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.
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.