Hi again saregamapa, and thanks for your question.
I haven't heard back from the authors I mentioned, but was able to
find several other articles and documents that summarize enough of the
data in those articles.
First off, the maximum absorption of D-ribose is 88-100% in the small
bowel (up to 200mg / kg / hr):
The above document also gives a brief summary of some of the research
results pertaining to D-ribose.
The following article also discusses some of the pharmacokinetics of
D-ribose in humans:
Hellsten Y, Skadhauge L, Bangsbo J. Effect of ribose supplementation
on resynthesis of adenine nucleotides after intense intermittent
training in humans. Am J Physiol Regul Integr Comp Physiol. 2004
The free full text of this article is available here:
This article states:
" The pharmokinetics of ribose suggest that 88 to 100% of an oral dose
(up to 200 mg × kg-1 × h-1) is absorbed from the small intestine and
distributed to various tissues including skeletal muscle (1). The
dosage used in the present study (3 g) was only 20% of this expected
upper limit of ribose bioavailability, suggesting the doses of ribose
were indeed able to be absorbed to some degree prior to the exercise
This document, submitted to the FDA by Humanetics Corporation in 1997
details a Ribose containing supplement consisting of up to 5 g of
ribose administered 2-4 times per day.
This is a 16 page PDF file with detailed summaries of the majority of
the research on D-ribose supplementation in humans up to the
mid-1990's. Exhibit B (Page 13 of the PDF) gives a table summarizing
studies where ribose was orally administered, along with safety
Here is another potentially interesting article, looking at the
effects of ribose supplementation on exercise:
Op 't Eijnde B, Van Leemputte M, Brouns F, Van Der Vusse GJ, Labarque
V, Ramaekers M, Van Schuylenberg R, Verbessem P, Wijnen H, Hespel P.
No effects of oral ribose supplementation on repeated maximal exercise
and de novo ATP resynthesis. J Appl Physiol. 2001 Nov;91(5):2275-81.
The free full text is available here:
This article more directly addresses your question, however, I have
been unable to locate a copy online or locate the authors:
Gross M, Reiter S, Zollner N. Metabolism of D-ribose administered
continuously to healthy persons and to patients with myoadenylate
Klin Wochenschr. 1989 Dec 4;67(23):1205-13.
Here's the abstract of this article:
"D-ribose was administered orally or intravenously over at least 5 h
to eight healthy volunteers and five patients with myoadenylate
deaminase deficiency. Intravenous administration rates were 83, 167,
and 222 mg/kg/h, which were well tolerated but oral administration of
more than 200 mg/kg/h caused diarrhea. The average steady state serum
ribose level ranged between 4.8 mg/100 ml (83 mg/kg/h, oral
administration) and 81.7 mg/100 ml (222 mg/kg/h, intravenous
administration). Serum glucose level decreased during ribose
administration. The intestinal absorption rate of orally administered
ribose was 87.8%-99.8% of the intake at doses up to 200 mg/kg/h
without first pass effect. Urinary losses were 23% of the
intravenously administered dose at 222 mg/kg/h. Ribose appeared to be
excreted by glomerular filtration without active reabsorption; a renal
threshold could not be demonstrated. The amount of ribose transported
back from the tubular lumen depended on the serum ribose level. There
was no difference in ribose turnover in healthy subjects and patients
with MAD deficiency."
On Google Scholar:
d-ribose bioavailability humans oral -rat -monkey supplement
Some other related articles:
I hope this information is useful. Please feel free to request
clarification prior to rating.