For every dollar worth of food stamps enrollees spend on fresh produce in a given month, they receive a one-to-one match, up to $10, $20 or $40, which they can spend only on more fruits and vegetables. The UC San Diego researchers who are studying the program varied the maximum reward amounts and assigned them randomly to participants to help determine the optimal dollar level for changing people's dietary habits.
The six participating Northgate stores -- two in each of the three participating counties -- use loyalty cards to tally produce purchases and distribute the credits. The amount of credit participants have earned and redeemed is itemized at the bottom of their receipts, and the credit carries over from month to month.
Research has shown that affordability is an obstacle to healthier eating for people of modest means. A 2013 study by researchers at Harvard and Brown universities estimated that a healthful diet costs about $550 a year more per person than an unhealthy one. "For many low-income families, this additional cost represents a genuine barrier to healthier eating," the authors concluded. "Yet, this daily price difference is trivial in comparison with the lifetime personal and societal financial burdens of diet-related chronic diseases."
A 2016 report by the U.S. Department of Agriculture revealed that food stamp recipients spend a smaller percentage of their grocery budgets on fruits and vegetables than other Americans do.
Financial incentives like the ones being tested in California can help narrow that gap.
A 2011 study of an incentive program in Massachusetts found that people on food stamps who got an extra 30 cents for every dollar they spent on fruits and vegetables consumed nearly a quarter-cup, or 26 percent, more fresh produce per day than recipients who did not get such an incentive.
This month, Mas Fresco began to enroll a second round of up to 2,000 people who will receive the incentive for one year. The current participants will continue in the program through June.
Prickitt said he hopes that even after their financial incentives end, participants will retain what they have learned about healthy eating and continue buying produce.
Food policy experts note that many other factors can influence a family's food choices, including lack of time.
"If parents are working more than one job or children are in more than one school or activity, how do you teach the skills of how you can prepare food, even on a busy weeknight?" said Dean Sidelinger, a pediatrician and child health medical officer for San Diego County.