News coverage and sales of products with trans fat: effects before and after changes in federal labeling policy.

INTRODUCTION The Food and Drug Administration mandated that food products list the amount of trans fat per serving on nutrition facts labels by January 1, 2006. There have been no coordinated efforts to raise awareness about trans fat since the policy went into effect, but news coverage may promote informed decisions about food purchases. This paper assesses whether news coverage influenced sales of products containing trans fat, between December 13, 2004, and June 24, 2007, both before and after the labeling policy went into effect. METHODS Sales data for products containing trans fat from a major grocery store chain with stores throughout Los Angeles County were merged with news coverage data from LexisNexis and ProQuest. Cross-sectional time-series regression was conducted in 2008 to assess the effect of news coverage on weekly unit sales volume for seven trans-fat products across 11,997 store-weeks. RESULTS News coverage effects were apparent for sales of two of the seven trans-fat products in the year before the trans-fat nutrition facts labeling policy went into effect (p<0.05 with Bonferroni correction). News coverage effects were observed for sales of six of the seven trans-fat products in the post-labeling period (p<0.05 with Bonferroni correction). For most products, effects were strongest at concurrent and 1-week lags, and they dissipated over time. CONCLUSIONS News coverage about trans fat, combined with labeling information, appears to influence consumer behavior in the short term. News coverage and product labeling may not be sufficient to promote sustained changes in trans-fat purchases.