Hi PJ, thanks for the illuminating post.  I'm afraid some of us may never agree on this topic, since a one size-fits-all type of recommendation, like that from the IOM doesn't work.  That said, if you are in the normal range for D and not severely deficient, you should be able to get by with 600-800 IUs, but that never worked for me and many others I know.

My first 25 OH D scores was 4!!  Yeah, I know reaaal low.  I also didn't have any malabsorption problems either.  I wasn't put on a 50,000 IU dose, but I did take 5,000 IUs a day and it was only this amount that finally raised my score.  I tried many other amounts 1,000, 2,000 you get the idea and my score rarely moved up.  So for me, the higher daily dose for 10 months did the trick.  Now I'm on about 1/5th of that just to maintain.

Good News is this advice can be used successfully for many, but not all, and I just don't want to see those struggling with this thinking they can raise their score on the dosages the IOM and others recommend.  One thing to remember, when someone is put on these high dosages by their Endocrinologist or Mineral Metabolism doc, it's only for a short time since this is a therapeutic dosage to cure an existing problem.  You rarely ever hear that someone stays on this dose for very long, usually a few months, depending on your score and how low it is.  The thing I don't like about the rx D, is it's always in the D2 form when you can get D3 in those high dosages at pharmacies and elsewhere, but when a doc is treating you they almost always use the rx D2 form that insurance companies cover.  I took D3 and was glad my doc didn't want to inject the D2 or tell me to talk it orally, since I don't think this form works well.

Thanks again for the great info!