Complex sentence: Walmart also promised to negotiate with suppliers with respect to nutritional issues, reduce prices for whole foods and vegetables, and open stores in low-income areas, so-called "food deserts", where there are no supermarkets.
Split into simpler sentences: Walmart also promised to negotiate with suppliers with respect to nutritional issues. Reductions in the prices of whole foods and vegetables were also promised as well as efforts to open stores in low-income areas, "food deserts", where there are no supermarkets.