Health literacy, literacy, numeracy and nutrition label understanding and use: a scoping review of the literature.

BACKGROUND
Low health literacy, literacy and numeracy have been identified as barriers to consumer understanding and the interpretation of nutrition-related information. To inform policy and dietetic practice, we examined the extent, range and nature of research on empirical relationships between health literacy, literacy or numeracy and the understanding and use of nutrition labels.

METHODS
A scoping review of the literature was conducted. A search of eight databases on 15 April 2014 and 26 May 2016 returned 651 and 173 records, respectively. After de-duplication and two levels of relevance screening, 16 studies were deemed eligible for inclusion in the present review.

RESULTS
The majority of studies were conducted in the USA and focused primarily on the use of back-of-pack nutrition labels. Empirical relationships reported between health literacy and nutrition label use were inconsistent and, in some cases, contradictory. The findings from studies examining empirical relationships between literacy, numeracy and nutrition label use suggest that consumers with lower literacy and numeracy: (i) differ from those with higher levels in some of the judgements that they make about food and (ii) may benefit from interventions designed to improve their understanding and use of nutrition label information. Measurement-related issues were identified, such as a reliance on self-reports of nutrition label use, as well as a lack of independence between some measures of health literacy and nutrition label understanding and use.

CONCLUSIONS
The empirical relationships between health literacy, literacy, numeracy and nutrition label understanding and use have not been well-studied. Additional attention is needed regarding the measurement-related issues identified in the present review.