"Overnight tea" is toxic and carcinogenic, so don't drink it? The truth is here

gossip

"Can tea help you lose weight and sober you up? Is overnight tea toxic and can cause cancer?"

Tea has always been regarded as a healthy drink. Some people believe that tea can help lose weight and sober up. Of course, there is another attitude towards overnight tea - "cancer-causing".

Rumor Analysis

These claims are incorrect. Don't expect drinking tea to achieve any specific effects. Although there are some studies on tea's ability to lose weight and sober up, the evidence is not sufficient. Overnight tea is not a big deal.

Does overnight tea cause cancer?

Nitrite increased but not much

There is no clear definition of how long overnight tea should be left overnight. Most people think that if the tea brewed today is left overnight, it will be considered overnight tomorrow. Some people also define overnight tea as tea that has been left overnight for more than 12 hours.

1

Nitrite causes cancer? Not much

Where does the nitrite in overnight tea come from? Tea and other plant-based foods produce nitrates during their growth because of nitrogen fertilizers, so there are nitrates in tea itself. Through the combined action of bacteria, reductase, etc., some nitrates will be reduced to nitrites.

In fact, nitrite exists in many foods. Nitrite is added actively in processed meat products, such as grilled sausages and luncheon meat, and is naturally contained in or comes from raw materials, such as green leafy vegetables and baby rice cereal. According to the national standard for food additives GB2760, the nitrite content of meat products is qualified as long as the content is below 30 mg per kilogram in most types.

The nitrite content in tea is much lower than these foods, and even lower than that in infant rice cereal, which has very high safety requirements. GB10769 "Infant Cereal Complementary Food" requires that the nitrite content of rice cereal should not exceed 2 mg per kilogram, but an experiment tested the nitrite content of overnight tea and found that the content was only about 0.02 mg per kilogram.

The Joint Expert Committee on Food Additives (JECFA) of the Food and Agriculture Organization of the United Nations and the World Health Organization has estimated that the safe daily intake of nitrite is 0.07 mg per kilogram of body weight. For an adult weighing 60 kg, long-term and daily intake of 4.2 mg may cause abnormal reactions in the body. Although the nitrite content of overnight tea is indeed higher than that of newly brewed tea, the content is very small. At least 210 liters of overnight green tea must be consumed to reach the toxic dose.

Therefore, although the nitrite content in overnight tea increases, it is only a small amount and it is difficult to reach a dose that is harmful to health, so there is no need to worry.

2

Bacteria growth? Not much

Tea contains tea polyphenols, which are natural antibacterial agents. Experiments have found that even if the tea is stored for more than 12 hours, the bacteria in the tea does not increase much. However, it is necessary to pay attention to the concentration of the tea. Generally, if more than 8g of tea is added to 100mL of tea, the antibacterial effect will be better.

3

Nutritional loss? It may increase

The nutritional content of tea is not high, but the antioxidant phytochemical components are more prominent, such as tea polyphenols, flavonoids, theanine, etc. Judging from the test results of the content of these components, the content of overnight tea is higher than that of freshly brewed tea, and the effect of scavenging free radicals is also better.

Drinking tea has many benefits

Can it help you lose weight and sober up?

1

Whether tea can help you lose weight depends on what you usually drink

The calories in tea are extremely low and can be almost ignored. Therefore, if you usually like to drink high-sugar, high-calorie drinks such as milk tea and juice, switching to tea is definitely a good choice, because it can help you reduce a lot of calorie intake, which is a great help in losing weight.

However, if water is your main drink, tea may not be of any direct help to your weight loss efforts, after all, the calorie difference between it and water is too small.

As for the claim that tea can "scrape away fat" and accelerate fat burning, there is currently no sufficient evidence to support it. Therefore, don't expect to lose weight easily by drinking tea alone. If you want to lose weight successfully, you still have to rely on a healthy diet and moderate exercise. Although tea is good, it cannot replace a healthy lifestyle.

In general, the effect of tea on weight loss depends on your eating habits and lifestyle. A rational view of the relationship between tea and weight loss and finding a healthy lifestyle that suits you is the key to successful weight loss.

2

Tea may help with hangovers, but don’t expect too much

To know whether tea can help you sober up, you first need to understand how alcohol is metabolized in the body.

When alcohol enters the human body, it is mainly metabolized by the liver. In the liver, alcohol is first oxidized into harmful acetaldehyde by enzymes. Fortunately, another enzyme in the liver can quickly convert acetaldehyde into relatively harmless acetic acid, which is then further metabolized into carbon dioxide and water, releasing energy.

The real way to sober up is to speed up the metabolism of alcohol in the body.

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Some experiments have found that theanine and tea polyphenols in tea can increase the activity of alcohol dehydrogenase and acetaldehyde dehydrogenase in the liver, which helps the metabolism of alcohol. However, most of the current experiments are animal experiments, and whether the same effect on humans is still needed. More research.

Tea contains caffeine , so some people think that caffeine helps to refresh the mind, which can offset the "delirium" caused by alcohol. But in fact, caffeine can only temporarily relieve the inhibition of the central nervous system and cannot help the metabolism of alcohol. This slight sobering effect is not a hangover.

In addition, drinking tea to sober up also has some potential risks and limitations. First, strong tea has a certain irritation to the gastric mucosa. Excessive drinking may aggravate the damage to the gastric mucosa and cause diseases such as gastritis and gastroduodenal ulcers. Secondly, some friends who are sensitive to caffeine will experience adverse reactions such as accelerated heartbeat after drinking strong tea or drinking too much tea, especially when drunk, this effect may be more obvious. Therefore, when drinking tea after drinking alcohol, you should pay attention to drinking in moderation and avoid excessive and too strong tea.

In general, drinking tea may help sober up to a certain extent, but it is not completely effective and has potential risks and limitations. If you want to reduce the harm of alcohol and sober up quickly, the best way is to drink less alcohol and drink more water.

Drinking tea is very particular

Drink with peace of mind and remember these 4 points

1

Don't drink hot

Some people like to drink tea immediately after brewing it with hot water. In fact, this is a very unhealthy practice. The International Agency for Research on Cancer (IARC) defines hot drinks above 65°C as Class 2A carcinogens. Drinking hot tea for a long time will increase the risk of esophageal cancer. Therefore, it is recommended to cool the tea before drinking.

2

Do not drink strong tea

Although tea is good, the tannic acid in it may hinder the body's absorption of key nutrients such as iron.

In addition, although the caffeine in tea can refresh the mind, excessive intake may stimulate the nervous system and cause insomnia, palpitations and other discomforts. Therefore, while we enjoy the fragrance of tea, we must also control the concentration of tea to avoid the negative effects of excessive drinking.

3

Do not take medication with tea

The therapeutic effect of a drug often depends on its concentration and metabolic rate in the body. Some substances in tea may combine with drug ingredients, thereby reducing the efficacy of the drug; caffeine may also stimulate gastric acid secretion and cause discomfort, which is undoubtedly worse for people who are taking medication.

4

Don’t drink tea before bed

Tea contains caffeine. If you have sleep disorders or are sensitive to caffeine, you should avoid drinking tea before going to bed to avoid affecting your sleep.

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References

[1] Li Yanyun, Wang Zijian, Pan Xingyu. Detection and analysis of nitrite content in overnight tea[J]. Modern Food. 2020(13):222-224.

[2] Liu Xiaoli, Jiang Shaojuan. Study on the antibacterial activity of overnight tea[J]. Guangzhou Chemical Industry, 2011, 39(23):61-62.DOI:10.3969/j.issn.1001-9677.2011.23.023.

[3] Dong Lu, Dai Zengying, Han Qing, et al. Research progress on the antibacterial effect of tea polyphenols[J]. Shandong Food Fermentation, 2014(3):3.DOI:CNKI:SUN:SDSF.0.2014-03-015.

[4] GB10769 Cereal-based complementary foods for infants and young children

[5] GB2760 Food Additives

[6] Food and Agriculture Organization World Health Organization. Evaluation of certain food additives. Fifty-ninth report of the Joint FAO/WHO Expert Committee on Food Additives. World Health Organ Tech Rep Ser. 2002;913:i-viii, 1-153, back cover. PMID: 12677645.

[7]Yasuyuki Sadzuka, Chieko Inoue, Saho Hirooka, Tomomi Sugiyama, Keizo Umegaki, Takashi Sonobe, Effects of Theanine on Alcohol Metabolism and Hepatic Toxicity, Biological and Pharmaceutical Bulletin, 2005, Volume 28, Issue 9, Pages 1702-1706, Released on J-STAGE September 01, 2005, Online ISSN 1347-5215, Print ISSN 0918-6158, https://doi.org/10.1248/bpb.28.1702

[8] Yang Yuexin, Ge Keyou. Chinese Nutrition Science Encyclopedia (Second Edition) [M]. People's Medical Publishing House: Beijing, 2019: 662

Planning and production

Author | Li Chun, National Registered Nutritionist

Review | Ruan Guangfeng, Deputy Director of Kexin Food and Health Information Exchange Center