Green Tea and Cancer

Written By: Dr. Adam McLeod, ND, BSc (Hons)

Green tea is a common beverage that can be found at any cafe yet it also has important therapeutic properties.

Epigallocatechin gallate (EGCG) is an extract from green tea that has shown great promise as an integrative cancer therapy. The mechanism of action is complicated because it interacts with multiple molecular pathways to inhibit the growth of cancerous cells. When cancer cells are exposed to EGCG, it triggers cell death by a variety of mechanisms^1,2,3,4. Not only does it inhibit the growth of cancerous cells, but it also slows down the rate of metastasis.

Although there is a wide range of EGCG content in green tea, a strong tea has about 70mg per tea bag. The therapeutic doses for EGCG (particularly in the context of cancer) is a minimum of 1500mg per day. Which means you would have to have approximately 20 green teas per day to reach this dose. Obviously this is not practical as a long term treatment plan so the best way to get the appropriate doses is through pill form. If you enjoy having green tea then you can certainly continue to do so but you will not be significantly contributing to the therapeutic effect of the EGCG.

One important characteristic of EGCG is that it acts as an anti-angiogenic substance. Angiogenesis is the growth of new blood vessels into a developing tumour. This process is necessary when cancer cells are spreading because the smaller growths need a blood supply to sustain their rapid growth. Cancer cells will often secrete chemicals that trick the human body into growing blood vessels into the tumour. EGCG helps to inhibit this process by inhibiting the viability of capillary tube formation and migration. This effect seems to be greatly enhanced by a new class of drugs called ERK inhibitors².

Tumour samples of mice treated with EGCG clearly show that the cancerous cells have reduced ERK activity while having enhanced p38 and JNK activity. In other words, the pathways that promote growth are down-regulated and the pathways that inhibit growth are up-regulated. The net effect is that the cancer does not grow or spread as quickly. Every molecular marker that was tested indicated that the cancer was less aggressive and more prone to cell death. If you perform a quick Google scholar search, you will see hundreds of well-controlled studies that consistently demonstrate this anti-cancer effect.

When EGCG is combined with curcumin at high doses, it helps to stabilize leukemias and lymphomas. There are many well-documented cases of patients with multiple myeloma who have had long-term disease stabilization by simply taking high doses of EGCG and curcumin. These natural compounds work synergistically to reduce inflammation and promote cell death in cancerous cells. The effectiveness of EGCG in multiple myeloma is undeniable, and this has resulted in a resurgence of research into its use as an adjunctive cancer therapy⁶.

There are a handful of chemotherapy drugs where the use of EGCG is contraindicated such as bortezomib (Velcade). There is contradictory information about the significance of this interaction, but it is still best to avoid combining EGCG with velcade¹⁵. Some doctors focus on this one interaction while ignoring the overwhelming evidence that EGCG often acts synergistically with other forms of chemotherapy. It is difficult to argue against the use of EGCG if you take the time to actually look at the evidence. When EGCG is combined with cisplatin, it not only significantly increases the effectiveness of the drug, it also dramatically reduces the side effect profile^7,8,9.

Recently in the media, concerns have been raised about the connection between EGCG and liver toxicity. These liver toxicity reactions that are potentially related to EGCG are exceptionally rare considering how regularly EGCG is consumed in the general population. There have been several documented case studies of liver toxicity that have been connected to use of EGCG. It appears that there may be a genetic predisposition to these rare reactions¹². At this point in the time mechanism of action for these reactions is unclear, however, it is in many cases likely due to a immune-allergic mechanism. In other words, it could be that some of these patients were just simply allergic to EGCG.

There is contradictory information regarding the impact of EGCG on liver as several animal studies indicate that it actually has a strong protective effect on the liver and kidneys¹⁰. I can tell you from experience that I have literally prescribed EGCG thousands of times and I have never seen even a hint of such reaction. EGCG is a exceptionally safe supplement when used appropriately and patients should not be fearful of using it due to a handful of exceptionally rare cases of liver toxicity.

EGCG is an example of a supplement where the quality makes a significant difference. In order to obtain the desired anti-cancer effect, you must take high doses of quality EGCG. Drinking green tea may be helpful in the context of cancer prevention, but when it comes to cancer treatment, you need much higher doses. Some physicians recommend that patients get EGCG administered by intravenous therapy to get the doses as high as possible. The doses required to enhance chemotherapy and promote cell death in cancerous cells are quite high, but they are obtainable by consuming EGCG orally. It is also important to point out that this treatment is cost effective and generally well tolerated by patients.

Dr. Adam McLeod is a Naturopathic Doctor (ND), BSc. (Hon) Molecular biology, Motivational Speaker and International Best Selling Author. He currently practices at his clinic in Vancouver, British Columbia where he focuses on integrative cancer care. https://www.yaletownnaturopathic.com

References:

1) Ahmad, Nihal, Sanjay Gupta, and Hasan Mukhtar. “Green tea polyphenol epigallocatechin-3-gallate differentially modulates nuclear factor κB in cancer cells versus normal cells.” Archives of biochemistry and biophysics 376.2 (2000): 338-346.

2) Shankar, Sharmila, et al. “EGCG inhibits growth, invasion, angiogenesis and metastasis of pancreatic cancer.” Frontiers in bioscience: a journal and virtual library 13 (2007): 440-452.

3) Hwang, Jin-Taek, et al. “Apoptotic effect of EGCG in HT-29 colon cancer cells via AMPK signal pathway.” Cancer letters 247.1 (2007): 115-121.

4) Shimizu, Masahito, et al. “EGCG inhibits activation of HER3 and expression of cyclooxygenase-2 in human colon cancer cells.” Journal of experimental therapeutics & oncology 5.1 (2004): 69-78.

5) Shah, Jatin J., Deborah J. Kuhn, and Robert Z. Orlowski. “Bortezomib and EGCG: no green tea for you?.” Blood 113.23 (2009): 5695-5696.

6) Shammas, Masood A., et al. “Specific killing of multiple myeloma cells by (-)-epigallocatechin-3-gallate extracted from green tea: biologic activity and therapeutic implications.” Blood 108.8 (2006): 2804-2810.

7) El-Mowafy, A. M., et al. “Novel chemotherapeutic and renal protective effects for the green tea (EGCG): role of oxidative stress and inflammatory-cytokine signaling.” Phytomedicine 17.14 (2010): 1067-1075.

8) Davenport, Andrew, et al. “Celastrol and an EGCG pro-drug exhibit potent chemosensitizing activity in human leukemia cells.” International journal of molecular medicine 25.3 (2010): 465-470.

9) Sarkar, Fazlul H., and Yiwei Li. “Using chemopreventive agents to enhance the efficacy of cancer therapy.” Cancer Research 66.7 (2006): 3347-3350.

10) Niu, Yucun, et al. “The phytochemical, EGCG, extends lifespan by reducing liver and kidney function damage and improving age‐associated inflammation and oxidative stress in healthy rats.” Aging Cell 12.6 (2013): 1041-1049.

11) Chen, Ju-Hua, et al. “Green tea polyphenols prevent toxin-induced hepatotoxicity in mice by down-regulating inducible nitric oxide–derived prooxidants.” The American journal of clinical nutrition 80.3 (2004): 742-751.

12) Church, Rachel J., et al. “Sensitivity to hepatotoxicity due to epigallocatechin gallate is affected by genetic background in diversity outbred mice.” Food and Chemical Toxicology 76 (2015): 19-26.