Studies
Find Health Benefits From Tea
A dozen
or so studies reported at the American Chemical Society
meeting show health benefits from tea that range from fighting fat to
fighting cancer.
In what seems to be the first study linking
immunity with tea, researchers in Boston found people who drank five
to six cups of black tea each day seemed to get a boost in that part
of the immune system that acts as a first line of defense against infection.
"We found that certain molecules were shared by
bacteria, parasites, and vegetables - and one of the vegetables was
tea," says study author Dr. Jack F. Bukowski, an assistant professor
of medicine at Harvard Medical School and staff rheumatologist at Brigham
and Women's Hospital.
"These molecules could activate a certain component
of the immune system called gamma delta T lymphocytes, which are very
important as the first line of defense against infection and tumors,"
he says.
"Vitamin
for the Immune System"
Dr. Bukowski and
his colleagues asked non-tea drinking, non-coffee drinking volunteers
to consume five to six cups of black tea infusion or instant coffee
for either two or four weeks.
They then took blood samples and tested the activity
of the immune system against bacteria.
"We found that samples taken after they drank tea
were able to react against the bacteria fivefold better by making a
very important protein called interferon gamma," Dr. Bukowski says.
"If you put two and two together, that should mean
you're going to be more able to fight off diseases because that's a
very important bacteria-fighting and virus- and tumor-fighting molecule,
but we did not go on to show that drinking tea actually protects you
against getting sick," he says. That will be the subject of the
next study.
Although the tea cannot be viewed as a cure, it could
be viewed "almost as a vitamin for the immune system," Dr.
Bukowski says. And more of these "vitamins" will probably
be found in vegetables, Dr. Bukowski adds, which means you should probably
have some vegetables with your tea.
Lab
Studies Look at Anti-Cancer Qualities
A second study
found that mice who had been genetically engineered to develop prostate
cancer, and who drank the equivalent of about six cups of tea a day,
did not end up developing tumors.
"Those animals who drank tea were substantially
protected and they lived longer," says study author Dr. Hasan Mukhtar,
a professor of cancer research at the University of Wisconsin in Madison.
No one knows if the same mechanism will be at play in
humans, but Dr. Mukhtar says he suspects that tea will have some effect
in some patients.
"China has the lowest prostate cancer rate in the
world and Japan is also very low, and they drink much more tea,"
he notes.
Another study found that a green tea extract reduced
body fat in mice, possibly by inhibiting the absorption of fats and
starches, and that drinking green tea may mitigate DNA damage from smokers
that could lead to mouth cancer.
Still other researchers are working on developing a
cream made up of tea polyphenols which would ward off skin cancer.
Finally, researchers
at the American Chemical Society meeting found that
drinking tea improved the function of blood vessels and platelets, and
may therefore reduce the risk of heart attack and stroke.
Always consult your physician for more information.
Online
Resources
American
Academy of Allergy, Asthma and Immunology
American
Cancer Society
American
Lung Association
Centers
for Disease Control and Prevention (CDC)
National
Heart, Lung, and Blood Institute (NHLBI)
National
Institutes of Health (NIH)
National
Women's Health Information Center
US Department
of Heath and Human Services
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October 2003
In
This Issue:
Studies
Find Health Benefits From Tea
"Vitamin
for the Immune System"
Lab
Studies Look at Anti-Cancer Qualities
People
with Asthma Cautioned about Melatonin
Online
Resources
Other
Resources:
Find
a St. John's Mercy Physician
St.
John's Mercy Center for New Health Options
Mental
Health Information
St.
John's Mercy Classes and Programs
People
with Asthma Cautioned about Melatonin
Melatonin,
a naturally occurring hormone that helps regulate the body's circadian
rhythms, may make asthma worse at night, a new study finds.
"We
found that patients who have nocturnal asthma have higher melatonin
levels than patients who do not have asthma," says study
author Dr. Rand Sutherland, at the National Jewish Medical and
Research Center in Denver.
"Higher
levels of melatonin were associated with a greater worsening of
lung function overnight," Dr. Sutherland says, following
his report in the Journal of Allergy and Clinical Immunology.
Melatonin
is produced by the pineal gland in the brain, and many people
take supplemental melatonin to help them sleep and to combat jet
lag.
In
the study, Dr. Sutherland and his colleagues recruited seven patients
with nocturnal asthma, 13 patients with non-nocturnal asthma,
and 11 patients without asthma. While the patients slept, the
researchers took blood samples every two hours.
Dr.
Sutherland's team also measured lung function before the patients
went to bed and again after they woke up.
Results
showed the patients with nocturnal asthma had the highest levels
of melatonin and the biggest drop in lung function.
In
addition, among patients with nocturnal asthma, lung function
dropped an average of 19 percent compared with 5 percent in patients
with non-nocturnal asthma. Among non-asthmatic patients, lung
function increased about 2 percent.
In
other experiments, melatonin has been shown to rev up inflammatory
cells and make them produce cytokines, which are inflammatory
markers, Dr. Sutherland notes.
"These
findings raise concern that high melatonin levels may play a role
in making asthma worse at night, and therefore people with asthma
should avoid taking supplemental melatonin," Dr. Sutherland
advises.
Dr.
Charles Irvin, director of the Vermont Lung Center at the University
of Vermont, says this study is the first real attempt to find
out the cause of nocturnal asthma.
"The
conclusion by Sutherland that patients with asthma should be cautious
about using melatonin is just right," Dr. Irvin says.
Patients
want to find non-pharmaceutical treatments, Dr. Irvin says, but
many of the alternatives may have active substances that may be
harmful. Many like melatonin are very powerful, he adds, and people
need to be careful about how they use these supplements.
"Patients
with mild asthma may try melatonin, but if their asthma gets worse,
they should stop it right away," Dr. Irvin says. "However,
people with nocturnal asthma should avoid taking melatonin altogether."
Always
consult your physician for more information.
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