Impact of a farmers’ market healthy food subsidy on the diet quality of adults with low incomes in British Columbia, Canada: a pragmatic randomized controlled trial

Adults with low incomes have lower diet quality than their higher income counterparts. In Canada, the British Columbia Farmers’ Market Nutrition Coupon Program (FMNCP) provides coupons to low-income households to purchase healthy foods in farmers’ markets. The objective of this study was to examine the impact of the FMNCP on the diet quality of adults with low incomes. In a pragmatic randomized controlled trial conducted in 2019, adults with low incomes (≥18 y) were randomly assigned either to an FMNCP intervention (n = 143) or a no-intervention control group (n = 142). The FMNCP group received 16 coupon sheets valued at $21 per sheet over 10–15 wk to purchase healthy foods from farmers’ markets. Participants completed a questionnaire and 2 24-h dietary recalls at baseline (0 wk), immediately post-intervention (10–15 wk), and 16-wk post-intervention (26–31 wk). Diet quality was calculated using the Healthy Eating Index-2015 (HEI-2015). Linear mixed-effects regression assessed differences in HEI-2015 total (primary outcome) and component scores (secondary outcomes) between the FMNCP and control groups at post-intervention and 16-wk post-intervention. Subgroup analyses examined program impacts by sex and age group (18–59 y, ≥60 y). There were no significant differences in HEI-2015 total scores between the FMNCP and control groups at post-intervention (−0.07; 95% CI: −4.07, 3.93) or 16-wk post-intervention (1.22; 95% CI: −3.00, 5.44) overall or between subgroups. There were no significant between-group differences in HEI-2015 component scores at post-intervention, although there were significant differences in component scores for dairy and fatty acids at 16-wk post-intervention. The FMNCP did not significantly improve diet quality among adults with low incomes over the study period. Further research is needed to explore whether higher subsidy amounts or a longer intervention period is needed to meaningfully improve diet quality among adults with low incomes. This trial was registered at [clinicaltrials.gov] as [NCT03952338].