Coupons for Healthy Intake Using Variable Economic Strategies (CHIVES)
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December 2016 – October 2018
December 16, 2020
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The CHIVES study aimed to test whether food vouchers redeemable only for fruit and vegetable purchases would improve fruit and vegetable consumption more than vouchers redeemable for any food. The CHIVES study also aimed to assess whether food vouchers redeemable only in one-week increments would improve fruit and vegetable consumption more than vouchers redeemable in monthly increments.
Nutrition assistance program reforms could affect socioeconomic disparities in obesity, cardiovascular disease, and type 2 diabetes, given both the wide-spread participation in these programs and the elevated rate of nutrition-related chronic disease among low-income Americans.
Whether these nutrition assistance programs can support healthier diets by subsidizing healthier food options or restricting food options has been the subject of extensive discussion. These programs assume that providing money for specific food categories will improve dietary intake by encouraging healthier food purchasing patterns. However, most people receiving nutrition assistance also use their own money for additional food purchases. When the CHIVES study was initiated, the extent to which such assistance alters dietary intake was unclear.
Program benefits delivered in a monthly lump sum may contribute to a “consumption cycle”—the tendency for low-income Americans to spend their benefits immediately after receiving their monthly payment and then have limited money for food by month’s end. CHIVES sought to determine whether increasing the frequency of benefit delivery could meaningfully modify dietary intake as this had not yet been assessed in a randomized trial.
A participant was eligible for the study if he or she was age twenty-one or older; had a household income less than 250 percent of the federal poverty level; had regular access to a phone; had English fluency sufficient to provide informed consent; and was a resident of San Francisco, California. A participant was excluded if he or she was participating in another dietary study or food voucher program, had a current diagnosis of cancer or congestive heart failure, or had plans to move out of San Francisco within the following year.
A total of 359 participants were randomized with 332 completing at least one dietary recall in month 6 for analysis. Of those randomized, 86 participants were randomly assigned to receive weekly fruit and vegetable–only vouchers, 90 to receive monthly fruit and vegetable–only vouchers, 92 to receive weekly unrestricted vouchers, and 91 to receive monthly unrestricted vouchers.
CHIVES was a randomized, 2×2-factorial, open-label trial. The factorial design was used to randomly assign participants to receive via mail either fruit and vegetable–only or unrestricted vouchers and either weekly or monthly vouchers. The four arms were therefore as follows: Recipients of weekly fruit and vegetable–only vouchers received four $5 vouchers every month, with each voucher valid for a specified week of the month. These vouchers were restricted to purchases of qualified fruit and vegetables, defined as fresh or frozen fruit, vegetables, or herbs without added sugars or fats. Recipients of monthly fruit and vegetable–only vouchers received four $5 vouchers every month, each valid for the entire month. Recipients of weekly unrestricted vouchers received four $5 vouchers every month, each valid for a specified week of the month. These vouchers allowed purchases of any Supplemental Nutrition Assistance Program (SNAP) eligible food. Recipients of monthly unrestricted vouchers received four $5 unrestricted vouchers every month, each valid for the entire month.
Fruit and vegetable intake was assessed by twenty-four-hour dietary recalls administered by phone by registered dietitians blinded to study allocation. Four dietary recalls were conducted in month 0, two during week 1 and two during week 4. Four follow-up dietary recalls were conducted during the final month of receiving vouchers (month 6), two during week 1 and two during week 4.
The primary outcome was change in fruit and vegetable intake measured in cup equivalents between baseline (month 0) and month 6 of the trial, using the National Health and Nutrition Examination Survey food grouping scheme to classify food items. Secondary outcomes included changes from month 0 to month 6 in the scores on the Healthy Eating Index and the Alternate Healthy Eating Index; voucher use rate (the percentage of vouchers mailed that were redeemed at participating vendors); change from month 0 to month 6 in food insecurity, as measured by the six-item Department of Agriculture Food Security Survey module; responses to an ease-of-use survey at month 6; and change in the consumption cycle (ratio of total calorie intake in week 4 to that in week 1).
Receiving fruit and vegetable–only vouchers did not significantly increase fruit and vegetable consumption compared with receiving unrestricted vouchers. Additionally, weekly vouchers did not significantly increase fruit and vegetable consumption compared with monthly vouchers.
Basu S, Gardner CD, White JS, et al. Effects Of Alternative Food Voucher Delivery Strategies On Nutrition Among Low-Income Adults. Health Aff (Millwood). 2019;38(4):577-584. doi:10.1377/hlthaff.2018.05405
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