Cancer has been the leading cause of death among Japanese people since 1981. In 2019, the number of Japanese people who died from cancer was 376,425 (220,390 men and 156,086 women), with the number increasing annually. One in two people (65.0% of men and 50.2% of women) is diagnosed with cancer at some point in their lives. Cancer is a disease that is very close to us and that anyone can contract.
Once cancer is contracted, early detection and treatment are crucial, but in the early stages of cancer development and progression, there are no symptoms. Therefore, regular check-ups and cancer prevention through lifestyle changes are essential.
Catechins contained in green tea have been shown through animal experiments to have effects that prevent and suppress cancer progression.
Cancer Prevention
The mechanism of cancer development can be broadly divided into three stages:
The genes of normal cells mutate.
Mutations in genes occur in succession, and cell proliferation becomes uncontrollable.
Cells become malignant, turning into cancer (malignant tumors).
Catechins can block all these stages and prevent carcinogenesis.
Anti-Cancer Action
So, what kind of action do catechins show against cells that have already become cancerous?
In the body, there are mechanisms to suppress the proliferation and metastasis of cancerous cells. One of which is "apoptosis," which encourages cells to die independently.
First, the structure of the membrane changes, and the cell swells. Next, the genes within the cell are fragmented, and the cell begins to split apart. The divided small cells are removed by immune cells.
Catechins induce apoptosis in cancer cells, leading to the death of cancer cells.
Studies Involving Humans
While the mechanisms of catechins' cancer prevention and anti-cancer effects are becoming more evident through animal testing, research is being conducted to verify whether catechins are similarly effective in humans.
A report from the Saitama Cancer Center Research Institute conducted a 10-year follow-up study from 1986 on 8,552 general residents aged 40 and over. Of the 8,552 participants, 419 who developed cancer were classified into three groups based on their daily green tea consumption: 3 cups or less, 4 to 9 cups, and 10 cups or more.
Comparing the age of cancer onset between the group that drank 3 cups or less and the group that drank 10 cups or more, the age for men went from 65.0 to 68.2 years, and for women from 67.0 to 74.3 years, suggesting that drinking green tea delays the onset of cancer.
Further research is expected to clarify the effectiveness of catechins in preventing and fighting cancer in humans.