The Nervous System
Lesson 9, Page 13 of 19

All of the above are true.


Another amino acid that serves as an important precursor for neurotransmitters is l-Glutamine. Studies have demonstrated that some behavior problems and autism in children are helped by l-glutamine supplementation. This amino acid also helps reduce cravings for sugar and alcohol and has been found to be an important supplement for those suffering from alcoholism and drug addiction, (which will be discussed further in another section of this lesson.) L-Glutamine supplentation seems to stimulate mental function helping in some cases to improve alertness and learning.


GABA (gamma-Aminobutyric acid) is a nonessential amino acid that functions as an inhibitory neurotransmitter in the central nervous system (decreases neuron activity.) GABA is the brain's natural calming agent. In Prescription for Nutritional Healing, James F. Balch, M.D. and Phyllis A. Balch, C.N.C., state that GABA can be taken to calm the mind and body in much the same way as tranquilizer drugs like valium and librium, but without the fear of addiction.

GABA has a slight relaxing or sedative effect which makes it ideal for use right before going to sleep. Many people report an improvement in the quality of their sleep and a feeling of well-being upon arising in the morning. Lucid or colorful dreams are also frequently reported.

Hundreds of clinicals studies have been conducted on GABA. Many of these indicate that it may help the release of human growth hormone, improve sleep cycles, alleviate pain and stabilise blood pressure. Most people experience some of GABA's benefits almost immediately, but to fully appreciate GABA's effectiveness a program of at least eight weeks is suggested. (See "GABA Rice" on page one of this Lesson.)


Melatonin is the substance that is secreted by the pineal gland when it is time for us to sleep. Scientists have discovered that 1 to 3 mg of melatonin, when taken 30 minutes before you wish to sleep, can greatly help the body overcome jet lag. Melatonin is also helpful for some people who have trouble falling to sleep—especially those who work night shifts and thus have to adjust their biological clocks often. One warning about melatonin: If it is taken on an regular basis it can cause grogginess during the day for some individuals. For that reason I recommend its use mostly for jet lag.

Herbs for the Nervous System

Ginkgo Biloba

Ginkgo biloba (Ginkgoaceae), or Maidenhair-Tree, is an ancient Chinese tree and one of the oldest still existing plants. Extracts from its leaves have been used in China for centuries for its health benefits. It wasn't until the 1960's that Ginkgo became widely known to the Western World. Today it is grown in many parts of the United States as an ornamental tree, and many Americans are beginning to discover what the Europeans have known for decades, and the Chinese for centuries, that Ginkgo has some remarkable health-enhancing effects.

Ginkgo biloba extract is one of the most popular over-the-counter medicines used in Europe, where the medical community has recognized it as effective in the treatment of cerebral insufficiency (decreased blood flow to the brain). Recent studies have demonstrated Ginkgo's therapeutic effects in the treatment of dementia (reduction of intellectual capacity), earning it the approval of the German BGA (Bundesgesundheit Amt).1 According to medical research, indications for Ginkgo biloba extracts include Alzheimer's disease and similar dementias, cerebral insufficiency due to stroke, and atherosclerotic disease of the peripheral arteries.2

There are two groups of substances in Ginkgo which scientists consider to be important; the flavonoids, effective as antioxidants, and the terpenes (ginkgolides), which function as anti-coagulants.2 The antioxidant action of Ginkgo has been shown to have beneficial effects on brain neurons subjected to ischemia (lack of oxygen). Myricetin and quercetin, the flavonoid constituents of Ginkgo biloba, are believed to be at least partly responsible.3

Ginkgo has repeatedly been shown to improve cognitive functions in humans and laboratory animals. As we saw in a previous section, decreases in cell membrane fluidity may be a major mechanism in age-related functional decline. A prime cause for the decrease in membrane fluidity is the presence of free radicals. With its antioxidant effect, Gingko biloba extract protects neuronal cell membranes from free radical damage.4 Additionally, Ginkgo helps the brain recover from damage quicker and more completely.5

A review of the scientific literature reveals that there is substantial experimental evidence to support the view that Ginkgo biloba extracts help protect nerve cells from damage due to hypoxia and ischemia (loss of oxygen supply usually due to arteriosclerosis or stroke).6 These studies have also shown that Ginkgo extract is virtually free of side-effects.7 In several placebo-controlled double-blind clinical studies, symptoms of cerebral insufficiency due to Alzheimer's disease and related dementias have been effectively and significantly influenced.2,7,8,9,10 A double blind study done in Denmark, for example, found that Ginkgo biloba extract improved concentration and memory in elderly patients with arterial insufficiency (poor circulation to the brain).11


We saw in the section of this lesson covering the neurotransmitters of the brain that Monoamine oxidase inhibitors (MAO Inhibitors or MAOIs) is a group of drugs that are sometimes effective in treating depression. However, these drugs have a potential for serious side-effects. Extracts of Ginkgo biloba leaves have been shown to inhibit MAO without any adverse side-effects. This is apparently the mechanism behind Ginkgo's reported anti-stress and anti-anxiety effects and leads some to believe that Ginkgo may prove to be an effective aid for individuals suffering from depression.12

Ginkgo for the Heart and Cardiovascular System

Ginkgo has been shown to increase the blood flow to cardiac muscle by reducing the arteriolar spasms that often accompany heart disease.13 Several studies have also shown that by its free radical scavenging ability, Ginkgo helps protect heart muscle from damage due to hypoxia (lack of oxygen.)14,15,16

In one medical study performed in China, extracts of Ginkgo were administered to forty-six coronary heart disease patients resulting in the alleviation of the symptom of angina, improved abnormal electrocardiograms, and decreased blood lipid levels.16 Ginkgo has been shown to have an inhibitory effect on blood platelet aggregation, (the clumping of platelets forming clots); and has been found to inhibit the increase of serum triglyceride levels in high cholesterol diet-treated mice.17

In a placebo-controlled study conducted in Switzerland, treatment with Ginkgo biloba extract produced a highly significant improvement in the walking ability of patients suffering from intermittent claudication, a condition in which severe pain is felt in the calves of the legs when walking due to an inadequate blood supply to the muscles.18

Other Benefits of Ginkgo

In addition to its beneficial effects for the nervous and cardiovascular systems, research has indicated that Ginkgo may hold promise for the treatment of impotence19 especially when combined with Gotu Kola herb. By its general antioxidant effect, it has also been found to significantly reduce impairments to the retina of the eye caused by free-radical damage.20,21 Ginkgo has been found to hold promise for individuals suffering from vertigo 22 and for hearing loss due to compromised blood flow.23,24 A medical study done in France found that Ginkgo helps the congestive symptoms of PMS, particularly breast symptoms.25 Finally, there is clear experimental evidence showing that Ginkgo is beneficial for chronic hepatitis because it helps the body arrest and even partially reabsorb liver fibrosis.26

The extract of Ginkgo is usually used in herbology because the herb must be concentrated for maximum effectiveness. In traditional Chinese medicine, the daily dosage was 3 to 6 grams of leaves as an infusion. The leaves are collected in the Fall after they have turned yellow.

Ginkgo extract is practically free of negative side-effects. Rarely individuals have reported headache, presumably because of the increased blood flow to the brain. If the dosage is reduced for these individuals this symptom may be eliminated. The time-release version of Ginkgo extract may also help prevent this relatively uncommon side-effect, since the dosage is released gradually.

Which of the following is true about the herb ginkgo?

It is one of the oldest still existing trees.
The Chinese have used it in herbal medicine for years.
It is one of the most popular herbal supplements used in Europe.
It has been shown to help dementia and memory loss.
All of the above.

(Select the best answer and click on the "Continue" button.)


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