Dietary Diversity Indicators and Their Associations with Dietary Adequacy and Health Outcomes: A Systematic Scoping Review

Abstract

Dietary diversity has long been recognized as a key component of diet quality and many dietary diversity indicators (DDIs) have been developed. This systematic scoping review aimed to present a comprehensive inventory of DDIs and summarize evidence linking DDIs and dietary adequacy or health outcomes in adolescents and adults. Two search strategies were developed to identify peer-reviewed articles published in English up until June 2018 and were applied to Medline, Web of Science, and Scopus. A 2-stage screening process was used to select the studies to be reviewed. Four types of DDIs were identified among 161 articles, the majority of them belonging to the food group-based indicator type (n = 106 articles). Fifty studies indicated that DDIs were proxies of nutrient adequacy, but there was a lack of evidence about their relation with nutrients to limit. Associations between DDIs and health outcomes were largely inconsistent among 137 studies, especially when the outcomes studied were body weight (n = 60) and noncommunicable diseases (n = 41). We conclude that the ability of DDIs to reflect diet quality was found to be principally limited to micronutrient adequacy and that DDIs do not readily relate to health outcomes. These findings have implications for studies in low- and lower-middle-income economies where DDIs are often used to assess dietary patterns and overall diet quality.

Keywords: adolescent; adult; body weight; diet quality; dietary diversity; health outcomes; indicators; noncommunicable diseases; nutrition.

FIGURE 1

Systematic literature review flowchart for article selection. (A) Flowchart for selection and inclusion of studies in the systematic review of the evidence of dietary diversity and its relation with measures of dietary adequacy. (B) Flowchart for selection and inclusion of studies in the systematic review of the evidence of dietary diversity and its relationship with health outcomes.

FIGURE 2

Distribution of studies according to the range of the theoretical maximum number of food items used in the food item–based indicators (when information available: n = 27 out of 56 studies).

FIGURE 3

Distribution of studies according to the number of food groups used in the food group–based indicators (when information available: n = 102 out of 106 studies).

FIGURE 4

Number of studies using the different types of dietary diversity indicators for adolescents and adults across the 161 articles included in this review. (A) Number of studies per type and per year. (B) Number of studies per type and per country income classification. DGI, dietary guidelines–based indicator; FGI, food group–based indicator; FII, food item–based indicator; HIE, high-income economies; LIE, low-income economies; LMIE, lower-middle-income economies; OI, other indicator; UMIE, upper-middle-income economies.

FIGURE 5

Studies investigating the relation between dietary diversity indicators and dietary adequacy (n = 50) by country income classification (A), type of dietary assessment (B), and measure of dietary adequacy(C). (D) Number of nutrients used in the measures of dietary adequacy. DGI, dietary guidelines–based indicator; FGI, food group–based indicator; FII, food item–based indicator; HIE, high-income economies; LIE, low-income economies; LMIE, lower-middle-income economies; MAR, mean adequacy ratio; MPA, mean probability of adequacy; NAR, nutrient adequacy ratio; OI, other indicator; PA, probability of adequacy; UMIE, upper-middle-income economies.

FIGURE 6

Results of studies investigating the relation between dietary diversity indicators and measures of dietary adequacy (n = 50) (A) or of excess nutrients (n = 14) (B), according to the type of indicator. DGI, dietary guidelines–based indicator; FGI, food group–based indicator; FII, food item–based indicator; OI, other indicator.

FIGURE 7

Studies investigating the associations between dietary diversity indicators and health outcomes (n = 137) by country income classification (A) or health outcomes (B). (C) Number of health outcomes studied by country income classification. DGI, dietary guidelines–based indicator; FGI, food group–based indicator; FII, food item–based indicator; HIE, high-income economies; LIE, low-income economies; LMIE, lower-middle-income economies; NCD, noncommunicable diseases; UMIE, upper-middle-income economies.

FIGURE 8

Results of studies investigating the associations between dietary diversity indicators and body composition (n = 60) (A), noncommunicable diseases and intermediate biomarkers of health (n = 41) (B), biomarkers of nutritional status (n = 19) (C), mental health and cognitive functions (n = 17) (D), mortality (n = 10) (E), and other health outcomes (n = 18) (F), according to country income classification. HIE, high-income economies; LIE, low-income economies; LMIE, lower-middle-income economies; UMIE, upper-middle-income economies.