Green tea’s anti-inflammatory and anticancer effects are well-studied and could offer some peace of mind to anyone afraid of developing cancer or facing the trials of cancer treatment.
Decades of research have looked at green tea’s cancer-fighting prowess, including a study published in 2022 in the International Journal of Molecular Sciences that demonstrated that the catechins (phytochemicals) found in the leaves of green tea can prevent a variety of cancers.
Green tea is also a promising angiogenesis inhibitor. This means its active components can prevent the development of new blood vessels from a pre-existing vasculature. Cancer triggers the creation of these new blood vessels in order to feed the tumor.
A study in Biomedicine and Pharmacotherapy goes even further stating, “Green tea and its polyphenolic substances (like catechins) show chemo-preventive and chemotherapeutic features in various types of cancer and experimental models for human cancers.” Chemo-preventatives are substances that prevent cancer while chemotherapeutics are substances that treat cancer.
These findings aren’t new. Studies published as early as 2003 and 2006, both in the International Journal for Cancer, report the same results—the consumption of green tea potentially inhibits the formation of new blood vessels (angiogenesis) and therefore reduces the risk of developing certain forms of cancer.
The effectiveness of green tea polyphenols (GTP) and its constituent epigallocatechin gallate (EGCG) in tumor regression was also shown by research published in Cancer Letters in 2007. In this animal study, mice were inoculated with human breast cancer MDA-MB-231 cells. Scientists considered the treatment with GTP and EGCG as “effective in delaying the tumor incidence as well as reducing the tumor burden.”
Active Components in Green Tea
Catechins are the responsible active healing agents in Camellia sinensis, green tea’s scientific name. They neutralize reactive oxygen and nitrogen species. Their derivatives include epicatechin, epigallocatechin, epicatechin gallate (ECG), and EGCG, the latter being the most potent anti-inflammatory and anticancer agent of all catechins.
A study published in Biochemical Pharmacology researched EGCG and verified its apparent abilities as a powerful antioxidant, preventing oxidative damage in healthy cells. The compound isn’t only anti-angiogenic but also has the ability to change the cell’s response to chemotherapy. Therefore, EGCG is called an anti-tumor agent.
The scientists add that “EGCG has great potential in cancer prevention because of its safety, low cost, and bioavailability,” which stands in stark contrast to other cancer drugs, preventative in nature, or as a treatment.
Tamoxifen and Raloxifene, for instance, are two commonly prescribed medications for the prevention of breast cancer. The average cost of a 30-day supply is about $90 without insurance. For insured patients who receive a prescription for EGCG from their doctor, the out-of-pocket cost might be as low as zero dollars. EGCG can increase the bioavailability of Tamoxifen and enhance the cytotoxicity of Raloxifine so talk to your doctor about drinking green tea if you are on these drugs.
Quality Matters
The origin and type of green tea leaves matter. Unfermented green tea is the best source of tea’s healthy compounds, a 2020 study published in the International Journal of Molecular Sciences found. When buying tea for medicinal reasons, differences in quality affect the amount of catechins and their antioxidant activity.A peer-reviewed Polish study published in 2018 had the goal of evaluating these markers, as well as the metal content (K, Na, Ca, Mg, Fe, Mn, Cu, Zn, Cr, Pb, Cd, and Ni) in the leaves. The observation included tea types cultivated in Japan, Sri Lanka, South Korea, India, China, and Japan with the following results:
- The highest amounts of catechins were observed in green tea samples from Korea and Japan. Teas from Nepal, India, and China were found to have the lowest concentration of these molecules.
- EGCG as the primary catechin was only found in one tea sample, which originated from China. Other samples were dominated by the metabolite EGC.
- Green teas from Sri Lanka showed the highest value of antioxidants. Whereas the highest EGCG concentration was found in a Japanese Sencha.
- Testing called principal component analysis revealed positive correlations between the EGCG content and the elements of copper (Cu) and calcium (Ca). Among others, both calcium and copper are considered essential minerals for human health. The latter was found in its highest concentration in original and blended green teas from China.
- Polyphenols, which are naturally occurring in plant foods and are beneficial for heart health, were traced back to samples of Korean Jeoncha tea. Japanese Matcha displayed the highest amount of chromium.
- Some teas were also heavily contaminated by toxic heavy metals. In general, this was the case in tea samples that originated in China and India. However, the paper emphasizes that “these values were far below appropriate norms for green teas.”
Some sources state that EGCG is most active, abundant, and condensed in matcha, which is considered the highest quality tea due to its unique chemical composition, prized flavor, and health-promoting properties, such as a high content of antioxidant and anti-inflammatory substances.
Types of Cancer Affected
According to the aforementioned study in the International Journal of Molecular Sciences, green tea catechins are widely described to be efficient in the prevention of lung cancer, breast cancer (reduced percentage mammographic density), esophageal cancer, stomach cancer, liver cancer, and prostate cancer.In addition to quality, the quantity and concentration of green tea are also important for its efficacy. Published in Cancer Causes & Control, a Japanese study suggests that drinking seven or more cups of green tea per day decreases the odds ratio of stomach cancer to 0.69 compared for those who drank seven cups a day compared to a baseline rate of 1 for those who rarely drank it. Occasional tea drinkers had a .62 odds ratio of colon cancer compared to a baseline of 1 for rare drinkers to 1. The study suggested occasional drinkers had a higher risk of rectum cancer, but other research found no impact.
To reduce the chance of gastric cancer by about 60 percent, individuals need to consume more than 250 g of green tea per month, a Chinese study reveals. This might also have protective effects on liver cancer, the study found.
Another Chinese study claims that drinking green tea seemed to have decreased the risk for the development of gastric cancer by 81 percent, liver cancer by 78 percent, and esophageal cancer by 39 percent among alcohol drinkers. Researchers even found a potential decrease in the risks of developing the three kinds of cancers among cigarette smokers, respectively by 16 percent, 43 percent, and 31 percent.
Specialists in the field have long reported on the chemo-preventative aspects of green tea. A review in Current Drug Targets from 2012 mentions “a large number of experimental studies using a variety of animal models,” as well as “many epidemiological studies” that had been recorded.
Green tea catechins work without causing major side effects. They prevent the development and progression of precancerous lesions, trials published in Molecular Nutrition & Food Research have shown.
Favorite Beverage in East Asia
Green tea’s biological effects, such as anti-mutation, antioxidation, and anti-tumor, certainly boost the popularity of East Asia’s favorite beverage. Even consumers in North Africa, the United States, and Europe enjoy the tea more and more for its antioxidant and anti-cancer qualities.A pooled analysis of prospective studies from the Asia Cohort Consortium, published in 2022 in the International Journal of Epidemiology, found that the consumption of at least five cups of green tea per day is associated with lower risks of death from all causes. Unfortunately, the findings remain controversial.
More Research Needed
Summaries of many studies note the positive effects of green tea. However, most mention that a generalization of the outcomes isn’t possible at this point, as much of the research has been conducted in East Asia, where the population is accustomed to the high consumption of green tea. Differences in diet and lifestyle also confound findings when compared to Americans.Researchers emphasize clearly that green tea can’t replace standard chemotherapy. Nonetheless, its beneficial effects may support the standard anti-cancer approach.
The author encourages readers to continue to visit and to be treated by their health care professionals, including physicians. The author is not acting in the capacity of a doctor, licensed dietician-nutritionist, or other licensed or registered medical professional.
