07/19/2025
โ๏ธ As it turns out, Vitamin D is technically a hormone, not a vitamin!
Here's how this sun-activated compound shapes your health.
Though commonly labeled a vitamin, vitamin D is more accurately classified as a steroid hormone due to its chemical structure and physiological actions.
Unlike traditional vitamins, which must be obtained through diet, vitamin D can be synthesized in the skin upon exposure to ultraviolet B (UVB) radiation.
Once formed, it behaves like a hormone, binding to the vitamin D receptor (VDR) in various cells and influencing gene expression. This hormonal activity allows it to regulate essential functions, including calcium and phosphate absorption, which are crucial for bone health and overall metabolic stability.
Chemically, vitamin Dโspecifically forms D2 (ergocalciferol) and D3 (cholecalciferol)โis a secosteroid, a subclass of steroids with a broken ring structure. Despite this variation, its activity mirrors that of classic steroid hormones like cortisol or estrogen. Vitamin Dโs influence extends beyond bone health, playing roles in immune modulation, cell proliferation, and even cardiovascular function. However, its potency also calls for caution; studies in animal models suggest that excessive intake can cause vascular calcification. This underscores the need for balance, advocating for safe sun exposure and mindful supplementation rather than high-dose regimens.
Source: Perez, C., & Yelinek, J. (2019). Emotions in storybooks: A comparison of storybooks that represent ethnic and racial groups in the United States. Psychology of Popular Media Culture, 8(3)