Usage and Understanding of Serving Size Information on Food Labels in the United States.

PURPOSE
To investigate consumer understanding and usage of serving size (SS) information on Nutrition Facts (NF) labels.

DESIGN
We analyzed three data sources: (1) U.S. Food and Drug Administration (FDA) Health and Diet Survey (HDS) 1994 (n = 1945), 1995 (n = 1001), and 2008 (n = 2584); (2) National Health and Nutrition Examination Survey (NHANES) 2005-2006 and 2007-2008 (n = 10,750); and (3) 2011 FDA Nutrition Facts Label Experimental Study (NFLES) (n = 9493). Data from FDA are cross-sectional and we focused on usage and meaning of SS.

SETTING
United States.

SUBJECTS
Adults (18+ years).

MEASURES
Both HDS and NHANES addressed how often participants used SS information and HDS also asked how SS is determined. Both NHANES and NFLES contained similar questions on the meaning of SS but NFLES also included an open-ended response option.

ANALYSIS
We included both quantitative and qualitative measures. Questions were analyzed by demographic variables and body mass index with frequencies, cross-tabulations, and χ² statistics reported.

RESULTS
HDS showed that the percentage of consumers who used SS information often or sometimes increased from 54% in 1994 to 64% in 2008. NHANES and NFLES data indicated that a majority of respondents had misinterpreted the meaning of SS. Women and obese individuals were more likely to use SS often or sometimes, but were also more likely to misinterpret the meaning of SS. A small subsample of NFLES participants expressed a distrust of the SS information.

CONCLUSION
There is a widespread misunderstanding about SS, suggesting the need for clearer NF labels or enhanced education efforts.