The health benefits of tea
A nice cup of tea is a refreshing start to the day for many people, or a welcome pick me up in the afternoon tea break.
In the UK, 165 million cups of tea are drunk every day. Britain is the second biggest tea drinking nation after Ireland.
Tea is made from the leaves of a bush called Camellia sinensis. For black tea, a process called oxidation turns the leaves from green to a dark brownish-black colour. Green tea comes from the same plant, but is not oxidised.
Oolong tea is made from leaves of the same plant that green and black teas come from. The difference lies in how long the leaves ferment. Green tea leaves are unfermented, while leaves for black tea are fully fermented. Oolong comes from leaves that are partially fermented.
But is there more to the cup of tea and any actual health benefits? We look at the evidence for the health benefits of ordinary black tea from a teapot or tea bag, and green tea.
There is evidence to back the use of tea as a pick me up, it contains caffeine and a stimulating substance called theophylline. These can speed up the heart rate and make you feel more alert.
Black tea extract is sold as a supplement.
Black tea is also full of healthy substances called polyphenols. Polyphenols are antioxidants that can help protect your cells from DNA damage.
One study found that drinking 3 cups of black tea a day lowered blood pressure, but UK experts said more research is needed to confirm the benefits.
Drinking black tea may help protect against type 2 diabetes, but further studies are needed to confirm an association.
Some scientists think that specific antioxidants in tea, including polyphenols and catechins, may help prevent some types of cancer. For example, some research shows that women who regularly drink black tea have a much lower risk of ovarian cancer than women who do not. More research is needed to confirm this. So far, research has shown that black tea does not lower the risk of breast, stomach, or colorectal cancer.
There is some evidence that the antioxidants in black tea may reduce atherosclerosis or clogged arteries and help lower the risk of heart attack.
Regularly drinking black tea may reduce stroke risk and also lower your risk of these conditions:
But more research about black tea's effect on these conditions is needed to be sure.
Early evidence hints that long-term use of black tea may also help protect against osteoporosis and lung cancer, but larger-scale studies are needed to confirm these uses.
As well as possible health benefits of back tea, some research suggests that post- menopausal women who drink tea may have a higher risk of developing rheumatoid arthritis than non-tea drinkers.