Total catechins

Research in experimental animals has found green tea or its extracts to be effective against chemically-induced cancers of the lung, breast, colon, liver, and skin, as well as a variety of gastrointestinal organs, cancers induced by chemical carcinogens; more excitingly, green tea extracts have been found to protect animals from existing, spontaneous prostate cancer. More important to us is the human evidence for the health benefits of green tea consumption. Extensive epidemiological evidence shows that people consuming high amounts of Japanese sencha green tea live longer develop less cancer, have healthier cholesterol levels, suffer less cardiovascular and liver disease, and may be less susceptible to heart attacks.

The evidence for the cancer-fighting powers of green tea is so strong that human clinical trials of green tea powders and extracts are now under way at the Memorial Sloan-Kettering Cancer Center and at other clinical centers in the United States.

How Much Tea?
But other studies have found no difference in cancer incidence among higher and lower drinkers of green tea. In the most infamous example, a study published in 2001 in the New England Journal of Medicine found no protective effect of green tea consumption against gastric cancer, despite the fact that numerous previous studies had found that drinking green tea does provide a shield against this killer. As with so many other things, the key appears to lie in the amount of green tea being consumed. In the New England Journal of Medicine study, drinking five or more cups of green tea a day put people into the highest consumption group. By contrast, the most consistent epidemiological evidence for a protective effect of green tea comes from the consumption of ten cups or more of Japanese sencha per day.

How Do You Get that in Pills?
Few Westerners drink this much green tea. So to get green tea's benefits, many health-conscious people have turned to standardized extracts of the green tea leaf itself. That seems to be an especially attractive option when many companies advertise small green tea pills which allegedly contain the equivalent of five to ten cups of green tea apiece. Unfortunately, nearly all green tea extract capsules contain only a fraction of the green tea "cup-equivalents" than their manufacturers claim.

These companies aren't flat-out lying, but they're using the wrong yardstick - or, to be more precise, the wrong cup. The problem is that the amount of EgCG (the main cancer-fighting component) and other goodies in a cup of green tea can vary over a wide range, depending on the kind of green tea, the region where it's grown, the brewing time, tea leaf, kind of teabag - and, of course, the size of the cup! By choosing to compare a supplement to the poorest-quality green tea infusions, supplement companies use "creative accounting" to evaluate the potency of their pills. They can inflate the comparison, asserting that their products' 100 to 200 milligrams of EgCG is equivalent to five to ten cups of green tea.

But this is just misleading. When all of these factors are taken into account, and when you consider that the most consistent research on green tea's health-enhancing effects in humans comes from drinkers of Japanese sencha, the "gold standard" cup of green tea can contains 150 milligrams of EgCG. This means, unfortunately, that few green tea capsules even deliver the equivalent of even one full cup of Japanese green tea a day - let alone the ten cups that is most consistently associated with good health and long life.

If you're looking to use green tea for longevity and to guard against age-related disease, it only makes sense to get the best-backed dose of the best-backed molecule. Indeed, it's these kinds of doses - 800 to 1600 milligrams of EgCG per day that are being used in the human clinical trials that have begun in the last few years.

The Caffeine Conundrum
Green tea contains very little caffeine compared to coffee - but of course, it can still add up if you start drinking ten cups of the steaming brew a day. Indeed, one clinical trial which has been using ground tea solids as its ‘drug' has reported significant side-effects - including insomnia, fatigue, confusion, nausea, diarrhea, stomach pain, and even vomiting - linked to the caffeine content.

Some green tea supplements are fully decaffeinated to avoid any such problems. While this approach is better than adding as much as 500 milligrams of extra caffeine to your day, these supplements are inherently less effective than real tea, because several studies have found that caffeine itself plays a significant role in the cancer-fighting powers of green tea.

There are other benefits to moderate intake of caffeine, despite the clear negative impacts of being a full-fledged caffeine junkie. For instance, a large body of research now suggests that modest caffeine consumption reduces your risk of developing Parkinson's disease - probably as a result of caffeine's ability to modulate adenosine A2A receptors in the brain. Another example: green tea polyphenols and caffeine synergize to increase the body's thermogenic fat-burning activity - effects with important implications for the Battle of the Bulge, which is an engagement important for health and vanity alike.

Thus, rigorously eliminating the caffeine content from green tea - whether you get it in cup or capsule - is not the best strategy for your long-term health. While a zero-tolerance approach may be the only way for a few extremely caffeine-sensitive individuals to get the benefits of EgCG, most people will be better off getting at least a little caffeine in with their green tea. Lightly-caffeinated green tea extracts provide a happy medium between caffeine-induced side effects and the loss of significant health benefits.

Putting it All in a Capsule
So getting the full benefits of green tea - an icon of Zen simplicity - turns out to involve taking a lot of factors into consideration. Green tea extracts should be HPLC standardized to their content of EgCG. They should make it convenient to get 1500 milligrams of EgCG a day, to match the strong epidemiological evidence of health benefits in Japanese sencha drinkers. And they should contain at least a little caffeine, so that the often-synergistic interactions between EgCG and caffeine can be unleashed. Put it all together, and you'll have squeezed a remarkable amount of health benefit into a few small capsules.

References

Fujiki H, Suganuma M, Imai K, Nakachi K. Green tea: cancer preventive beverage and/or drug. Cancer Lett. 2002 Dec 15; 188(1-2): 9-13.

Mukhtar H, Ahmad N. Tea polyphenols: prevention of cancer and optimizing health. Am J Clin Nutr. 2000 Jun; 71(6 Suppl): 1698S-702S.

Nakachi K, Matsuyama S, Miyake S, Suganuma M, Imai K. Preventive effects of drinking green tea on cancer and cardiovascular disease: epidemiological evidence for multiple targeting prevention. Biofactors. 2000; 13(1-4): 49-54.

Tokunaga S, White IR, Frost C, Tanaka K, Kono S, Tokudome S, Akamatsu T, Moriyama T, Zakouji H. Green tea consumption and serum lipids and lipoproteins in a population of healthy workers in Japan. Ann Epidemiol. 2002 Apr; 12(3): 157-65.

Shibata K, Moriyama M, Fukushima T, Kaetsu A, Miyazaki M, Une H. Green tea consumption and chronic atrophic gastritis: a cross-sectional study in a green tea production village. J Epidemiol. 2000 Sep; 10(5): 310-6.

Inoue M, Tajima K, Hirose K, Hamajima N, Takezaki T, Kuroishi T, Tominaga S. Tea and coffee consumption and the risk of digestive tract cancers: data from a comparative case-referent study in Japan. Cancer Causes Control. 1998 Mar; 9(2): 209-16.

The acute effect of green tea consumption on endothelial function in healthy individuals.
European Journal of Cardiovascular Prevention & Rehabilitation. 15(3):300-305, June 2008.
Nikalaos A, Charalambos V, Konstantinos A, Baou K, Vasiliadou C, Pietri P, Xaplanteris P, Stepanadi E, Stefanadis C.

BACKGROUND: Tea consumption is associated with decreased cardiovascular risk. Flow-mediated dilatation (FMD) of the brachial artery is related to coronary endothelial function and it is an independent predictor of cardiovascular risk. Black tea has a beneficial effect on endothelial function; the effect, however, of green tea on brachial artery reactivity has not been defined yet.
DESIGN AND METHODS: We studied 14 healthy individuals (age 30+/-3 years) with no cardiovascular risk factors except from smoking (50%) on three separate occasions on which they took: (a) 6 g of green tea, (b) 125 mg of caffeine (the amount contained in 6 g of tea), or (c) hot water. FMD of the brachial artery was measured before each intervention and 30, 90, and 120 min afterward. High-sensitivity C-reactive protein, interleukins 6 (Il-6) and 1b (Il-1b), total plasma antioxidative capacity, and total plasma oxidative status/stress were measured at baseline and at 120 min after each intervention.
RESULTS: Resting and hyperemic brachial artery diameter did not change either with tea or with caffeine. FMD increased significantly with tea (by 3.69%, peak at 30 min, P<0.02), whereas it did not change significantly with caffeine (increase by 1.72%, peak at 30 min, P=NS). Neither tea nor caffeine had any effect on high-sensitivity C-reactive protein, Il-6, Il-1b, total plasma antioxidative capacity, or total plasma oxidative status/stress.
CONCLUSION: Green tea consumption has an acute beneficial effect on endothelial function, assessed with FMD of the brachial artery, in healthy individuals. This may be involved in the beneficial effect of tea on cardiovascular risk.


Tea Catechin Consumption Reduces Circulating Oxidized Low-Density Lipoprotein.
International Heart Journal. 2007;48(6):725-732.
Shigenobu Inami, Masamichi Takano, Masanori Yamamoto, Daisuke Murakami, Kenichiro Tajika, Kenji Yodogawa, Shinya Yokoyama, Norihiko Ohno, Takayoshi Ohba, Junko Sano, Chikao Ibuki, Yoshihiko Seino and Kyoichi Mizuno.

It has been reported that green tea consumption reduces the risk of coronary artery disease and cardiac events. Catechin is a major constituent of Japanese green tea and an antioxidant. Lipids and oxidization of low-density lipoprotein cholesterol (LDL-C) play important roles in atherosclerosis. Therefore, we evaluated the effect of catechin intake on the lipid profile and plasma oxidized LDL. The study population consisted of 40 healthy adult volunteers (10 men, 30 women). Catechin was extracted from green tea leaves. The subjects were randomly divided into two groups, a catechin group (n = 29) and a control group (n = 11). In the catechin group, catechin (500 mg: equivalent to 6 or 7 cups of green tea) was administered orally. Venous blood samples were obtained before eating a meal at the start and after 4 weeks without any lifestyle modification. Plasma oxidized LDL assay was performed with a sandwich-type enzyme immunoassay using anti-oxidized phosphatidylcholine monoclonal antibody. The baseline lipid profiles and tea consumptions were similar between the two groups. Plasma oxidized LDL was significantly decreased after catechin administration (from 9.56 ± 9.2 to 7.76 ± 7.7 U/mL, P = 0.005), while plasma LDL-C, triglyceride, and HDL-C concentrations did not change. Catechin decreased the plasma oxidized LDL concentration without significant change in plasma LDL concentration. The mechanism of the beneficial effects of green tea on coronary artery disease might result from a decrease in plasma oxidized LDL.


Roles for epigallocatechin gallate in cardiovascular disease and obesity: an introduction.
J Am Coll Nutr. 2007 Aug;26(4):362S-5S
McKay DL, Blumberg JB.

After water, tea from Camellia sinensis is the most consumed beverage worldwide. Tea is rich in catechin flavonoids that possess an array of bioactivity including antioxidant, anti-inflammatory, apoptotic, and probiotic mechanisms of action that may contribute to some of the putative health benefits associated with tea intake. A substantial body of evidence indicates that tea and its principal catechin, epigallocatechin gallate (EGCG) may contribute to a reduction in the risk of cardiovascular disease. Recent studies suggest EGCG may also have a positive impact on glucose tolerance and thermogenesis with implications for an effect on the pathogenesis of type 2 diabetes mellitus and obesity, respectively. This introduction to a symposium on EGCG's role in cardiovascular disease and obesity presented at the 2006 annual meeting of the American College of Nutrition provides a background on tea and tea flavonoids and their possible relationship to health promotion and disease prevention.


Epigallocatechin-3 gallate prevents cardiac hypertrophy induced by pressure overload in rats.
J Vet Sci. 2007 Jun;8(2):121-9.
Hao J, Kim CH, Ha TS, Ahn HY.

Pressure overload diseases, such as valvular stenosis and systemic hypertension, manifest morphologically in patients as cardiac concentric hypertrophy. Prevention of cardiac remodeling due to increased pressure overload is important to reduce morbidity and mortality. Epigallocatechin-3 gallate (EGCG) is a major bioactive polyphenol present in green tea which has been found to be a nitric oxide-mediated vasorelaxant and to be cardioprotective in myocardial ischemia-reperfusion injury. Therefore, we investigated whether EGCG supplementation could reduce in vivo pressure overloadmediated cardiac hypertrophy. Cardiac hypertrophy was induced by suprarenal transverse abdominal aortic constriction (AC) in rats. Three weeks after AC surgery, heart to body weight ratio increased in the AC group by 34% compared to the sham group. EGCG administration suppressed the load-induced increase in heart weight by 69%. Attenuation of cardiac hypertrophy by EGCG was associated with attenuation of the increase in myocyte cell size and fibrosis induced by aortic constriction. Despite abolition of hypertrophy by EGCG, transstenotic pressure gradients did not change. Echocardiogram revealed that increased left ventricular systolic dimensions and deteriorated systolic function were relieved by EGCG. These results suggest that EGCG prevents the development of left ventricular concentric hypertrophy by pressure overload and may be a useful therapeutic modality to prevent cardiac remodeling in patients with pressure overload myocardial diseases.


Angiogenesis and cancer prevention: a vision.
Recent Results Cancer Res. 2007;174:219-24.
Noonan DM, Benelli R, Albini A.

Angiogenesis is necessary for solid tumor growth and dissemination. In addition to angiogenesis, it has become increasingly clear that inflammation is a key component in cancer insurgence that can promote tumor angiogenesis. We noted that angiogenesis is a common and key target of most chemopreventive molecules, where they most likely suppress the angiogenic switch in premalignant tumors, a concept we termed angioprevention. We have shown that various molecules, such as flavonoids, antioxidants, and retinoids, act in the tumor microenvironment, inhibiting the recruitment and/or activation of endothelial cells and phagocytes of the innate immunity. N-acetyl-cysteine, and the green tea flavonoid epigallocatechin-3-gallate (EGCG) and the beer/ hops-derived chalcone Xanthohumol all prevent angiogenesis in the Matrigel sponge angiogenic assay in vivo and inhibit the growth of the highly angiogenic Kaposi's sarcoma tumor cells (KS-Imm) in nude mice. The synthetic retinoid 4-hydroxyfenretinide (4HPR) also shows anti-angiogenic effects. We analyzed the regulation of gene expression they exert in primary human umbilical endothelial cells (HUVEC) in culture with functional genomics. Expression profiles obtained through Affymetrix GeneChip arrays identified overlapping sets of genes regulated by anti-oxidants. In contrast, the ROS-producing 4HPR induced members of the TGFbeta-ligand superfamily, which, at least in part, explains its anti-angiogenic activity. NAC and the flavonoids all suppressed the IkB/NF-kappaB signaling pathway even in the presence of NF-kappaB stimulation by TNFalpha, and showed reduced expression of many NF-kappaB target genes. A selective apoptotic effect on transformed cells, but not on endothelial cells, of the anti-oxidants may be related to the reduced expression of the NF-kappaB-dependent survival factors Bcl2 and Birc5/surviving, which are selectively overexpressed in transformed cells by these factors. The repression of the NF-kappaB pathway suggests anti-inflammatory effects for the antioxidant compounds that may also represent an indirect role in angiogenesis inhibition. The green tea flavonoid EGCG does target inflammatory cells, mostly neutrophils, and inhibits inflammation-associated angiogenesis. The other angiopreventive molecules are turning out to be effective modulators of phagocyte recruitment and activation, further linking inflammation and vascularization to tumor onset and progression and providing a key target for cancer prevention.


Green Tea Consumption and Mortality Due to Cardiovascular Disease, Cancer, and All Causes in Japan
The Ohsaki Study
Shinichi Kuriyama, MD, PhD; Taichi Shimazu, MD; Kaori Ohmori, MD, PhD; Nobutaka Kikuchi, MD; Naoki Nakaya, PhD; Yoshikazu Nishino, MD, PhD; Yoshitaka Tsubono, MD, PhD; Ichiro Tsuji, MD, PhD
JAMA. 2006;296:1255-1265.

Context Green tea polyphenols have been extensively studied as cardiovascular disease and cancer chemopreventive agents in vitro and in animal studies. However, the effects of green tea consumption in humans remain unclear.
Objective: To investigate the associations between green tea consumption and all-cause and cause-specific mortality.
Design, Setting, and Participants: The Ohsaki National Health Insurance Cohort Study, a population-based, prospective cohort study initiated in 1994 among 40 530 Japanese adults aged 40 to 79 years without history of stroke, coronary heart disease, or cancer at baseline. Participants were followed up for up to 11 years (1995-2005) for all-cause mortality and for up to 7 years (1995-2001) for cause-specific mortality.
Main Outcome Measures: Mortality due to cardiovascular disease, cancer, and all causes.
Results: Over 11 years of follow-up (follow-up rate, 86.1%), 4209 participants died, and over 7 years of follow-up (follow-up rate, 89.6%), 892 participants died of cardiovascular disease and 1134 participants died of cancer. Green tea consumption was inversely associated with mortality due to all causes and due to cardiovascular disease. The inverse association with all-cause mortality was stronger in women (P = .03 for interaction with sex). In men, the multivariate hazard ratios of mortality due to all causes associated with different green tea consumption frequencies were 1.00 (reference) for less than 1 cup/d, 0.93 (95% confidence interval [CI], 0.83-1.05) for 1 to 2 cups/d, 0.95 (95% CI, 0.85-1.06) for 3 to 4 cups/d, and 0.88 (95% CI, 0.79-0.98) for 5 or more cups/d, respectively (P = .03 for trend). The corresponding data for women were 1.00, 0.98 (95% CI, 0.84-1.15), 0.82 (95% CI, 0.70-0.95), and 0.77 (95% CI, 0.67-0.89), respectively (P<.001 for trend). The inverse association with cardiovascular disease mortality was stronger than that with all-cause mortality. This inverse association was also stronger in women (P = .08 for interaction with sex). In women, the multivariate hazard ratios of cardiovascular disease mortality across increasing green tea consumption categories were 1.00, 0.84 (95% CI, 0.63-1.12), 0.69 (95% CI, 0.52-0.93), and 0.69 (95% CI, 0.53-0.90), respectively (P = .004 for trend). Among the types of cardiovascular disease mortality, the strongest inverse association was observed for stroke mortality. In contrast, the hazard ratios of cancer mortality were not significantly different from 1.00 in all green tea categories compared with the lowest-consumption category.
Conclusion: Green tea consumption is associated with reduced mortality due to all causes and due to cardiovascular disease but not with reduced mortality due to cancer.
Author Affiliations: Division of Epidemiology, Department of Public Health and Forensic Medicine, Tohoku University Graduate School of Medicine (Drs Kuriyama, Shimazu, Ohmori, Kikuchi, Nakaya, and Tsuji), and Division of Health Policy, Tohoku University School of Public Policy (Dr Tsubono), Sendai, Japan; Division of Epidemiology, Miyagi Cancer Center Research Institute, Natori, Japan (Dr Nishino).


Green tea: cancer preventive beverage and/or drug.
Cancer Lett. 2002 Dec 15; 188(1-2): 9-13.
Fujiki H, Suganuma M, Imai K, Nakachi K.

Green tea and (-)-epigallocatechin gallate (EGCG) are now acknowledged cancer preventives in Japan and has made it possible for us to establish the concept of a cancer preventive beverage. For the general population, we recommend 10 cups of green tea daily supplemented with green tea tablets. For cancer patients following treatment, we here present new evidence that green tea and a cancer preventive drug, sulindac, have synergistic preventive effects. An approach to develop green tea capsules as a cancer preventive drug in the US is discussed, aiming at taking full advantage of this cancer preventive beverage.


Tea polyphenols: prevention of cancer and optimizing health.
Am J Clin Nutr. 2000 Jun; 71(6 Suppl): 1698S-702S; discussion 1703S-4S.
Mukhtar H, Ahmad N.

The tea plant Camellia sinesis is cultivated in >30 countries. Epidemiologic observations and laboratory studies have indicated that polyphenolic compounds present in tea may reduce the risk of a variety of illnesses, including cancer and coronary heart disease. Most studies involved green tea, however; only a few evaluated black tea. Results from studies in rats, mice, and hamsters showed that tea consumption protects against lung, forestomach, esophagus, duodenum, pancreas, liver, breast, colon, and skin cancers induced by chemical carcinogens. Other studies showed the preventive effect of green tea consumption against atherosclerosis and coronary heart disease, high blood cholesterol concentrations, and high blood pressure. Because the epidemiologic studies and research findings in laboratory animals have shown the chemopreventive potential of tea polyphenols in cancer, the usefulness of tea polyphenols for humans should be evaluated in clinical trials. One such phase 1 clinical trial is currently under way at the MD Anderson Cancer Center in collaboration with Memorial Sloan-Kettering Cancer Center. This study will examine the safety and possible efficacy of consuming the equivalent of > or =10 cups (> or =2.4 L) of green tea per day. The usefulness of tea polyphenols may be extended by combining them with other consumer products such as food items and vitamin supplements. This "designer-item" approach may be useful for human populations, but it requires further study.


Preventive effects of drinking green tea on cancer and cardiovascular disease: epidemiological evidence for multiple targeting prevention.
Biofactors. 2000; 13(1-4): 49-54.
Nakachi K, Matsuyama S, Miyake S, Suganuma M, Imai K.

The significance of drinking green tea in prevention of two of the main lifestyle-related diseases, cancer and cardiovascular disease, was demonstrated in terms of a prospective cohort study on a total of 8,552 general residents in Saitama Prefecture, Japan. On the basis of the follow-up study, we revealed decreased relative risk of cancer incidence for those consuming over 10 cups a day, compared with those consuming below 3 cups: 0.54 (95% confidence interval, 0.22-1.34) for men, 0.57 (0.34-0.98) for women, and 0.59 (0.35-0.98) for both sexes. Furthermore, a significant delay in cancer onset was associated with increased consumption of green tea. Next, decreased relative risk of death from cardiovascular disease was 0.58 (0.34-0.99) for men, 0.82 (0.49-1.38) for women, and 0.72 (0.60-1.04) for members of both sexes consuming over 10 cups a day. Finally, we evaluated the life-prolonging effects of drinking green tea on cumulative survival, using the life table.


Green tea consumption and serum lipids and lipoproteins in a population of healthy workers in Japan.
Ann Epidemiol. 2002 Apr; 12(3): 157-65.
Tokunaga S, White IR, Frost C, Tanaka K, Kono S, Tokudome S, Akamatsu T, Moriyama T, Zakouji H.

PURPOSE: To examine the relation between green tea consumption and serum lipids and lipoproteins.
METHODS: The subjects were 13,916 workers (8476 men and 5440 women) aged 40-69 years at over 1000 workplaces in Nagano prefecture, central Japan. They underwent health screening offered by a single medical institute between April 1995 and March 1996 and did not have morbid conditions affecting serum cholesterol levels. Serum concentrations of total cholesterol, high-density lipoprotein (HDL) cholesterol and triglycerides were measured at the screening. The consumption of green tea and other life-style characteristics were ascertained by a questionnaire. The data were analyzed with multivariate linear model.
RESULTS: Daily consumption of green tea was reported by 86.7% of subjects. Green tea consumption was, statistically, significantly associated with lower levels of serum total cholesterol in both men and women while its associations with serum triglycerides and HDL cholesterol were not statistically significant. The inverse association of serum total cholesterol with green tea consumption appeared to level off at the consumption of more than 10 cups/day. Excluding the outlying subjects drinking more than 10 cups/day (0.4%), the regression analysis adjusting for age, body mass index, ethanol intake, smoking habit, coffee intake, and type of work showed that daily consumption of one cup of green tea was associated with a reduction in serum total cholesterol by 0.015 mmol/L (95% confidence interval 0.006 to 0.024, p < 0.001) in men and 0.015 mmol/L (0.004 to 0.025, p < 0.01) in women. After additional adjustment for selected dietary factors, the inverse association remained statistically significant; one cup of green tea per day was associated with a reduction in serum total cholesterol by 0.010 mmol/L (0.001 to 0.019, p = 0.03) in men and 0.012 mmol/L (0.001 to 0.022, p = 0.03) in women.
CONCLUSION: Consumption of green tea was associated with lower serum concentration of total cholesterol in Japanese healthy workers age 40-69 years; however, green tea consumption was unrelated to serum HDL-cholesterol and triglycerides.


Green tea consumption and chronic atrophic gastritis: a cross-sectional study in a green tea production village.
J Epidemiol. 2000 Sep; 10(5): 310-6.
Shibata K, Moriyama M, Fukushima T, Kaetsu A, Miyazaki M, Une H.

Chronic atrophic gastritis (CAG) is well known as a precancerous lesion of the stomach, and Helicobacter pylori (H. pylori) infection increases the risk of CAG. While recent studies have reported that green tea consumption decreases the risk of gastric cancer, there has been no study analyzing the relationship between green tea consumption and the both risks H. pylori infection and CAG. We conducted a cross-sectional study on 636 subjects living in a farming village in Japan to examine the relationship among green tea consumption, H. pylori infection, and CAG. Smoking, alcohol drinking, consumption of four beverages, including green tea, and of five foods were investigated as lifestyle factors that may affect H. pylori infection and CAG. The measurement of H. pylori-IgG antibodies was used to define H. pylori infection, and serum pepsinogens were used to define of CAG. The unconditional logistic regression model was used for analyzing each odds ratio (OR). H. pylori infection was positively associated with the risk of CAG (OR = 3.73; 95% confidence interval [CI], 2.59-5.36). High green tea consumption (more than 10 cups per day) was negatively associated with the risk of CAG, even after adjustment for H. pylori infection and lifestyle factors associated with green tea consumption (OR = 0.63; 95% CI, 0.43-0.93). These results support the hypothesis that high green tea consumption prevents CAG.


Tea and coffee consumption and the risk of digestive tract cancers: data from a comparative case-referent study in Japan.
Cancer Causes Control. 1998 Mar;9(2):209-16.
Inoue M, Tajima K, Hirose K, Hamajima N, Takezaki T, Kuroishi T, Tominaga S.

OBJECTIVES: The purpose of this study was to examine the hypothesis that tea and coffee consumption have a protective effect against development of digestive tract cancers.
METHODS: A comparative case-referent study was conducted using Hospital-based Epidemiologic Research Program at Aichi Cancer Center (HERPACC) data from 1990 to 1995 in Nagoya, Japan. This study comprised 1,706 histologically diagnosed cases of digestive tract cancers (185 esophagus, 893 stomach, 362 colon, 266 rectum) and a total of 21,128 non-cancer outpatients aged 40 years and over. Logistic regression was used to analyze the data, adjusting for gender; age; year and season at hospital-visit; habitual smoking and alcohol drinking; regular physical exercise; fruit, rice, and beef intake; and beverage intake.
RESULTS: The odds ratio (OR) of stomach cancer decreased to 0.69 (95 percent confidence interval [CI] = 0.48-1.00) with high intake of green tea (seven cups or more per day). A decreased risk was also observed for rectal cancer with three cups or more daily intake of coffee (OR = 0.46, CI = 0.26-0.81).
CONCLUSIONS: The results suggest the potential for protective effect against site-specific digestive tract cancer by consumption of green tea and coffee, although most associations are limited only to the upper category of intake and have no clear explanation for site-specificity.