Abstract

BackgroundDiet quality is a major contributor to human health. In addition, antioxidants have a great contribution to several chronic conditions. The purpose of this study was to evaluate if dietary total antioxidant capacity (TAC) can be considered as a measure of diet quality in a Middle Eastern country. MethodsIn this cross-sectional study on 6,724 Iranian adults, we used a validated food frequency questionnaire (FFQ) to assess dietary intakes. Data derived from the FFQ was used to calculate dietary TAC and well-known diet quality scores including alternate healthy eating index (AHEI) and dietary diversity score (DDS). Dietary TAC was calculated based on the ferric reducing-antioxidant power (FRAP) values reported in earlier publications. AHEI and DDS have also been constructed based on previous publications. Cross-classification was used to examine the agreement between these measures. ResultsMean age and BMI of study participants were 36.89 +/- 8.08 y and 24.97 +/- 3.87 kg/m(2), respectively. We found that individuals in the highest tertile of dietary TAC had higher scores of AHEI (57.53 +/- 0.20 vs. 52.03 +/- 0.20, P < 0.001) and DDS (5.56 +/- 0.03 vs. 4.15 +/- 0.03, P < 0.001) compared with those in the lowest tertile. Participants' distribution on the basis of the cross-classification analysis indicated that the classifications were in exact agreement for 42.6, within an adjacent tertile for 33.05, and in gross misclassification for 20 of individuals. When this was examined between dietary TAC and DDS, we found that exact agreement in the classifications was for 59.2 of participants. Notably, a very low proportion of gross misclassification was seen in this regard such that only 6 of participants were classified in the opposing tertiles, indicating additional support for a good agreement. ConclusionWe found that dietary TAC might be considered as a proper measure for the assessment of diet quality because it was well correlated with well-known measures of diet quality including DDS and AHEI scores.