Designing Food Voucher Programs to Reduce Disparities in Healthy Diets

Improving diets through increased food and vegetable (F&V) consumption significantly reduces the risk of cardiovascular disease (CVD). Programs increasing the accessibility and affordability of F&Vs among low-income Americans have been hindered by the food consumption cycle associated with poverty: the tendency to over-consume calories shortly after receiving funds at the beginning of each month, draining the budget for F&V purchases, or for all food purchases, by month's end. An emerging theory about dietary behavior suggests that providing funds for food in smaller installments distributed throughout the month will smooth the consumption cycle and improve healthy eating-counteracting the tendency to respond to lump sum, once-monthly funding installments by purchasing calorie-dense foods immediately after funds are received. The theory also suggests that funds targeted toward specific healthy foods (e.g., F&Vs) will improve diets more than untargeted funds, despite the inconvenience of utilizing targeted funds. We will rigorously test both hypotheses in a real-world setting by comparing alternative approaches for delivering food purchasing vouchers. We have established and tested the infrastructure to provide vouchers accepted by numerous food sellers (e.g., supermarkets, corner shops) in low-income neighborhoods. Leveraging this infrastructure, we will conduct a randomized trial with a two-by-two factorial design, comparing $20 of vouchers valid for one month to four $5 vouchers each valid for a sequential week of the month (lump sum versus distributed funding), and comparing vouchers restricted to F&V purchases to vouchers redeemable for any food (targeted versus untargeted funding). Low-income adults (N=288) recruited through our community partners will be randomized to one of four 6-month interventions: monthly targeted, monthly untargeted, weekly targeted, or weekly untargeted vouchers. Participants will be assessed through efficient verbal 24-hour dietary recalls validated among low-literacy populations, to determine daily consumption of F&Vs and metrics of overall dietary quality at months 0, 6 and 12 (6 months after vouchers end). Additional surveys will identify moderators and mediators of dietary improvement.

Inclusion Criteria: age ≥21 years; household income <250% of the federal poverty level; has regular access to a phone; understands English sufficiently to provide informed consent; a resident of the City of San Francisco as defined by official municipal boundaries; willing to be randomized. Exclusion Criteria: participating in a diet including any other dietary or nutrition study; currently has diagnosed cancer or congestive heart failure; is pregnant; planning to move in the next year.