The only way to get efficient
D3 (which is not a
vitamin but a steroid hormone miscalled a
vitamin) is from UVB. Supplementation with enough D3 could compensate a lack of sun exposure. As with B complexes, you will always get flushing as it is not well absorbed no matter how you take it, food contains B, complexes are potent but you are most likely to absorb what you need and flush the rest. With a really healthy diet, I don't see the point of supplementing with potent B, C, A.