I Was told I was low in vitamin D and read that vitamin D3 is the vitamin to take. It's all confusing to me. I am a 69 year old female with severe Crohns Disease, anemia (just had two more blood transfusions) and arthritis. A combination of D3, Magnesium and Calcium made a huge difference with my arthritis pain, but I'm not really sure which D I should be taking or how much is safe. I don't want to cause another problem in my enthusiasm to help my arthritis