By Stephen Janz, Clinic Director, Kenmore Centre for Health
Tea is the most widely consumed drink worldwide after water. Often associated with English culture Tea drinking originated in China where it was used as a medicinal drink during the Shang dynasty about 3000 years ago. It took until the 17th century for tea drinking to be popular in England and eventually spread throughout the world. Tea is the dried leaves of a number of varieties of the plant Camellia sinensis. Once picked and dried, leaves which are more highly oxidised through processing become black tea which makes up about 80% of tea consumed. Leaves which undergo minimal oxidation become the naturally lower caffeinated green tea, and although only making up about 20% of worldwide tea consumption it is this form that is of interest in health research. In addition to caffeine which provides a mild stimulant effect, green tea contains a number of medical compounds including L-theanine which has a relaxing effect, and polyphenols providing a rich source of antioxidants which are responsible for most of green teas other medicinal properties.
So just what is green tea good for? It’s a pretty long list and research is ongoing but so far there is evidence for the use of green tea for · Weight loss – we all probably remember the weight loss tea scams, however it appears that drinking green tea before an exercise session increases the effectiveness of fat burning catecholamines released during exercise · UV skin damage – UK researchers have found that the equivalent of 2 cups of green tea a day reduced inflammation following UV exposure. This does not mean throw away your sunscreen but it does suggest a simple measure worth trying to further protect your skin · Improved memory – once again a couple of cups of green tea a day appears to improve recall ability · May reduce the risk of various types of cancers, probably due to the antioxidants in green tea · May be protective against Alzheimer’s and Parkinson’s disease · May reduce the risk of dental carries and reduce bad breath due to its inhibitory effect on common mouth bacteria · Green tea can reduce blood sugar levels and reduce insulin sensitivity, possibly reducing the risk of developing type 2 diabetes · Lowers total and LDL cholesterol.
How should you take your green tea? The best choice is a simple infusion of hot water (not more than 870) and quality tea leaves. Commercial drinks undergo additional processing and added sugar so straight away the health benefits are obscured. The good news is many of these benefits can be achieved with one to three cups of green tea a day. To achieve some effects such as cholesterol lowering benefits up to 10 cups a day are necessary which for many people is too much caffeine. In these cases a decaffeinated green tea extract might be a better choice.