After water, tea is the world’s most popular beverage. It is estimated that in excess of 750 million litres of tea are consumed around the world each day and in Australia more than 22 million cups of tea are drunk daily. All of the 3000 varieties of tea around the world are made from the Camellia sinensis plant. The varieties derive from the locations in which the plants are grown, some additives (such as bergamot to make Earl Grey) and differences in processing.
It is important to note that herbal teas are not included in that 3000 figure and that they are made from entirely different plants. Herbal teas are made from plants such as chamomile, peppermint and ginger (plus hundreds of others) where the flowers, leaves or roots are dried and then extracted to make the hot drink. Herbal teas are lovely and healing (sometimes) and lend themselves to all sorts of combinations but they are not what we are talking about here. In this article, we are referring to the tea that originated in China dating back thousands of years and which acclaimed novelist George Orwell called “one of the mainstays of civilisation”.
The common belief is that tea (from Camellia sinensis) is quite a healthy drink — but is that an accurate perception or just something we want to believe?
There are three basic varieties of tea. Black tea is made using fermentation that arises from an enzyme called polyphenol oxidase. After picking, leaves for green tea are steamed to inactivate this enzyme so that fermentation does not take place. Oolong tea requires partial oxidation of the leaf so we aren’t granting that one a category of its own. Then there is white tea, made from the new buds plucked before they have opened. It has nothing to do with milk but it looks white because the bud is covered in downy hairs. Approximately 76 per cent of tea made is black, 22 per cent is green and the remaining two per cent is shared between white tea and oolong. These tea types deserve a little deeper contemplation (perhaps over a cup of Darjeeling?).
This is what most people are referring to when they use the word “tea”. Black tea undergoes the most processing of all the tea types. The stages involved in tea production are withering (softening the leaves to reduce moisture), rolling (to break the leaf cells and start the oxidation process), oxidation (this develops the tea’s aroma, colour and taste) and then drying. Tea ferments as a result of the energy released by the breaking of chemical bonds during the oxidation process. It is the heat of the drying phase that stops the enzymes in the tea leaves, which drive the oxidation.
Green tea is fermented to oolong tea and then to black tea. As this fermentation process occurs, the polyphenol (flavonoids known as catechins) compounds in green tea are broken down to form a variety of chemicals known as theaflavins. These theaflavins aren’t as potent as catechins but they still provide health benefits.
In producing black tea, two different methods are used. The orthodox method creates quality loose-leaf teas while the cut-tear-curl method produces broken leaves and dust that are used for tea bags.
Green tea undergoes a minimal amount of processing compared to black tea. For green tea, freshly harvested leaves are immediately steamed or pan-fried to prevent oxidation and fermentation. The leaves are then rolled to rupture the leaf cells and facilitate the drying process. This form of processing preserves a high proportion of the natural antioxidants (catechins) in the tea.
There are many varieties of green tea available including sencha (a roasted Japanese green tea) and gyokura (an expensive fine tea). Matcha is a powdered green tea that dates back to the 12th-century and is made from high-quality whole leaves that are finely ground into powder. Since whole leaves are used, you get even higher levels of antioxidants in matcha than in other green teas.
The leaves for white tea are harvested at a younger age than for green or black teas. White tea leaves are harvested just before the leaf fully opens when it is still covered in white, silvery hairs (hence the name “white” tea). There is a very small window for picking white tea, just a few days in early spring, and the leaves must be harvested with great care.
White tea leaves are not rolled or steamed but just air-dried in sunlight with the result that there are approximately three times as many antioxidant polyphenols in white tea as in green tea. Among white tea, there are four varieties: silver needle (made only from the silvery white tea buds), white peony (made from the buds and leaves), long-life eyebrow (made from just the leaves) and tribute eyebrow (made from a specific tea bush and processed slightly differently).
Caffeine in tea
Similar to antioxidant polyphenols, the caffeine content of tea varies depending on the type and the way it is brewed. A smaller-leaf tea will release more of its caffeine than a larger-leaf tea. If the water has cooled before being poured over the leaves, then less caffeine will be released. However, in general terms, white tea has around six to 25 milligrams of caffeine per cup, green tea around 8-36mg, oolong tea 12-50mg and black tea anywhere from 23-110mg per cup. Most of the caffeine, around 80 per cent, is released from the tea in the first 30 seconds of brewing. So, if you want to have a decaf tea, pour hot water over the leaves, then after 45 seconds pour off that water and then re-brew with fresh hot water using the same leaves.
Tea drinking can be a beautiful moment of tranquillity and reflection in your day. To maximise your cup of tea, choose a loose-leaf variety and steep it for three to five minutes to extract up to 85 per cent of the flavonoids. Big leaves need to steep for longer while tiny pieces of tea infuse faster.
If you like milk with your tea, you needn’t worry because although a scare campaign went around for a while regarding the effect of tea in your milk, studies show that most of the antioxidants from tea are still absorbed whether you enjoy your tea with milk or even a dab of honey and lemon. If you like to sweeten your tea, keep in mind that if you are drinking five or six cups a day and adding two sugars or an artificial sweetener, then that’s a lot of sugar or sweetener (check out the sections on both sugar and artificial sweeteners in this publication).
The organic difference
The tea plant prefers a warm and wet climate with at least 135 millimetres of rain per year and soil that is well drained. It will grow well up to 7000 feet above sea level. Only the final two leaves and new bud from each stalk are picked and traditionally women have done the harvesting as their smaller hands are thought to be more suited to the fine task. So if you do decide to have a go at growing tea, don’t get too excited when it comes to harvest; be delicate about it.
Over the last 50 years, tea production, like all agriculture, has tended towards more chemically intensive fertilising and pest control methods. This leads to increased soil erosion and pesticide exposure for the workers. In the last decade, however, there has been a strong resurgence in organic methods of tea growing. The benefits of organic tea over conventional tea are both obvious and subtle.
Pesticide residues can inevitably find their way into teas. While testing for pesticides in tea does take place, any residues found can be hard to trace since the majority of teas on the market are “blends”, meaning that they are made from leaves from a variety of sources. The subtler effect of organic growing comes in the health benefits provided by tea.
As mentioned later, it is the antioxidant flavonoids that exist in tea that yield its many health properties. Plants produce these flavonoids as protection against infection and in harsh conditions. Extensive use of pesticides and herbicides on tea crops will eventually reduce the need for the plant to produce flavonoids. So the tea produced by conventional means may well have less health-giving properties than the organic alternative.
Since the new growth of tea plants is continually harvested, they draw heavily on the soil and therefore reflect directly the nutrition derived from that soil. Synthetic fertilisers and pesticides are believed to adversely affect the flavour of tea. Organic tea crops take longer to harvest but this leads to better tea as the long maturing process enhances the flavour.
Tea in your garden
Tea is high in nitrogen and contains minerals such as magnesium, potassium, zinc and fluoride that are needed for healthy plants. You can sprinkle used tea leaves on the ground to enrich your soil or you can add them to your compost. Even leaves removed from tea bags will be useful. Plants that particularly like tea leaves are tomato, capsicum, chilli and eggplant. If you have some leftover liquid tea, don’t throw it away but instead add it to your watering can; using green tea in this way may even discourage insects. To speed up the decomposition process and enrich your compost, pour a few cups of strongly brewed tea into the heap.
Tea does contain caffeine but the most significant chemicals in tea are flavonoids. The major of these flavonoids are called catechins. The concentration of these catechins depends on the type of tea and the method of preparation. The highest concentration (690 micrograms per millilitre) is found in brewed hot tea made from leaves. Instant tea has about 100mcg/mL and iced tea has less again. Many studies tell us that tea has a range of health-promoting effects. Tea can:
- Protect your brain and reduces your risk of developing Alzheimer’s disease
- Lessen anxiety
- Reduce cancer risk
- Boost blood to the heart
- Lower blood pressure
- Lower bad cholesterol
- Reduce overall heart risk
- Improve elastic tissue content of the skin
The antioxidant effects of tea and the capacity of polyphenols to cause blood vessels to open up indicate that tea is good for your heart and it seems that is true of all types of tea. A study from the Archives of Internal Medicine showed that just half a cup of oolong or green tea daily was associated with a reduction in the risk for high blood pressure of 46 per cent. Another study from that same journal showed that two to three cups of black tea a day caused useful drops in blood pressure.
Research in the journal BMJ Open examined data from Data Mining International on tea consumption in 50 countries gathered in 2009. The data showed that the biggest tea-consuming nation in the world is Ireland (two kilograms per capita per annum) followed closely by the United Kingdom and then Turkey. The lowest levels of black tea consumption are in Mexico, Morocco, China, Brazil and South Korea. Analysis showed that black tea consumption did lower the risk of developing type 2 diabetes.
The Queensland Institute of Medical Research conducted this study looking at almost 2800 Australian women; of these, 1368 women had developed ovarian cancer. Their analysis showed that drinking one or more cups of green tea daily may reduce your risk of developing ovarian cancer by 40 per cent. This is not to say that black tea will not provide any benefit but green tea is the best source of polyphenols and so showed the strongest link.
Studies have found that women who drink more green tea are less likely to develop breast cancer. Around three to four cups per day seem to offer benefits. In laboratory and animal studies, a chemical known by the acronym EGCG (epigallocatechin gallate) from green tea has been shown to limit the growth of breast cancer cells and other types of cancer cells. In a study from Columbia University Medical Centre, women were given either 400mg, 600mg or 800mg of polyphenon E or a placebo twice daily for six months. Blood and urine samples were taken at the beginning of the study and then at two, four and six months. Polyphenon E significantly reduced levels of a chemical called hepatocyte growth factor that is known to promote tumour cell growth, migration and invasion of healthy tissue.
In a study from the journal Molecular Nutrition & Food Research, researchers tested two groups of mice, one of which had been given EGCG from green tea and one which had not. The mice were trained for three days to find a visible platform in their maze. They were then trained for seven days to find a hidden platform. Those given EGCG found the hidden platform much faster indicating that their memory and spatial awareness had been given a boost.
In a study from The American Journal of Clinical Nutrition, it was found that among elderly people, those who drank four or more cups of green tea daily, compared to those who drank one cup or less, were 44 per cent less likely to have symptoms of depression regardless of other lifestyle factors.
Results of a study published in the European Journal of Nutrition showed that mice fed a high-fat, high-sugar diet still lost weight when extracts of green tea and black tea were added to their food. Interestingly, the two types of tea acted in different ways to produce weight loss. Green tea acted via the liver while black tea encouraged the growth of bacteria in the gut that promotes lean muscle mass and simultaneously discouraged the growth of bacteria linked to obesity.
All in all, tea does have many positive health effects.
The popularity and healing potential of tea has not escaped the eager eyes of marketeers. Not content with you brewing your beverage at home, they have seen the potential for tea to be a pre-bottled convenience drink. With all of these tea “soft drinks” available on the market, research by the American Chemical Society looked specifically at pre-bottled tea drinks to examine exactly what is in them.
To put the results in perspective, first keep in mind that the average cup of home-brewed black tea (with or without milk) contains between 50 and 150mg of polyphenols depending on brewing time and quality of tea. The results of the analysis showed that in a standard 475mL bottle of “tea”, there were for the six brands tested 3, 4, 13, 40, 43 and 81mg of polyphenols. In the worst of these instances, you would have to drink at least 17 of these bottled teas to get the same polyphenol intake as from the lowest-level single cup of home-brewed black tea.
Then there is the issue of added sugar. Despite being very healthy, polyphenols taste bitter. To provide a convenience drink that tastes “good”, marketers reduce the amount of actual tea used in their bottled teas and add sugar and other taste enhancers.
In short, unless you have thoroughly investigated and can really trust a brand, then why not drink bottled water when on the go and keep your tea drinking as a convenient time waster at the office or momentary distraction from the insanity of parenting?
Tea is a very healthy drink but there is a wide variation in the quality of tea products available so choose wisely. Your best option is a leisurely pot-brew of your favourite blend.