Bert Gold wrote:
>> Dima,
>> My reading of the aforemented PNAS paper by Levine et al., (1996)
> disagrees with the very high dose vitamin C protocols which were
> advocated by Pauling and Szent-Gyorgyi, without providing any firm
> evidence on the issue, and without mentioning these great
> investigators by name.
>> Conclusions in the PNAS paper are limited to a new RDA for
> ascorbate for men in their 20s.
>> Bert Gold
> San Francisco
>> Dima Klenchin (klenchin at macc.wisc.edu) wrote:
>> : Q: is it really confirmed by research, or the current state of affair
> : is simply that kilogram amounts of ascorbic acid don't hurt (apparently)?
>> : - Dima
One repeated criticism regarding the ascorbic acid
hypothesis is that ascorbic acid (AA) is water soluble, which means
that absorption of AA would probably occur via a transport
mechanism. Such a mechanism would be saturable, and therefore, the
body might not be able to absorb the mega-dosages of AA which Dr.
Pauling advocates (well, advocated). In a very rapid scan of
Medline, I found studies measuring AA uptake in astrocytes, cornea
cells, epithethial cells with evidence showing a Na+ dependence of
AA uptake as well as inhibition of transport by various anion
transporter blockers. However, I don't know the gold standard
studies nor do I have the knowledge to judge the quality of studies
in this area?
At what level is AA transport across gut epithelial
membranes saturated? How does it compare with estimated
concentrations of AA in the gut at the mega-dosages suggested by
Linus Pauling? Moreover, Dr. Pauling said that the proper amount
of AA should be titrated to just below a threshold which causes
diarrhea. Does this imply that not all of the recommended AA is
not absorbed and that some of its beneficial impact is achieved in
the colon.
Richard Kondo
Cardiovascular Research Lab
UCLA