Free radicals and Aging (antioxidants)
Peter H. Proctor
pproctor at neosoft.com
Sat Jul 13 11:00:10 EST 1996
In article <Pine.SOL.3.91.960710145914.21124D-100000 at interchg.ubc.ca> browley at UNIXG.UBC.CA (Brian Rowley) writes:
>From: browley at UNIXG.UBC.CA (Brian Rowley)
>Subject: Free radicals and Aging (antioxidants)
>Date: 10 Jul 1996 14:59:48 -0700
>The other thing to think about is that rodents have a greatly inferior
>antioxidant system to humans. Our blood is almost saturated with uric acid
>(sometimes it crystalizes in the joints to cause gout). We also do not
>produce our own vitamin C, unlike most rodents. It turns out that uric
>acid is a greatly superior antioxidant to vitamin C, or so I've heard.
>Vitamin C, in really high doses, actually increases free radicals, so I
>have also heard. So we humans perhaps traded vitamin C for uric acid
>somewhere along the way for that particular antioxidant niche, giving us
>greater longevity. And humans produce more SOD per gram of tissue when
>corrected for metabolic rate. What I'm trying to say is that just because
>antioxidants increase life expectancy of rodents by 30% does not
>necessarily imply that they will do the same for people. We have such a
>good system already, there is less to improve on. Something to consider
It gets even worse. Uric acid is a good example. Yes, it is a good
antioxidant and probably substtitutes for ascorbate in Human evolution.
( BTW, I originally suggested this, he says modestly ).
OTOH, like ascorbate and other strong reducing substances , uric acid
can actually mediate radical oxidations by reducing oxygen to it radical
forms. In fact, this may account for the pathogensis of hyperuricemic
diseases such as the lesch-Nyhan syndrome. Same with a lot of other
so-called "antioxidants". Such processes may actually contribute to some
human diseases. See P. Proctor, Free Radicals and Human Disease, in CRC
Handbook of Free Radicals and Antioxidants, Vol. 1 (1989 ) p211.
Peter H. Proctor, PhD, MD
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