Vitamin D, a steroid hormone synthesized primarily in the skin upon exposure to ultraviolet light, is widely deficient across global populations. This study aimed to fill the data gap in Western Romania by measuring 25-hydroxy-vitamin D levels in a cohort of 7141 from Arad County. It was observed that women, younger adults (18–29 years), and older adults (70–79 years) had notably lower vitamin D levels compared to the average population. Additionally, there was a rise in vitamin D levels over the four-year span of 2018–2022, coinciding with the COVID-19 pandemic. Our research provides fresh data on those most susceptible to vitamin D deficiency and lays the groundwork for educational campaigns on vitamin D supplementation benefits.
