D-Ribose was postulated to help CFS/Fibromyalgia in 2004 in several papers. Recently it has been demonstrated to help 66% of CFS/Fibromyalgia patients. It is a neuroprotective (protects the brain and will likely help with brain fog).
See also these posts
In terms of microfloras, several gut bacteria appear to require/prefer this sugar according to PubMed. It has been explicitly identified as being used by the healthful Escherichia Coli Nissle 1917 in a 2007 study. Whether this is part the mechanism of action is unclear at present.
Since this is a simple sugar, all sources should be equivalent, so the best buys are shown below.
The dosages used in the studies was 5gm done 3 times a day.
Remember, 1 in 3 will see no help from this. The reason may be variation in microflora between responders and non-responders.
(c) 2012 Ken Lassesen