living in food desert areas often rely on fast-food restaurants and convenience stores. The chain expects the stores it opens in such areas to benefit 4.8 million consumers.

“With more than 45% of our stores located in areas that don’t have access to fresh food, Walgreens is uniquely positioned to bring more food options to Americans and also provide needed pharmacy, health and wellness services directly in those communities,” president and chief executive officer Greg Wasson said during the White House event.

Walmart, which has opened 218 stores in areas designated by the Department of Agriculture as food deserts, pledged to open as many as 300 stores in such locations by 2016.

Meanwhile, Supervalu said it would open 250 stores in food deserts, using its Sav-A-Lot discount grocery concept to fill the void in a variety of underserved markets. The company expects its stores to attract 3.75 million shoppers weekly.

The Department of Agriculture defines “food deserts” as low-income areas where more than 500 people or 33% of the population live more than one mile from an affordable food store. In rural towns the distance is 10 miles.

Obama praised the retailers for their recognition of what she says is a serious problem for a growing number of low-income Americans and said she was grateful for their efforts to aid the people living in those areas.

“The commitments that you all are making today have the potential to be a game changer,” she said. “When these stores succeed, they can serve as anchors in our communities.”

The first lady, who has made the battle against childhood obesity one of her main priorities, noted that one of every three American children is overweight or obese, leading some scientists to predict that today’s youth could become the first generation to have shorter lives than the previous generation.

More than 6.5 million children live in areas considered to be food deserts, Obama said, noting that the lack of nutritional food in these neighborhoods is a major contributor to the childhood obesity problem.

The government and the private sector need to work together to eliminate food deserts, according to Obama.

“With your commitments today, you all are showing us what’s possible,” she said. “This isn’t some mysterious issue that we can’t address. We know the answer. It is right there.”