Alpha lipoic
acid - A relatively
unknown antioxidant is actually more potent than its better-known
cousins, such as vitamins C and E, and could prove useful in
treating disease and protecting the body against the daily
assaults that lead to disease and aging, according to a University
of California
Berkeley Scientist.
The antioxidant
is alpha lipoic acid, currently used in Europe to treat peripheral
nerve degeneration (neuropathy) resulting from diabetes. It could
have much broader use in treating disease, however, and may have
general health benefits when taken as a daily supplement like
other antioxidants. It is already available in some health food
stores as a "metabolic antioxidant."
"Alpha
Lipoic Acid
could have far-reaching consequences in the search for prevention
and therapy of chronic degenerative diseases such as diabetes and
cardiovascular disease," says Lester Packer, one of the
leading researchers in the area of antioxidants—vitamin E and
alpha-lipoic acid in particular—and a professor of molecular and
cell biology at the University of California at Berkeley.
"And because it’s the only antioxidant that can easily get
into the brain, it could be useful in preventing damage from a
stroke," he says.
Packer and other
scientists discussed new data on the effects of oxidants and
antioxidants in various areas of biology at a meeting earlier this
month in Santa Barbara of the Oxygen Club of California, an
international group of scientists. Antioxidants are chemicals that
defuse free radicals—destructive chemicals produced by the body
and thought to contribute to aging and ailments ranging from heart
disease to stroke.
Alpha Lipoic
Acid for Stroke
Survival
Known for more than 30 years and once thought to be a vitamin,
alpha-lipoic acid was recognized as an antioxidant a mere seven
years ago, and only recently have scientists discovered how it
works in the body. New data from Packer’s laboratory reported in
this month’s issue of Brain Research show that alpha lipoic acid
can significantly increase survival in rats that have suffered a
stroke, if given before the stroke occurs.
Though
pretreatment with alpha-lipoic acid is impractical, the results
prove the importance of this antioxidant in preventing cell and
tissue damage, Packer says. Studies several years ago showed a
similar role for lipoic acid in preventing tissue damage and death
after a heart attack.
How alpha
lipoic acid works
All
antioxidants (including alpha lipoic acid), the best known are vitamin C and E, beta-carotene,
and related carotenoids, and a family of chemicals called
flavonoids—work by disarming deadly free radicals before they
wreak havoc on cells and tissue in the body.
Essentially
"toxic waste" generated by most normal processes in the
body, from breathing to digestion, free radicals are thought to
contribute to disease and aging. While the body’s normal load of
antioxidants is thought to be sufficient to limit damage from free
radicals, many people take supplements in hopes of reducing free
radical damage even further, and maybe reducing the chance of
developing cancer, heart disease and diabetes.
Also, part of the
reason nutritionists is recommended eating fruits and vegetables
is because they provide large doses of antioxidants. Citrus and
tomatoes contain vitamin C, yellow and orange vegetables provide
large amounts of beta-carotene, fruits have loads of flavonoids
and many natural foods, especially grains, contain vitamin E.
Evidence
strong for Alpha lipoic acid, but not conclusive
Over the years
evidence has accumulated to support the value of taking extra
antioxidants, to the extent that the FDA is now considering
whether to allow health claims on bottles of these supplements.
"Though the evidence is largely circumstantial that
antioxidants are beneficial, it continues to become
stronger," Packer said. "We would be foolish not to take
account of this evidence."
What 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 the
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 show 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 antioxidants levels to determine
whether they can protect against disease, they were unable to find
a way to increase glutathione levels.
Increases
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.
"Just 10 years ago
scientists had a simplistic view of free radicals and
antioxidants," Packer says.
"Today,
knowledge of a global antioxidant network has emerged which is
linked to the metabolic energy producing process—a new
perspective that is leading to an explosion of basic research and
therapeutic studies."
Some of this
recent research was reported at the Oxygen Club meeting in early
February. For example, Packer and Chandan K. Send, a researcher
from Finland, described how alpha-lipoic acid regulates aspects of
the immune system, in particular immune cells called
T-lymphocytes. Other scientists discussed the use of alpha-lipoic
acid in AIDS therapy and the treatment of diabetes.
