George Orwell, in his famous classic, Animal farm, wrote, ‘all animals are equal, but some are more equal than others’.
This memorable Orwell’s statement holds true for tea. There are different types of tea and among them some confer superior healthy and medicinal benefits than others.
The term healthy teas, in this case, mean tea that offers extra benefits to human health beyond the basic nutrients, quenching of thirst and stimulation.
There are basically three types of tea depending on the processing technique. These are: unfermented, partially fermented and fully fermented tea. The term fermentation is actually used erroneously, it should be oxidised teas.
Types of tea
Tea plant, scientifically known as Camellia sinensis is evergreen tree which grows in high altitude regions. In Kenya, it does very well around Mt. Kenya, Kericho and other highlands.
The young leaves are harvested either by hand, shears or by machines and delivered to factories for processing.
Depending on the level of oxidation of tea leaves during processing, the following teas are obtained; White tea, Green tea, Oolong tea, Black tea, Pu’erh tea and Roobios tea (red tea). Tea beverage is obtained when any of these teas is added to boiling water.
White tea, as the name suggests is white in colour and is the healthiest of all types of teas.
To process white tea, the buds and young tea leaves are picked when they are very undeveloped, shortly before they are fully open. Sometimes the young buds are sheltered/covered from sunlight to prevent development of the green pigment called chlorophyll that is found in plants.
The plucked young leaves are immediately steamed and dried; these two processes are sometimes done in the farm. Quick and minimum processing helps the white tea to retain the highest levels of antioxidants and has the lowest level of caffeine than any other tea.
The closest cousin of white tea in powerful health constituents is green tea. Chinese were the first to make green tea. Chinese used to expose the plucked and chopped tea leaves to vapour from hot water shortly after harvesting followed by drying in the sun. At the outset, it was thought that this was just a drying process. It is now known that the process did more than drying; it inactivated an enzyme in tea called polyphenol oxidase. Inactivation of polyphenol oxidase ensured this enzyme did not interfere with the good compounds in the tea leaves. The final colour of this type of tea remains green after processing; leading to the name, green tea.
Nowadays, green tea is processed by steaming (scientifically known as blanching) the plucked tea leaves and drying them immediately after cutting and rolling. This inactivates the enzymes leaving all the healthy and medicinal chemicals in green tea unaffected or slightly affected.
Green tea is well known for its super health benefits, but it is poorly received by many consumers due to its flavour. But the trend is changing.
Oolong tea is a partially oxidised tea. Processing of Oolong tea follows similar steps as green tea, but the cut and rolled tea leaves stand for slightly longer periods (usually less than an hour) before drying. The waiting period prior to drying allows the enzymes to partially breakdown some chemical in tea leaves lowering its healthy qualities. This greenish-black tea falls in-between green tea and the well known black tea.
If the tea leaves are withered, macerated and allowed to stand for longer periods of time usually between 90 and 120 minutes before drying, the enzymes break down the chemicals producing the black tea. This is the most common and widely consumed tea.
Pu’erh is a type of tea which comes from the large leaves of a tea plant. Its processing is similar to that of black tea. The uniqueness of this tea is that, once picked it is piled and aged for as long as 50–100 years.
Roobios tea comes from a shrub in South Africa. It is naturally caffeine free – making it a good choice for those do not prefer caffeine.
Origin of tea
The origin of tea as a beverage is traced back to China during the reign of emperor, Shen Nung in about three thousand years Before Christ (BC). Tea was accidentally discovered when wind blew leaves into a kettle of boiling water.
‘‘Tea can provide vigour to the body, contentment of mind, and determination of purpose’’ those were the complimentary words from the Chinese Emperor after drinking tea. In other words, he was referring to stimulation of body and mind.
From China, the practice of tea drinking spread to Japan and India from where it was exported to England. The English popularized and commercialized tea. From England, tea spread to her colonies and America.
Tea is the most popular and widely consumed beverage in the world, second to water and well ahead of beer, wine and carbonated soft drinks.
Among the types of tea, green and oolong tea are commonly consumed in Asian countries mainly China, Japan, India and Thailand, while black tea is most popular in European countries, their colonies and America.
Black tea accounts for 80% of tea consumed in the world while green tea accounts for approximately 18%, Oolong tea and the other types of tea account for the remaining 2%.
Black tea versus green tea
Generally, drinking of tea is associated with several health and medicinal benefits derived from chemicals called catechins which have antioxidant properties.
In terms of medicinal and health properties, white tea is the best followed by green, Oolong and the least rated is black tea[1].
Although white tea is the best, it is little known and its price is a little bit prohibitive leaving green and black tea competing for the market.
Black and green teas compete on two different platforms. Black tea’s popularity is based on its wide acceptance and consumption in Europe, America and Africa, while green tea’s popularity stems from its medicinal and health benefits.
Quantitatively, green tea has twice the amount of antioxidants compared to black tea per serving. This makes green tea more protective to the body cells against degenerative damages of oxidation.
The high levels of antioxidants in green tea are due to less severe processing. On the other hand, the long period before drying of chopped leaves in black tea causes the good chemicals to change to less effective chemicals.
In black tea production, major part of the catechins is transformed into other less effective compounds called theaflavins and thearubigens. Although these chemicals impart the desired characteristic properties and taste in black tea, they are less powerful than the parent catechins. Owing to these changes, the catechin content in green tea is three times higher than in black tea. This makes green tea superior to black tea in health and medicinal properties.
The American Medical Association shows that green tea can lower cholesterol levels, high blood pressure, and reduce the risk of strokes (especially in men)[2].
The National Cancer Institute reports that because of the highly effective anti-oxidants in green tea, it can ward off various types of cancer[3].
There are many other therapeutic values in green tea, including, aiding digestion, blood purification, strengthening teeth and bones, boost immune system, enhance heart function, suppress aging, fights viruses, and lowers blood sugar levels.
In 2005, Sumpio from Yale University in Connecticut, USA, observed that although there is high rates of consumption of tobacco in Asian countries and Japan in particular, they have low case of heart related diseases and lung cancers compared to European and American countries. This paradox (Asian paradox) has been associated with high consumption of green tea in the region[4].
The benefits of green tea become apparent when at least one and half litre of green tea is consumed per day. For example a big study involving 1400 men in Japan older that 40 showed a decreased amount of bad cholesterol in the blood for those who drank over 6 glasses (1500 millilitres) of green tea per day[4].
Black tea has been shown to have medicinal properties similar to green tea but the results are not very convincing and sometimes they are controversial.
For example, black tea consumption has been shown to reduce the cases of heart diseases in Netherlands and America but not in England. It is thought that it is because the English add milk to tea which is not the practice in America and Netherlands. The milk is thought to interfere with antioxidants[5].
Despite consistent data showing that black tea is inferior to white and green tea in antioxidants, it has been scientifically shown to reduce the incidences of rectal cancer in Russian men and women. A study showed that black tea consumption was more effective in women than in men due to lower alcohol consumption among the women.
Another undesirable aspect of black tea is the caffeine content. Although caffeine is good in moderate amounts; it is undesirable in high levels. Comparing the five common types of teas, black tea has the highest caffeine content followed by Oolong and lowest in green and white tea.
“Black” and “green” in tea are what “white” and “red” are to wine.
Other types of teas
Flavoured tea
Flavoured tea can either be green, Oolong or black tea with added flavour. The flavour may be artificial, natural or a spice. Flavours are mostly added in tea bags due to easy of incorporation.
It is also common to find packed loose tea leaves mixed with single or a mixture of spices such as cinnamon and ginger.
Tea flavouring improves the flavour and consumer acceptability with little or not health benefit.
Herbal teas
The term herbal tea refers to herbs that are made into an infusion in a similar way with tea. Herbal teas are not manufactured directly from tea leaves but from herbs.
The herbal teas include infusion from herbs such as rosemary, lemon grass, peppermint, camomile, mint and lemon myrtle. The dried part of the herb is steeped in hot water allowing the flavour and other compounds from the herb to infuse into the water.
Available in pure, just single herb per packet or blended mixture, herbal teas are popular because of their fragrance, antioxidant properties and therapeutic applications.
Herbal teas have lower antioxidants compared to green tea and black tea. The herbal teas with the highest antioxidants include lemon myrtle, guava, oregano, mint and peppermint.
Iced tea
Iced tea can be made from tea leaves or other herbs. It is normally sold as an extract in liquid form packed in tetra packs or bottles. It is very common in Austria, Belgium and Netherlands. The consumer does no preparation except to pour into a glass and to enjoy.
In Kenya, there are several bottled iced teas in the market. In addition there are powdered flavoured teas that can be reconstituted.
Instant tea
To meet the demands of modern life, there are instant teas. These are freeze dried granules which are quick to make but may not deliver the full flavour of tea.
Bottom line
Tea offers many health and medicinal benefits. The health and medicinal benefits are in the following decreasing order: white tea, green tea, Oolong tea and black tea. The level of caffeine increases in the opposite order, black tea having the highest and white tea the least. Addition of milk to tea, whether green or black may interfere with the beneficial action of the antioxidants.
References
1. Medicinal and therapeutic potentialities of tea (Camellia sinensis L.) – A review. Food Research International, 2009. 42(5–6): p. 529-535.
2. All teas are not created equal: The Chinese green tea and cardiovascular health. International Journal of Cardiology, 2006. 108(3): p. 301-308.
3. Nurulain T, Z., Green tea and its polyphenolic catechins: Medicinal uses in cancer and noncancer applications. Life Sciences, 2006. 78(18): p. 2073-2080.
4. Green Tea, the “Asian Paradox,” and Cardiovascular Disease. Journal of the American College of Surgeons, 2006. 202(5): p. 813-825.
5. Dual effect of milk on the antioxidant capacity of green, Darjeeling, and English breakfast teas. Food Chemistry, 2010. 122(3): p. 539-545.