Experts share the latest research
on the health effects of the aromatic beverage.
Lea Wee reports
A cup of tea wakes you up in the
morning, rounds off an evening meal and, well, they do not call it teatime for
nothing.
Now, it has been further confirmed
that tea leaves steeped in boiling water are good for health as well.
Tea is good for hydration, said Ms
Wong Yuefan, a senior dietician at the National Healthcare Group Polyclinics.
It also helps keep a person’s
weight under control and his mind mentally sharp.
Researchers from Singapore and
overseas have also found that tea contains chemical components such as
catechins that may prevent diseases.
Here are h five main health benefits
of tea.
1. Hydration
Tea is a calories-free beverage
which is good for hydration, said Ms Wong. She said: “It is common myth that
tea acts as a diuretic and may be dehydrating because of its caffeine content.”
A cup of tea contains about 40 to
60mg of caffeine. A cup of coffee contains more- about 60 to 180 mg of
caffeine.
The daily recommended caffeine
intake for a healthy adult is not more than 300mg or about five cups of tea,
said Ms Wong.
Research shows that this amount of
caffeine does not lead to dehydration.
Caffeine has a diuretic effect
only if a person takes more than 500 to 600 mg of it a day, said Ms Wong.
People who drink caffeinated
beverages also typically develop a tolerance to caffeine, she said. Hence, any
initial diuretic effect is diminished over time.
2. Weight management
Tea, when served without milk or
sugar, contains virtually no calories, said Ms Wong
This makes tea an ideal choice for
people who wish to maintain a healthy weight.
There is also some evidence that
catechins, a group of flavonoids found in high quantities in green tea and, to
a lesser extent, in black tea, may be useful in preventing obesity and other
lifestyle-related diseases, said Ms Wong.
A 2005 study in the American
Journal of Clinical Nutrition found that daily consumption of tea containing a
total of 690mg of catechins for 12 weeks can help to reduce body fat.
Of course, this applies only to
tea which has no sugar or milk added to it.
3. Mental alertness
Studies show that black tea has a
positive effect on a person’s levels of mental alertness.
The key ingredient is said to be
L-theanine, an amino acid found only in tea leaves. Each cup of black tea
contain 5 to 23mg of L-theanine, depending on the blend and brewing method.
Studies show that drinking two to
there cups of tea increases alpha brain activity gradually over time with its
effect becoming apparent after 80 minutes and lasting as long as 105 minutes.
Alpha brain waves occur when
people are in a state of physical and mental relaxation, but are aware of what
is happening around them.
A rise in alpha brain activity is
associated with an increase in alertness.
4. Cognitive performance
A 2010 study on more than 700
Chinese adults in Singapore by the Yong Loo Lin School of Medicine at the National
University of Singapore found that tea(black, oolong and green tea) was
associated with better cognitive performance, including memory, executive
function and information processing speed.
The authors said in their paper
published in the Journal of Nutrition, Health and Ageing, that this could be
due to the synergistic effect of many of its chemical components, such as
theanine, flavonoids (catechines) and vitamin C.
5. Cancer and Parkinson’s disease
Laboratory research has shown that
catechins found in green and black tea may prevent the onset and progression of
cancer.
A study of 63,000 middle aged and
elderly Chinese Singaporeans in the Singapore Chinese Health Study – conducted
by Yong Loo Lin School of Medicine at the National University of Singapore
between 1993 and 2007 – showed that women who drink green tea daily could
possibly have a lower risk of breast
cancer.
Also, men and women who drink
black daily had a lower incidence of Parkinson’s disease and possibly diabetes.
Parkinson’s disease is a
neuro-degenerative disorder that often leads to tremors and problems with
balance, walking and coordination.
A separate team of researchers
from the Yong Loo Lin School of Medicine and National Neuroscience Institute
later identified a component in green tea, a catechin call EGCG, that provides
cellular protection against Parkinson’s disease.
The researchers, who published
their findings in the Journal of Neuroscience, said their findings hold promise
for the development of more effective drugs fro patients afflicted with this
debilitating disorder.
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