As a big-box behemoth, Wal-Mart (NYSE: WMT) has grown associated with cheap, even junky, food. But in response to healthier eating trends, the discount giant wants to repair that reputation.

Headlines increasingly blare warnings about an epidemic of obesity in America. Unhealthy food sadly tends to be cheaper, and many American families simply can't afford more nutritious options. Now Wal-Mart wants to help alleviate that problem. The company's U.S. chief executive officer, Bill Simon, said in a statement, "No family should have to choose between food that is healthier for them and food they can afford."

The megaretailer plans to alter thousands of food items in the next four years, decreasing sodium by 25% and sugar by 10%. It will also eradicate trans fats and partially hydrogenated oils. Wal-Mart also vowed to help American families save $1 billion on fresh produce, and will devise a labeling system to identify healthier foods on its shelves.

Health-related initiatives are another way to try to get grocery shoppers in the door -- and increase overall customer goodwill. Whole Foods Market (Nasdaq: WFMI) recently revealed similar health-oriented initiatives, including consumer education, presumably in an attempt to differentiate itself from grocery rivals such as Safeway, Kroger, SUPERVALU, Target, and of course, Wal-Mart.

Of course, these other companies won't ignore Whole Foods' behavior. Wal-Mart's clearly trying not to miss out on any increasing healthy eating trends that smaller grocers like Whole Foods could dominate. I previously theorized that big-box discount retailers might have trouble catering to healthier eaters, but perhaps I spoke too soon.

Wal-Mart's plans parallel its previously announced efforts to foster more environmental sustainability in its stores and supply chain. Both of these programs mean that Wal-Mart will work closely with suppliers, more or less pressuring them to do things its way, including making their processes more efficient. There's no doubt that Wal-Mart can exert immense clout, since it attracts 140 million shoppers every single week.

Changes like these benefit consumers by giving them more and better choices. However, there's no guarantee that Wal-Mart's push for healthier foods will help it steal customers from grocers like Whole Foods, nor that its traditional clientele will respond well to the new menu. We'll have to wait and see how shoppers vote with their wallets.

Add your food for thought about Wal-Mart's plan for healthy, cheap eats in the comments box below.

Wal-Mart is a Motley Fool Inside Value selection. Whole Foods is a Motley Fool Stock Advisor recommendation. Wal-Mart is a Motley Fool Global Gains pick. The Fool owns shares of SUPERVALU and Wal-Mart. Try any of our Foolish newsletter services free for 30 days.

Alyce Lomax owns shares of Whole Foods Market. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.