The Effects of Green Tea on Diabetes and Gut Microbiome in db/db Mice: Studies with Tea Extracts vs. Tea Powder.

Green tea extracts and tea catechins have been shown to prevent or alleviate diabetes. The present study tests the hypothesis that green tea leaves in powder form (GTP), which also contain fiber and other water non-extractable materials, are more effective than the corresponding green tea extracts (GTE) in impeding the development of diabetes in db/db mice. Female db/db mice were treated with a diet containing 1% of GTE, 2% of GTE, 2% of GTP (with the same catechin content as 1% GTE) or 1% GTP. The 1% GTE group had lower food intake, water consumption, body weight and fasting blood glucose levels than the control group, while 2% GTP did not have any significant effect. Dietary 1% GTE also preserved ß-cell insulin secretion. However, 1% GTP increased food intake, water consumption and blood glucose levels. Microbiome analysis with 16S rRNA gene V4 sequencing showed that the gut microbiota was modified by GTE and GTP, and a few bacterial guilds were associated with blood glucose levels. In the Random Forest regression model, the leading predictor of metabolic outcome was food consumption, followed by changes in some bacterial guilds. The results illustrate the importance of food consumption and gut microbiota in affecting the progression of diabetes.

Bioavailability of Black Tea Theaflavins: Absorption, Metabolism, and Colonic Catabolism.

Data obtained with in vitro fecal incubations and a feeding study indicate black tea theaflavin and its galloyl derivatives are not absorbed in detectable amounts in either the upper or lower gastrointestinal tract. The theaflavin skeleton is comparatively resistant to degradation by colonic bacteria with a 67% recovery being obtained after a 24 h incubation, which yielded 21 phenolic and aromatic catabolites. The theaflavin galloyl moiety was removed by the microbiota, and the released gallic acid further transformed to 3-O- and 4-O-methyl gallic acids, pyrogallol-1-sulfate and pyrogallol-2-sulfate, which were excreted in urine in amounts equivalent to 94% of intake. The main urinary product potentially derived from breakdown of the theaflavin skeleton was 3-(4'-hydroxyphenyl)propionic acid. A number of the colonic catabolites originating from gallic acid and theaflavins has been reported to be bioactive in ex vivo and in vitro models with a variety of potential modes of action.

A six-month crossover chemoprevention clinical trial of tea in smokers and non-smokers: methodological issues in a feasibility study.

BACKGROUND: Chemoprevention crossover trials of tea can be more efficient than parallel designs but the attrition and compliance rates with such trials are unknown. METHODS: Attrition (dropouts) and compliance with treatment were assessed in a 25-week randomized, placebo controlled, crossover, feasibility clinical trial of four tea treatments to investigate the effect of tea on oral cancer biomarkers. Each treatment lasted 4 weeks with 2 weeks of washout in between. Participants were 32 smokers and 33 non-smokers without any evidence of premalignant oral lesions. The interventions consisted of packets of green tea, black tea, caffeinated water, or placebo. Participants were assigned to each treatment for four weeks, and were instructed to drink five packets per day while on the treatment. Dropout from the trial and compliance (consumption of ≥85% of the prescribed treatment packets) are the main outcome measures reported. RESULTS: There was a high rate of dropout (51%) from the study, and the rates were significantly higher among smokers (64%) than non-smokers (36%). Among participants who completed the study the rate of compliance was 72%. The highest rates of dropouts occurred between the first and second treatment visits in both smokers (38% dropout) and non-smokers (18% dropout). Throughout the study smokers were more likely to dropout than non-smokers. Black tea treatment was associated with the highest rates of dropout among smokers (37%), but was associated with the lowest rate of dropout among non-smokers (4%). CONCLUSIONS: In a study conducted to test the feasibility of a four-treatment crossover tea trial, a high rate of dropout among smokers and non-smokers was observed. Multi-arm crossover tea trials might pose a higher burden on participants and research is needed to improve adherence and treatment compliance in such trials. TRIAL REGISTRATION NUMBER: ISRCTN70410203.

Tea catechins and their applications as supplements and pharmaceutics.

Green tea polyphenols have been reported to have many beneficial health effects. This review describes the development of Polyphenon(®) E as a standardized green tea polyphenol preparation for many clinical trials and as an FDA-approved medication to treat genital warts. The procedures involving this process and the subsequent development of a similar product Theaphenon(®) E are discussed.

The sphingosine kinase-1 survival pathway is a molecular target for the tumor-suppressive tea and wine polyphenols in prostate cancer.

The sphingosine kinase-1/sphingosine 1-phosphate (SphK1/S1P) pathway has been associated with cancer promotion and progression and resistance to treatments in a number of cancers, including prostate adenocarcinoma. Here we provide the first evidence that dietary agents, namely, epigallocatechin gallate (EGCg, IC(50)≈75 µM), resveratrol (IC(50)≈40 µM), or a mixture of polyphenols from green tea [polyphenon E (PPE), IC(50)≈70 µM] or grapevine extract (vineatrol, IC(50)≈30 µM), impede prostate cancer cell growth in vitro and in vivo by inhibiting the SphK1/S1P pathway. We establish that SphK1 is a downstream effector of the ERK/phospholipase D (PLD) pathway, which is inhibited by green tea and wine polyphenols. Enforced expression of SphK1 impaired the ability of green tea and wine polyphenols, as well as pharmacological inhibitors of PLD and ERK activities, to induce apoptosis in PC-3 and C4-2B cells. The therapeutic efficacy of these polyphenols on tumor growth and the SphK1/S1P pathway were confirmed in animals using a heterotopic PC-3 tumor in place model. PC-3/SphK1 cells implanted in animals developed larger tumors and resistance to treatment with polyphenols. Furthermore, using an orthotopic PC-3/GFP model, the chemopreventive effect of an EGCg or PPE diet was associated with SphK1 inhibition, a decrease in primary tumor volume, and occurrence and number of metastases. These results provide the first demonstration that the prosurvival, antiapoptotic SphK1/S1P pathway represents a target of dietary green tea and wine polyphenols in cancer.

Green tea epigallocatechin gallate exhibits anticancer effect in human pancreatic carcinoma cells via the inhibition of both focal adhesion kinase and insulin-like growth factor-I receptor.

The exact molecular mechanism by which epigallocatechin gallate (EGCG) suppresses human pancreatic cancer cell proliferation is unclear. We show here that EGCG-treated pancreatic cancer cells AsPC-1 and BxPC-3 decrease cell adhesion ability on micro-pattern dots, accompanied by dephosphorylations of both focal adhesion kinase (FAK) and insulin-like growth factor-1 receptor (IGF-1R) whereas retained the activations of mitogen-activated protein kinase and mammalian target of rapamycin. The growth of AsPC-1 and BxPC-3 cells can be significantly suppressed by EGCG treatment alone in a dose-dependent manner. At a dose of 100 µM which completely abolishes activations of FAK and IGF-1R, EGCG suppresses more than 50% of cell proliferation without evidence of apoptosis analyzed by PARP cleavage. Finally, the MEK1/2 inhibitor U0126 enhances growth-suppressive effect of EGCG. Our data suggests that blocking FAK and IGF-1R by EGCG could prove valuable for targeted therapy, which can be used in combination with other therapies, for pancreatic cancer.

Green tea (-)-epigalocatechin-3-gallate inhibits KIT activity and causes caspase-dependent cell death in gastrointestinal stromal tumor including imatinib-resistant cells.

Imatinib, a selective tyrosine kinase inhibitor, has been used as a standard first-line therapy for gastrointestinal stromal tumor (GIST) patients. Unfortunately, most patients responding to imatinib will eventually exhibit the resistance, the cause of which is not fully understood. The serious clinical problems of imatinib-resistance demand alternative treatment strategy. (-)-Epigallocatechin-3-gallate (EGCG), a main component of green tea catechin, has been demonstrated potential anti-tumor effects on various types of cancer cells. Here, we report for the first time that EGCG has shown anti-tumor effects on gastrointestinal stromal tumor cell line GIST-T1 by suppressing cell proliferation and eventually inducing cell death via caspase-dependent pathways. GIST-T1 and imatinib resistant GIST-T1 (GIST-T1 IR) cells were used to assess the effects of EGCG. In both cell types, KIT activity was completely inhibited after 4 h treatment with 60 muM EGCG. EGCG specifically inhibited activated KIT, which was demonstrated by using Ba/F3 cells transfected with human wild-type KIT construct. At a dose of 30 muM EGCG, the KIT activity remains but at more than 40 muM EGCG, the KIT activity was abolished in these transfected-Ba/F3 cells. Our results suggest that EGCG has a promising potential as a natural KIT inhibitor and therefore it could be used as a novel therapeutic or preventive reagent for GISTs including the imatinib-resistant cases.

Lung cancer inhibitory effect of epigallocatechin-3-gallate is dependent on its presence in a complex mixture (polyphenon E).

Green tea has been shown to exhibit cancer-preventive activities in preclinical studies. However, (-)-epigallocatechin-3-gallate (EGCG) alone was shown to be ineffective in preventing lung tumorigenesis in mice by aerosol administration. In this study, Polyphenon E and Polyphenon E without EGCG were administered by aerosol delivery to A/J mice 2 weeks after carcinogen treatment and continuing daily throughout the remainder of the study (20 weeks). An improved aerosol delivery system with a custom-built atomizer, an efficient solvent remove system, and a nose-only exposure chamber was used to provide aerosols with stable size distribution. There were no significant differences in the size distributions of Polyphenon E and Polyphenon E without EGCG. With a relatively low dose level (4.19 mg/kg), Polyphenon E decreased tumor multiplicity by 53%, whereas Polyphenon E without EGCG at the same dose failed to inhibit lung carcinogenesis. These results indicate that aerosol administration can be an effective approach in chemoprevention study, and aerosolized Polyphenon E can significantly inhibit pulmonary adenoma formation and growth in A/J mice. Furthermore, in aerosolized form, EGCG, which is thought to be the most active component of Polyphenon E, has to be present with other tea catechins to show chemopreventive activity on lung tumorigenesis.

Black tea polyphenols modulate xenobiotic-metabolizing enzymes, oxidative stress and adduct formation in a rat hepatocarcinogenesis model.

The present study was designed to investigate the modulatory effects of black tea polyphenols (Polyphenon-B) on phase I and phase II xenobiotic-metabolizing enzymes and oxidative stress in a rat model of hepatocellular carcinoma (HCC). Liver tumours induced in male Sprague-Dawley rats by dietary administration of rho-dimethylaminoazobenzene (DAB) increased cytochrome P450 (total and CYP1A1, 1A2 and 2B isoforms), cytochrome b(5), cytochrome b(5) reductase, glutathione S-transferase (GST total and GST-P isoform) and gamma-glutamyltranspeptidase (GGT) with decrease in quinone reductase (QR). This was accompanied by enhanced lipid and protein oxidation and compromised antioxidant defences associated with increased expression of the oxidative stress markers 4-hydroxynonenal (4-HNE), anti-hexanoyl lysine (HEL), dibromotyrosine (DiBrY) and 8-hydroxy 2-deoxyguanosine (8-OHdG). Dietary administration of Polyphenon-B effectively suppressed DAB-induced hepatocarcinogenesis, as evidenced by reduced preneoplastic and neoplastic lesions, modulation of xenobiotic-metabolizing enzymes and amelioration of oxidative stress. Thus, it can be concluded that Polyphenon-B acts as an effective chemopreventive agent by modulating xenobiotic-metabolizing enzymes and mitigating oxidative stress in an in vivo model of hepatocarcinogenesis.

Bioavailability of polyphenon E flavan-3-ols in humans with an ileostomy.

To investigate the degree of absorption of flavan-3-ols in the small intestine, human subjects with an ileostomy ingested 200 mg of Polyphenon E, a green tea extract, after which ileal fluid and urine, collected over a 24-h period, were analyzed by high-performance liquid chromatography with photodiode array and mass spectrometric detection. The data obtained indicated that although approximately 40% of flavan-3-ol intake is recovered in ileal fluid, substantial quantities are absorbed in the small intestine. Moreover, 14 urinary metabolites, comprising sulfates, glucuronide, and methylated derivatives, were identified and quantified. All were metabolites of (epi)catechin or (epi)gallocatechin, representing 47 +/- 2% and 26 +/- 9%, respectively, of the ingested parent compound. These high recoveries indicate that these flavan-3-ols absorbed in the small intestine are much more bioavailable than most dietary flavonoids. No 3-O-galloylated flavan-3-ols or their metabolites were detected in urine. The absence of urinary flavan-3-ol metabolites after ingestion of 200 mg of (-)-epigallocatechin gallate indicates that there is no removal of the 3-O-galloyl group in vivo, and hence, this does not account for the high urinary recovery of (epi)gallocatechin metabolites after ingestion of Polyphenon E. Increasing the intake of Polyphenon E, by feeding doses of 200, 500, and 1500 mg, led to increased urinary excretion of (epi)catechin metabolites but not metabolites of (epi)gallocatechin. Coingestion of 200 mg of Polyphenon E with bread, cheese, or glucose did not significantly modify the absorption, metabolism, and excretion of flavan-3-ols. It does not necessarily follow, however, that the same would occur when flavan-3-ols are ingested with more complex food matrices.

A green tea component suppresses posttranslational expression of basic fibroblast growth factor in colorectal cancer.

BACKGROUND & AIMS: Green tea catechins are known to have anticarcinogenic effects. Epigallocatechin-3-gallate (EGCG) accounts for almost 50% of the total catechin content in green tea extract and has very potent antioxidant effects. EGCG also inhibits angiogenesis, possibly through the inhibition of proangiogenic factors including vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), which in turn, inhibits tumor growth and metastasis. However, the exact molecular mechanism by which EGCG suppresses bFGF expression is not known. Our objective was to elucidate the molecular mechanisms by which EGCG inhibits bFGF expression in colorectal cancer. METHODS: We examined posttranslational regulation of bFGF by EGCG in human colorectal cancer cells. We also examined bFGF in intestinal tumor formation of APC(Min/+) mice with and without catechin treatment. RESULTS: The bFGF protein was quickly degraded in the presence of EGCG, but a proteasome inhibitor suppressed this degradation. EGCG was also found to increase ubiquitination of bFGF and trypsin-like activity of the 20S proteasome, thereby resulting in the degradation of bFGF protein. Furthermore, EGCG suppressed tumor formation in APC(Min/+) mice, compared with vehicle-treated mice, in association with reduced bFGF expression. CONCLUSIONS: The ubiquitin-proteasome degradation pathway contributes significantly to down-regulation of bFGF expression by EGCG. Catechin compounds have fewer adverse effects than chemotherapeutic agents and hence can be used as proof-of-concept in cancer therapeutics to suppress growth and metastasis by targeting proteins such as bFGF.

Green tea catechins prevent cognitive deficits caused by Abeta1-40 in rats.

Amyloid beta peptide (Abeta)-induced oxidative stress is involved in the pathogenesis of Alzheimer's disease (AD). In contrast, green tea catechins confer potent antioxidative defense to brain neurons. Therefore, we examined whether long-term administration of green tea catechins [Polyphenon E (PE): 63% of epigallocatechin-3-gallate, 11% of epicatechin, 6% of (-)-epigallocatechin and 6% of (-)-epicatechin-gallate] prevents cognitive impairment in an animal model of AD, rats infused with Abeta1-40 into the cerebral ventricle. Five-week-old male Wistar rats fed with an MF diet were randomly divided into two groups: 0.0% PE (rats administered with water only) and 0.5% PE (rats administered with 5 g/L of PE). Twenty weeks after the PE administration, the 0.0% PE group was divided into the Vehicle group (rats infused with the solvent used for dissolving Abeta) and the Abeta(1-40)-infused rat group (Abeta group), whereas the 0.5% PE group was divided into the PE+Vehicle group (PE-preadministered vehicle-infused rats) and the PE+Abeta group (PE-preadministered Abeta-infused rats). Abeta1-40 or vehicle was infused into the cerebral ventricle using a mini osmotic pump. Behavioral changes in the rats were assessed by an eight-arm radial maze. PE administration for 26 weeks significantly decreased the Abeta-induced increase in the number of reference and working memory errors, with a concomitant reduction of hippocampal lipid peroxide (LPO; 40%) and cortico-hippocampal reactive oxygen species (ROS; 42% and 50%, respectively). Significantly reduced levels of LPO in the plasma (24%) and hippocampus (25%) as well as those of ROS in the hippocampus (23%) and cortex (41%) were found in the PE+Vehicle group as compared with the Vehicle group. Furthermore, rats with preadministered PE had higher ferric-reducing antioxidation power of plasma as compared with the Vehicle group. Our results suggest that long-term administration of green tea catechins provides effective prophylactic benefits against Abeta-induced cognitive impairment by increasing antioxidative defenses.

Preventive effects of polyphenon E on urinary bladder and mammary cancers in rats and correlations with serum and urine levels of tea polyphenols.

Polyphenon E, a standardized mixture of green tea polyphenols, was examined for its chemopreventive efficacy against chemically induced urinary bladder and mammary cancers. In the present study, Polyphenon E was administered after the last dose of 4-hydroxybutyl(butyl)nitrosamine, or roughly 30% of the way into the experiment. Polyphenon E (100 or 250 mg/kg body weight/d) caused a dose-dependent decrease in palpable urinary bladder tumors [low dose, 14 of 34; high dose, 6 of 35; controls, 20 of 34 (P < 0.01)]. In the mammary cancer model, Polyphenon E [333 or 1,000 mg/kg body weight (BW)/d] was administered beginning 5 days after a single dose of methylnitrosourea. In contrast to its significant efficacy in bladder tumor prevention, Polyphenon E had a minimal effect in the prevention of mammary cancers. Levels of polyphenols were determined in the urine and serum of rats. Relatively high levels of various polyphenols (and metabolites) were found in the urine. However, virtually no epigallocatechin-3-gallate was observed in the urine because of low systemic bioavailability; although it represents almost 65% of the polyphenols in Polyphenon E. Levels of polyphenols in serum were 50 x to 1,000 x less than were observed in urine. The bioavailability of these tea polyphenols to different organ sites may contribute to the differing preventive efficacy of Polyphenon E against urinary bladder and mammary cancers.

Effects of dietary catechins on glucose tolerance, blood pressure and oxidative status in Goto-Kakizaki rats.

Effects of green tea catechins comprising EGCg, EGC, ECg, EC, GCg, GC, Cg, and C were determined on blood glucose tolerance and oxidative stress status in type 2 diabetic Goto-Kakizaki (GK) rats. GK rats fed the catechin-containing diet tended to maintain blood glucose and systolic blood pressure at lower levels in the latter stages of the feeding period of 76 d, compared to those not receiving dietary catechins (control group). The blood glucose tolerance test performed on days 48-49 showed that GK rats fed the catechins had lower blood glucose levels than GK rats not fed catechins during the 120 min after glucose loading. In catechin-fed rats, amounts of 8-OH dG and albumin excreted into the urine determined on days 71-72, and kidney ACE activity determined on day 76, were lower than those in control rats. From these results it is concluded that dietary catechins may be effective in delaying the progression of diabetes and the associated oxidative stress.

Gargling with tea catechin extracts for the prevention of influenza infection in elderly nursing home residents: a prospective clinical study.

OBJECTIVES: To evaluate the effects of gargling tea catechin extracts on the prevention of influenza infection in elderly nursing home residents. DESIGN: A prospective study conducted for 3 months from January to March 2005. SETTINGS/LOCATION: A nursing home in Japan. SUBJECTS: A total of 124 elderly residents of at least 65 years of age were enrolled in the study. Seventy-six residents (83 +/-8.2 years, mean +/-standard deviation; 24 men, 52 women) gargled with tea catechin extract (catechin group) and were compared with 48 age- and sex-matched residents who gargled without tea catechin extracts (control group). All the residents were vaccinated with an influenza vaccine until early December 2004. INTERVENTIONS: catechin group: gargling with the tea catechin extract solution (200 microg/mL catechins, 60% of catechins comprise epigallocatechin gallate); control group: gargling without the catechin extract solution. In both groups, gargling was performed three times daily for 3 months. OUTCOME MEASURES: The incidence of influenza infection during the study was compared between the two groups. A safety evaluation was conducted to observe adverse events during the study. RESULTS: The incidence of influenza infection was significantly lower in the catechin group (1.3%, one resident) than in the control group (10%, five residents) calculated by multivariate logistic regression analysis (p = 0.028; odds ratio, 15.711; 95% confidence interval, 1.883-399.658). No adverse events, such as respiratory tract irritation, an obstruction, or allergic bronchial spasm, were observed during the study. CONCLUSIONS: This prospective study demonstrating the effect of catechin gargling on the prevention of influenza infection in the elderly is the first to be reported in the literature. Further randomized, controlled studies are needed to confirm the effects of catechin gargling on the prevention of influenza infection.

Antiproliferative and apoptosis inducing effect of lactoferrin and black tea polyphenol combination on hamster buccal pouch carcinogenesis.

Combination chemoprevention using tea polyphenols as one of the components has received growing consideration in recent years. The present study was designed to evaluate the antiproliferative and apoptosis inducing effects of bovine lactoferrin (bLF) and black tea polyphenol (Polyphenon-B: P-B) combination on 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis. Topical application of DMBA for 14 weeks induced buccal pouch tumours that showed aberrant expression of cytokeratins, a marker for epithelial carcinomas. This was associated with increased cell proliferation and evasion of apoptosis as revealed by upregulation of proliferating cell nuclear antigen, NF-kappaB, mutant p53, Bcl-2 and downregulation of Bax, Fas and caspase 3 protein expression. Although dietary administration of bLF and Polyphenon-B alone significantly reduced tumour incidence, combined administration of bLF and Polyphenon-B was more effective in inhibiting HBP carcinogenesis by restoring normal cytokeratin expression, inhibiting cell proliferation and inducing apoptosis. These findings suggest that a "designer item" approach will be useful for human oral cancer prevention strategies.

Efficacy of polyphenon E, red ginseng, and rapamycin on benzo(a)pyrene-induced lung tumorigenesis in A/J mice.

The objective of this investigation was to determine the efficacy of several novel agents in preventing lung tumorigenesis in mice. We evaluated polyphenon E, red ginseng, and rapamycin in A/J mice treated with the tobacco-specific carcinogen benzo(a)pyrene for their ability to inhibit pulmonary adenoma formation and growth. We found that treatment with polyphenon E exhibited a significant reduction on both tumor multiplicity and tumor load (tumor multiplicity x tumor volume) in a dose-dependent fashion. Polyphenon E (2% wt/wt) in the diet reduced tumor multiplicity by 46% and tumor load by 94%. This result provided key evidence in support of a phase II clinical chemoprevention trial of lung cancer. Administration of red ginseng in drinking water decreased tumor multiplicity by 36% and tumor load by 70%. The mammalian target of rapamycin inhibitor rapamycin showed significant efficacy against lung tumor growth in the tumor progression protocol and reduced tumor load by 84%. The results of these investigations demonstrate that polyphenon E, red ginseng, and rapamycin significantly inhibit pulmonary adenoma formation and growth in A/J mice.

Long-term administration of green tea catechins improves spatial cognition learning ability in rats.

Green tea catechins confer potent biological properties including antioxidation and free-radical scavenging. We investigated the effect of long-term oral administration of green tea catechins (Polyphenon E, PE: EGCG 63%; EC 11%; EGC 6%; ECG 6%) mixed with water on the spatial cognition learning ability of young rats. The learning ability of rats administered PE (0%, 0.1%, 0.5%) for 26 wk was assessed in the partially baited 8-arm radial maze. Relative to controls, those administered PE had improved reference and working memory-related learning ability. They also had lower plasma concentrations of lipid peroxides and greater plasma ferric-reducing antioxidation power than controls. Furthermore, rats administered PE had lower hippocampus reactive oxygen species concentrations than controls. We suggest that this improvement in spatial cognitive learning ability is due to the antioxidative activity of green tea catechins.

A randomized clinical study of tea catechin inhalation effects on methicillin-resistant Staphylococcus aureus in disabled elderly patients.

OBJECTIVES: To evaluate the effects of tea catechin inhalation on methicillin-resistant Staphylococcus aureus (MRSA) in disabled elderly patients. DESIGN: Seven days, randomized, prospective study. SETTING: Three hospitals in Japan. PARTICIPANTS: Seventy-two patients aged 78 +/- 11 years (mean age +/- standard deviation) with cerebrovascular diseases, classified as disabled according to the activity of daily living and were either bedridden or required assistance for standing, and showing presence of MRSA in sputum. INTERVENTIONS: Inhalation of 2 mL tea catechin extract solution along with saline (3.7 mg/mL catechins, 43% of catechins are composed of epigallocatechin gallate), or saline alone, 3 times daily using a handheld nebulizer for 7 days. MEASUREMENTS: The endpoint of efficacy was the reduction rates of MRSA in sputum. The safety measure was the adverse events observed during the 7 days of inhalation. RESULTS: The reduction rates calculated as the summation of decrease and disappearance of MRSA in sputum at 7 days were 47% (17 of 36 patients) in the catechin group and 15% (5 of 33 patients) in the control group; the difference in the reduction rates between the 2 groups was statistically significant (P = .014). The disappearance rate of MRSA in sputum was higher in the catechin group (31%; 11 patients) when compared with the control group (12%; 4 patients), however the difference in the disappearance rate between the 2 groups was not statistically significant (P = .091). No adverse events, such as respiratory tract obstruction, allergic bronchial spasm, or skin eruption, including laboratory changes, were observed during the study. CONCLUSION: The catechin inhalation appeared to reduce the MRSA count in sputum. However, the application of tea catechin inhalation as a supplementary treatment for controlling MRSA infection remains controversial.