It's interesting that multi-vitamins sometimes have D2 instead of D3. What does that mean? Vitamin D2 is from plants, it's ergocalciferol. It comes from plants that are irradiated by sunlight ...

Most vitamin D3 supplements available over-the-counter are sold in dosages between 1000–5000 IU, but some are higher. “Ask for your provider’s recommendation as to what dosage, if any ...

In population studies, low levels of vitamin D in the body have been associated with a higher risk of type 2 diabetes.