Vitamin D3 is a specific type of vitamin D. The term "vitamin D" encompasses several related compounds, with D2 and D3 being the most important forms for humans. The key distinction lies in their source and effectiveness.
Vitamin D: The Big Picture
Vitamin D is a fat-soluble vitamin crucial for calcium and phosphorus regulation, impacting bone health, immune function, and more. It exists in various forms, but D2 and D3 are the primary ones found in supplements and foods.
Vitamin D3: The Animal Form
Vitamin D3 (cholecalciferol) is the form naturally produced in the skin upon sun exposure. It's also found in animal-sourced foods like fatty fish and egg yolks. Research suggests D3 is significantly more effective than D2 at raising and maintaining blood levels of vitamin D, often exhibiting two to three times greater storage in the body. This increased potency is a major reason why many prefer D3 supplements.
Vitamin D2: The Plant Form
Vitamin D2 (ergocalciferol) is found in plants and fortified foods. While it shares the overall functions of vitamin D, it's generally less effective at raising and sustaining vitamin D blood levels compared to D3.
Key Differences Summarized:
| Feature | Vitamin D3 (Cholecalciferol) | Vitamin D2 (Ergocalciferol) |
|---|---|---|
| Source | Animals, sunlight | Plants, fortified foods |
| Effectiveness | Higher | Lower |
| Body Production | Yes | No |
In short, when people refer to "vitamin D," they often mean either D2 or D3. However, D3, being more efficiently utilized by the body, is frequently the preferred form in supplements.
