The role of vitamin D as an essential nutrient is paramount for human health. Research over the past decades has revealed that vitamin D deficiency is particularly widespread in Europe, posing an even greater problem among the elderly population. This vitamin deficiency can have numerous health consequences, especially concerning diseases such as cardiovascular issues, cancer, and osteoporosis. There are various forms of vitamin D, and the level of 25-hydroxyvitamin D is most commonly used to assess vitamin D status. However, the most active form of vitamin D metabolites in the body is 1,25-dihydroxyvitamin D, which mediates the hormonal effects of vitamin D. The majority of vitamin D levels in the…