re: Antioxidants

Mark Crosby (
Mon, 23 Jun 1997 10:24:02 -0700 (PDT)

Anders Sandberg wrote:
<There seem to be some controversy about antioxidants since the
negative results reported in NEJM last year, and some positive results
published later. At present it is uncertain if (say) vitamin C or E
does some good or not (beside their obvious uses), but it is clear
that eating a lot of fruits and vegetables promotes a longer and
healthier life, possible due to antioxidants or other substances.>

The following URL
provides information on the antioxidant alpha-lipoic acid and itís
role in the bodyís anitoxidant recycling process:

<What [Lester] Packer has fleshed out in recent years is how
alpha-lipoic acid and other antioxidants interact in a complex
recycling process in the body. He showed several years ago, for
example, that vitamin E "recycles" vitamin C in the body; that is,
after vitamin E has disarmed or oxidized a free radical, vitamin C can
come along and return vitamin E to fighting form. The two vitamins
thus work together to prevent free radical damage in the body, Packer
says. Since then he and his colleagues have shown that, in turn,
vitamin C can be recycled by glutathione, an antioxidant produced only
in the body. The cycle continues with another antioxidant, NADPH -- a
coenzyme, or chemical essential to the action of other enzymes --
recycling glutathione.

Despite this detailed understanding of the antioxidant cycle, when
Packer and other researchers tried to boost antioxidant levels to
determine whether they can protect against disease, they were unable
to find a way to increase glutathione levels. Glutathione cannot be
taken by mouth like vitamins C and E because it is broken down in the
stomach before it reaches the bloodstream. Alpha-lipoic acid proved to
be the missing link, Packer says. Not only does it act as an
antioxidant itself, it also stimulates production of glutathione,
giving cells a double dose of antioxidant. It also is easily absorbed
when taken orally, and once inside cells is quickly converted to its
most potent form, dihydrolipoic acid.

Because both alpha-lipoic acid and dihydrolipoic acid are
antioxidants, their combined actions give them greater antioxidant
potency than any natural antioxidant now known, Packer says. He notes
another property of alpha-lipoic acid that makes it a great
antioxidant. Since it is soluble in both water and fat, it can move
into all parts of the cell to neutralize free radicals. Vitamin C, on
the other hand, is limited to the watery parts of cells because it is
soluble only in water; while vitamin E is soluble only in fat and
sticks to the fatty parts of cells.

Packer says alpha-lipoic acid also is important in cell metabolism, or
the production of energy inside the cell. Without alpha-lipoic acid,
cells cannot utilize sugar to produce energy and they shut down. This
makes alpha-lipoic acid a metabolic antioxidant, able to draw on the
cell's own metabolism to magnify its protective effects and that of
other antioxidants.>

Mark Crosby
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