Why does drinking tea have many benefits?

How much effect does tea have on health care? For China people, drinking tea for health preservation is a tradition that has been passed down for thousands of years. In recent years, more and more studies have shown that tea has anti-cancer, cardiovascular protection and radiation protection ... It seems that all health hazards in people's lives can be solved by a cup of tea. Then, what nutrients are there in tea, can they play a health-preserving role, and how to drink them to maximize their health-preserving role? In this issue, we invite top domestic tea experts to answer these questions that everyone is most concerned about. How to drink tea is the best for your health. Preventing cancer is the main function of tea. Professor Han Chi, a researcher at the Institute of Nutrition and Food Safety of China Center for Disease Control and Prevention, has been engaged in the research of tea nutrition and efficacy for decades, and is the leading tea expert in China. He told reporters that the exact health care effects of tea at present include preventing cancer (including lung cancer, esophageal cancer, liver cancer, colon cancer and so on). ), regulating blood lipid, lowering blood sugar, enhancing immune function and preventing smoking injury. "Drinking tea can repair DNA damaged by smoking, and the effect is very good. This is our conclusion through human experiments and the world's leading conclusion. " Han Chi explained, "There are many studies on tea all over the world, but most of them are animal experiments, which are made of tea extracts. And we are conducting human experiments with tea soup soaked in tea leaves, which proves that people can get such benefits as long as they insist on drinking tea correctly in their daily lives. " Jiang Heyuan, an associate researcher at the Tea Research Institute of Chinese Academy of Agricultural Sciences, who mainly studies tea and health, told reporters that there are many effective nutrients in tea, such as tea polyphenols, theanine, vitamins and caffeine. "According to the production principle, China tea can be divided into six categories, namely green tea, black tea, yellow tea, white tea, green tea and black tea. Later, some reprocessed teas, such as scented tea, were developed on the basis of six categories. " Jiang Heyuan said that all kinds of teas have different active ingredients and different effects. Green tea protects cardiovascular system. Green tea belongs to non-fermented tea, represented by West Lake Longjing, Dongting Biluochun and Huangshan Mao Feng. Its main function is to prevent cancer and cardiovascular diseases, and it also has the functions of antioxidation, improving immunity, inhibiting and killing bacteria. White tea relieves anxiety. "White tea is classified according to different methods, including two kinds," said Han Chi. One is Anji white tea, which is familiar to everyone. It is actually a kind of green tea. Because it tastes more mellow than green tea, it is very popular in recent years. Jiang Heyuan said that the main function of white tea is to protect the brain, enhance memory and reduce anxiety. In addition, theanine in white tea can neutralize the effect of caffeine. "People who are afraid that drinking tea will affect their sleep can drink some white tea." There is also a kind of white tea produced in Fuding, Fujian. "This kind of tea produces less than ordinary green tea and tastes heavier. According to the current research, this kind of tea has a good effect of regulating immunity and lowering blood sugar, "Han Chi said. Green tea and black tea lower cholesterol. Green tea belongs to semi-fermented tea, and the representative varieties are Wuyi Rock Tea (Dahongpao), Tieguanyin, Frozen Top Oolong Tea, Fenghuang Danzong and so on. Black tea belongs to fully fermented tea, and its representative varieties are Qi Hong in Anhui and Dianhong in Yunnan. Black tea in India and Sri Lanka is also a world-famous brand. "Because of fermentation, black tea is less irritating than green tea and has different effects. It can promote blood circulation and lower cholesterol." Jiang Heyuan told reporters. Black tea reduces weight and fat. Black tea belongs to post-fermented tea, and Pu 'er tea is the most familiar one, in which the total amount of tea polyphenols is high, which has a good effect of reducing fat and weight. According to reports, Beenaert of Henri Rondo Hospital in Paris? Professor Giaccotto gives 20 patients with hyperlipidemia three bowls of Yunnan Pu 'er tea every day. A month later, he found that the patient's blood lipid almost decreased 1/4. According to Japan's "Health" magazine, Pu 'er tea can inhibit weight gain and reduce cholesterol and triglycerides in the blood. "Some famous teas, such as Qianming Tea in Longjing, have the same active ingredients as ordinary tea, and the content may be different." Jiang Heyuan explained that tea before the Ming Dynasty had higher theanine and vitamin C content and lower tea polyphenols content because it was picked early. "For health reasons, people don't have to buy particularly expensive tea," Han Chi reminded. So which kind of tea is the most nutritious? Two experts believe that in terms of total polyphenols, each kind of tea is similar. But because the processing technology of green tea is the simplest, the nutrients are better preserved. How to drink tea is the best for your health. After choosing tea, how to make it play its greatest role is also a science. Han Chi said: "Different teas have different methods of preservation, brewing and drinking." Preservation: Tea leaves are most afraid of moisture and odor. Tin bottles, porcelain jars and colored glass bottles are the best containers for preservation. Secondly, we should use tin cans, wooden boxes and bamboo boxes. Plastic bags and cartons are the worst. The container should be dry, clean and free of peculiar smell. Well-preserved tea should be placed in a dry and ventilated place, not in a damp, high temperature, unclean or exposed place. There must be no irritating articles such as camphor, medicines, cosmetics, cigarettes and washing products in these places. The new green tea of that year can also be sealed and put into the freezer, which can be kept for 3-6 months. Brewing: the longest time for tea washing 15 seconds. "Now everyone likes to wash tea when drinking tea, but I don't approve of excessive washing tea." Han Chi said that we found in the experiment that the leaching rate of effective components in green tea was over 70% and that in black tea was over 60%. In other words, washing tea too much will lose a lot of nutrients. Jiang Heyuan reminded that if tea leaves must be washed, the washing time should not exceed 15 seconds. Green tea and white tea, it is best not to wash. "But there is one exception. People who are sensitive to caffeine can wash it before drinking tea, because the caffeine in it is leached faster than tea polyphenols, and quick washing can remove some caffeine. " Drinking:12g per day is most suitable. Jiang Heyuan suggested that for ordinary people, it is appropriate to drink about 12 grams of tea every day and brew it three or four times. People who eat more greasy food and have a large amount of alcohol and tobacco can appropriately increase the amount of tea. Pregnant women and children, neurasthenia, tachycardia, should be appropriate to reduce the amount of tea. Han Chi reminded that with the popularity of Kung Fu tea, people drink tea "more and more hot", which is very wrong. "People drink tea for health care, but drinking hot tea will increase the incidence of cancer such as esophageal cancer, which is not worth the candle. The best temperature for drinking tea should be about 60 degrees, not more than 70 degrees. " In addition, you can drink different teas at different times of the day: drink a cup of light green tea in the morning to refresh your mind; Drinking jasmine tea in the morning has a pleasant fragrance and can improve work efficiency; Drink a cup of black tea in the afternoon to get rid of difficulties and refresh yourself; Getting together with friends or family at night and making a pot of oolong or Pu 'er will not affect sleep. We might as well try this arrangement of drinking tea some day. It is no exaggeration to say that tea is a treasure. As long as it is used well, "stale" tea can also exert its residual heat. One is overnight tea. Jiang Heyuan said that there is no harm in drinking overnight tea, but tea leaves are easily oxidized, so there are often refreshments on the cups of overnight tea. In addition, the temperature is high in summer, and tea leaves are easily contaminated by bacteria, moldy and rancid, leading to diarrhea, so it is best not to drink overnight tea in summer. If you don't want to pour it out, you can also use it for the following purposes: 1 Overnight tea is rich in acid and fluorine, which can not only prevent capillary bleeding, but also play a role in sterilization and anti-inflammation, such as oral bleeding and skin bleeding, and can be used for bathing and gargling; 2. Wash your hair with overnight tea to treat scalp itching; If you rinse your mouth with overnight tea three times a day, bad breath will bother many people.