Although laboratory experiments and case-control studies have suggested that the consumption of green tea provides protection against gastric cancer, few prospective studies have been performed.
In January 1984, a total of 26,311 residents in three municipalities of Miyagi Prefecture, in northern Japan (11,902 men and 14,409 women 40 years of age or older), completed a self-administered questionnaire that included questions about the frequency of consumption of green tea. During 199,748 person-years of follow-up, through December 1992, we identified 419 cases of gastric cancer (in 296 men and 123 women). We used Cox regression to estimate the relative risk of gastric cancer according to the consumption of green tea.
Green-tea consumption was not associated with the risk of gastric cancer. After adjustment for sex, age, presence or absence of a history of peptic ulcer smoking status, alcohol consumption, other dietary elements, and type of health insurance, the relative risks associated with drinking one or two, three or four, and five or more cups of green tea per day, as compared with less than one cup per day, were 1.1 (95 percent confidence interval, 0.8 to 1.6), 1.0 (95 percent confidence interval, 0.7 to 1.4), and 1.2 (95 percent confidence interval, 0.9 to 1.6), respectively (P for trend=0.13). The results were similar after the 117 cases of gastric cancer that were diagnosed in the first three years of follow-up had been excluded, with respective relative risks of 1.2 (95 percent confidence interval, 0.8 to 1.8) 1.0 (95 percent confidence interval, 0.7 to 1.5), and 1.4 (95 percent confidence interval, 1.0 to 1.9) (P for trend=0.07).
In a population-based, prospective cohort study in Japan, we found no association between green-tea consumption and the risk of gastric cancer.
"Chemopreventive activities of EGCG were associated with the inhibition of tumorigenic signaling including β-catenin, c-Myc, pAkt, cyclin D1, etc.84,85 However, a few studies which covered different areas in Japan did not observe a relationship between green tea consumption and stomach cancer.139,140 Several clinical trials with curcumin have been reported in GI cancers,141,142 among which curcumin could decrease lymphocytic glutathione-S-transferase86 and prostaglandin E2 production87 in patiens with colorectal cancer and reduce polyp number and size in patients with FAP.88 Resveratrol has potent anti-inflammatory and anticarcinogenic effect through mainly scavenge of free radicals, by which its unique aromatic structure.143 "
[Show abstract][Hide abstract] ABSTRACT: Despite substantial progress in screening, early diagnosis, and the development of noninvasive technology, gastrointestinal (GI) cancer remains a major cause of cancer-associated mortality. Chemoprevention is thought to be a realistic approach for reducing the global burden of GI cancer, and efforts have been made to search for chemopreventive agents that suppress acid reflux, GI inflammation and the eradication of Helicobacter pylori. Thus, proton pump inhibitors, statins, monoclonal antibodies targeting tumor necrosis factor-alpha, and nonsteroidal anti-inflammatory agents have been investigated for their potential to prevent GI cancer. Besides the development of these synthetic agents, a wide variety of the natural products present in a plant-based diet, which are commonly called phytoceuticals, have also sparked hope for the chemoprevention of GI cancer. To perform successful searches of chemopreventive agents for GI cancer, it is of the utmost importance to understand the factors contributing to GI carcinogenesis. Emerging evidence has highlighted the role of chronic inflammation in inducing genomic instability and telomere shortening and affecting polyamine metabolism and DNA repair, which may help in the search for new chemopreventive agents for GI cancer.
Gut and liver 03/2013; 7(2):137-49. DOI:10.5009/gnl.2013.7.2.137 · 1.81 Impact Factor
"At the moment tea is the second most popular beverage in the world (after water) (Cheng, 2006). The detailed analysis of green tea is relevant in the terms of preventive effect on metastasis of lung, breast cancer (Ruhl et al., 2005) prevention of inflammation, thrombosis (as the reasons of primary heart attacks and cardiovascular diseases) (Tsubono et al., 2001), *Corresponding author. E-mail: firstname.lastname@example.org. "
[Show abstract][Hide abstract] ABSTRACT: The aim of the research was to analyze the composition of biologically active compounds, to determine the correlation between the concentration of biologically active compounds and antioxidant activity, the dependence of extractive compounds on the extraction time, the quality of different tea preparation forms (daily tea, infusions, decoctions) of those teas found in Lithuanian market. Four specimens of green tea from different regions of the world have been chosen as the object of analysis. Quality criteria's have been analyzed by using gravimetric and spectrophotometric methods. Detailed analysis has been performed using high performance liquid chromatography (HPLC) technique. With reference to analysis results it can be stated that in the aspect of relation to antioxidant activity/phenolic compounds, the teas with highest numbers in these dimensions were those from China region. The least numbers in antioxidant activity, dry residue and phenolic compounds were of teas from Sri Lanka. We tested the hypothesis that all green teas have phenolic compounds as their biological active compounds and because of this group of active compounds they distinguish antioxidant activity. The study gave strong evidence that green tea as a daily preparation and as well as pharmaceutical form (infusions, decoctions, capsules of green tea extract) may be used as preventive measures for cancerogenous processes, prostate cancer, renal or liver diseases because of it's antioxidant and free radical binding properties.
[Show abstract][Hide abstract] ABSTRACT: Green tea has been suggested to have a chemopreventive effect against various cancers including stomach cancer. The aim of this study is to elucidate the relationship between green tea consumption and stomach cancer risk by meta-analysis.
Eighteen observational studies were identified using MEDLINE, THE COCHRANE LIBRARY, RISS, and a manual search. Summary relative risks/odds ratios (RR/ORs) for the highest versus non/lowest green tea consumption levels were calculated on the basis of fixed and random effect models. Subgroup analyses were used to examine heterogeneity across the studies.
The combined results indicate a reduced risk of stomach cancer with intake of green tea (RR/OR=0.86, 95% CI=0.74-1.00). Subgroup analysis with six studies that reported differences between the highest and lowest consumption levels equal to or greater than five cups/day revealed a statistically significant protective effect (RR/OR=0.68, 95% CI=0.53-0.87).
Green tea appears to play a protective role against the development of stomach cancer. The results also suggest that a higher level of green tea consumption might be needed for a clear preventive effect to appear. This conclusion, however, should be interpreted with caution because various biases can affect the results of a meta-analysis.
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