I was really surprised to be Vitamin D deficient since I have very pale skin and live in a sunny state. Pale skinned people are supposedly able to get all our Vit. D from 20 minutes or so in the sun. I'm now taking 50,000 IU per week! I think up to 4,000 IU is said to be okay without Dr.'s approval.
I thought this was a little excessive, but here's an article suggesting it's safe.https://www.sciencedirect.com/science/article/abs/pii/S0960076018306228?via=ihub