The star of herbal brain boosters is the extract of the leaves of the
Ginkgo biloba tree, which is revered for its ability to improve
memory, thinking, reasoning, and general mental alertness. Ginkgo
increases blood circulation through the brain to boost the brain's energy
and metabolism. It is an antioxidant and facilitates the transmission of
nerve signals.
Ginkgo biloba has a long, colorful history. It is the oldest tree on
Earth, with fossils showing it to be more than 200 million years old. In
fact, it's the last survivor of an ancient family of trees. You can say
that it is the "Ishi" of the trees. (Ishi was the last surviving member
of his tribe.) About 2,000 years ago, the Ginkgo biloba was nearly
extinct; Chinese monks saved it, because they considered it to be a
sacred tree. After that, they grew ginkgo in their temples. The extract
from the leaves was used as a brain tonic by Chinese herbalists. The name
means "biloba." If you look at a ginkgo leaf, you'll see that its veins
spread out in two directions, so that it looks as if the leaf is cut into
two separate halves, like the lobes of the brain.
The ginkgo tree can now be found all over the world. It has won
acceptance by physicians in Europe, where doctors write more than a
million prescriptions a month to improve brain circulation.
Research into ginkgo's effects on humans shows that it speeds up the
flow of blood and oxygen through the body and brain. It increases the
manufacture of adenosine triphosphate (ATP), which is sometimes described
as the "universal energy molecule." The theory is that ginkgo extract
facilitates brain functioning by helping it to better metabolize glucose,
which produces oxygen, the brain's main source of fuel and energy.
Additionally, ginkgo keeps the brain arteries from clogging up with blood
platelets, by keeping the arteries flexible so that the platelets don't
collect together on the artery walls. It helps the nerve cells transmit
signals from one to another. Ginkgo is a vasodilator, which means it
dilates the blood vessels, especially tiny capillaries. This increased
circulation helps protect the nerves from the damage that can result from
a reduced supply of blood and oxygen, as often occurs with age. If all
these benefits aren't enough, this astounding herb is hailed for its role
as an antioxidant and its ability to improve circulation, which protects
nerves from damage from reduced blood and oxygen supplies, and
contributes to protection from the damage by free radicals.
The active components of ginkgo leaves are flavonoid molecules called
ginkgo heterosides, several terpene molecules, and organic acids,
including vitamin C. The Ginkgo biloba extract (GBE) prepared from the
leaves is marketed in Europe as Tanakan, Rokan, and Tebonin. Culture,
harvesting, and extraction processes are standardized and controlled,
which makes treatment more reliable and research on its effects easier.
In The Healing Power of Herbs, Michael Murray reviews a substantial and
impressive body of research that supports traditional folk wisdom about
ginkgo's beneficial impact on short-term memory, mental alertness, and
general brain functioning. He says that GBE promotes an increased rate of
nerve transmission, improved synthesis and turnover of cerebral
neurotransmitters, and promotion of acetylcholine receptors in the
hippocampus.
GBE can help people just beginning to experience a decline in their
cognitive functioning due to Alzheimer's disease or other symptoms of
aging. Research has shown that in aged animals GBE can normalize
acetylcholine receptors in the hippocampus and increase cholinergic
transmission, which helps Alzheimer's victims. But Murray cautions that
GBE can delay but not prevent onset of Alzheimer's. On the other hand, he
says, GBE is usually effective in reversing decline when the mental
deficit is due to vascular insufficiency or depression.
Ginkgo extract is usually administered in a concentrated powdered form
or in a tincture. Murray reports that at least eight days are necessary
before the first effects are manifested, and that most people notice
benefits within two to three weeks, Pelton says that very high doses have
improved short-term memory in as little as one hour. But, generally, it
is a relatively slow-acting substance. Ginkgo products are available in
most health-food stores. The typical regime involves taking it three
times a day, since ginkgo has a half-life of about three hours, with most
of the substance having dissipated after about six hours.
No side effects from the leaf extract have been reported in the
scientific literature. The ginkgo fruit, on the other hand, probably
should be avoided, because it causes severe allergic reactions similar to
that of poison ivy and poison oak in most people who even touch it.
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horticulture
Harvesting the Leaves
Brief Notes on Ginkgo biloba
Ginkgo Biloba - Maiden Hair Tree
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GINKGO BILOBA: A Nootropic Herb?
Time Life Electronic Encyclopedia: GINKGO
