"Don't drink overnight tea, it's very toxic and can cause cancer!"
Mr. Zhao has always had the habit of drinking tea. There is a thermos cup on his desk, with tea leaves brewed in it. He can drink it for a day. He didn't finish the tea yesterday, so he started drinking it again today. Unexpectedly, his colleague told him that overnight tea cannot be drunk, because after soaking for a long time, the carcinogen nitrite will produce, not to mention that he is still using a thermos cup, and heavy metals will be precipitated after a long period of soaking in tea.
"In the past, I always soaked a jar of tea in my hometown. I drank it for several days, but I didn't see anything wrong?" This was the first time Mr. Zhao heard of this statement and felt it was not credible.
"Tea in the past was good tea, natural and pollution-free. It's hard to say that tea is now. Last time I drank overnight tea once, and I had diarrhea." A colleague said angrily, "It's better to trust this kind of thing than trust it without it."
1. Can't you drink overnight tea? Will it really cause cancer?
Generally speaking, drinking water may produce nitrite. The water will be in a high temperature and hypoxic environment during heating and boiling, so the conversion rate of nitrate in the water will be accelerated. After boiling water, the longer it is left, the higher the nitrite content inside it, especially the increase in the content in the overnight water is more obvious.
nitrite itself is not a carcinogen, but after entering the body, it will react with the amine substances in the food under the action of gastric acid to form a super strong carcinogen nitrosamine , which is a world-recognized carcinogen. The results of nitrite toxicology research show that ingestion of at a time can lead to acute poisoning in people, and 3g can lead to death.
So the question is, how many nitrites are there in overnight tea?
Han Gezhi Middle School once conducted an experiment. The experiment selected three types of tea, black tea, green tea and Tieguanyin . Take 1g each and add 50ml of hot water, then cool it to room temperature, and leave it for different times. Finally, the nitrite content in the tea leaves was determined and analyzed by Gris's colorimetric method.
Over time, the changes in nitrite in the tea water are as follows:
①0 hours:
Tieguanyin content is 0.0075 mg/L, black tea content is 0.008 mg/L, and green tea content is 0.0087 mg/L.
②8 hours:
Tieguanyin content is 0.0063 mg/L, black tea content is 0.0137 mg/L, and green tea content is 0.0176 mg/L.
③12 hours:
Tieguanyin content is 0.0202mg/L, black tea content is 0.0229mg/L, and green tea content is 0.0263mg/L.
It is not difficult to see from the results that as the placement time increases, the nitrite content in the tea leaves will also increase. However, after 12 hours of storing the three teas, the nitrite content inside is less than 1 mg/L, which does not exceed the safety standards, so there is no need to worry too much.
In our lives, the real "big nitrite" is not overnight tea. The nitrite content contained in these foods is terrible.
2. These are much more harmful than overnight tea.
General Office of the National Health and Family Planning Commission Report on the national food poisoning incident in 2015 pointed out that there are four most common causes of nitrite poisoning .
First, the appearance of nitrite is similar to Ordinary edible salt , and many people mistakenly regard it as ordinary salt;
Second, people in many areas of my country have the habit of Homemade processing meat . If you consume meat products with excess nitrite content, it may also induce poisoning;
Some html l2 vegetables that have been stored for too long, rotten, and not pickled for a long time, or foods that have been stored for too long after being cooked, , etc., will increase the nitrite content in these foods, and blind intake may lead to poisoning;
, 4, , the nitrite content in well water in some areas is very high, and after cooking food with well water for too long, people may be poisoning after intake.
Tea is actually a natural enemy of nitrite. The tea polyphenols, catechins and other antioxidants contained in it can remove nitrites and block nitrosamine synthesis after entering the body.
Tea has a history of thousands of years in my country. For people in Guangdong and Fujian, they have to make tea and drink it every day. Do you know? Studies have found that drinking tea may help prolong life!
3. New research: Drinking two cups of tea a day may prolong life
Recently, a paper was published in the "Yearbook of Internal Medicine" that conducted a follow-up analysis of nearly 500,000 British people for 11 years. Compared with people who don’t drink tea, it was found that:
1. Drink 2 to 3 cups of tea every day: related to the reduction of all-cause risk of 13%. Drink 4 to 5 cups of tea every day: related to the reduction of all-cause risk of 12%. Drink 6 to 7 cups of tea every day: related to the reduction of all-cause risk of 12%. Drink 8 to 9 cups of tea every day: related to the reduction of all-cause risk of 9%. Drink more than 10 cups of tea every day: related to the reduction of all-cause risk of 11%. l11
However, in the study, the capacity of a cup of tea is not pointed out. Chinese Academy of Engineering Liu Zhonghua once suggested that 9-10g tea leaves are brewed into three times a day for drinking. Tea contains catechin, theoflavin, theanine , tea polysaccharide and other health-friendly ingredients. Drinking tea for a long time is conducive to the comprehensive improvement of physical fitness.
Drinking tea is such a great benefit to health, but in life, many people are a little difficult to choose a cup for drinking tea, and they don’t know which cup is safer and more suitable.
4. What is the safest "cup" to use when drinking tea regularly?
I believe everyone has heard of the saying that the thermos cannot make tea. It is said that it is because the heavy metal inside the thermos will precipitate after making tea. Is this true?
In fact, using a thermos cup to make tea will not cause the metal inside to precipitate, nor will it cause corrosion to stainless steel . But even so, it is not recommended to make tea in a thermos cup. is because soaking tea leaves in hot water for a long time will cause the vitamins in the tea leaves to be destroyed, and the taste and flavor of the tea will also be reduced. It is recommended to use a special tea set or glass cup to make tea.
There are many rumors about tea. We must learn to identify rumors. We must not believe some false remarks and bring unnecessary psychological burden to ourselves. #组合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合合� 500,000 people followed up for 11 years and found that two cups of tea per day were related to a 13% reduction in the risk of death from all causes, and black and green tea was good. Singularity . 2022.10.4
[3] "What to eat can remove nitrites". National Party Media Information Public Platform 2019.6.13
[4] "Two academicians talk about healthy drinking tea: follow the rules for a day, a year, and a lifetime". National Party Media Information Public Platform. 2021-10-31
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