Vitamin D Levels Among Iraqi Population: Regional and Seasonal Variations

Fluctuations in vitamin D (VITD) impact the health status of individuals across the globe. The present study aimed to assess the seasonal and regional variations in VITD status among the Iraqi population and highlight the extent of these differences across age and gender groups.

A total of 5,014 participants attending a single-consultation outpatient clinic for routine blood tests from three different regions of Iraq [the North (N, 825), the Middle (N, 3277), and the South (N, 912) regions] were recruited. The participants from the Middle region were enrolled throughout the seasons of the year (January through December 2023), whereas participants from the North and South regions were enrolled only during the winter season.

The study revealed a wide range level of VITD spanning from 3 - 110 ng/mL (mean 26.5 ± 15.7 ng/mL). Deficiency (levels < 20 ng/mL) was found in 39% of participants, including 11% with severe deficiency (< 10 ng/mL). Females had significantly higher VITD levels than males. Seasonal analysis revealed significantly lower VITD levels during the winter season (24.8 ± 14.3 ng/mL) as compared to the spring and summer (28.3 ± 14.6 and 28.5 ± 15.5 ng/mL, respectively), while significantly higher levels were observed in autumn (31.3 ± 16.4 ng/mL). Regionally, lower VITD levels were recorded in the North of Iraq (21.7 ± 17 ng/mL) compared to the Middle and Southern regions (24.8 ± 14.3 and 25.1 ± 14.2 ng/mL, respectively). VITD levels also varied by age, with the youngest age groups (< 15, and 16 - 30 years) consistently exhibiting the highest deficiency rates throughout the year and across all regions, with the highest rates observed in winter and the Northern region.

Deficient VITD status in Iraq was found in almost one-third of the population. Deficiency levels were high in the young-age groups in all the regions and seasons. Clear regional and seasonal variations in the 25(OH)D level were spotted among the Iraqi population.