Usual Intake Distribution of Vitamins and Prevalence of Inadequacy in a Large Sample of Iranian At-Risk Population: Application of NCI Method

Abstract

Objective: This study provides an assessment of usual intake distribution of vitamins and estimating prevalence of inadequacy and excess among a large representative sample of middle-aged and elderly people in central regions of Iran. Design: A cross-sectional study that is a second follow-up to the Isfahan Cohort Study (ICS). Setting: The study setting included urban and rural areas from 3 cities (Isfahan, Najafabad, and Arak) in central regions of Iran. Subjects: Subjects included 1922 people aged 40years and older, with a mean age of 55.9 +/- 10.6; 50.4 were male and the majority (79.3) were urban. Measures and Analysis: Dietary intakes were collected using a 24-hour recall and 2 food records. Distribution of vitamins intake was estimated using traditional and national cancer institute (NCI) methods. The proportion of subjects at risk of vitamin intake inadequacy or excess was estimated using the estimated average requirement (EAR) cut-point method and the tolerable upper intake levels (UL) index. Results: There were differences between values obtained from traditional and NCI methods, particularly in the lower and upper percentiles of the intake distribution. High prevalence of inadequacies for vitamins A, D, E, B-2, B-3 (especially among females), and B-9 was observed. Significant gender differences were found in terms of inadequate intakes for vitamins A, B-1, B-2, B-3, B-6, B-9, B-12, and C (p < 0.05). Conclusion: Imbalanced vitamin intake was observed in the middle-aged and elderly Iranian population. Nutritional interventions particularly through population-based educational programs in order to improve diet variety and consume nutrient supplements may be necessary.