specific disease. Dietary supplements make the following
claims:
health claims. These statements indicate a relation-
ship between an ingredient in the supplement and the
reduction in the risk of developing a disease or con-
dition. (e.g. Increased intake of folic acid by pregnant
women helps reduce the risk of neural tube defects in
their offspring.)
nutrient content claims. These statements describe the
amount of supplement in the product and may contain
words such as ‘‘high in,’’ ‘‘good source of,’’ ‘‘fortified,’’
‘‘enriched,’’ or ‘‘high potency.’’
structure or function claims. These claims describe
how the supplement may affect organs or systems in
the body without mentioning a specific disease or
condition. (e.g. Calcium builds strong bones.).
Labels with structure or function claims must also
contain the words ‘‘This statement has not been eval-
uated by the FDA. This product is not intended to
diagnose, treat, cure, or prevent any disease.’’Active ingredients in green tea
Green tea contains a group of compounds called
polyphenols. Polyphenols have strong antioxidant
properties.Antioxidantshelp protect the body against
damage caused by free radicals. Free radicals are
formed during normal metabolic processes. The quan-
tity of free radicals in the body may also be increased
by exposure to environmental toxins, ultraviolet light,
and radiation. Free radicals have a strong tendency to
react with and damage other compounds, especially
those in DNA (genetic material) and certainfats(lip-
ids) in cell membranes. Antioxidants react with free
radicals to neutralize them. The damage that free rad-
icals cause to cells is believed to play a role in the
development of certain diseases, especially cancer.
Many of the health claims for green tea and green tea
extract are based on the fact that green tea leaves
contain 30–40% polyphenol antioxidants that are
capable of neutralizing free radicals and, by extension,
help prevent disease. In comparison, black tea con-
tains only 3–10% polyphenols.
The six major polyphenols in green tea belong to a
group called catechin compounds. The most active of
these catechins is epigallocatechin gallate (EGCG).
Some manufacturers of green tea extract standardize
the amount of polyphenols and EGCG in each capsule.
Standardization ranges from 50–90% polyphenols
or 100–750 mg of polyphenols. By comparison, one
brewed cup of green tea contains about 50–150 mg
polyphenols. U. S. law does not require the standard-
ization of dietary supplements, so consumers shouldread all labels carefully. Green tea also containscaf-
feineand caffeine-like compounds. Caffeine is a central
nervous system stimulant. The average cup of green tea
contains about 50 mg of caffeine. Decaffeinated green
tea is available. It contains little or no caffeine but still
contains polyphenols. All teas, including green tea,
contain tannin. Tannin is an astringent that slows secre-
tions and helps control bleeding.Health claims
Health claims for green tea are based on the way
the active ingredients act in laboratory (test tube)
studies and in animal studies. The results of green tea
studies in humans have been mixed, and the FDA’s
official position is that the evidence for health benefits of
green tea is not strong enough to meet the requirements
of conventional medicine.However, some studies are
promising. The National Center for ComplementaryKEY TERMS
Antioxidant—A molecule that prevents oxidation.
In the body antioxidants attach to other molecules
called free radicals and prevent the free radicals
from causing damage to cell walls, DNA, and
other parts of the cell.
Astringent—A substance that reduces secretions,
dries and shrinks tissue, and helps control bleeding.
Dietary supplement—A product, such as a vitamin,
mineral, herb, amino acid, or enzyme, that is
intended to be consumed in addition to an individ-
ual’s diet with the expectation that it will improve
health.
Diuretic—A substance that removes water from the
body by increasing urine production
Free radical—An unstable, highly reactive molecule
that occurs naturally as a result of cellular metabo-
lism, but can be increased by environmental toxins,
ultraviolet and nuclear radiation. Free radicals dam-
age cellular DNA and are thought to play a role in
aging, cancer, and other diseases. Free radicals can
be neutralized by antioxidants.
Traditional Chinese Medicine (TCM)—An ancient
system of medicine based on maintaining a balance
in vital energy or qi that controls emotions, spiritual,
and physical well being. Diseases and disorders
result from imbalances in qi, and treatments such
as massage, exercise, acupuncture, nutritional and
herbal therapy is designed to restore balance and
harmony to the body.Green tea