It very much depends. There are genes having a strong influence on vitamin D metabolism, and there are people for whom 5k I.U. are too much. (Essentially, they

It very much depends. There are genes having a strong influence on vitamin D metabolism, and there are people for whom 5k I.U. are too much. (Essentially, they are metabolizing D3 into calcitriol and the other form I keep forgetting too fast)