How Healthy is Tea?
For Chinese people, drinking tea for health is a tradition that has been passed down for thousands of years. In recent years, more and more research has been conducted on the health benefits of tea: cancer prevention, cardiovascular protection, radiation protection... It seems that all the health hazards in life can be resolved by a simple cup of tea. So, what are the nutritional components in tea? Can it truly promote health? How should one drink it to maximize its health benefits? In this issue, we invite top tea experts in China to answer these most frequently asked questions.
Cancer Prevention is the Primary Benefit of Tea
Professor Han Chi, a researcher at the National Institute of Nutrition and Food Safety of the Chinese Center for Disease Control and Prevention, has been researching the nutrition and efficacy of tea for decades and is one of the leading tea experts in China. He told reporters that the currently more certain health benefits of tea include preventing cancer (including lung, esophageal, liver, colon, etc.), regulating blood lipids, lowering blood sugar, enhancing immune function, and preventing damage from smoking.
“Drinking tea can repair DNA damaged by smoking, and the effect is very good. This is a conclusion we have drawn from human experiments, which can be considered a leading conclusion worldwide,” Han explained. “There is a lot of research on tea around the world now, but most of it is animal experiments using tea extracts. We, on the other hand, conducted human experiments using brewed tea, proving that people can obtain these benefits as long as they persist in drinking tea correctly in their daily lives.”
Jiang Heyuan, an associate researcher at the Tea Research Institute of the Chinese Academy of Agricultural Sciences, who is mainly engaged in research on tea and health, told reporters that the effective nutritional components in tea are diverse, such as the well-known tea polyphenols, as well as theanine, vitamins, caffeine, etc. “According to the production principle, Chinese tea is divided into six major categories: green tea, black tea, yellow tea, white tea, oolong tea, and dark tea. Later, some reprocessed teas, such as scented tea, were developed based on these six categories,” Jiang said. The effective components and functions of various teas are different.
Green tea protects the cardiovascular system. Green tea belongs to unfermented tea, with representatives including West Lake Longjing, Dongting Biluochun, and Huangshan Maofeng. Its main functions are to prevent cancer and cardiovascular diseases, as well as to provide antioxidant effects, improve immunity, and inhibit and kill bacteria.
White tea relieves anxiety. “White tea is classified into two types depending on the classification method,” Han said. One is the more familiar Anji white tea, which is actually a type of green tea. Due to its milder taste compared to green tea, it has become very popular in recent years. Jiang said that the main functions of white tea include protecting brain nerves, enhancing memory, and reducing anxiety. In addition, theanine in white tea can neutralize some of the effects of caffeine. “People who are afraid that drinking tea will affect their sleep can drink some white tea.” The other type is white tea produced in the Fuding area of Fujian. “This type of tea has a smaller output and a heavier taste than ordinary green tea. According to current research, it has good effects on regulating immunity and lowering blood sugar,” Han said.
Oolong tea and black tea lower cholesterol. Oolong tea belongs to semi-fermented tea, with representative varieties including Wuyi rock tea (Da Hong Pao), Tieguanyin, Dongding oolong tea, and Phoenix Dancong; black tea belongs to fully fermented tea, with representative varieties including Keemun black tea from Anhui and Dianhong black tea from Yunnan. Black tea from India and Sri Lanka is also a world-renowned famous product. “Because it is fermented, black tea is less stimulating than green tea, and its functions are also different. It can promote blood circulation and lower cholesterol,” Jiang told reporters.
Dark tea helps with weight loss and fat reduction. Dark tea belongs to post-fermented tea, and the most familiar one is Pu-erh tea. It has a high total content of tea polyphenols and has a good effect on lowering fat and losing weight. According to reports, Professor Bernard Jacotot of Henri-L Hospital in Paris gave 20 patients with high blood lipids three bowls of Yunnan Pu-erh tea a day. After a month, it was found that the fat in their blood had decreased by almost a quarter. The Japanese magazine "Health" also introduced that Pu-erh tea can inhibit weight gain and reduce cholesterol and triglycerides in the blood.
“Some famous varieties of tea, such as the Mingqian tea from Longjing, have the same effective components as ordinary teas, but the content may vary,” Jiang explained. Mingqian tea, because it is picked early, has higher levels of theanine and vitamin C, but lower levels of tea polyphenols. “For health considerations, people don't need to buy particularly expensive tea,” Han reminded. So which tea is the most nutritious? The two experts believe that in terms of the total amount of polyphenols, each type of tea is similar. However, because the processing of green tea is the simplest, its nutrients are preserved more completely.
How to Drink Tea for the Best Health Benefits
After choosing the right tea for you, how to make it play the greatest effect is also a science. Han said: “Different teas have their own rules for storage, brewing, and drinking.”
Storage: Tea is most afraid of moisture and odor. The best containers for storage are tin bottles, porcelain jars, and colored glass bottles; followed by iron tins, wooden boxes, and bamboo boxes; plastic bags and paper boxes are the worst. The container must be dry, clean, and odor-free. After storing the tea, it is best to place it in a dry and ventilated place, not in a damp, high-temperature, unclean, or sun-exposed place. These places should not have strong-smelling items such as camphor, medicine, cosmetics, cigarettes, or detergents. The new green tea of the year can also be sealed and placed in the freezer of the refrigerator, where it can be stored for 3-6 months.
Brewing: Rinse the tea for no more than 15 seconds. “Nowadays people like to rinse tea, but I don't agree with over-rinsing it,” Han said. In our experiments, we found that after rinsing green tea twice, the leaching rate of its active ingredients was over 70%, and for black tea, it was over 60%. That is to say, if you rinse the tea too much, nutrients will be lost in large quantities. Jiang Heyuan reminded that if the tea must be rinsed, the rinsing time should not exceed 15 seconds. Green tea and white tea are best not rinsed. “But there is one exception: people who are sensitive to caffeine can rinse it once before drinking, because caffeine leaches out faster than tea polyphenols, and a quick rinse can remove some of the caffeine.”
Drinking: 12 grams per day is the most suitable. Jiang Heyuan suggests that for ordinary people, drinking about 12 grams of tea a day, brewed in 3-4 times, is appropriate. People who eat greasy food and have a large amount of tobacco and alcohol can appropriately increase the amount of tea. Pregnant women, children, people with neurasthenia, and those with tachycardia should reduce their tea intake accordingly. Han also reminded that with the popularity of gongfu tea, people are drinking “hotter and hotter tea,” which is very wrong. “People drink tea for health, but drinking hot tea will increase the incidence of esophageal cancer and other cancers, which is not worth the loss. The best temperature for drinking tea should be around 60 degrees, not exceeding 70 degrees.”
In addition, you can drink different teas at different times of the day: drink a light cup of green tea in the morning to refresh your mind and clear your heart; drink jasmine tea in the morning for its pleasant aroma to improve work efficiency; drink a cup of black tea in the afternoon to relieve drowsiness and refresh your mind; in the evening, gather with friends or family, brew a pot of oolong or Pu-erh, which has a unique charm and will not affect sleep. You might as well try this daily tea schedule.
Leftover Tea Can Still Be Useful
It is no exaggeration to say that tea is a treasure. As long as it is used properly, “stale” tea can still be useful.
First, overnight tea. Jiang Heyuan said that drinking overnight tea is actually not harmful, but tea is easily oxidized, so tea stains are often left on the cup overnight. In addition, the temperature is relatively high in summer, and tea is easily contaminated by bacteria, leading to mold and spoilage, which can cause diarrhea. Therefore, it is better not to drink overnight tea in summer. If you can't bear to pour it out, it can also be used for the following purposes: 1. Overnight tea is rich in acids and fluorides, which can not only prevent capillary bleeding but also has a bactericidal and anti-inflammatory effect. It can be used for washing and gargling for oral or skin bleeding; 2. Washing hair with overnight tea can relieve scalp itching; 3. Bad breath troubles many people. If you gargle with overnight tea three times a day