title: Beverage purchases from stores in Mexico under the excise tax on sugar sweetened beverages: observational study.
abstract: OBJECTIVE
  What has been the effect on purchases of beverages from stores in Mexico one year after implementation of the excise tax on sugar sweetened beverages?
  
  
  METHODS
  In this observational study the authors used data on the purchase of beverages in Mexico from January 2012 to December 2014 from an unbalanced panel of 6253 households providing 205 112 observations in 53 cities with more than 50 000 inhabitants. To test whether the post-tax trend in purchases was significantly different from the pretax trend, the authors used a difference in difference fixed effects model, which adjusts for both macroeconomic variables that can affect the purchase of beverages over time, and pre-existing trends. The variables used in the analysis included demographic information on household composition (age and sex of household members) and socioeconomic status (low, middle, and high). The authors compared the predicted volumes (mL/capita/day) of taxed and untaxed beverages purchased in 2014-the observed post-tax period-with the estimated volumes that would have been purchased if the tax had not been implemented (counterfactual) based on pretax trends.
  
  
  CONCLUSIONS
  Relative to the counterfactual in 2014, purchases of taxed beverages decreased by an average of 6% (-12 mL/capita/day), and decreased at an increasing rate up to a 12% decline by December 2014. All three socioeconomic groups reduced purchases of taxed beverages, but reductions were higher among the households of low socioeconomic status, averaging a 9% decline during 2014, and up to a 17% decrease by December 2014 compared with pretax trends. Purchases of untaxed beverages were 4% (36 mL/capita/day) higher than the counterfactual, mainly driven by an increase in purchases of bottled plain water.
  
  
  CONCLUSIONS
  The tax on sugar sweetened beverages was associated with reductions in purchases of taxed beverages and increases in purchases of untaxed beverages. Continued monitoring is needed to understand purchases longer term, potential substitutions, and health implications.
  
  
  BACKGROUND
  This work was supported by grants from Bloomberg Philanthropies and the Robert Wood Johnson Foundation and by the Instituto Nacional de Salud Pública and the Carolina Population Center. The authors have no competing interests. No additional data are available.
authors.affiliation: Center for Health Systems Research, Instituto Nacional de Salud Pública, Universidad No 655 Colonia Santa María Ahuacatitlán, Cuernavaca, Morelos, Mexico.
authors.forename: M Arantxa
authors.initials: MA
authors.lastname: Colchero
authors.affiliation: Department of Nutrition and Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27516, USA.
authors.forename: Barry M
authors.initials: BM
authors.lastname: Popkin
authors.affiliation: Nutrition and Health Research Center, Instituto Nacional de Salud Pública, Mexico.
authors.forename: Juan A
authors.initials: JA
authors.lastname: Rivera
authors.affiliation: Department of Nutrition and Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27516, USA shuwen@unc.edu.
authors.forename: Shu Wen
authors.initials: SW
authors.lastname: Ng
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001628:Beverages / Q000191:economics* / Q000706:statistics & numerical data; D002648:Child; D002675:Child, Preschool; D003132:Commerce / Q000191:economics / Q000706:statistics & numerical data; D019422:Dietary Sucrose; D005191:Family Characteristics; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008800:Mexico; D008875:Middle Aged; D012959:Socioeconomic Factors; D013549:Sweetening Agents; D013660:Taxes; D055815:Young Adult
chemical_list: D019422:Dietary Sucrose; D013549:Sweetening Agents