Health Benefits of Tea
Studies have shown that tea has considerable health benefits. Tea contains specific phytochemicals that are thought to help prevent cancer, and perhaps slow down aging. Specifically tea contains, "Epigallocatechin gallate, Flavonoids, Tannins, Caffeine, Polyphenols, Boheic acid, Theophylline, Theobromine, Anthocyanins, Gallic acid"1.
By eliminating free radicals that degrade the DNA within cells, flavonoids in tea have an antioxidant effect. The tannins in tea bind with proteins which can, as a result, help reduce diarrhea. The catechins in tea may help reduce fat induced weight gain by improving abdominal fat oxidation.
There is some controversy over whether tea causes dehydration. A study documented in the European Journal of Clinical Nutrition found that tea hydrates the body nearly as well as water with the added benefit of antioxidants2. The primary reason for the belief that tea causes dehydration is the caffeine content. However, it appears that the caffeine in tea is not at high enough levels to have a noticeable effect. According to the National Library of Medicine, a study was done under extreme conditions on mountain climbers at Everest where hot tea was the main source of hydration for one group and the control group were given fluids with no caffeine. No difference was found in their ability to retain water3.
The amount of caffeine in tea is considerably less than that in coffee. Even so, it is a prominent source of this substance. Caffeine can have the effect of enhancing mental alertness, but at the same time reducing the body's ability to rest when needed.
Some studies show that tea has an effect on lowering LDL cholesterol. This helps prevent the build-up of plaque in blood vessels, consequently reducing heart disease.4 Tea also contains fluorides, about the same amount that is contained in fluoridated water. Because of this it does help prevent tooth decay. Conversely, tea also has the effect of staining teeth.
Tea has been shown to boost the immune system. It is thought to prep the immune system to fight invasions of bacteria, fungi, and viruses. It does this through a substance called L-theanine, which is broken down in the liver into ethylamine which increases the response of gamma-delta T-cells. These T-cells are the body's first line of defense against germs.
Drinking tea does help increase bone density somewhat. However, studies have shown that older people who consumes large quantities of tea are only slightly less likely to break a hip or wrist over time.5
Although scientific studies have not proved it to the be case (or disproved it), in many cultures tea bags are thought to reduce swelling and inflammation around the eyes, and also to reduce wrinkles. It is thought that the tannin present in tea does the trick. But that same tannin may also reduce the amount of absorption of minerals when taken internally.
On the whole, most nutritionists would agree that tea consumption, if not taken to excess, is positively beneficial to human health.
<< InDepthInfo on Tea | The History of Tea >>
- Phytochemicals in Tea
- European Journal of Clinical Nutrition article on Tea
- NCBI on Caffeine in Tea and Hydration
- WHFoods on Tea and Cholesterol
- Oxford Journal on Tea and Osteoperosis