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Posts tagged Green Tea
Green Tea Extract Appears to Keep Cancer in Check in Majority of CLL Patients
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An extract of green tea appears to have clinical activity with low toxicity in chronic lymphocytic leukemia (CLL) patients who used it in a phase II clinical trial, say researchers at Mayo Clinic.
The findings were presented June 7 during the annual meeting of the American Society of Clinical Oncology (ASCO). They are the latest in a series of Mayo studies to show promise for use of the chemical epigallocatechin gallate (EGCG) — the major component of green tea — in reducing the number of leukemia cells in patients with CLL. Mayo first tested EGCG in a variety of laboratory assays about eight years ago, and it was found to reduce the survival of CLL leukemic cells. This laboratory finding was followed by a successful phase I clinical trial — the first time green tea extract had been studied in CLL patients.
“Although only a comparative phase III trial can determine whether EGCG can delay progression of CLL, the benefits we have seen in most CLL patients who use the chemical suggest that it has modest clinical activity and may be useful for stabilizing this form of leukemia, potentially slowing it down,” says Tait Shanafelt, M.D., a Mayo Clinic hematologist and lead author of the study.
“These studies advance the notion that a nutraceutical like EGCG can and should be studied as cancer preventives,” says Neil Kay, M.D., a hematology researcher whose laboratory first tested the green tea extract in leukemic blood cells from CLL patients. “Using nontoxic chemicals to push back cancer growth to delay the need for toxic therapies is a worthy goal in oncology research — particularly for forms of cancer initially managed by observation such as CLL.”
Drs. Shanafelt and Kay caution that EGCG is not a substitute for chemotherapy. All of the patients Mayo tested with EGCG were early stage, asymptomatic CLL patients who would not otherwise be treated until their disease progressed. The extract was supplied by the National Cancer Institute (NCI) and Polyphenon E International for these initial clinical trials.
CLL is a blood cancer that is a hybrid between leukemia and lymphoma. Progression of the disease is measured by the quantity of leukemia cells in the blood and bone marrow as well as enlargement of lymph nodes due to infiltration by the leukemia cells. In the phase I study, published in May 2009 in the Journal of Clinical Oncology, researchers found that the blood lymphocyte (leukemia cell) count was reduced in one-third of participants, and that the majority of patients who entered the study with enlarged lymph nodes due to involvement by CLL saw a 50 percent or greater reduction in their lymph node size.
Using the highest dose tested in the phase I study, the researchers launched their phase II clinical trial in an additional 36 patients. The results presented at the ASCO meeting evaluate the effects in these 36 patients as well as the six patients from the phase I trial treated at the same dose (total 42 patients). Results from 41 patients who have completed the study show that 31 percent of patients had a 20 percent or greater sustained reduction in blood leukemia count, and 69 percent of patients with enlarged lymph nodes saw a reduction of node size of 50 percent or greater.
In all, 69 percent of CLL patients had a biological response to EGCG as evidenced by a 20 percent or greater sustained reduction in blood lymphocyte count and/or a 50 percent or greater reduction in lymph node size, the researchers say.
Because EGCG was being studied in patients who did not otherwise need treatment, the researchers took a rigorous approach toward studying side effects. Most clinical trials of therapeutic agents only report grade 3 and higher side effects, but the researchers looked at and reported grade 1 and grade 2 as well. While a number of patients had transient grade 1 or 2 side effects, only three of 42 experienced a grade 3 side effect during their six months of treatment.
“All in all, the treatment was well tolerated with very mild side effects in most patients,” Dr. Shanafelt says.
The researchers say that the prior publications on the effects of EGCG on CLL leukemia cells in the laboratory and the data from the published phase I study have been widely disseminated via the Internet by patient advocacy groups. Based on information from patients and colleagues throughout the country, the Mayo researchers have become aware that many CLL patients nationwide have started to use EGCG supplements, which are readily available over the counter.
“Without a phase III clinical trial, we cannot make a recommendation that EGCG be used by CLL patients, but those who want to take supplements should consult with their oncologists and need to receive appropriate monitoring using laboratory tests,” Dr. Kay says.
The study was funded by grants from the NCI, the Mayo Comprehensive Cancer Center and from donors and patient advocacy foundations.
ScienceDaily (June 4, 2010)
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Polyphenols in Red Wine and Green Tea Halt Prostate Cancer Growth, Study Suggests
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In what could lead to a major advance in the treatment of prostate cancer, scientists now know exactly why polyphenols in red wine and green tea inhibit cancer growth. This new discovery, published online in The FASEB Journal, explains how antioxidants in red wine and green tea produce a combined effect to disrupt an important cell signaling pathway necessary for prostate cancer growth. This finding is important because it may lead to the development of drugs that could stop or slow cancer progression, or improve current treatments.
“Not only does SphK1/S1P signaling pathway play a role in prostate cancer, but it also plays a role in other cancers, such as colon cancer, breast cancer, and gastric cancers,” said Gerald Weissmann, MD, editor-in-chief of The FASEB Journal. “Even if future studies show that drinking red wine and green tea isn’t as effective in humans as we hope, knowing that the compounds in those drinks disrupts this pathway is an important step toward developing drugs that hit the same target.”
Scientists conducted in vitro experiments which showed that the inhibition of the sphingosine kinase-1/sphingosine 1-phosphate (SphK1/S1P) pathway was essential for green tea and wine polyphenols to kill prostate cancer cells. Next, mice genetically altered to develop a human prostate cancer tumor were either treated or not treated with green tea and wine polyphenols. The treated mice showed reduced tumor growth as a result of the inhibited SphK1/S1P pathway. To mimic the preventive effects of polyphenols, another experiment used three groups of mice given drinking water, drinking water with a green tea compound known as EGCg, or drinking water with a different green tea compound, polyphenon E. Human prostate cancer cells were implanted in the mice and results showed a dramatic decrease in tumor size in the mice drinking the EGCg or polyphenon E mixtures.
“The profound impact that the antioxidants in red wine and green tea have on our bodies is more than anyone would have dreamt just 25 years ago,” Weissmann added. “As long as they are taken in moderation, all signs show that red wine and green tea may be ranked among the most potent ‘health foods’ we know.”
ScienceDaily (June 9, 2010)
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New Evidence That Green Tea May Help Improve Bone Health
1742 days
Researchers in Hong Kong are reporting new evidence that green tea – one of the most popular beverages consumed worldwide and now available as a dietary supplement – may help improve bone health. They found that the tea contains a group of chemicals that can stimulate bone formation and help slow its breakdown.
The beverage has the potential to help in the prevention and treatment of osteoporosis and other bone diseases that affect million worldwide, the researchers suggest.
In the new study, Ping Chung Leung and colleagues note that many scientific studies have linked tea to beneficial effects in preventing cancer, heart disease, and other conditions. Recent studies in humans and cell cultures suggest that tea may also benefit bone health. But few scientific studies have explored the exact chemicals in tea that might be responsible for this effect.
The scientists exposed a group of cultured bone-forming cells (osteoblasts) to three major green tea components – epigallocatechin (EGC), gallocatechin (GC), and gallocatechin gallate (GCG) – for several days. They found that one in particular, EGC, boosted the activity of a key enzyme that promotes bone growth by up to 79 percent. EGC also significantly boosted levels of bone mineralization in the cells, which strengthens bones. The scientists also showed that high concentrations of ECG blocked the activity of a type of cell (osteoclast) that breaks down or weakens bones. The green tea components did not cause any toxic effects to the bone cells, they note.
ScienceDaily (Sep. 18, 2009) http://www.sciencedaily.com/releases/2009/09/090916103424.htm
http://www.ilifelink.com/egcg_350_mg_x_60_capsules.html
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Green Tea Shows Promise As Chemoprevention Agent For Oral Cancer
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Green tea extract has shown promise as cancer prevention agent for oral cancer in patients with a pre-malignant condition known as oral leukoplakia, according to researchers at The University of Texas M. D. Anderson Cancer Center.
The study, published online in Cancer Prevention Research, is the first to examine green tea as a chemopreventative agent in this high-risk patient population. The researchers found that more than half of the oral leukoplakia patients who took the extract had a clinical response.
Long investigated in laboratory, epidemiological and clinical settings for several cancer types, green tea is rich in polyphenols, which have been known to inhibit carcinogenesis in preclinical models. Still, clinical results have been mixed.
“While still very early, and not definitive proof that green tea is an effective preventive agent, these results certainly encourage more study for patients at highest risk for oral cancer,” said Vassiliki Papadimitrakopoulou, M.D., professor in M. D. Anderson’s Department of Thoracic/Head and Neck Medical Oncology, and the study’s senior author. “The extract’s lack of toxicity is attractive — in prevention trials, it’s very important to remember that these are otherwise healthy individuals and we need to ensure that agents studied produce no harm.”
In the Phase II dose-finding study, 41 M. D. Anderson oral leukoplakia patients were randomized between August 2002 and March 2008 to receive either green tea extract or placebo. Participants took the extract, an oral agent, for three months at one of three doses — 500 per meter squared of body mass (mg/m2); 750 mg/m2 or 1,000 mg/m2 — three times daily. To best assess biomarkers, participants also underwent a baseline and 12-week biopsy, an important component in the design of the study, the researchers say.
“Collecting oral tissue biopsies was essential in that it allowed us to learn that not only did the green tea extract appear to have benefit for some patients, but we pointed to anti-angiogenic effects as a potential mechanism of action,” said Anne Tsao, M.D., assistant professor in the Department of Thoracic/Head and Neck Medical Oncology, and the study’s first author. “While preliminary because our patient population was so small, this gives us direction for further study.”
Of those taking green tea at the two highest doses, 58.8 percent had a clinical response, compared with 36.4 percent in the lowest extract dose and 18.2 percent in the placebo arm. At an extended follow-up with a mean of 27.5 months, 15 participants had developed oral cancer, with a median time to disease development of 46.4 months.
Although not statistically significant, the green tea extract also improved histology and trended towards an improvement in a number of biomarkers that may play a vital role in predicting cancer development.
Another important finding, say the researchers, was that that the extract was well tolerated. Side effects, including insomnia and nervousness, were mostly seen in the high-dose group but produced no significant toxicity.
“While these are encouraging findings, much more research must be done before we can conclude that green tea may prevent oral or any other type of cancer. It’s also important to remind people that this trial enrolled very few participants who, at the highest dose levels took the equivalent of eight cups of green tea three times a day,” said Papadimitrakopoulo. “We need to further understand if green tea offers longer-term prevention effects for patients.”
Papadimitrakopoulo and Tsao think that future studies with green tea in this high-risk population should focus on participants being exposed to the supplement for a longer time period. The researchers also stressed that the green tea extract studied in this trial was never sold over-the-counter and/or the Internet, both of which are not highly regulated. Rather, the compound was exclusively developed as a pharmaceutical.
According to the American Cancer Society, more than 35,720 are expected to be diagnosed with oral and/or pharynx cancer and the five year survival rate is less than 50 percent.
The study was funded by Ito En, the company that produced the green tea extract.
In addition to Papadimitrakopoulou and Tsao, other M. D. Anderson authors on the study include: Waun Ki Hong, M.D., professor and chair of the Division of Cancer Medicine; Jack Martin, D.D.S., professor in the Department of Dental Oncology; Li Mao, M.D., adjunct professor and Xi Ming Tang, M.D., Ph.D. research scientist, both of the Department of Thoracic/Head and Neck Medical Oncology; Adel El-Naggar, M.D., Ph.D., professor in the Department of Pathology; Iganacio Wistuba, M.D., professor in the Department of Pathology-Research; Kirk Culotta, Phar M.D., Department of Pharmacy Pharmacology Research; Ann Gillenwater, M.D., professor in the Department of Head and Neck Surgery; J. Jack Lee, Ph.D., professor and Diane Liu, both of the Department of Biostatistics. Other authors include Yuko Sagesaka of Ito En, Ltd.
ScienceDaily (Nov. 5, 2009) http://www.sciencedaily.com/releases/2009/11/091105084848.htm
For additional info on Green Tea and its active ingredient EGCG:
http://drzarkov.com/blog/?p=307
http://www.ilifelink.com/egcg_350_mg_x_60_capsules.html
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Antifibrotic Effects of Green Tea
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Several studies have shown that lipid peroxidation stimulates collagen production in fibroblasts and hepatic stellate cells (HSC), and plays an important role in the development of liver fibrosis. Hepatoprotective effects of green tea against carbon tetrachloride, cholestasis and alcohol induced liver fibrosis were reported in many studies. However, the hepatoprotective effect of green tea in dimethylnitrosamine (DMN)-induced models has not been studied.
A research article published on November 7, 2009 in the World Journal of Gastroenterology addresses this question. The research team, led by Prof. Hong-Yon Cho from Korea University examined the protective effect of green tea extract (GT) on hepatic fibrosis in a rat HSC line and in a rat model of DMN-induced hepatic fibrosis.
The results showed GT administration prevented the development of hepatic fibrosis in the rat model of DMN-induced liver fibrosis. These results were confirmed both by liver histology and by quantitative measurement of hepatic hydroxyproline content, a marker of liver collagen deposition. Accordingly, inhibition of proliferation, reduced collagen deposition, and type 1 collagen expression were observed in activated HSC-T6 cells following GT treatment. These results imply that GT reduced the proliferation of activated HSC and down regulated the collagen content and expression of collagen type 1, thereby ameliorating hepatic fibrosis.
The researchers drew a conclusion that green tea may protect liver cells and reduce the deposition of collagen fibers in the liver. Green tea provides a safe and effective strategy for improving hepatic fibrosis.
ScienceDaily (Nov. 25, 2009) http://www.sciencedaily.com/releases/2009/11/091118101359.htm
For a more detailed discussion of EGCG and the medical studies that support its use, see the article at:
http://www.ilifelink.com/egcg_350_mg_x_60_capsules.html
