5000 IU is high dose. 10,000 is really high. A more moderate dose would be 1000 to 2000 daily. If you live in a northern state, your Vitamin D level will vary with season. And with increased use of sunscreen (which is a good thing), it can be hard to get enough Vitamin D. I'm not opposed to anyone taking Vitamin D (I take it actually). I just want people to take it in moderation unless there is a very clear reason for taking high doses (and there are indications for that).