Tea without poison: How good is it?February 10, 2013, 8:33 pm
By Dr Upul Wijayawardhana
'I will make a pot of tea'
Whatever it may be-a calamity, a traffic death, a robbery, an accident, or for that matter, a celebration this is what happens in most British Soaps (equivalent of our teledramas), and even in detective dramas! A pot of tea makes people come together to calm them down or to celebrate! I must confess, I have not watched many teledramas probably because of the intruding advertisements!
Unfortunately, Sri Lankan television has adopted the American way, programmes sandwiched between advertisements than the other way round, which is what it should be! Fortunately, in Britain BBC is free of advertisements and commercial television broadcasts have around fifteen minute blocks of programmes interspersed with around five minutes of advertisements; enough time to put on a quick boiling kettle, drop a tea bag into a mug and brew a quick cup of tea to refresh! Many would say how civilized!!
Hold it! Is this the way to drink tea? What? Making tea with a tea bag? Purists would be shocked! Realists will argue that convenience matters! Leaving aside the arguments; as to the best way to make tea or when pouring, milk first or after tea, we tea drinkers will be interested to know whether, in addition to the well known though rather paradoxical stimulating as well as calming properties, drinking tea has any health benefits; at least no harmful effects in view of one of the constituents, caffeine which has been blamed perhaps unfairly.
Medcinal drink, three
As I mentioned in my previous article, tea was discovered over 3,000 years ago as a medicinal drink, in the Yunnan province of China during the Shang Dynasty and is today the most consumed beverage in the world second only to water.
There are different types of tea with myriads of flavours, multiple additives and prepared in different ways. To add to the confusion, there are herbal teas which have no tea at all, being infusions of herbs, spices, roots, flowers etc., and really should be called 'tisane'. Rooibos or 'Red tea' from South Africa that became popular recently, due to claimed but unsubstantiated health benefits, also falls into to this category.
I remember, as little children, adding hot water to Hibiscus flowers to make a brew and watch it change colour with the addition of lime juice; perhaps, the first inadvertent scientific experiment we did! Today, Hibiscus is a well known 'tea' as are Chamomile, Peppermint and Rosehip. All leaves have antioxidants to prevent damage from the constant exposure to the sun. Therefore, any 'tea' is likely to have health benefits but genuine tea derived from the dried tender leaves of the Camellia sinensis plant has greater benefits than most, as it has many other beneficial compounds.
Though there are six varieties of tea; white, yellow, green, oolong, black and post-fermented (Pu-erh) tea, yellow and Pu-erh are not usually available in the market.75% of the tea consumed in the world is black though in China and Japan the most popular is green tea. Iced tea is the most popular tea in the US; it is consumed in large amounts but is far from healthy as it is full of sugar! No surprise obesity is becoming a huge problem in the US!
After picking, tea leaves begin to oxidize and darken due to the breakdown of chlorophyll, the green pigment, by enzymes in the cells which releases tannins. This process called fermentation can be stopped by heating and resultant wilting. The method of preparation affects flavor as well as the nutritional content. Black tea is made from leaves that are wilted and fully oxidized, oolong is wilted and only partly oxidized, green is wilted but not oxidized while white tea is neither wilted nor oxidized, made from very tender buds before they acquire chlorophyll.
Before exploring the possible benefits of tea, it may be prudent to point out the possible disadvantages. Tea plant has a high sensitivity to and absorption of environmental pollutants like fluoride and aluminium, old leaves containing high levels of both. Though the danger from aluminium is only theoretical, it is advisable for people living in high fluoride areas to moderate tea consumption but in low fluoride areas this may be an advantage, preventing tooth decay.
Like most leaves, tea has oxalate and those with kidney stones need to be careful. Probably, a greater danger comes from 'Pol-pala' which is traditionally considered to be good for renal stones but very unlikely, as it has high oxalate content.
Caffeine is the other constituent which has been under suspicion. Though very high doses of caffeine can cause dehydration even the strongest cup of coffee does not do so. Tea is safe, as an average cup of tea having only half the amount of caffeine in a cup of coffee. Therefore, it is perfectly safe to drink tea instead of water. Boiling gets rid of germs in water and a cup of tea is cheaper than bottled water and certainly not deadly like fizzy drinks!
By the way, coffee is not all bad. Recent research shows that drinking one or two cups of coffee a day may prevent dementia but, like for tea, most studies we base our conclusions on are case-control studies, comparing two groups of people with different habits. If we are to be sure, we need proof from double blind clinical trials, where both the prescribing physician and the patient are not aware whether the active substance or a placebo is taken but this sort of study is easier said than done when it comes to food and beverages. Therefore, we should make judgment on the best available data and come to reasonable conclusions.
L-theanine is an amino acid in tea, which crosses the blood-brain barrier, a physiological barrier that prevents unwanted substances from getting from blood to the brain. A recent study has shown that a small dose of theanine, about the amount in a cup of tea, induces changes in alpha waves on an EEG, an electrical recording of brain waves. Alpha waves are associated with relaxation. Theanine has been shown to increase focus and concentration as well as promote relaxation. Japan has approved the use of theanine in food and drinks. The Federal Drug Administration of USA has given it a 'generally recognized as a safe ingredient' status. Several manufacturers sell beverage containing theanine but it is cheaper to drink tea! A small study in 2003 showed that tea drinkers had five times higher levels of anti-bacterial proteins in the blood than coffee drinkers, most likely due to theanine. This suggests that tea may help in overcoming infections.
Tea is rich in tannin and so is red wine. It is the tannin that gives the astringent effect on the palate and, you may be surprised to learn, a cup of tea has much more tannin than a glass of wine. Both contain other organic compounds called polyphenols which also have antioxidant effects. Tea is rich in catechins, specially white and green teas, but research by the US Department of Agriculture has shown that there is very little difference in the antioxidant effect between green and black tea.
What is the importance of anti-oxidants? When cells in our body use oxygen for energy, by-products called 'free radicals' are produced which can damage the inner lining of blood vessels as well as trigger changes in cells that may lead to cancer, diabetes etc. Anti-oxidants mop up free radicals and prevent the harm they may cause. Other rich sources of antioxidants are bright coloured fruits & vegetables, citrus fruits like oranges& limes, nuts & seeds and fish & shellfish. Vitamins A, C, & E also have antioxidant properties. On the other hand, oxidative stress is caused by smoking and sunburn.
Antioxidant properties of tea
The powerful antioxidant property of tea is likely to help in many ways:
*Drinking three or four cups of tea daily has been shown to reduce the chance of having a heart attack. (Tea also reduces the level of cholesterol and fat in blood though in small amounts). A Japanese study has shown that those who drank more than five cups of green tea daily had a 26% reduction in death from a heart attack or a stroke compared to those who drank one cup or less. The effect was more pronounced in women.
*A review in 2009 of 51 green tea studies showed drinking three to five cups a day lowered the risk of ovarian, colorectal, lung and prostate cancers.
*Drinking one to four cups of black or green tea has been linked with a lower risk of Parkinson's disease, according to the National Institute of Health of USA.
*There is data to show that tea reduces lung damage in smokers and prevent lung cancer but it is better not depend on tea to do the prevention but give up the killer fag!
A consensus document on Complementary and Integrative Medicine produced by an expert committee of the American College of Cardiology states that tea drinking appears to be protective against Coronary Heart Disease in a number of epidemiologic studies. It also comments that there are a number of favourable mechanistic investigations but add that there are no prospective studies.
The comment by David L Katz, Director of Yale University's Prevention Research Centre is the most apt:
'There are pearls of real promise here, but they have yet to be strung'
While waiting for confirmation, we can be sensible and continue to drink tea with the knowledge that it is the best beverage available which is very likely to have multiple health benefits. As stressed in my previous article, we have to avoid the poison, sugar, which I have just discovered may be addictive like some drugs.
What about milk? It is better avoided as a small European study in 2007 found that milk blunted the beneficial effects on the heart. It is better to drink black tea and perhaps, the best is green tea.
With all this positive data, I am saddened to find Ceylon tea to be an increasingly difficult commodity to find in super markets, at least in UK. Though we are still the fourth largest producers of tea, behind China, India and Kenya (whose tea plantations benefitted by the exodus of our tea planters due to the short sighted policies of the Bandaranaike governments), it is shocking to see our tea production is declining while others are increasing.
Is it not time to get up from our slumber, produce more tea and promote the best tea in the world? Why could not our tea board, or whatever body that is supposed to promote, come up with slogans like:
'Tea prevents heart attacks: Drink the best - Ceylon Tea'
'Tea prevents some cancers: Drink the best - Ceylon Tea'
Whatever they do or do not do, let us enjoy this refreshing beverage which, most likely, has multiple health benefits. One word of warning! Please don't drink boiling hot tea as it had been shown that gulping drinks, very hot increases the chances of getting cancer of the gullet.
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