Iranian researchers published a study in 2009 indicating that drinking a cup of hot tea daily can increase the risk of esophageal cancer. Moreover, when the tea water temperature is between 65°C and 69°C, the risk of esophageal cancer doubles. Once the water temperature exceeds 70°C, the incidence of esophageal cancer increases eightfold. If the tea is consumed within 2 minutes of being poured, the risk of developing esophageal cancer is about five times higher than if it is waited for 4 minutes before drinking. Another study found that a tea temperature between 56°C and 60°C is more beneficial to health when drinking tea.
In addition to the potential cancer risk from tea that is too hot, Taiwanese nutritionist Zhang Silan reminds that pesticide residues in tea leaves can also be detrimental to health. If you are concerned about pesticide residues, you can discard the first infusion of water. When brewing tea, keep the lid open to not trap the steam, allowing some pesticide substances to evaporate with the steam. When purchasing tea, it is also advisable to choose organic tea, which is relatively safer. So, what is the principle behind tea's anti-cancer effects, and which types of cancer can be prevented by drinking tea in daily life?
I. How to Prevent Cancer by Drinking Tea
1. The anti-cancer effect of green tea
Some studies at home and abroad have shown that regardless of the type of tea, it has varying degrees of preventive and therapeutic effects on chemically induced or metastatic tumors in experimental animals. Both endogenous and exogenous free radicals have carcinogenic effects, but natural antioxidants can scavenge free radicals. Therefore, the anti-cancer and anti-tumor effects of these natural antioxidants have garnered significant attention. Green tea is rich in natural antioxidants such as "tea polyphenols." Consumed before or after meals, various antioxidants work synergistically to scavenge free radicals, which further enhances the anti-cancer and anti-tumor effects of green tea.
Brown Rice Green Tea
2. "Green Tea Polyphenols" are an important substance in green tea's anti-cancer properties
The content of green tea polyphenols in green tea is five times that of ordinary tea. Green tea can reduce the incidence of certain cancers, but scientists previously did not understand what substance was responsible for this preventive effect or how it worked, making it impossible to determine the effective daily amount of green tea one should consume.
Green tea polyphenols may be just one of the anti-cancer substances in green tea. They also found that the molecular structure of green tea polyphenols is similar to that of the anti-cancer drug Methotrexate.
DHFR is crucial for both healthy and cancerous cells. Green tea polyphenols bind strongly to DHFR, but less strongly than Methotrexate, so the side effects on healthy cells are smaller than those of the anti-cancer drug.
3. The anti-cancer effect of Pu-erh tea
After comparing the effects of various green teas, it was determined that Pu-erh tea has a stronger effect in killing cancer cells. After long-term consumption of Pu-erh tea by cancer patients, cancer cells became more polygonal, shrank into a round shape, had reduced pseudopodia, and lost their ability to adhere and migrate; some even detached, floated, and were lost. The remaining cells became smaller, rounder, and concentrated, with pyknosis of the nucleus, condensation or disappearance of chromatin, vacuoles appearing in the nucleus and cytoplasm, pyknosis or fragmentation of the nucleolus, contraction or mutual condensation of chromosomes, a reduction in ribosomes, and expansion of mitochondria and endoplasmic reticulum. RNA synthesis decreased and nuclear division ceased. These changes demonstrate that under the pharmacological action of Pu-erh tea, cancer cells tend towards death through degeneration.
II. Which cancers can be prevented by drinking tea
1. Drinking tea to prevent prostate cancer
Recent research shows that drinking either black tea or green tea can help prevent prostate cancer. It also aids in lowering cholesterol, reducing cellular damage caused by smoking, and even preventing heart disease.
Foreign researchers investigated 20 male patients with prostate cancer. They drank 5 cups of green tea, black tea, etc., daily before surgery. After surgery, analysis of their blood samples and prostate tissue revealed higher levels of phenols in their tissue samples. When black tea, green tea, or soda was added to the culture medium of cancer cells, the growth rate of the cancer cells slowed significantly.
2. Drinking green tea is beneficial for preventing ovarian cancer
Recently, Australian and Chinese researchers discovered through experiments that green tea can reduce the incidence of ovarian cancer in women. Women who drink green tea daily can reduce their incidence of ovarian cancer by nearly 60% compared to other women.
Researchers from Curtin University in Australia and Zhejiang Cancer Hospital in China conducted an experiment on 900 women to understand the causes of ovarian cancer. Among them, 254 had been diagnosed with ovarian cancer, and 652 were healthy women. The results showed that daily tea consumption, especially green tea, significantly reduced the incidence of ovarian cancer in women. In addition to tea, other factors such as smoking, oral contraceptives, physical exercise, and family history of ovarian cancer also have varying effects on its incidence.
3. Drinking green tea can prevent skin cancer
Researchers at Dartmouth Medical School in New Hampshire, USA, have found that drinking several cups of tea daily can reduce the risk of two common types of skin cancer.
According to Reuters, the research team led by Judy Reese studied the eating habits and health of 2,200 adults and found that tea drinkers had a lower risk of squamous cell carcinoma and basal cell carcinoma, two common skin cancers. People who drank more than one cup of tea a day had a 20% to 30% lower risk of these cancers than non-tea drinkers.
Research shows that tea contains an antioxidant called EGCG, which can limit the damage of ultraviolet radiation to the skin. This effect is more pronounced in people who have been drinking tea for decades and drink at least two cups a day.
The experts on the research team pointed out that the above findings do not mean that drinking tea replaces sun protection. There is no evidence that drinking tea reduces the risk of skin cancer for people who get sunburned multiple times.
Brown rice and green tea