Can d2 and d3 be taken at the same time? also, does vitamin d affect the absorption of other vitamins and supplements?

I don't really know: why you would be taking both of them. Vitamin D2 is made by plants; vitamin D3 is made by human skin when exposed to sunlight.Foods may be fortified with either. I would pick one or the other (most supplement with D3) as they metabolize to the same form in the body. There is some affect of vitamin D on blood sugar as well as on liver metabolism/cytochrome P450 enzyme system.Review with pharmacist