GREEN TEA NEWS & INFO
New studies and other green tea
information are constantly emerging from laboratories and research centers
around the world. You can keep abreast of the latest news and learn
some interesting green tea facts by checking
out the entries on this page.
There'll be new entries regularly, so keep coming back for more!
November 10, 2008
Green Tea and Chronic Fatigue Syndrome
Chronic fatigue syndrome (CFS) is a disease that can make you so tired
and depressed you can't perform normal daily tasks. This constant
feeling of exhaustion is persistent (lasting longer than 6 months), and
physical or mental activity can make it even worse. Unfortunately, rest
doesn't usually improve the symptoms.
Although the cause of CFS in unclear, some studies have shown that
oxidative stress (the excess production of free radicals) may be
involved. Since green tea has powerful antioxidant properties, a team of
researchers in India wondered if it might also have anti-CFS effects.
To find
out, they induced fatigue in mice specially bred to develop chronic
fatigue syndrome. The researchers did this by forcing the mice to swim
in a water-filled glass cylinder for 6 minutes every day for 7 straight
days. As expected, the mice developed signs of oxidative stress: their
lipid peroxidation levels went up, while levels of glutathione (the
body’s most powerful antioxidant) went down.
As the
days went by, the mice also took on an “immobile posture” earlier and
earlier in each session. When mice are forced to swim in a container
from which they can’t escape, they quickly adopt a sort of “frozen”
posture, moving only as much as they have to in order to keep their
heads above water. This immobile posture is believed to be a sign of
despair or depression indicating that the animals have given up hope of
escaping. In studies, antidepressant drugs reduce both of these signs of
depression – the onset and the duration of the
immobile posture.
So what happened when the mice were given green tea extract or green tea
catechins? Compared to the mice in the control group, their lipid
peroxidation levels were lower, their glutathione levels were restored,
and the increased immobility time was reversed. In other words, green
tea protected the mice against oxidative stress and
depression/despair, both of which are linked to CFS. The researchers
concluded that green tea extract and catechins “could be used as
potential agents in the management of CFS…”
(Singal
A, Kaur S, Tirkey N, Chopra K. Green tea extract and catechin ameliorate
chronic fatigue-induced oxidative stress in mice.
J Med Food
2005;8(1):47-52.)
October
27, 2008
Green Tea and Running Endurance
If you're looking for a way to extend your workouts, you
might just try a cup of green tea. In a study of the effects of green
tea extract on running endurance and energy metabolism in animals, mice
were given either a standard diet or a standard diet plus green tea
extract for 8-10 weeks. Then they were put on treadmills to see how long
they could run until becoming exhausted.
The mice that received the largest amount of green tea extract (.5%) ran
a full 30% longer than those that received no green tea extract.
They were also found to have higher levels of glycogen in their muscles
and more free fatty acids in their blood. This indicates that their
bodies were sending more fuel to the muscles, where it was needed, and
less to the adipose tissue, where it would be stored -- most likely the
reasons for the increased endurance. Another benefit of green tea was a
significant decrease in lactic acid in the animals’ blood, which
translates to less post-workout muscle soreness.
(Murase
T, Haramizu S, Shimotoyodome A, et al. Green tea extract improves
running endurance in mice by stimulating lipid utilization during
exercise. Am J Physiol Regul Integr Comp Physiol
2006;290(6):R1550-6.
October 20, 2008
Green Tea - Truly a Medicine
We’ve often referred to green tea as a “steaming cup of
medicine,” but now the U.S. Food and Drug Administration (FDA) has made
its medicinal status official. A special extract of green tea has been
approved for use as a prescription drug for the external treatment of
genital and perianal warts caused by human papilloma virus (HPV).
Polyphenon E Ointment
(also called Veregen) is the first prescription botanical drug approved
by the FDA under the drug amendments of 1962 requiring that drugs be
proven both safe and effective before being marketed in the U.S.
Two phase-III clinical
trials have shown that applying this ointment three times daily for up
to 16 weeks is highly effective in the clearing of genital warts, with
clearance of all or most warts (> 50%) seen in approximately 78% of
patients. The ointment apparently works by activating the body's
defenses and inhibiting some of the major functions of the papilloma
virus.
(Ahn
WS, Yoo J, Huh SW, et al. Protective effects of green tea extracts
(polyphenon E and EGCG) on human cervical lesions. Eur J Cancer Prev
2003;12(5):383-90.)
October 13, 2008
“Drinking Green Tea Makes the
Mouth Clean” – Traditional Japanese Saying
Asians have long been in the habit
of drinking tea after eating meals or sweets, and scientific research
shows that this makes sense. Dental caries (cavities) are the result of
bacteria called S. mutans, which use sugars in the mouth to
produce a sticky substance called plaque. The plaque coats the teeth and
gives the bacteria something to cling to, so more and more bacteria can
gather. And while they’re producing plaque, the S. mutans
bacteria also produce an unfortunate byproduct called lactic acid, which
eats into the tooth enamel. This combination of plaque buildup and
lactic acid is responsible for the decay that occurs in our nearly
indestructible tooth enamel.
Research has shown that green tea catechins can help fight tooth decay
in several ways: by making it harder for the bacteria to cling to the
teeth, inhibiting the production of plaque, and destroying some of the
S. mutans bacteria -- and these effects can occur with as little
as one cup of green tea!
In addition, a recent
study published in Caries Research has found that green tea’s
EGCg helps reduce the ability of S. mutans to produce the
enamel-destroying acid. In this study, volunteers either rinsed their
mouths with an EGCg solution or with plain water, then rinsed their
mouths again 30 minutes later with a sucrose solution to give S.
mutans something to work on. Later, plaque samples were taken and
the acidity of the samples was measured.
When the volunteers had
pre-rinsed with the EGCg solution, the acidity of the plaque was
significantly lower than it was when they had pre-rinsed with plain
water. Less acid means less tooth decay. So having a cup of green tea
after you eat that candy bar might not be a bad idea…
(Hirasawa
M, Takada K, Otake S. Inhibition of acid production in dental plaque
bacteria by green tea catechins. Caries Research
2006;40(3):265-70.)
September 22, 2008
Green Tea Delays Strokes in Stroke-Prone
Rats
To test the effects of green tea catechin extract on the
development of strokes, Japanese researchers used rats that were
specially bred to develop severe hypertension and spontaneous stroke at
early ages. The average lifespan of these rats was about 100 days.
The rats were divided into two groups: The control group received
plain water, while the other group received water containing 0.5% green
tea catechin extract, beginning at 5 weeks of age. Then the researchers
watched the animals to see when they would suffer strokes.
The average age at which a stroke occurred in the control group was
79 days. However strokes in the green tea group were delayed an average
10 days, occurring at an average of 89 days of age.
Although 10 days may not sound like much, it equals 10% of the
lifespan of many of the rats. The green tea group also showed
significantly lower increases in blood pressure in the later stages of
life, compared to the control group.
The researchers concluded that “continuous ingestion of green tea
catechins from an early age prevented the development of spontaneous
stroke in M-SHRSP [malignant stroke-prone spontaneously hypertensive
rats], probably by inhibiting the further development of high blood
pressure at later ages.”
(Ikeda
M, Suzuki C, Umegaki K, et al. Preventive effects of green tea catechins
on spontaneous stroke in rats. Med Sci Monit 2007;13(2):BR40-45.)
September 15, 2008
Green Tea and Obesity: A Review of Key Studies
Green tea has recently become the latest weapon in the war on
weight. But does it really work? The results of some new studies are
promising, indicating that green tea can increase the rate of calorie
burning, reduce body fat levels and even prevent excess weight gain. And
although most tests have been performed on laboratory animals, at least
one with humans showed that taking in the equivalent of 3 cups of green
tea per day helped the body burn a significant amount of additional
calories.
A 1999
study published in the American Journal of Clinical Nutrition
looked at the effects of green tea extract on energy "burning" in
humans.1 Men who took daily doses of green tea extract
containing EGCg plus caffeine in an amount equivalent to that found in
about 3 cups of green tea, burned about 80 more calories per day than
those who didn’t take the extract. (Just taking caffeine without EGCg
didn’t have the same effect.) And while 80 calories per day may not seem
like much, over the course of a year that adds up to 29,200 calories, or
a little more than 8 pounds lost – without making any other changes!
In a study involving animals, green tea
extract actually helped prevent obesity. Two groups of mice were placed
on a high-fat diet designed to ensure weight gain. At the same time, one
group received green tea extract while the other did not. The mice that
were given green tea extract ended up gaining 47% less weight than those
who didn’t get the extract.2
In another animal study, green tea
extract actually helped to reverse established obesity. In a 2005
study published in the Annals of Nutrition and Metabolism, rats
were deliberately overfed to make them obese. Then they were given
supplemental EGCg, which markedly decreased the amount of fat tissue in
their bodies, reversing their obesity.3
Why would green tea make a difference in the amount of fatty tissue
one carries? The EGCg contained in the tea is believed to rev up the
fat-burning effects of brown fat, send glucose to muscle tissue where it
is more likely to be burned (rather than to fat tissue, where it’s more
likely to be stored), and inhibit the action of fat-digesting enzymes,
so that ingested fat is less likely to be broken down and absorbed by
the body.
Footnotes:
1)
Dulloo AG, Duret C, Rohrer D, et al. Efficacy of a green tea extract
rich in catechin polyphenols and caffeine in increasing 24-h energy
expenditure and fat oxidation in humans. Am J Clin Nutr
1999;70(6):1040-50.
2)
Shimotoyodome A, Haramizu S, Inaba M, et al. Exercise and green tea
extract stimulate fat oxidation and prevent obesity in mice. Med Sci
Sports Exerc 2005;37(11):1884-92.
3)
Wolfram S, Raederstorff D, Wang Y, et al. TEAVIGO (epigallocatechin
gallate) supplementation prevents obesity in rodents by reducing adipose
tissue mass. Ann Nutr Metab 2005;49(1):54-63. Epub 2005 Feb 25.
August 28, 2008
The Eyes Have It!
A study published in the December 2006 issue of Brain Research
has found that EGCg can help prevent degeneration of the retina of the
eye caused by oxidative stress (free radical damage).
In diseases involving
retinal degeneration, like glaucoma and age-related macular
degeneration, the photoreceptor cells (rods and cones) suffer damage and
die when exposed to free radical generators such as sunlight and high
oxygen tension. Researchers wanted to see if EGCg, with its strong
antioxidant abilities, could ward off oxidative stress and protect the
retina.
They injected sodium
nitroprusside (SNP), a substance known to cause radical damage to
retinal tissue, into the eyes of rats. Sure enough, they saw a decrease
in the function of the rods and cones and an increase in cell death. But
when the SNP was accompanied by an injection of EGCg, the signs of
retinal damage where significantly less.
Although we’re not
suggesting you start injecting green tea into your eyeballs(!), we do
think this is another interesting piece of evidence showing green tea’s
formidable antioxidant abilities and their potential for warding off
disease.
(Zhang
B, Osborne NN. Oxidative-induced retinal degeneration is attenuated by
epigallocatechin gallate. Brain Res 2006;1124(1):176-87.)
August 11,
2008
Green
Tea & Huntington's Disease
Huntington’s disease (HD) is a devastating inherited illness that causes
the gradual breakdown and death of brain cells that control thinking,
feeling and movement. It results in a loss of intellectual function, as
well as emotional changes and uncontrolled movements, with early
symptoms being depression, mood swings, trouble learning new tasks and
difficulty remembering things. Although the cause of HD has been traced
to a single gene, there is currently no way to stop or reverse the
disease, which typically lasts for 15-20 years and is always fatal.
Recently
scientists have found that green tea’s EGCg strongly inhibits an initial
step in the development of HD. All cells in the body contain a protein
called huntingtin, and all proteins have very complex structures that
have to fold in a certain way in order to work properly. In people with
HD, the huntingtin protein develops an abnormally long stretch of a
repeated amino acid, making the protein more likely to misfold. This
mutated huntingtin clumps together, building up inside and outside the
brain cells, and eventually causing brain cell death.
But
researchers from Berlin, Germany have found that, in "test tube"
studies, EGCg can interfere with the misfolding and clumping of mutated
hungtintin proteins. EGCg also inhibited misfolding in flies
genetically programmed to develop large amounts of mutated huntingtin.
Although we have a long way to go before we can say for sure that green
tea helps prevent Huntington’s disease, these studies appear to be
initial steps in developing a new approach to understanding and treating
this terrible illness.
(Ehrnhoefer
DE, Duennwald M, Markovic P, et al. Green tea
(-)-epigallocatechin-gallate modulates early events in huntingtin
misfolding and reduces toxicity in Huntington’s disease models. Hum
Mol Genet 2006;15(18):2743-51.)
July 28,
2008
Even If You Smoke…
Everybody knows that smoking is bad for you.
One of the worst things it does is to damage the endothelium, the
innermost lining of the arteries. This lining is actually a bona fide
organ, releasing hormones that control the widening and narrowing of the
arteries, to make sure the blood flows properly. When the endothelium
becomes damaged by cigarette smoke, the artery walls get thicker,
stiffer and narrower, a condition called endothelial dysfunction.
With endothelial dysfunction, the arteries
don’t relax and widen as easily. This makes it harder for the heart to
pump blood through them, raising the blood pressure and increasing the
heart’s workload. It’s also easier for blockages to form within the
arteries, partly because they’ve become narrower, and partly because
their injured linings provide a great place for plaque to get a foothold
and start to build up. No wonder even light smokers are twice as likely
to have a heart attack as nonsmokers!
The good news is that green tea appears to protect against endothelial
damage and, as a result, may be able to help lower the risk of heart
attacks even in chronic smokers. In a study published in Circulation
Journal, 20 young healthy smokers were given daily doses of 8 g.
green tea (about the equivalent of 4 cups). After just two weeks,
certain markers of endothelial dysfunction had significantly declined.
The researchers concluded that drinking green tea may be an effective
way to prevent cardiovascular events in chronic smokers.
(Kim
W, Jeong MH, Cho SH, et al. Effect of green tea consumption on
endothelial function and circulating endothelial progenitor cells in
chronic smokers. Circulation Journal 2006;70(8):1052-57.
July 14, 2008
Gimme A Head With Hair!
EGCg may do a lot of things, but can it help you grow more hair?
Researchers from Seoul National University College of Medicine in Korea
decided to try to find out. They measured the effects of EGCg on the
growth of hair follicles in a test-tube environment. They also looked at
what happened when EGCg was applied to cells called dermal papilla cells
(DPCs) that live in the hair follicle itself and play a key part in hair
growth.
EGCg not only stimulated the growth of DPCs in both test tube
cultures and in the human scalp, it also promoted growth of the hair
follicles. The researchers concluded that EGCg stimulates human hair
growth by increasing DPC proliferation and slowing the rate of
cell-programmed death.
(Kwon OS, Han JH, Yoo HG, et al. Human hair
growth enhancement in vitro by green tea epigallocatechin-3-gallate
(EGCG). Phytomedicine 2007 Aug; 14(7-8):551-55.)
July 7, 2008
Tissue Preservation Without Freezing
We’ve all heard about cryopreservation - preserving living
tissues by freezing and storing them at super low
temperatures. Cryopreservation works by stopping all biological
activity, including the biochemical reactions that would normally lead
to cell death. But the process is far from perfect. Cell injury or death
can and does occur, especially during the initial freezing and
warming stages.
But now, thanks to green tea, there may be a much
gentler option. A
researcher at Kyoto University in Japan has demonstrated that several
kinds of tissues can actually be preserved at room temperature when
green tea polyphenols are added to a conventional cell culture medium.
He found that tissues such as blood vessels, cartilage, islet cells (the
cells responsible for making insulin), and corneas can be preserved for
several months at room temperature as long as they are immersed
in this green tea polyphenol-containing medium.
(Hyon
SH. A non-frozen living tissue bank for allotransplantation using green
tea polyphenols. Yonsei Med J 2004;45(6):1025-34.)
June 30, 2008
Lemon Increases Bioavailability of Catechins
The catechins in green tea are rather unstable in
non-acidic environments like the intestines; in fact, less than 20
percent of them remain after digestion. But a recent study published in
Molecular Nutrition and Food Research found that adding citrus
juice (lemon, orange, grapefruit or lime) to brewed green tea increased
the post-digestion catechin levels up to five times. The
most effective kind of juice was lemon juice, which made a full 80
percent of the catechins stay put!
The study doesn't say if the lemon juice was fresh or bottled,
although it seems both should work since their nutritional value is much
the same. However, fresh lemon juice does have almost twice as much
vitamin C as the bottled kind. And since vitamin C has a stabilizing
effect on the catechins, fresh juice might be your best choice.
(Green
RJ, Murphy AS, Schulz B, et al. Common tea formulations modulate in
vitro digestive recovery of green tea catechins. Mol Nutr Food Res
2007;51(9):1152-62.)
June 16, 2008
Don't Fear the Reaper
Well, I’ve said it before and I’ll say it again: Drinking green tea is
one of the best things you can do for your health. A study published in
the September 13, 2006 edition of the Journal of the American Medical
Association shows that green tea can actually decrease the risk of
death - in some cases by as much as 25%!
Researchers tracked 40,530 Japanese adults age 40 to 79 who had no
history of stroke, coronary heart disease or cancer for 11 years, noting
the amount of green tea they drank. The volunteers lived in an area in
northeastern Japan where 80% of the population drinks green tea, with a
majority taking in at least 3 cups a day. After 11 years, the
researchers found a 16 percent lower risk of death from all causes
in those who drank at least 5 daily cups of green tea, compared to those
who drank less than one cup. And during the first 7 years of the study,
the death rate was even lower, with 26% fewer deaths in the heavy tea
drinkers.
(Kuriyama
S, Shimazu T, Ohmori K, et al. Green tea consumption and mortality due
to cardiovascular disease, cancer, and all causes in Japan: the Ohsaki
study. JAMA 2006;296(10):1255-65)
June 9, 2008
Stressed Out? Try a Cup of Tea!
A new British study has found that drinking tea on a regular
basis may help you recover more quickly from the stresses of everyday
life. The study found that those who drank tea (in this case, black tea)
were able to “de-stress” and relax more quickly than those who drank a
tea substitute.
Seventy-five young male tea drinkers participated in the study,
during which they gave up their regular tea, coffee and caffeinated
beverages. Instead, for a period of six weeks, they consumed a tea
concoction four times a day. Half of the participants received a
fruit-flavored caffeinated tea mixture made up of the constituents of an
average cup of black tea; the other half received a caffeinated placebo
drink that tasted just like the first drink but did not contain tea’s
active ingredients.
The volunteers were then asked to complete stressful tasks while
important measures of stress were taken, including blood cortisol, blood
pressure and blood platelet activity. They were also asked to self-rate
their stress levels.
The tasks caused substantial increases in blood pressure, heart rate
and subjective stress ratings in both of the groups. But 50 minutes
after completing the tasks, the cortisol levels of the tea drinkers had
dropped an average of 47 per cent, compared to only 27 per cent in the
non-tea drinkers. Blood platelet clumping in the tea drinkers was also
reduced – a good sign as high levels increase the risk of clots and
heart attacks – and they reported a greater degree of relaxation than
the non-tea drinkers.
Time for a tea break?
(Steptoe A, Gibson EL, Vuonovirta R, et al. The effects of tea on
psychophysiological stress responsivity and post-stress recovery: a
randomised double-blind trial. Psychopharmacology (Berl.)
2007;190(1):81-89.)
June 1, 2008
Green Tea vs. Ovarian Cancer
Ovarian cancer is a particularly deadly form of the disease as it is
virtually symptomless in its early stages. By the time it’s detected,
it’s usually advanced and survival rates are not encouraging. But two
recent studies have shown that drinking green tea may reduce the risk of
developing ovarian cancer in the first place, and increase the survival
time of those who do get the disease.
An epidemiologic study of 61,057 women compared the tea consumption
habits of those who developed ovarian cancer to those who did not
develop the disease. For each daily cup of tea consumed (whether green
or black), there was an 18% lower risk of ovarian cancer.1
In a study reported in the International Journal of Cancer in 2004,
254 women with epithelial ovarian cancer were studied, then followed up
after 3 years. Of the green tea drinkers, 78% survived until the time of
the follow-up interview, compared with only 48% of the non-tea drinkers.2
Footnotes:
1)
Larsson SC, Wolk A. Tea consumption and ovarian cancer
risk in a population-based cohort. Arch Intern Med 2005;165(22):2683-86.
2)
Zhang M, Lee AH, Binns CW, et al. Green tea consumption
enhances survival of epithelial ovarian cancer. Int J Cancer
2004;112(3):465-69.
May 26, 2008
Green Tea and Superbugs
Ever wondered if you should be drinking green tea when you’re taking
antibiotics? Medical researchers from Egypt’s Alexandria University say
you should! They were curious about green tea’s effects on antibiotics:
Would green tea interfere, have no effect or increase the effects of
these medications? To find out, the researchers tested the combination
of drinking green tea while taking various antibiotics against 28
disease-causing microorganisms, some of which were resistant to our most
powerful antibiotics. They found that in every single case, green tea
enhanced the antibiotics’ ability to kill the bacteria and, in some
cases, increased their effectiveness as much as three times!
At the same time, green tea decreased the
drug resistance of almost all bacteria tested, making them more
susceptible to the bactericidal effects of the antibiotics. This is
important because an alarming number of drug-resistant strains of
bacteria are evolving, requiring stronger and stronger antibiotics to
keep them under control. But the use of more potent antibiotics just
encourages the evolution of even mightier superbugs, and scientists fear
that one day we may be at the mercy of superbugs we can’t control. So
green tea’s ability to reduce bacterial drug resistance is welcome
news.
The researchers concluded that drinking green tea
while taking antibiotics appeared to increase the action of antibiotics
and reduce the drug resistance of bacteria, even in superbug strains.
And, in certain instances, even a small amount of green tea was able to
produce these results.
(Society
for General Microbiology (2008, April 1). Green tea helps beat
superbugs, study suggests. ScienceDaily. Retrieved May 22, 2008,
from http://www.sciencedaily.com/releases/2008/03/080330200640.htm)
May 19, 2008
Green Tea Extract Fights Cell Death Due
to Oxygen Deprivation
When the body’s cells are deprived of oxygen (a condition called
hypoxia), they're in big trouble - without enough oxygen, cells die. A
heart attack can be one result of hypoxia. When a coronary artery
becomes blocked, it can’t deliver enough oxygen to the area of the heart
muscle it serves. As a result, that part of the heart muscle “dies.”
But what if there were a substance that could protect cells from the
effects of oxygen deprivation and maybe even prevent cell death?
In a recent study, researchers investigated the power of green tea
extract to prevent cell death related to a lack of oxygen.
The researchers used cells taken from a human liver tumor and divided
them into two groups. The cells in the control group were deprived of
oxygen. The cells in the test group were pre-treated with varying
concentrations of green tea’s EGCg in extract form (using doses of 12.5,
25, 50 and 100 micromoles), and then deprived of oxygen.
About 40% of the cells in the control group died.
In
contrast, the cells that had been exposed to the lowest amounts of EGCg
(12.5 micromoles) showed a 10 percent reduction in cell death. But the
cells that had been exposed to the highest amounts of EGCg (100
micromoles) were all still alive at the end of the experiment.
(Park
HJ, Shin DH Chung WJ, et al. Epigallocatechin gallate reduces
hypoxia-induced apoptosis in human hepatoma cells. Life Sci
2006;78(24)2826-32.)
May 12, 2008
Bottled or Brewed?
Have you ever wondered if bottled green tea has the same
health benefits as freshly brewed? In most cases, the answer appears to
be no. Researchers at Oregon State University found that the polyphenol
content and antioxidant activity found in some bottled tea products were
10 to 100 times lower than those found in brewed tea!
Why? A major reason is the health-promoting catechins are sensitive
to heat and oxygen, making them easy to destroy during the processing,
transporting and storing of bottled tea. Another problem is that many
bottled tea products are made from tea extracts, which have far fewer
antioxidants than brewed tea. To make matters worse, bottled tea
products are often loaded with sugar or high fructose corn syrup which,
besides being unhealthy and unnecessary, might contribute to catechin
breakdown.
If you still want to drink bottled green tea, look for a high quality
product made from brewed tea containing no added sweeteners that has the
polyphenol or catechin content listed on the label. Your best bet is a
product that contains at least 75 mg polyphenols or 50 mg EGCg per cup.
(http://oregonstate.edu/dept/ncs/newsarch/2005/Oct05/teaprotection.htm)
May 5, 2008
Attention, All Seniors!
If you’re concerned about protecting the health of your brain as you
age, start drinking green tea. In a study of green tea’s effect on
cognitive function (the ability to think, remember and concentrate),
published in the American Journal of Clinical Nutrition,
researchers looked at 1003 Japanese people age 70 or older. They
evaluated the volunteers’ cognitive function and also measured the
frequency of their green tea consumption. The researchers concluded that
drinking higher amounts of green tea was associated with a lower
incidence of cognitive impairment.
Specifically, drinking 4-6 cups of green tea per week (or 1 cup per
day) lowered the incidence of cognitive impairment by 38%. And drinking
2 or more cups of green tea per day lowered the incidence of cognitive
impairment by an astounding 54%! What an easy (and tasty) way to cut
your risk almost in half!
(Kuriyama
S, Hozawa A. Ohmori K, et al. Green tea consumption and cognitive
function: a cross-sectional study from the Tsurugaya Project 1. Am J
Clin Nutr 2006;83(2):355-61.
April 28, 2008
Green
Tea, the “Selective” Bacteria-Killer
One of the amazing effects of tea polyphenols is their ability to
destroy pathogenic (disease-causing) bacteria like E. coli,
Salmonella, Staphylococcus aureus and Clostridium
inside the body, particularly in the digestive tract. But if tea
polyphenols are strong enough to kill major pathogens, do they also kill
the “friendly” bacteria in your intestinal tract – the ones you need to
digest and absorb your food properly?
To find out, scientists from the National University of Singapore
looked at the effects of different tea polyphenols extracted from Yunnan
Chinese tea on the growth of 28 kinds of bacteria, both “friendly” and
pathogenic, found in the intestines.
As expected, the polyphenols inhibited the growth of pathogenic
bacteria, especially Clostridium perfringens (a common cause of
food poisoning), Clostridium difficile (linked to colitis), and
Bacteroides (a cause of abscesses if the bacteria manage to
escape from the intestines). However the gut’s “friendly”
bacteria, including Bifidobacterium and Lactobacillus,
were relatively unaffected by the tea polyphenols.
In short, tea was able to increase the "friendly" bacteria while decreasing
the "unfriendly" bacteria, thus changing the balance of bacteria in the
gut for the better.
(Lee
HC, Jenner AM, Low CS, Lee YK. Effect of tea phenolics and their
aromatic fecal bacterial metabolites on intestinal microbiota.
Research in Microbiology 2006;157(9):876-84.
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