Vitamin D, also known as calciferol, is a fat-soluble vitamin that functions as a hormone within the body. This vitamin is essential for the regulation of calcium and phosphate in the bloodstream, which maintains healthy bones and teeth¹².

Sources of Vitamin D

• Synthesis by Skin: The primary natural source of Vitamin D is the synthesis that occurs in the skin upon exposure to ultraviolet B (UVB) radiation from sunlight¹.
• Dietary Sources: Foods such as oily fish (e.g., salmon, mackerel), fortified dairy products, and egg yolks provide Vitamin D. However, dietary sources alone are often insufficient to meet daily needs for many people²³.
• Supplements: Vitamin D can also be obtained from supplements, most commonly in the form of Vitamin D2 (ergocalciferol) and Vitamin D3 (cholecalciferol). Vitamin D3 is considered more potent and effective³.

Functions of Vitamin D

• Bone Health: Vitamin D promotes calcium absorption in the gut, aiding in the formation and maintenance of strong bones and preventing disorders like rickets in children and osteomalacia in adults².
• Muscle Function: It is necessary for muscle contraction and overall muscle function⁴.
• Immune System: Vitamin D modulates the immune response and may reduce the risk of infections and autoimmune diseases⁵.
• Other Roles: It has been implicated in cell growth, neuromuscular function, inflammation reduction, and glucose metabolism⁶.

Vitamin D Deficiency

Vitamin D deficiency can lead to reduced bone density, increasing the risk of fractures and osteoporosis. Symptoms of deficiency may include bone pain, muscle weakness, and a higher predisposition to infections⁶. Certain populations, such as those with limited sun exposure, older adults, and people with darker skin, are at greater risk of deficiency³.

Footnotes

1. Better Health, "Vitamin D" ↩ ↩²

2. NCBI, "Vitamin D Sources, Metabolism, and Deficiency: Available Compounds and Guidelines for Its Treatment" ↩ ↩² ↩³

3. NCBI, "Sports Health Benefits of Vitamin D" ↩ ↩² ↩³

4. Office of Dietary Supplements - NIH, "Vitamin D" ↩

5. NCBI, "Vitamin D and the Immune System" ↩

6. NCBI, "Benefits and requirements of vitamin D for optimal health: a review" ↩ ↩²