A Default Option to Improve Nutrition for Adults with Low Income Using a Prefilled Online Grocery Shopping Cart

OBJECTIVE:To determine whether a prefilled online grocery shopping (default) cart improves the nutritional quality of groceries purchased compared with receiving nutrition education (NE).DESIGN:Longitudinal study.SETTING:Three food pantries in the US.PARTICIPANTS:Thirty-eight adults with low income.INTERVENTION:Groceries were purchased online for 5 consecutive weeks. After a baseline shopping trip, participants were randomized to receive NE or a nutritionally balanced prefilled online grocery shopping cart (ie, default cart) before shopping (from week 1 [T1] to week 4 [T4]).MAIN OUTCOME MEASURES:Diet quality (Healthy Eating Index [HEI-2015] scores), energy, and energy density of each online cart (ie, grocery purchases).ANALYSIS:Piecewise linear mixed-effects models.RESULTS:From baseline to T1, HEI-2015 scores in the default condition significantly increased (95% confidence interval [CI], 9.79-23.39), whereas total calories (95% CI, -10,942 to -1,663) and energy density (95% CI, -0.70 to -0.45) significantly decreased compared with NE. Improved HEI-2015 scores were maintained through T4. Calories and energy density increased from T1 to T4 in the default condition, but values remained lower (ie, more healthful) than the NE condition. In the NE condition, outcomes did not significantly change during the intervention.CONCLUSIONS AND IMPLICATIONS:Providing an online default cart may improve the nutritional quality of grocery purchases. However, future research is warranted to assess whether adding a second nudge later in the intervention or combining the NE and default cart further promotes healthy purchasing behavior.