The british have been drinking tea for more than 300 years, today, it accounts for nearly half the fluid intake of a British adult. But can you have a too much of a good thing ? There is sometimes nothing more reviving than a cup of tea, but in fact it has little nutritional value although the milk or sugar added may supply around 40n calories. However, the stimulant such as caffeine that tea contains can accelerate the heart rate, increase alertness, and help respiration by dilating the airways of the lungs. Asingle cup of tea provides about 40 mg of caffeine, which is almost wtice the amount present in most cola drinks and about
two thirds the level found in a cup of instant coffee.The tannins in tea are not as useful however. They give it body but can interfere with iron absorption, especially if tea is drunk with iron rich foods. Toddlers should not be given tea because their digestive system are less able to cope with its chemicals stimulant and there is the posibility of developing iron deficiency anemia. Tanins can also stain teeth, particularly dental work. Mouthwashes which contains chlorhexidine should not be used immediately prior to drinking tea because the chemical can accentuate the staining effect.
Tea also contain considerable levels of quercetin, one of the many naturally occuring chemical compounds thatare known as bioflavonoids. Although preliminary research indicates that quercetin might be involved in causing cancer, more recent work suggests that high intakes of bioflavonoids, which are strong antioxidants, are associated with a decreased risk of cancer and heart disease.In particular,green tea and Oolong are thought to have specific anti cancer properties. However, there is still conflicting evidence and the encouraging results of the laboratory experiments have not yet been replicated in population studies. Other constituents of the besides added flavourings such as bergamot, include fluoride (0.25 mg in a cup) and manganese (0.5 mg per cup). people suffering from peptic ulcer should avoid strong black tea because, light coffee,it stimulates acidic, gastric,seretion and may cause irritation; insted, they should drink weak tea with milk. Tea as also been known to precipitate MIGRAINE in sensitive individuals; it is not known, however, whether this is due to its bioflavonoid or its caffeine content. |
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