title: The impact of a supermarket nutrition rating system on purchases of nutritious and less nutritious foods.
abstract: OBJECTIVE
  The current study examines the impact of a nutrition rating system on consumers' food purchases in supermarkets.
  
  
  METHODS
  Aggregate sales data for 102 categories of food (over 60 000 brands) on a weekly basis for 2005-2007 from a supermarket chain of over 150 stores are analysed. Change in weekly sales of nutritious and less nutritious foods, after the introduction of a nutrition rating system on store shelves, is calculated, controlling for seasonality and time trends in sales.
  
  
  METHODS
  One hundred and sixty-eight supermarket stores in the north-east USA, from January 2005 to December 2007.
  
  
  METHODS
  Consumers purchasing goods at the supermarket chain during the study period.
  
  
  RESULTS
  After the introduction of the nutrition ratings, overall weekly food sales declined by an average of 3637 units per category (95 % CI -5961, -1313; P<0·01). Sales of less nutritious foods fell by 8·31 % (95 % CI -13·50, -2·80 %; P=0·004), while sales of nutritious foods did not change significantly (P=0·21); as a result, the percentage of food purchases rated as nutritious rose by 1·39 % (95 % CI 0·58, 2·20 %; P<0·01). The decrease in sales of less nutritious foods was greatest in the categories of canned meat and fish, soda pop, bakery and canned vegetables.
  
  
  CONCLUSIONS
  The introduction of the nutrition ratings led shoppers to buy a more nutritious mix of products. Interestingly, it did so by reducing purchases of less nutritious foods rather than by increasing purchases of nutritious foods. In evaluating nutrition information systems, researchers should focus on the entire market basket, not just sales of nutritious foods.
authors.affiliation: 1Department of Policy Analysis and Management,Cornell University,2312 MVR Hall,Ithaca,NY 14853,USA.
authors.forename: John
authors.initials: J
authors.lastname: Cawley
authors.affiliation: 2Mathematica Policy Research,Cambridge,MA,USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Sweeney
authors.affiliation: 3Division of Nutritional Sciences,Cornell University,Ithaca,NY,USA.
authors.forename: Jeffery
authors.initials: J
authors.lastname: Sobal
authors.affiliation: 4Charles H. Dyson School of Applied Economics and Management,Cornell University,Ithaca,NY,USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Just
authors.affiliation: 4Charles H. Dyson School of Applied Economics and Management,Cornell University,Ithaca,NY,USA.
authors.forename: Harry M
authors.initials: HM
authors.lastname: Kaiser
authors.affiliation: 4Charles H. Dyson School of Applied Economics and Management,Cornell University,Ithaca,NY,USA.
authors.forename: William D
authors.initials: WD
authors.lastname: Schulze
authors.affiliation: 5Department of Human Development,Cornell University,Ithaca,NY,USA.
authors.forename: Elaine
authors.initials: E
authors.lastname: Wethington
authors.affiliation: 4Charles H. Dyson School of Applied Economics and Management,Cornell University,Ithaca,NY,USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Wansink
mesh_terms: D001628:Beverages / Q000009:adverse effects / Q000032:analysis / Q000145:classification* / Q000191:economics; D002755:Choice Behavior; D003258:Consumer Behavior; D005502:Food / Q000009:adverse effects / Q000145:classification* / Q000191:economics; D005504:Food Analysis; D005515:Food Labeling; D006801:Humans; D009511:New England; D009518:New York; D018673:Nutrition Policy; D009753:Nutritive Value
keywords: Consumer behaviour; Food choice influences; Nutrition ratings system; Purchasing influences; Supermarkets
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