Green tea has long been linked to a host of positive health benefits on the human body. These benefits accrue due to the many antioxidants that green tea contains. A special mention is required for the benefits of green tea on cancer.

However, in spite of its healthy advantage, the question that still lingers and remains unanswered, is whether: “Does drinking green tea have any benefit on cancer or does it help prevent cancer.?”

There is so far no evidence to suggest the amount you should drink to prevent cancer or reduce its risk. There is also no concluded study to suggest which type of cancer, it can prevent.

How might green tea help prevent cancer?

Nevertheless, the fact remains that the composition of green tea is rich in polyphenols. These are micronutrients that are loaded with antioxidants.

Polyphenols in green tea include catechins, theaflavins, tannins, and flavonoids. They also include  epigallocatechin gallate (EGCG), epigallocatechin, epicatechin gallate, and epicatechin; flavanols such as kaempferol, quercetin, and myricitin are also present in green tea. These are all the cancer-fighting elements in your morning brew.

These antioxidants destroy the free radicals formed during cell metabolism, which may protect cells from DNA damage and inhibit the growth of proteins that promote tumor growth.

In animal studies conducted in the laboratory, polyphenols from tea have inhibited tumor cell growth and induced apoptosis.

But, these are animal studies and we need evidence from human studies to prove its benefits on cancer. The evidence from human studies now is mixed.

Does green tea kill cancer cells?

According to scientists, a compound found in green tea, epigallocatechin-3-gallate (EGCG), may activate a cycle that kills oral cancer cells without harming healthy cells. This finding could lead to more modified therapies to treat oral cancer, as well as other cancers.

Green tea can kill oral cancer cells without interfering with healthy cells. According to a study published in the journal Molecular Nutrition and Food Research, the compound epigallocatechin-3-gallate (EGCG) brings about a transformation in the mitochondria that kills the cancer cells, while keeping the healthy ones intact. This sets off a cycle with more damage being caused to the cancer cells until they undergo programmed cell death

Research further showed that EGCG did not cause this effect in normal cells. In fact, it increased the protective capabilities of normal healthy cells.

Green tea and cancer stem cells

In recent years, the active ingredient in green tea, epigallocatechin-3-gallate (EGCG), has been shown to fight cancer cells.

Many cancer patients on chemotherapy do not respond to it. They often develop resistance to it within a few years.

Although, while chemotherapies kill the cancer cells, they leave the cancer stem cells unharmed. These unharmed stem cells can cause a relapse within months or years.

A relapse is usually stronger and more aggressive and harder to treat because the stem cells are more resilient. Most patients with a relapse do not respond to chemotherapy at all.

Green tea, because of the exceptional properties in its active ingredient, EGCG, helps kill these resilient cells.

Some doctors, therefore, recommend that patients with cancer, drink it or take its supplements, as natural protection.

Why do cancer patients drink green tea?

Phytonutrients like catechins in green tea stimulate the production and function of detoxifying agents in our body, which help to detoxify carcinogens. This has been supported by research conducted by the National Cancer Institute.

Cancer patients widely consume green tea and its extracts. However, there is no clinical evidence that drinking it slows down tumor progression in humans. In fact, there is evidence that green tea might hamper anticancer treatment.

There is some evidence, which suggests that consuming this beverage might reduce the risk of developing some cancers. But, that evidence is not strong enough to certify confirmation.

Nevertheless, the belief that green tea benefits cancer exists. People with cancer, therefore, drink it because they believe it will:

  • improve their immune system, which will help them in fighting cancer
  • improve overall health
  • get rid of toxins and detoxify the body
  • treat their cancer

How much should you drink to prevent cancer?

There are different opinions on how many cups of green tea you should drink daily to get maximum benefit. Manufacturing companies often suggest having between 3 and 5 cups a day.

According to a Japanese study, “Consuming over 10 cups per day (corresponding to 2.5 g green tea extract) significantly prevented lung cancer

According to Healthline, the ideal amount of this beverage to drink depends on the cancer site.

  • For oral cancer – 3 to 4 cups
  • Prostate cancer – 5 cups
  • Stomach cancer – 5 or more cups
  • Breast cancer – drinking 3 cups or more daily reduced the risk of recurrence
  • Pancreatic cancer – 5 or more cups

Effect on cancer treatment

  • Cancer patients whose treatment includes bortezomib (Velcade) should not drink green tea because it can stop Velcade from working. This study was done on animals and we need more research to find out if it has the same effect on humans.
  • Similarly, cancer patients on radiotherapy should avoid drinking green tea.