Tea - Health Benefits?
June 5th 2006 04:38
TEA - Health Benefits?
Tea leaves are the dried leaves of a species of Camellia (a close relative of those grown by people in their gardens). There are two main types of tea - green and black. These come from the same plant, but are treated differently: green tea is heated soon after picking and is then left as it is; but black tea is dried and then exposed to the air before it is heated. As a result, green and black teas vary in appearance and taste, as well as have a different chemical composition. Green tea is more common in Asia, and black tea more common in Western countries.
Other popular types of tea include: Chinese tea such as Jasmine and Oolong, Afternoon tea (a blend of Darjeeling and Ceylon tea), Iced Tea (more than 80 % of all the tea consumed in the US is served as iced tea) and, my personal favourite – Chai Tea, which is a spiced milky tea, usually containing cinnamon, ginger, cloves and cardamom.
According to ABC’s Catalyst program, tea contains 30-100mg of caffeine, and instant coffee 60-100mg. The recommended maximum caffeine intake is between 400 and 600mg daily. Other sources reveal greater differences of caffeine content between tea and coffee.
An interesting fact - tea has no effect on iron absorption when consumed between meals, but may decrease the uptake of iron from plant foods when consumed with a meal. So try not to drink tea with your meals.
For several years it has been suspected that drinking tea might help protect against heart disease. This is mainly thought to be because of the ‘antioxidant’s found in tea. These chemicals help protect blood cholesterol (among other blood components) from being oxidised. Oxidation of cholesterol turns it into a form that is strongly associated with increased risk of heart disease. This antioxidant effect of tea may also be helpful in reducing the risk of some cancers. There are other ways in which tea may be beneficial to health, too. For example, the same chemicals that appear to protect blood cholesterol also reduce the likelihood that blood will clot in the arteries of the heart, which is the immediate cause of most heart attacks.
Most studies show that tea drinkers have significantly less risk of heart disease than non-drinkers. Tea also claims to be good for your teeth, liver, skin, immune system and blood pressure amongst many other things. It can even be considered a preventative and treatment for cancer. It is also said that tea has ‘minus kilojoules’, which helps drinkers lose weight (celery is said to be another food with ‘minus kilojoules’, where eaters burn more kilojoules digesting it than ingesting it!).
Please remember though that a lot of the studies set out to prove the health benefits of tea don’t consider all factors - for example, coffee drinkers tend to smoke more than tea drinkers, so the association of tea with better health may not be entirely correct. But as far as I'm aware, there haven't been any studies proving tea is bad for you (in reasonable quantities of course) - so go ahead and have another cuppa!
References
http://www.ofspirit.com/jakemayer1.htm
http://www.nutritionaustralia.org/Food_Facts/FAQ/tea_and_heart_disease_faq.asp
http://www.therealteacompany.co.uk/health/healthy.html
http://www.tea.co.uk/index.php?pgId=46
http://www.teausa.com/general/216g.cfm
Image 1 in the Public Domain - http://en.wikipedia.org/wiki/Image:HCAM13.jpg
Image 2 under the terms of the GNU Free Documentation License - http://en.wikipedia.org/wiki/Image
tir_frying_Xi_Hu_Longjing.png
Tea leaves are the dried leaves of a species of Camellia (a close relative of those grown by people in their gardens). There are two main types of tea - green and black. These come from the same plant, but are treated differently: green tea is heated soon after picking and is then left as it is; but black tea is dried and then exposed to the air before it is heated. As a result, green and black teas vary in appearance and taste, as well as have a different chemical composition. Green tea is more common in Asia, and black tea more common in Western countries.
Other popular types of tea include: Chinese tea such as Jasmine and Oolong, Afternoon tea (a blend of Darjeeling and Ceylon tea), Iced Tea (more than 80 % of all the tea consumed in the US is served as iced tea) and, my personal favourite – Chai Tea, which is a spiced milky tea, usually containing cinnamon, ginger, cloves and cardamom.
A tea plant
According to ABC’s Catalyst program, tea contains 30-100mg of caffeine, and instant coffee 60-100mg. The recommended maximum caffeine intake is between 400 and 600mg daily. Other sources reveal greater differences of caffeine content between tea and coffee.
An interesting fact - tea has no effect on iron absorption when consumed between meals, but may decrease the uptake of iron from plant foods when consumed with a meal. So try not to drink tea with your meals.
Tea roasting...
For several years it has been suspected that drinking tea might help protect against heart disease. This is mainly thought to be because of the ‘antioxidant’s found in tea. These chemicals help protect blood cholesterol (among other blood components) from being oxidised. Oxidation of cholesterol turns it into a form that is strongly associated with increased risk of heart disease. This antioxidant effect of tea may also be helpful in reducing the risk of some cancers. There are other ways in which tea may be beneficial to health, too. For example, the same chemicals that appear to protect blood cholesterol also reduce the likelihood that blood will clot in the arteries of the heart, which is the immediate cause of most heart attacks.
Iced tea, becoming more and more popular in the U.S
Most studies show that tea drinkers have significantly less risk of heart disease than non-drinkers. Tea also claims to be good for your teeth, liver, skin, immune system and blood pressure amongst many other things. It can even be considered a preventative and treatment for cancer. It is also said that tea has ‘minus kilojoules’, which helps drinkers lose weight (celery is said to be another food with ‘minus kilojoules’, where eaters burn more kilojoules digesting it than ingesting it!).
Please remember though that a lot of the studies set out to prove the health benefits of tea don’t consider all factors - for example, coffee drinkers tend to smoke more than tea drinkers, so the association of tea with better health may not be entirely correct. But as far as I'm aware, there haven't been any studies proving tea is bad for you (in reasonable quantities of course) - so go ahead and have another cuppa!
References
http://www.ofspirit.com/jakemayer1.htm
http://www.nutritionaustralia.org/Food_Facts/FAQ/tea_and_heart_disease_faq.asp
http://www.therealteacompany.co.uk/health/healthy.html
http://www.tea.co.uk/index.php?pgId=46
http://www.teausa.com/general/216g.cfm
Image 1 in the Public Domain - http://en.wikipedia.org/wiki/Image:HCAM13.jpg
Image 2 under the terms of the GNU Free Documentation License - http://en.wikipedia.org/wiki/Image
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