Advances in Anthropology
2013. Vol.3, No.4, 198-202
Published Online November 2013 in SciRes (http://www.scirp.org/journal/aa) http://dx.doi.org/10.4236/aa.2013.34028
Green Tea: A Potential Alternative Anti-Infectious Agent
Catechins and Viral Infections
University of North Carolina at Chapel Hill, Chapel Hill, USA
Received February 14th, 2013; revised March 17th, 2013; accepted April 13th, 2013
Copyright © 2013 Jennifer Tran. This is an open access article distributed under the Creative Commons Attribu-
tion License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original
work is properly cited.
Tea is the second most consumed beverage in the world, following water. Black, oolong, and green tea
are products of a perennial tree or shrub called Camellia sinensis. Camellia sinensis is native to Mainland
China and is referenced in Chinese literature at least 5000 years ago. Since its discovery, green tea has
been heralded as having several health benefits associated with its consumption. Traditionally, green tea
has been used for a variety of medicinal purposes, such as the prevention and treatment of a variety of
cancers, mental alertness, weight loss, lowering cholesterol level, and UV protection. Studies have shown
that catechins, the polyphenols found in tealeaves, are effective as anti-infectious agents by affecting the
infection process instead of specifically targeting the virus. This treatment strategy has the potential of
reducing the prevalence of drug-resistant viruses and the reliance on anti-viral drug therapies. This paper
will explore the efficacy of green tea in preventing infections by the hepatitis B and C, influenza and hu-
man immunodeficiency virus.
Keywords: Catechins; Viral Infections; Green Tea; Camellia Sinensis; HIV; Influenza; Hepatitis; Ancient
China; Coevolution; Phytochemicals; Phenols
Tea is a widely consumed beverage worldwide. In order for
something to be considered a tea, the beverage must be produc-
ed from the leaves of the evergreen plant, Camellia sinensis,
which is a member of the Thaceae family. Black, oolong, and
green tea are brews of this plant, but vary in their processing
method and degrees of fermentation and oxidation. Steaming
fresh leaves produces green tea, which results in the preserva-
tion of the color (hence the name) and in the highest concentra-
tions of antioxidants in a tea. Studies have shown that the posi-
tive health benefits of green tea may be due to these antioxi-
dants (also known as catechins, the tea polyphenols).
Green tea is widely popular in East Asia (particularly in
China and Japan), whereas, black tea is the preferred tea in the
West. But green tea’s popularity is increasing and is being con-
sumed by more people worldwide due in part to increasing
awareness of the many health benefits that green tea is said to
have as concluded by many scientific studies on this subject
(Random History, 2008).
In Chinese history, the consumption of green tea has been
referenced as far back as the third century B.C. But according
to Chinese folklore, the beginnings of the tea culture began
around 2737 B.C. (Cultural China 2007-2010). The process of
brewing the tealeaves in hot water was discovered accidentally
by the second Emperor of China, Shen Nung. Shen Nung, also
an herbalist who studied plants and herbs, was in the courtyard
of his palace boiling water in order to safely drink it when a
breeze stirred the branches of a tree causing the leaves to drop
into his pot of boiling water. Shen Nung found the combination
to be refreshing and stimulating, and thus the Chinese tea cul-
Tea was consumed primarily for its medicinal properties. As
an herbal medicine, Camellia sinensis leaves were added to
food to provide nutrients and also used as an antidote for poison
(Cultural China, 2007-2010). Chinese people prefer to drink tea
after their meals to take advantage of its benefits in aiding di-
gestion. It was also used to increase alertness and alleviate the
effects of depression and nervous conditions (Random History,
The first written reference to the consumption of tea was in
350 A.D. in a Chinese dictionary (Cultural China, 2007-2010).
During the Tang Dynasty (618-907 A.D.), tea cultivation and
trade increased leading to a period considered the “golden age”
of tea, which is also when tea drinking evolved into an art form
(Cultural China, 2007-2010). In 780 A.D., Lu Yu wrote a book
called Ch’a Ching, or the Tea Classic, that outlined how to
grow and cultivate the plant, how to brew the tea and how to
perform a complicated formal tea ceremony that involved twen-
ty-seven pieces of equipment (Cultural China 2007-2010). The
complexity of the ceremony limited it to wealthy individuals
such as scholars, officials, and members of the royal court. The
manual became the standard for cultivation and production in
China, and eventually became the foundation of a tea ceremony
that emerged in Japan (Moxham, 2003). It was also during the
Tang Dynasty that other flavors, such as jasmine and lotus,
were being incorporated in the brew (Random History, 2008).
Tea remained costly and was limitedly available to royalty
until the fall of the Mongolian empire in 1368 A.D. (Green Tea
Earth, 2010). As tea cultivation and trade increased, the bever-
age became more available to members of every class. For
example, Chinese seamen drank green tea for its high amount
of vitamin C that warded off scurvy and Buddhists chewed the
leaves to help them with their meditation (Green Tea Earth,
2010). People have found that by drinking tea, their health had
improved, their emotions were soothed, and their perceptions
were heightened (Cultural China, 2007-2010). Tea also became
an economic and political tool utilized by China via trade
throughout mainland Asia (Cultural China, 2007-2010). Com-
pressed tealeaves were used as currency to barter (i.e. for horses)
and kept the Chinese army mobile.
Between 729 and 800 A.D., green tea arrived in Japan
(Green Tea Earth, 2010). Emperor Shōmu, the 45th Emperor of
Japan, gave powdered green tea as gifts to Buddhist monks. In
Japan, the teas Sencha (green tea made from un-ground leaves),
Matcha (green tea made from powder) and Bancha (green tea
made from leaves harvested between summer and autumn)
were first introduced with varying processing levels of the
leaves that had harvested at different times (Green Tea Earth
2010). The tea ceremony became an important practice in Japan
that reflected their desire for peace and harmony.
Because of China’s economic superiority and self-sufficiency,
they were able to limit trade to Canton and prohibit Europeans
from entering and communicating with Chinese merchants
(Cultural China, 2007-2010). Tea was introduced to the West in
1606, with the first shipment to Europe being green tea (Green
Tea Earth, 2010). Tea became popular in Europe and was in
high demand in the eighteenth century, but China was able to
deny them access to the product. In response, Europeans intro-
duced opium to the Chinese resulting in a deficit in China’s
economy in the mid-1800s, forcing the country to open the
country to foreign trade (Cultural China, 2007-2010).
Food that defines a culture often has enhancement properties.
Green tea is especially popular in East Asia, particularly in
China and Japan. The Chinese have a saying that translates into,
“Firewood, rice, oil, salt, sauce, vinegar and tea are the seven
necessities to begin a day” (Travel China Guide, 1998-2012).
Tea is mentioned because it is an important beverage and a
source of water in Chinese culture. Another phrase used is “Cu
Cha Dan Fan”, which is used to describe a simple meal and
translates to “coarse tea and tasteless dinner.” (Travel China
Guide, 1998-2012) These phrases emphasize the importance
and prevalence of tea in Chinese daily life.
Green tea is not treated simply as something to be consumed
but is also an art form with symbolic references. The tea proc-
ess is well-defined by the Tea Classic, from its cultivation to its
consumption. Tea and tea wares (teapots, teacups, and tea sets)
should match surrounding elements, which underlies the ulti-
mate goal of Chinese culture of harmonious unity of human
beings with nature (Travel China Guide, 1998-2012). Tea also
has been compared to personal characteristics to describe taste
and fragrance, and is a symbol of elegance. Regarded as the
most Zen-like drink, tea has a unifying characteristic that pro-
duces a feeling of calmness and eliminates inequalities between
individuals when sharing a cup of tea (Travel China Guide,
1998-2012). It is described as a beverage of opposites, while
still creating harmonious combinations; it is spiritual and mate-
rial, invigorating and pacifying (Travel China Guide, 1998-
As other people are introduced to and incorporate green tea
into their lives, a unique tea culture is formed. In Japan, there is
a rigorous tea ceremony called chanoyu which emerged during
the twelfth century that reflects the nation’s character of mak-
ing full use of every resource (Travel China Guide, 1998-2012),
and evolved to become “a precise pattern of behavior designed
to create a quiet interlude during which the hosts and guests
strive for spiritual refreshment and harmony with the universe”
(Pettigrew, 2004). The goal of the tea ceremony is to promote
world peace through a spiritual cultivation that encourages
simplicity and humility (Sen, 1998; Random History, 2008). In
the West, tea may be consumed with sugar and milk and served
with desserts to create a leisurely and romantic atmosphere
(Travel China Guide, 1998-2012).
Although varying tea-drinking habits exist, it is obvious that
tea is enjoyed worldwide and has meaning and value to each
culture despite how long tea has been present in that region.
Green tea is becoming more well known for its medicinal prop-
erties and can be consumed in a variety of ways to take advan-
tage of them, such as, in a beverage, in food products enhanced
with tea catechins, or in concentrated capsules.
Phytochemicals are biologically active compounds found in
plants. Catechins are the bioactive compounds found specifi-
cally in the leaves of Camellia sinensis. With increasing speci-
ficity, catechins can be defined as phytochemicals, polyphenols,
flavonoids, and tannins.
Polyphenols describes the chemical compound structure of
having several hydroxyl functional groups (−OH) attached to
an aromatic hydrocarbon group (Xie et al., 2012). Categorized
as secondary metabolites, polyphenols can also be divided into
smaller subgroups. One subgroup of polyphenols is flavonoids,
which has its own subdivision of flavanol monomers (or cate-
chins). Phenols are widely spread throughout the plant kingdom,
which suggests a beneficial adaptation had occurred early in
human and plant history that was naturally selected for. It also
suggests that there exists a long coevolutionary history between
phenolic acids and the consumers of plants that contain them.
Phenols are essential for the fitness of the plants (i.e. growth
and reproduction) and are produced as a defense response against
pathogens. Recent interests in phenolic compounds stem from
their potential protective role against oxidative damage diseases
(coronary heart disease, stroke, and cancers) and its possible
utility as a natural antioxidant.
Catechins are antioxidants that scavenge for free radicals that
can damage DNA, change the cell, cause cell death, and con-
tribute to cancer, blood clots and atherosclerosis (University of
Maryland Medical Center, 2011). These compounds may be
able to do this by neutralizing free radicals and reducing or
even helping prevent some of the damage they cause. Catechins
are more concentrated in green tea due to its minimal process-
ing. They make up approximately 30% to 40% of the dry
weight of green tea leaves (Molinari et al., 2006). Some of the
primary catechin compounds include epicatechin, epigallocate-
chin, epicatechin-3-gallate, and epigallocatechin gallate (EGCG)
(Molinari et al., 2006). Epigallocatechin gallate is the most
Open Access 199
studied and most active catechin in green tea. It makes up ap-
proximately half of the total catechins (University of Maryland
Medical Center, 2011). EGCG is the main active ingredient in
green tea leaves and has a molecular formula of C22H18O11
Health Effects and Benefits
Green tea has many well-known effects and benefits. It has
anti-diabetic, hypocholesterolemic, anti-inflammatory, anti-car-
cinogenic, anti-cavity, thermogenic, probiotic, antimicrobial
and antiviral properties (Song & Seong, 2007; Molinari et al.,
Population-based and in vitro studies have been conducted to
show that catechins may help kill cancerous cells and stop their
aberrant growth in bladder, breast, ovarian, colorectal, esopha-
geal, lung, pancreatic, prostate, and skin cancer (University of
Maryland Medical Center, 2011).
Green tea’s antimicrobial properties are effective against a
variety of microbes, which include Helicobacter pylori (gastric
malignancy), Staphylococcus aureus (MRSA), Oral strepto-
cocci (dental caries), Mycobacterium tuberculosis (tuberculo-
sis), Bacillus cereus (food poisoning), Escherichia coli O157
(severe diarrhea and kidney failure), Legionella pneumophila
(pneumonia), Candida albicans (candidiasis), and Chlamydia
trachomatis (chlamydia) (Song & Seong, 2007).
Its antiviral properties are effective against HIV, influenza,
Epstein-Barr, Herpes, Hepatitis B and C, and Human T-cell
lymphotropic virus type 1 (HTLV-1; leads to adult T-cell leu-
kemia) (Song & Seong, 2007; Xu et al., 2008; Ciesek et al.,
2011). Because the use of antiviral drugs can cause the emer-
gence of drug-resistant viral strains, the cultural adoption of
green tea consumption appears to be a potential effective anti-
infection agent with minimal (if any) negative consequences.
Materials and Methods
For this paper, I used the PubMed search engine to find and
analyze studies designed to determine the effect that phytoche-
micals extracted from green tea had on various infections. I nar-
rowed my selection by reviewing papers that focused on viral
infections, and that were conducted as either a population or in
vitro study using human cells. The studies I selected were pub-
lished between 2008 and 2011.
Hepatitis B and C
Hepatitis is the irritation and inflammation of the liver due to
a viral infection. The Hepatitis B virus (HBV) is endemic in
Asia (Xu et al., 2008). An in vitro study conducted by Xu et al.
(2008) involved the combination of natural green tea extract
with an HBV cell line (HEPG2-N10) to determine the 50% ef-
fective concentration on the expression of viral antigens
(HBsAg and HBeAg), extracellular HBV DNA and intracellu-
lar replicative intermediates and nuclear covalent closed circu-
lar DNA, and HBV mRNAs. The study yielded results for the
50% effective concentration of green tea extract on HBsAg
(5.02 g/mL), HbeAg (5.681 g/mL), extracellular HBV DNA
(19.81 g/mL) and intracellular HBV DNA (10.79 g/mL). The
authors concluded that green tea extract and EGCG in particu-
lar inhibits the Hepatitis B virus in vitro.
The Hepatitis C virus (HCV) is a major cause of liver cirrho-
sis and hepatocellular carcinoma (Ciesek et al., 2011). Another
in vitro study conducted by Ciesek et al. (2011) combined 100
M of epigallocatechin-3-gallate (EGCG) to a medium of in-
fected cells (hepatoma cell lines and primary human hepato-
cytes). EGCG was identified as an inhibitor of HCV entry by
inhibiting infectivity of HCV during inoculation and disrupting
the initial step of HCV cell entry by inhibiting viral attachment
to the cell.
Influenza is due to the infection of the respiratory system
(nose, throat, and lungs) by RNA viruses. Evidence has been
found to suggest that catechins, especially EGCG, have viruci-
dal effects on all three major human influenza viruses (A/H1N1,
A/H3N2 and B) (Song et al., 2005).
In a population-based study of schoolchildren in Kikugawa
City, Japan, Park et al. (2011) distributed an anonymous ques-
tionnaire survey twice during the 2008-2009 endemic type A
influenza season to 2050 elementary school students in a tea
plantation area in Japan. The age range of the participants was 6
to 13 years old. The study found that an adjusted odds ratio in-
versely associated with consumption of 1 cup/day to <3 cups/
day was .62 in cases of confirmed influenza by the antigen test,
and that associated with consumption of 3 - 5 cups/day compar-
ed with <1 cup/day was .54. There was no significant assump-
tion with the consumption of >5 cups/day. Therefore, Park et al.
(2011) concluded that the consumption of 1 - 5 cups/day of
green tea might prevent influenza infection in children.
A randomized, double blind placebo-controlled trial of 197
healthcare workers in three healthcare facilities for the elderly
was conducted during the 2009-2010 influenza season in Higa-
shimurayama, Japan by Matsumoto et al. (2011) The partici-
pants were divided into two groups: green tea catechins/the-
anine (N = 98) and control (N = 99). The first group received
capsules containing 378 mg of catechins and 210 mg of the-
anine to take daily. The control group received placebos. The
incidence of clinically defined influenza infection and labora-
tory-confirmed influenza with viral antigen, and the time for
which the patient was free from clinically defined influenza
infection were measured. They found that 4 participants in the
experimental group and 13 from the control group reported in-
cidences of clinically defined influenza infection. On the other
hand, only 1 of the experimental group and 5 from the control
group had laboratory-confirmed influenza, which is statistically
insignificant. Matsumoto et al. concluded that green tea cate-
chins and theanine (an amino acid found naturally in green tea)
might be effective prophylaxis for influenza infection among
healthcare workers for the elderly.
Human Immunodeficiency Virus (HIV)
HIV is an infection caused by a lentivirus that incorporates
the viral RNA sequence into the host genome by reverse tran-
scription. It gradually destroys the immune system and causes
acquired immunodeficiency syndrome (AIDS). Catechins have
inhibitory effects throughout the infection life cycle. They
compromise the physical integrity of the virion, bind to the host
cells, blocking post-absorption entry, and prevent the replica-
tion of the viral genome by inhibiting reverse transcriptase
(Pandey & Rizvi 2009). EGCG has been found to bind directly
to CD4 (the glycoproteins found on the surface of T lympho-
cytes), which consequently, inhibits gp120 binding.
One study conducted by Li et al. (2011) combined EGCG to
HeLa-CD4-LTR-beta-gal cells. They found that the 50% effec-
tive concentration was relatively low (1.6 and 2.0 M) for both
HIV-1 (IIIB) and HIV-2 (EHO) infections. Using a time-of-
addition assay, it was determined that the inhibitory profile of
EGCG was identical to that of a non-nucleoside reverse tran-
scriptase inhibitor, MKC-442. When a nucleoside reverse tran-
scriptase inhibitor, 3’-azido-3’-deoxythymidine or AZT, was
also added to the cell culture, it was discovered that EGCG and
AZT synergistically inhibited HIV infection. They concluded
that EGCG might act mainly as an allosteric reverse transcrip-
tase inhibitor (Li et al., 2011).
Another in vitro study was conducted by adding EGCG to
peripheral blood mononuclear cell cultures. The study was done
by Hauber et al. (2009) to determine if EGCG had an effect on
semen-derived enhancement of HIV infection. Peptide fragments,
derived from prostatic acidic phosphatase, are secreted in large
amounts into human semen and form amyloid fibrils that cap-
ture HIV virions and direct them to target cells (Hauber et al.,
2009). The study showed that EGCG targets semen-derived en-
hancer of virus infection (SEVI) for degradation, inhibits its ac-
tivity and abrogates semen-mediated enhancement of HIV-1 in-
fection in the absence of cellular toxicity.
Concerns and Criticisms
The consumption of green tea and its potential anti-infectious
properties have been criticized for several reasons. The first is
the cultural factors that may confound these studies. Because
green tea is more widely consumed in East Asia, especially in
China and Japan where the tea culture is well embraced, there is
a worry that the link made between green tea catechins and its
health benefits may actually be due to other cultural practices
shared by these populations, such as another staple in their diet.
Because studies have been conducted in human cell cultures,
there is evidence to suggest that green tea catechins do provide
these health benefits as a property of their catechins and that
they may be amplified or isolated in certain cultures because of
its green tea culture.
Another critique of catechins is its bioavailability to humans
by drinking green tea. But through these studies presented, it
appears that an individual could get several health benefits from
drinking less than 5 cups of green tea daily, not only for green
tea’s invigorating, refreshing qualities but also as an aid in di-
gestion, and prevention of viral infections and cancer.
As with all phytochemicals, there is a concern that excessive
consumptions will have detrimental effects. Due to the obesity
epidemic, there is an increasing interest in diet products and
weight-less supplement, which include green tea extract pack-
aged in pills. A case report conducted by Molinari et al. (2006)
presented a 44-year-old female of European descent suffering
from worsening acute liver failure. She was participating in a
weight-loss program for 6 months that recommended increased
physical activity and the intake of dietary supplements contain-
ing green tea extract with a concentration of 720 mg/day. Re-
ports like this one have shown a correlation between patients
presented with marked liver toxicity in the form of acute heap-
titis and the consumption of supplements containing green tea
extracts. These cases of toxicity were limited to individuals and
resolved after discontinuation of the supplementation (Molinari
et al., 2006). This underlies the necessity for an increase in
awareness and education of the use of supplementation. Based
on a preliminary search, there are no studies that have presented
any adverse consequences of drinking green tea suggesting that
it is most likely safe to consume green tea as a beverage with
little to no risk.
The Coevolution of Humans and Plants
The interactions between Camellia sinensis and humans have
lasted for thousands of years and the strength of these interac-
tions varies between cultures. As is self-evident, green tea has
grown into a culture that encompasses many practices that
range from its cultivation to its consumption in China. This
relationship between humans and Camellia sinensis is high-
lighted by the numerous health benefits green tea is found to
have. But this is only one aspect of their interconnected history.
The cultivation of Camellia sinensis has outlined the role of
humans in the evolution of this species. Through artificial se-
lection, certain traits have been selected for over time, which
has led to less diversity within the species and a divergence ge-
notypically and phenotypically of domesticates from their wild
counterparts. Although the effect of humans over plants is
much more apparent phenotypically, plants have an effect on
humans, as well. The phytochemicals produced by plants must
create an appeal for humans to invest the time and energy into
the care of the plant.
Since its discovery, Camellia sinensis has been domesticated
in a way that appealed to humans who chose certain mutations
that they found desirable, which resulted in the increase in pre-
valence of particular mutated genes. These mutated genes are
preserved in the species and encode proteins that may affect
humans’ own biology and behavior. Catechins are necessary for
the plant’s growth, reproduction, and defense; therefore, it is
likely that the catechin level has increased over time because of
its integration into the culture, for only the most resilient strains
would have survived and been selected for by the cultivators.
Also, green tea has been used for its medicinal properties al-
most immediately after its discovery. This purposeful use of
green tea may have resulted in other behaviors in humans that
led to the selection for plants with higher catechin levels.
As indicated by the Chinese manual, the Tea Classic, humans
play an active role in determining when and where the plant
should be grown and how it should be cultivated. The plant is
most suitable to hot and humid climates and is cultivated in low
rows for easy harvesting (Pettigrew, 2004). Although fermenta-
tion makes the export of tea easier, the unfermented version of
tea remains the preferred tea in the East and is increasing in
popularity in other parts of the world. This preference may be a
result of humans’ conscious or subconscious desire for cate-
chins and their health benefits.
The consumption of green tea has a history that spans back to
over 5000 years. Traditionally, it was prescribed for a number
of ailments while also being consumed for its refreshing quali-
ties and the prevention of future health problems. Starting in
China, the green tea craze has expanded worldwide to become
the second most consumed drink after water. This increase in
popularity is in part due to the increasing awareness of green
tea’s many health benefits. Besides its soothing and invigorat-
ing capabilities, it is consumed for its anti-diabetic, hypocho-
lesterolemic, anti-inflammatory, anti-carcinogenic, anti-cavity,
antimicrobial and antiviral properties (Song & Seong, 2007).
Open Access 201
The active ingredients in green tea that contributes to these pro-
perties are the phytochemicals called catechins, in particular
epigallocatechin gallate, the main and most active catechins.
Studies have shown that EGCG is effective in preventing infec-
tion by the hepatitis, influenza, and human immunodeficiency
viruses. Because EGCG affects the viral infection process ra-
ther than targeting the virus specifically, drinking green tea may
be a potential effective anti-infection agent without the negative
consequences of anti-viral drugs/treatment that leads to the de-
velopment of new drug-resistant strains and a constant need for
the development of new drugs.
The education of people about the numerous benefits of
drinking green tea may lead to the adoption of this practice by
other cultures. The change is small and easy to do. Green tea is
widely available and is often processed in a way that it is pre-
served for a great length of time. By making green tea more
available outside of coffee shops, Chinese restaurants, and gro-
cery stores, there is a potential for a cascading effect to occur
resulting in many positive changes, such as the reduced reliance
on commercial drugs, and the reduced incidence and prevalence
rates in high cholesterol, diabetes, cancer, cavities, and infec-
tions. Green tea has great potential in improving the health of
people worldwide. With its rapid increase in popularity, a heal-
thier world may be on the horizon.
The author would like to thank the editors of this manuscript
and the reviewers who contributed their time. The author would
also like to acknowledge Dr. Fatimah Jackson for her guidance,
support and assistance throughout the research process.
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