Green tea may relieve GI side effects of common cancer drug

Green tea has many health benefits. Now research shows it may be helpful for cancer patients.(studiolopa/iStock)

Drinking green tea has many benefits for the human body. Not only is it a refreshing drink, it is also known for its health benefits. Among other beneficial effects, it is an antioxidant and inhibits hypertension.

A Japanese study has shown that green tea extract shows promise for cancer patients. On March 27, a study presented at the pharmaceutical society of Japan’s annual meeting in Nagoya, Japan, showed that green tea extract can alleviate severe diarrhea caused by the cancer drug irinotecan (CPT-11). The study was presented by Dr. Tomoo Hosoe of Tokyo’s Hoshi University.

Green Tea and Chemo Side Effects

Irinotecan is an anti-tumor drug used for many types of cancer, including colon cancer. However, the chemotherapy drug has serious side effects, including diarrhea.

Irinotecan causes diarrhea due to its SN-38G content. In the intestine, the bacteria β-glucuronidase converts SN-38G into SN-38, which inhibits tumor growth. However, the process also damages the intestinal mucosa.

In a study on mice, Dr. Hosoe’s team found that the high levels of catechin—a natural antioxidant—in green tea extract inhibit irinotecan-induced diarrhea.

The researchers divided the mice into two groups. One group was given irinotecan alone, and the other group was given irinotecan plus green tea extract. The results showed that the mice given only irinotecan had a 3.5-fold increase in fecal water content (diarrhea). In the other group, mice given a combination of green tea extract and irinotecan showed a 1.5-fold increase in diarrhea, which was significantly less than that of the irinotecan-only group.

In terms of the activity of β-glucuronidase-producing bacteria, the number of bacteria was significantly reduced in the group mixed with green tea extract compared to the group given irinotecan alone. Moreover, the increased dose of green tea extract was more effective in reducing the activity of β-glucuronidase.

Green Tea: More Good News for Cancer Patients

For years, Japanese researchers have studied the connection between green tea and cancer. While most studies focus on the role of green tea in preventing cancer, a 2004 study showed that green tea extract had an inhibitory effect on the growth of tumor angiogenesis. Researchers at Japan’s Osaka University studied the effect of green tea extract on blood vessel growth using human umbilical vein endothelial cells (HUVEC). Twenty-four hours after the addition of green tea extract (0-25 mg/ml) to endothelial cells cultured in the medium, cell viability, cell proliferation capacity, cell migration capacity, and cell formation capacity were analyzed.

The results showed that the cell viability of endothelial cells did not change, but cell proliferation, tube formation, and cell migration abilities were significantly reduced, depending on the concentration of green tea extract added. In addition, the activity of vascular endothelial growth factor (VEGF) in endothelial cells, was also reduced as the dose of green tea extract was increased.

The research team concluded that green tea extract inhibited tumor angiogenesis by reducing the expression of VEGF receptors. The results of the study were published in the Japanese Society for Home Economics Research Publications in May 2004.

The Long History of Tea in Japan

The history of tea began in China and spread throughout the world. During the Tang Dynasty (618-907 A.D.), tea was introduced from China to Japan. At that time, during Japan’s Nara period (710-1192 A.D.), the country was attempting to learn and adopt the more advanced Chinese systems and culture. Tea was extremely precious and only a very small number of nobles and monks could enjoy it.

During the Kamakura period (1192-1392 A.D.) in Japan, a Japanese Buddhist priest named Zen master Eisai visited China and brought back green tea leaves to Japan. Eisai wrote “How to Stay Healthy By Drinking Tea,” which recorded the effects of tea leaves and how to make tea. The first complete book on tea in Japan, Eisai’s book had a major impact on the spread of tea culture.

Nowadays, most of the tea roasted in Japan is green tea. In fact, Japanese tea is generally referred to as Japanese green tea. There are various types of green tea, including sencha, mint tea, green tea, and bancha. Green tea is grown extensively in Japan.