Mapping Definitions, Measures, and Methodologies for Assessing Dietary Diversity in the Nutrition Literature: Results of a Systematic Scoping Review

Dietary diversity (DD) is an established pillar of healthy eating in dietary guidelines, but definitions, measurement, and meanings vary across settings. This scoping review aimed to clarify how DD has been conceptualized, operationalized, and measured as a healthy eating indicator, and to examine the methods and areas of improvement for research on this topic. A systematic search of peer-reviewed and gray literature was conducted using 5 bibliographic databases, organizational websites, and hand-searches addressing food variety, DD, and balanced or mixed diet in the general population in developed settings. Publications in English, French, Persian/Farsi, and Chinese were included. Extracted data were synthesized by quantitative content analysis. We identified 941 publications eligible for inclusion and randomly sampled 20% for data extraction (n = 190). Literature on DD, published since 1985, came from Asian (n = 88, 46%) and Anglo-European (n = 47, 25%) countries, mostly used food-frequency questionnaires (54%), and reported a total of 322 measures (208 assessed whole-diet diversity; 114 measured within-group diversity) and were less commonly validated (14%). Three-quarters of all measures used simple counting (n = 247) and others also weighted (n = 11) or categorized (n = 37) the counts; 25 measures calculated DD as a relative proportion. Across measures, the mean total DD score was 21.99 items or 'groups' (median, 10; range, 1-248). The 208 whole-diet DD measures were widely named and operationalized as 5-6 major food groups alone (n = 23) or in combination with subgroups or items (n = 131). Measurement of within-group diversity has grown since 2010. Over half of 114 within-group diversity measures assessed fruit and/or vegetable diversity, 25% assessed meat/alternatives diversity, 10% assessed grain diversity, and 8% assessed dairy diversity. There is wide variation in the definitions, measures, scoring methods, and foods included in nutrition literature regarding DD. To our knowledge, this is the first comprehensive, international overview of the topic, demonstrating the urgent need for standardization of DD as a research agenda to advance nutrition and food science.