A comparison of diet quality indices in a nationally representative cross-sectional study of Iranian households

BACKGROUND: Iranian diet quality has been evaluated using indices that have not been created based on Iranian dietary guidelines. This study aimed to examine the applicability of two diet quality indices by examining their associations with nutrient adequacy, nutrient intakes and sociodemographics. METHODS: Dietary data were collected using three 24-h dietary recalls from Iranian households. Nutrient adequacy was assessed using World Health Organization/Food and Agriculture Organization 2002 (WHO/FAO) cut points. Household diet quality was calculated using the Healthy Eating Index (HEI) and Diet Quality Index-International (DQI-I). Sociodemographics of the household members were assessed. Regression analyses were used to examine associations between diet quality and nutrient adequacy, and between sociodemographics and diet quality. RESULTS: A total of 6935 households were included in the analysis. Higher household diet quality was associated with adequate intake of calcium (HEI: OR 1.11, 95% CI: 1.10, 1.13; DQI-I: OR 1.14, 95% CI: 1.13, 1.16), vitamin C (HEI: OR 1.19, 95% CI: 1.17, 1.20; DQI-I: OR 1.12, 95% CI: 1.11, 1.12) and protein (HEI: OR 1.01, 95% CI: 1.00, 1.02; DQI-I: OR 1.09, 95% CI: 1.08, 1.09). Higher household diet quality was associated with household heads who were older (> 56 years old) (HEI: β 2.06, 95% CI: 1.63, 2.50; DQI-I β 2.90, 95% CI: 2.34, 3.45), higher educated (college/university completed) (HEI: β 4.54, 95% CI: 4.02, 5.06; DQI-I: β 2.11, 95% CI: 1.45, 2.77) and living in urban areas (HEI: β 2.85, 95% CI: 2.54, 3.16; DQI-I: β 0.72, 95% CI: 0.32, 1.12). CONCLUSIONS: Based on associations with nutrient adequacy and sociodemographics, the applicability of two diet quality indices for assessing the diet quality of Iranian households was demonstrated. Results also indicated DQI-I may be more applicable than HEI for evaluating Iranian nutrient adequacy. Findings have implications for the design and assessment of diet quality in Iranian populations. Future research should examine the link between these diet quality indices and health outcomes. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12937-020-00646-5.