Dietary intake of Vitamin D pattern and its sociodemographic determinants in the Southwest of Iran, Khuzestan: An application of marginalised two-part model

Background: Dietary intake of Vitamin D is an effective public health strategy to improve the current low Vitamin D status of populations. This research aimed to identify subpopulations at greater risk for Vitamin D deficiency. We studied the sociodemographic factors that are potentially associated with dietary intake of Vitamin D in the Iranian population. To do so, we used a marginalised two-part (MTP) model to control for the substantial proportion of zero Vitamin D intake. Methods: Data from 180 cross-sectional random samples were recorded. Dietary intake of Vitamin D was assessed using a 168-item validated food frequency questionnaire. Sociodemographic factors associated with intake of Vitamin D were explored using MTP-Weibull. Results: Mean (standard deviation) daily dietary Vitamin D intake was 0.54 (0.70) μg/day which was below the standard recommended level for all participants. The 'fish, milk and eggs' food group contributed 50% of total dietary intake of Vitamin D. Higher intake was associated with higher levels of education (P = 0.003). Furthermore, the odds of Vitamin D intake was associated with smoking status (odds ratio = 0.613, confidence interval: 0.407-0.914); where smoking decreases the chance of having a non-zero Vitamin D intake by 38.7%. Conclusion: Dietary intake of Vitamin D is below the recommended levels in our study in Iran, a developing country. We identified that education level and smoking status are associated with low intake. This result could lead to the straightforward recommendation for smokers and less-educated individuals to increase their intake of Vitamin D-rich foods.