title: Effects of price discounts and tailored nutrition education on supermarket purchases: a randomized controlled trial.
abstract: BACKGROUND
  Traditional methods to improve population diets have largely relied on individual responsibility, but there is growing interest in structural interventions such as pricing policies.
  
  
  OBJECTIVE
  The aim was to evaluate the effect of price discounts and tailored nutrition education on supermarket food and nutrient purchases.
  
  
  METHODS
  A 2 x 2 factorial randomized controlled trial was conducted in 8 New Zealand supermarkets. A total of 1104 shoppers were randomly assigned to 1 of the following 4 interventions that were delivered over 6 mo: price discounts (12.5%) on healthier foods, tailored nutrition education, discounts plus education, or control (no intervention). The primary outcome was change in saturated fat purchased at 6 mo. Secondary outcomes were changes in other nutrients and foods purchased at 6 and 12 mo. Outcomes were assessed by using electronic scanner sales data.
  
  
  RESULTS
  At 6 mo, the difference in saturated fat purchased for price discounts on healthier foods compared with that purchased for no discount on healthier foods was -0.02% (95% CI: -0.40%, 0.36%; P = 0.91). The corresponding difference for tailored nutrition education compared with that for no education was -0.09% (95% CI: -0.47%, 0.30%; P = 0.66). However, those subjects who were randomly assigned to receive price discounts bought significantly more predefined healthier foods at 6 mo (11% more; mean difference: 0.79 kg/wk; 95% CI: 0.43, 1.16; P < 0.001) and 12 mo (5% more; mean difference: 0.38 kg/wk; 95% CI: 0.01, 0.76; P = 0.045). Education had no effect on food purchases.
  
  
  CONCLUSIONS
  Neither price discounts nor tailored nutrition education had a significant effect on nutrients purchased. However, the significant and sustained effect of discounts on food purchases suggests that pricing strategies hold promise as a means to improve population diets.
authors.affiliation: School of Population Health, The University of Auckland, Auckland, New Zealand. c.nimhurchu@ctru.auckland.ac.nz
authors.forename: Cliona
authors.initials: C
authors.lastname: Ni Mhurchu
authors.forename: Tony
authors.initials: T
authors.lastname: Blakely
authors.forename: Yannan
authors.initials: Y
authors.lastname: Jiang
authors.forename: Helen C
authors.initials: HC
authors.lastname: Eyles
authors.forename: Anthony
authors.initials: A
authors.lastname: Rodgers
mesh_terms: D000328:Adult; D003132:Commerce; D003365:Costs and Cost Analysis; D004032:Diet / Q000191:economics / Q000592:standards; D005227:Fatty Acids / Q000191:economics*; D005260:Female; D005502:Food / Q000191:economics*; D005518:Food Preferences; D005523:Food Supply / Q000191:economics; D015438:Health Behavior; D006266:Health Education; D006801:Humans; D008297:Male; D008875:Middle Aged; D009520:New Zealand; D016896:Treatment Outcome
chemical_list: D005227:Fatty Acids