Vitamin D is a crucial fat-soluble vitamin involved in several bodily functions. It helps the body absorb calcium, which is essential for building and maintaining strong bones[^1^][^2^]. A deficiency in vitamin D can lead to bone diseases such as osteoporosis in adults and rickets in children[^2^]. Moreover, vitamin D plays an essential role in the immune system, helping to fight off infections, and has functions in nervous and muscle systems[^1^].

Our bodies produce vitamin D naturally when exposed to sunlight, hence it's often called the "sunshine vitamin"[^3^]. However, it can also be obtained from certain foods and supplements. Foods rich in vitamin D include fatty fish like salmon and tuna, beef liver, cheese, egg yolks, and mushrooms. Additionally, many foods are fortified with vitamin D, including some dairy products, cereals, and orange juice[^3^][^4^].

Vitamin D supplements are available in two forms: D2 (ergocalciferol) and D3 (cholecalciferol). Both have been found effective in maintaining appropriate serum vitamin D levels, although D3 might be more effective at sustaining those levels for a longer duration[^4^].