There are a lot of nutrients in tea, but because of the small amount, and the fact that limited percentage of them are dissolvable in water, their effects on human health is little. On the other hand, tea polyphenol includes catechin，flavone，flavone glycosides, and anthocyanin. These are called Phytochemicals, a group of substances that are antioxidative and anti-aging. According to medical research, tea prevents and helps to cure cancer, and plays an indispensable role in the war on cancer.
Tea causes cancer?
Some reports suggest that rather than preventing cancer, tea is carcinogenic. They offer various reasons; let us carefully examine each of them.
- Drinking Pu-erh tea is most likely to cause cancer?
Reason: There is the saying about Pu-erh tea: the older the more fragrant, but during the reserve process, it is easy to be contaminated by aflatoxin and that can cause cancer.
Truth: Pu-erh tea needs a few years’ fermentation，during which various kinds of bacteria must take part, but aflatoxin is not among them. As to whether aflatoxin will contaminate Pu-erh tea if it grows mold during fermentation and storage process, that depends on the storeage method and environment. Some research shows aflatoxin is unlikely to grow in Pu-erh tea, therefore it is scientifically implausible to say that Pu-erh tea causes cancer.
- Tea contains tannin that causes cancer?
Reason: according to Dangers from Tea written by Juliette Morton, a botanist from the University of Miami, tea contains dangerous tannin that can lead to esophagus cancer.
Truth: Juliette’s article was published in 1987, but existing evidence shows that tea contains polyphenol that includes 30 kinds of polyphenol substances instead of tannin. These substances not only causes no harm to the human body, they help to lower cancer incidence. Therefore it is wrong to mistake tea polyphenol as tannin.
- Overnight tea causes cancer?
Reason: Overnight tea contains secondary amine that may turn into carcinogenic nitrosamine.
Truth: Overnight tea refers tea that is made the day before, after a long time, tea polyphenols oxidize and oxidation products darken its color. However, these oxidation products are non-toxic. As to secondary amine, it exists in almost all kinds of food, especially in preserved food, hence overnight tea is no the main source of secondary amine. Moreover, to turn secondary amine into nitrosamine, certain conditions and materials are necessary for the transformation; therefore it is not necessary that the tiny amount of secondary amine contained in overnight tea will turn into nitrosamine. Thus overnight tea does not cause cancer.
4 Tea made in thermal mug causes cancer?
Reason: When using thermal mug to make tea, tea is soaked in high-temperate water for a long time, which damages its vitamins and increases carcinogenic substances.
Truth: Some people prefer to use thermal mug for making tea in order to drink hot tea. Although boiled water does damage to the nutrients in tea, there are no scientific evidence to support the claim that it also increases carcinogenic substances. Because thermal mug seals temperature, tea loses nutrients in this kind of environment, which may also change its nutrients. Therefore it is wise not to use thermal mugs for making tea or to avoid high-temperature sealed environment.
Based on the analysis above, those claims that tea causes cancer do not have scientific support, instead, there are many research to verify tea’s anti-cancer effects. Therefore tea plays constructive role in preventing cancer. However, this does not mean that all kinds of tea or any way of drinking tea is healthy; there are a lot to learn about drinking tea, without paying attention to these details, tea’s benefits could be wasted and turned into harms.