Eliminating food deserts in the U.S. has been a priority on both the federal and state levels for some time now. According to the U.S. Department of Agriculture, up to 2.4 million people live in food deserts — most of these people live in low-income urban neighborhoods or isolated rural areas of the country. With rare access to healthy, fresh foods, like fruits and vegetables, these people face an increased risk of becoming overweight or obese and developing diseases like diabetes and heart disease. Unfortunately, efforts to improve access may be unfruitful.

According to a new study published in the journal PLOS Medicine, initiatives to reduce food deserts and improve local diets may be all for naught. This was the conclusion Harvard researchers came to after analyzing four studies involving food desert interventions in four different neighborhoods in the country: Philadelphia, New York City, Pittsburgh, and Los Angeles. Each time a healthy supermarket was introduced, there was no improvement in fruit or vegetable intake. There weren’t any positive changes in residents’ body mass index (BMI) either.

“We just should not expect the reduction of food deserts to have much impact on the prevailing health crisis of our time,” the study’s co-authors Jason Block and S V Subramanian wrote, according to a press release. “We need to focus our efforts on initiatives more likely to improve dietary quality and decrease disparities.”

This isn’t the first time research has shown food desert programs aren’t working. A November study found that while opening a supermarket in a food desert increased residents’ satisfaction with living in their neighborhood, it did little to improve their diets — only a small margin started eating healthier.

Childhood obesity rates are rampant in low-income areas, and experts suspect limited access to healthy foods has been to blame. However, in another study, a team of researchers from NYU Langone Medical Center set out to investigate two food deserts in the Bronx to figure out how they affected the local children’s diets. They too found that while new supermarkets could supply a variety of healthful foods, they did little to improve children’s diets.

Block and Subramanian proposed introducing education initiatives, changes in food assistance programs, and taxing unhealthy food items. It’s pointless to provide healthy food to a community that doesn’t know how to cook it, or understand the value of eating healthy and changing food preferences. Financial constraints also come into play, which is why government-subsidies could also be used to encourage locals to buy more fruits and vegetables, and fewer processed foods.

“Addressing disparities in dietary quality may have important payoffs for the health of the population,” the authors wrote. “We should promote policies and programs to support these changes [and] build a necessary infrastructure to promote healthy food consumption in any neighborhood.”

Source: Block JP and Subramanian SV. Moving Beyond “Food Deserts”: Reorienting United States Policies to Reduce Disparities in Diet Quality. PLOS Medicine. 2015.