Research on green tea and its pro-health properties, antioxidising potential and the impact of compounds it contains on gastrointestinal microflora is conducted by scientists from the Institute of Animal Reproduction and Food Research of the Polish Academy of Sciences in Olsztyn. They are also researching the sensory properties of green tea.

Prof. Ryszard Amarowicz, head of Department of Chemical and Physical Properties of Food told PAP that in our culture green tea is not always accepted, sole like it, others do not, but in Asia nobody could live without green tea, Asians drink 5-6 cups a day.

According to the researchers, green tea is the source of two basic kinds of compounds. The first is caffeine, the same compound that is found in coffee. Caffeine in tea was originally called theine. The second group are phenolic compounds - catechins.

Caffeine is a psychoactive compound, after ingestion of tea tiredness subsides, activity increases, mind sharpens, concentration improves, some people believe that drinking green tea delays the onset of dementia and has preventive effect in neurodegenerative diseases such as Parkinson\'s disease or Alzheimer\'s. Interestingly, green tea, just like coffee, is addictive - said Prof. Amarowicz.

The second class of compounds are phenolic compounds which, in the case of green tea are known as catechins. They exhibit antioxidant activity and as natural antioxidants they "sweep" free radicals from our body, thereby preventing a number of diseases. Unfortunately, although the catechin content in green tea is high, their assimilation by the human body is low.

Prof. Amarowicz emphasised that catechins may protect "bad" cholesterol from oxidation, and this process starts atherosclerotic lesions in humans. Besides, drinking green tea raises blood content of "good cholesterol".

"There are some general beliefs about the effects of drinking green tea on the human body. It is widely believed that it is anti-cancer and anti-sclerotic" - said Prof. Amarowicz.

Such common beliefs were addressed 10 years ago by the US Food and Drug Administration - FDA. The agency issues opinions on products entering the US market. When giving its opinion about products or drugs it takes into account all the available results of research on the subject.

In 2005, responding to the request of green tea producers, FDA stated that there was no reliable evidence that drinking green tea could be linked to reduction in the incidence of certain types of cancer: lung, intestine, esophagus, pancreas and ovaries. FDA also emphasised that there was limited evidence of the fact that drinking green tea had a positive impact on the prevention of breast and prostate cancer. A year later, the same organization reported that there was no evidence of the fact that drinking green tea could be linked to a reduced risk of cardiovascular disease. In the same year, however, the organization issued a positive opinion about the ointment produced on the basis of green tea.

According to Prof. Amarowicz, there are studies that show the positive effects of green tea. In animal studies it was observed that in mice green tea inhibited the development of bowel cancer by 50 percent. In Japan, researchers observed a group of 40 thousand people for several years. They found that in this group mortality from cardiovascular disease in those who drank at least five cups of green tea per day was about 25 percent lower than in others.

He emphasised that there is also evidence that green tea expedites fat burning in the body by more than ten percent. The Japanese have shown that drinking green tea contributes to the burning of fat in the body. That is why extracts of phenolic compounds are ingredients in preparations for slimming.

According to the researchers drinking green tea also increases sensitivity to insulin in the human body. The drink thus protects against diabetes. Catechins in green tea also have anti-inflammatory and antibacterial activity.

PAP - Science and Scholarship in Poland, Agnieszka Libudzka

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