Vitamin D is one of those nutrients that touches almost everything. Interestingly, Vitamin D is technically a hormone rather than a vitamin. We started calling it “Vitamin D” because it was discovered alongside other vitamins in the early 20th century. That was before scientists fully understood how it was produced and used by the body. By the time its hormonal nature was recognized, the name had already stuck.
Vitamin D is produced in the skin through sun exposure. It influences hundreds of processes throughout the body, from immune defense and mood to bone density and muscle strength. Unfortunately, Vitamin D deficiency is quietly widespread, affecting an estimated one billion people globally.
Sunlight is the most natural source of Vitamin D, but not everyone can get enough sun exposure to trigger significant production. That may be because of skin tone, age, geography, or the amount of time someone spends indoors. For most people, diet and supplementation fill the gap that sunlight can’t provide.
Vitamin D is carried through the body via immune cells. That means that it is directly involved in how the immune system identifies threats and mounts a response. It also contributes directly to reducing cellular inflammation.
When Vitamin D levels are too low, the body becomes slower to defend against threats.
It also benefits the immune system through several other methods. It can support calcium absorption, muscle function, cardiovascular health, and emotional well-being.
In other words, Vitamin D is not some minor nutrient. It is, instead, a foundational piece of your overall health. Testing levels first is always wise. Needs vary, and more is not always better.