Introduction to Tea
Green, Black or Herbal?
Boosts the Body's Defense
Perfect Hot Tea
Tannic Acid in Tea
Tea in Cooking
Tea Web Sites
Black, Green or Herbal?
First cultivated in China nearly 5,000 years ago, tea is consumed in greater quantity
worldwide than any other beverage except water. The beverage is made from the leaves
of the plant Camellia sinensis, which is native to India and perhaps parts of
China and Japan.
Black, green and oolong teas are all made from this plant but differ in their methods
of preparation. All tea leaves are withered, rolled and heated, but black teas go through
an oxidative process known as fermentation before the final heating process. Oolong teas
are partially fermented.
Herbal teas are not derived from Camellia sinensis, but from the leaves, bark,
roots, seeds and flowers of other plants. These teas have not been associated with the
many healing benefits related to black and green teas.
Source: Columbia Encyclopedia, Sixth Edition; Tea Association, Tea Council and
Specialty Tea Registry (STAR)
What is green tea?
Green tea comes from a large shrub with evergreen leaves.
The shrub is native to eastern Asia. It has leathery, dark
green leaves and fragrant, white flowers. The dried, cured
leaves have been used to prepare brewed drinks for more than
Green tea and black tea come from the same plant, but green
tea leaves are less processed than black tea. (Black tea is
fermented but green tea is not.) Green tea retains many
chemicals of the fresh leaf.
The scientific name for green tea is Camellia sinensis.
Common names include green tea and Chinese tea.
What is green tea used for?
Green tea is said to have effects that are antimicrobial
(fights bacteria), antimutagenic (prevents mutation of
bacteria), and antioxidant (helps reduce harmful chemicals
in the body).
Green tea is thought to:
- Reduce the risk of cancer and other fatal diseases.
- Lower lipid (cholesterol/fat) blood levels.
- Help prevent dental cavities.
- Treat stomach problems (such as diarrhea and vomiting).
How is green tea taken?
Green tea can be drunk, or it can be swallowed in the form
of a tablet or capsule. An active ingredient of green tea
used in the tablets or capsules is called epigallocatechin.
Follow the directions printed on the product label.
What are the side effects?
Side effects are possible in people who have sensitive
stomachs. Heartburn, stomach irritation, loss of appetite,
and diarrhea could result from drinking large amounts of
Green tea has caffeine in it, which could cause side effects
- a need to urinate more often
- an increase in blood pressure
- an increase in your heart rate.
What precautions are there?
- If you are pregnant, trying to get pregnant, or
breast-feeding, avoid drinking green tea because the caffeine it
contains may be harmful to the baby.
- If you have a weakened cardiovascular system (heart and
circulatory system), kidney disease, or abnormally high
levels of thyroid hormone, you should not take green tea
without the approval of your doctor.
- If you are prone to spasms or have certain psychic
disorders (such as panicky states of anxiety), you should
not use green tea without the approval of your doctor.
- Green tea may worsen asthma.
- Green tea may decrease the effect of warfarin (Coumadin).
If you are taking this medicine, talk to your doctor
before taking green tea.
- If you are being treated for a medical condition
(especially if you are taking prescription medicine), you
should get the approval of your doctor before taking any
- Some natural remedies have the same effects as
prescription medicines. This means there is a danger of
being overmedicated. If you have any unusual effects
while taking any natural remedy, get advice from a doctor
Remember when taking any natural remedy:
- "Natural" does not always mean safe.
- Natural remedies and prescription medicines may interact.
- Lack of standardization may result in products with
different strengths and effects.
- Lack of quality control may allow contamination of
- If you are pregnant or breast-feeding, you should get the
approval of your doctor before taking any natural remedy.
- Follow dosage recommendations on the package. Do not
- Do not use natural remedies for long periods of time
without advice from your doctor.
- If you have any questions about any natural remedy, ask
- Infants, children, and the elderly should not use natural
remedies without advice from a health care professional.
Keep all natural remedies and medicines out of the reach of
The information included here is based on information found
in scientific journals, study reports, news releases, and
other publications. The author and publisher make no
warranty, expressed or implied, as to the accuracy and
complete nature of the information. Nothing herein should
be interpreted as a recommendation by the author or
publisher for the use of any natural remedy.
Developed by Clinical Reference Systems.
Published by McKessonHBOC Clinical Reference Systems.
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