Additional Research Shows Possible Benefits of Green Tea

By CP Staff

A new clinical trial examined the potential benefits of green tea extract in individuals at risk for developing oral cancers. According to 2009 data from the American Cancer Society, approximately 28,500 new cases of oral cavity and oropharyngeal cancers will be diagnosed this year.

In this new study, subjects with high-risk, pre-malignant oral lesions were supplemented with 500, 750 or 1,000 mg/m2 of green tea extract or a placebo three times per day for 12 weeks. The oral lesions were evaluated by biopsy at the beginning of the study and again after the 12 weeks of supplementation.

The results showed that there was a higher positive response rate seen in the oral pre-malignant lesions in the groups receiving the green tea extract, compared to the lesions in the placebo group. Furthermore, the researchers found that the higher doses of green tea extract showed improved response rates, indicating a dose-response effect. In fact, nearly 60 percent of the subjects taking the two highest doses of the green tea extracts had a positive clinical response compared to only 18 percent in the placebo group. There was also an improvement in the cells microscopic appearance by 21.4 percent compared to the placebo group, which improved by 9.1 percent. However, these findings did not reach statistical significance.

Biomarkers were also evaluated to evaluate the mechanism of action of the green tea extract on the oral pre-malignant lesions. The researchers showed that in the subjects that responded to the green tea extract, there was a decrease in stromal VEGF, a chemical signal produced by cells that stimulates the growth of new blood vessels, thus allowing cancer cells to grow their own blood supply. Cyclin D1, a protein that plays a role in the regulation of the cell cycle and interacts with tumor suppressor proteins, was also reduced. Stromal VEGF and cyclin D1 were increased in the non-responsive subjects.

The researchers concluded, “Higher doses of green tea extract may improve short-term (12-week) oral pre-malignant lesion outcome. The present results support longer-term clinical testing of green tea extract for oral cancer prevention.”

Reference:

Tsao AS, Liu D, Martin J, Tang XM, Lee JJ, El-Naggar AK, Wistuba I, Culotta KS, Mao L, Gillenwater A, Sagesaka YM, Hong WK, Papadimitrakopoulou V. Phase II randomized, placebo-controlled trial of green tea extract in patients with high-risk oral premalignant lesions. Cancer Prev Res (Phila Pa). 2009 Nov;2(11):931-41.

Individuals who do not want to consume large amounts of green tea as a beverage can take green tea extract capsules. The green tea extract capsules available from Complementary Prescriptions are very low in caffeine and have a high EGCG content. EGCG also is found in ImmuneAssist^® 24/7 along with other synergistic, immunomodulating ingredients.