Brewing the benefits of tea

The nutrition team

The drinking of tea stretches back into ancient times. It can easily be traced back over 5000 years in China, although it probably has been consumed for even longer. As long as people have been drinking tea, there have been stories of its benefits to health. This warm beverage not only contains caffeine but also contains a wide variety of compounds that may be good for everything from your teeth to your heart.

While a wide variety of herbs can be used for making tea, for 'regular' tea, there is only one kind of tea plant - Camellia sinensis. There are three basic types of tea; green, black, and oolong. All three types of tea come from the same plant; the differences in the teas are a result of processing methods.

Black tea - the tea that is most commonly drunk in the UK today, is made by withering, rolling, fermenting and drying the young leaves.

Green tea is made by steaming and drying them. The leaves aren't permitted to ferment and oxidise as in black tea, thereby preserving many more nutrients - particularly the polyphenols.

Oolong tea is allowed to partially oxidise, meaning it is left to dry out slightly more. It is the polyphenols in tea that are being touted as the main compounds responsible for the possible beneficial effects of tea on cancer and cardiovascular disease.

What are polyphenols?

Polyphenols are antioxidants. Antioxidants neutralize the damaging effects of oxygen molecules and free radicals that are present in the body. Free radicals are very powerful oxidants, which means that they can damage cells in the body and over time, this damage may lead to cancer or cardiovascular disease.

What the antioxidant actually does is to grab hold of these free and hold on to them so that they cannot cause any more damage. They then bind the free radical to another chemical that also prevents it from causing damage on a more permanent basis, and the antioxidant goes back to find another free radical.

Polyphenols, the antioxidants in tea, are chemicals that are often referred to as tannins, that give tea the slightly bitter taste, especially when it is left to brew for a long time. Close to 40% of a green tea leaf is made of polyphenols.

The task of extracting, purifying and identifying the various compounds in tea is a long and difficult process. However, it seems that the more scientists know about what is in tea, the more they are convinced that the Chinese may have been right all along when it comes to the health benefits of tea.

Nearly four times as much black tea is produced and consumed as compared to green tea, with taste, rather than nutrient content, being credited for the higher demand. Polyphenols have a strong taste, and as black tea has only about half the polyphenol content of green tea, it also has a milder flavour.

Just think of the tea you may be served whilst dining out at a Chinese meal - it has almost a perfumed flavour, quite unlike the tea we drink every day.

In addition to its cancer fighting properties, green tea polyphenols exert other healthy effects on the body. They can also sometimes help to fight bacteria and infections in our body.

A number of studies also indicate that green tea can not only lower serum LDL cholesterol levels, but when consumed in high quantities (10 cups per day), they can raise HDL levels – both are good results. So what is the message the experts are sending?

In simple terms drinking green leaf tea is good for you. So try to incorporate some into your daily life. Instead of your usual cup of coffee or black tea in the morning, perhaps try some green tea instead, or leave some green tea bags in an airtight container at work - you may be glad of something a little different now and then.

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