Imagine having a grocery store pull up right outside your home, stocked with affordable fruits, vegetables and everyday essentials. For people who struggle to get to a supermarket, that could make shopping much easier. But would it also lead to healthier eating?
A new study published in JAMA Network Open found that bringing mobile grocery stores to low-income housing communities didn't significantly improve residents' overall diet quality or fruit and vegetable consumption. However, participants did consume less sodium, suggesting that the service may have influenced some food choices.
Researchers at the University of Minnesota studied 242 adults living in 12 subsidized housing communities in the Minneapolis-St. Paul area. Six communities received weekly visits from the Twin Cities Mobile Market, a grocery store inside a converted bus, while the others served as a comparison group.
The markets carried approximately 170 products, including produce, meat, dairy and pantry staples. Prices were generally lower than at major local grocery stores, and shoppers could use SNAP benefits and additional discounts.
After about six months, researchers examined what participants were eating. They found no significant differences between the groups in overall diet quality, fruit and vegetable intake, calories consumed or added sugar intake. There was also no significant improvement in whether residents had reliable access to enough food.
One result stood out. Participants in communities served by the mobile markets consumed an estimated 397 milligrams less sodium per day than those in the comparison group. That could be meaningful for heart health, since too much sodium can contribute to high blood pressure.
But another finding may help explain why the markets didn't produce broader dietary improvements.
Among participants who shopped at the mobile markets, nearly 96% said they'd recommend the service to others. Yet fewer than half of participants in the market group had shopped there during the fifth and sixth months of the study.
Researchers suggested several possible reasons. Residents may have preferred larger stores with more choices, stuck with familiar shopping habits or found the markets' limited hours inconvenient. Mechanical problems also interrupted some scheduled visits.
The findings suggest that bringing affordable groceries closer to home doesn't necessarily mean people will change where they shop or what they eat.
That question has come up in other food-access research. A recent study of older adults found that participants used substantially more of their free produce benefits when groceries were delivered directly to their homes rather than requiring them to visit a mobile market.
The new study has limitations. Participants were mostly older adults, with an average age of about 66, and all lived in one metropolitan area. Relatively few participants used the markets regularly, and interruptions in service may have affected the results.
That doesn't mean improving access to nutritious food isn't worthwhile. Previous research has found benefits from other grocery assistance programs, although results have varied.
Instead, this study raises a practical question: Is bringing healthy food closer enough, or do programs also need to fit more naturally into the ways people already shop, cook and eat?
The study was supported by the National Institutes of Health, primarily through the National Institute of Nursing Research.