US National Library of MedicineNational Institutes of Health

Food Funct.2014 Jul 25;5(7):1613-20. doi: 10.1039/c4fo00209a.

Effects of blackteaon body composition and metabolic outcomes related to cardiovascular disease risk: a randomized controlled trial.

Bøhn SK,Croft KD,Burrows S,Puddey IB,Mulder TP,Fuchs D,Woodman RJ,Hodgson JM.

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Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Norway


There is increasing evidence thatteaand its non-caffeine components (primarily flavonoids) contribute to cardiovascular health. Randomized controlled trials have shown thatteacan improve cardiovascular disease risk factors. We have previously reported a non-caffeine associated beneficial effect of regular blackteaconsumption on blood pressure and its variation.


To explore the non-caffeine associated effects of blackteaon body weight and body fat distribution, and cardiovascular disease related metabolic outcomes.


regulartea-drinking men and women (n = 111; BMI 20-35 kg m(-2)) were recruited to a randomized controlled double-blind 6 month parallel-designed trial. Participants consumed 3 cups per day of either powdered blackteasolids (tea) or a flavonoid-free flavour- and caffeine-matched placebo (control). Body weight, waist- and hip-circumference, endothelial function and plasma biomarkers were assessed at baseline, 3 months and 6 months.


Compared to control, regular ingestion of blackteaover 3 months inhibited weight gain (-0.64 kg, p = 0.047) and reduced waist circumference (-1.88 cm, P = 0.035) and waist-to-hip ratio (-0.03, P = 0.005). These effects were no longer significant at 6 months. There were no significant effects observed on fasting glucose, insulin, plasma lipids or endothelial function.


Our study suggests that short-term regular ingestion of blackteaover 3 months can improve body weight and body fat distribution, compared to a caffeine-matched control beverage.






Volume 53, Number 22, Pages 8706-8713 (November 2005)

Tagliazucchi D, Verzelloni E, Conte A


Effect of some phenolic compounds and beverages on pepsin activity during simulated gastric digestion.


Department of Agricultural Science, University of Modena and Reggio Emilia, Italy.

The effect of some polyphenols (resveratrol, catechin, epigallocatechin-3-gallate, and quercetin) and beverages (red wine and green tea) on the enzymatic activity of pepsin during the digestion of three different substrates (pork meat, insoluble azocasein, and denatured hemoglobin) has been investigated. The tested polyphenols and beverages increase the initial velocity of the reaction, and the activating effect is concentration dependent. The order of effectiveness of polyphenols in increasing the initial velocity of the reaction is resveratrol > or = quercetin > epigallocatechin-3-gallate > catechin. The kinetic data obtained with soluble denatured hemoglobin show that the K(m) for the substrate is not changed, whereas the V(max) of the reaction is increased. Pepsin activity follows a simple Michaelis-Menten kinetic suggesting that k(3) is increased by polyphenols. To the authors' knowledge, the present study is the first demonstration that some polyphenols and related beverages are able to enhance the enzymatic activity of pepsin.


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Volume 22, Number 2, Pages 165-170 (March 2006)

Dryden GW, Song M, McClain C.


Polyphenols and gastrointestinal diseases.

Departments of Medicine, University of Louisville, Kentucky, USA.

PURPOSE OF REVIEW: This article will review the role of polyphenols in gastrointestinal diseases. Ingested polyphenols are concentrated in the gastrointestinal tract and are not well absorbed into the rest of the body. Thus, the high luminal concentrations achieved support a potential for therapeutic uses in the gastrointestinal tract. Additionally, there is great interest from the general public in complementary and alternative medicine. RECENT FINDINGS: Dietary polyphenols are a major source of antioxidants consumed by humans. Polyphenols possess not only antioxidant properties but also antiviral, antibacterial, antiinflammatory and anticarcinogenic effects, as well as the ability to modulate certain signaling pathways such as nuclear factor-kappaB activation. Green tea polyphenols have been shown to have efficacy in various models of inflammatory bowel disease. Silymarin, or milk thistle, is hepatoprotective against many forms of experimental liver injury and is widely used in human liver diseases, such as hepatitis C and alcoholic cirrhosis, with an excellent safety profile (but with unclear efficacy). SUMMARY: Substantial in-vitro and animal studies support the beneficial effects of polyphenols in many gastrointestinal diseases. Well designed multicenter trials in humans, such as those called for in the 2005 National Institutes of Health Requests for Applications for Silymarin Centers, will be critical for defining the safety, appropriate dosing and therapeutic efficacy of such agents.


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European Journal of Clinical Investigation


Volume 36, Number 2, Pages 113-122 (February 2006)

Green tea polyphenol (-)-epigallocatechin-3-gallate inhibits ethanol-induced activation of pancreatic stellate cells.


Third Department of Internal Medicine, University of Occupational and Environmental Health, School of Medicine, Kitakyushu, Japan.

BACKGROUND: Activated pancreatic stellate cells (PSCs) play a central role in the pathogenesis of pancreatic fibrogenesis and inflammation. Ethanol, a major cause of chronic pancreatitis, directly induces PSC activation and oxidative stress. Inhibition of PSC activation or stimulation to PSC might be an effective therapeutic strategy for the prevention of pancreatic fibrosis, and (-)-epigallocatechin-3-gallate (EGCG), a major component of green tea extracts, is a potent antioxidant of polyphenols. Therefore, we examined the mechanisms through which ethanol induces oxidative stress on PSCs and evaluated the effect of EGCG on activation and cell functions of ethanol-stimulated PSCs. MATERIALS AND METHODS: The PSCs were isolated from the pancreas of male Wister rats with Nycodenz gradient methods and cells between passages one and four were used. Isolated PSCs were cultured with ethanol (50 mM) in the absence or presence of EGCG (5 microM or 25 microM). RESULTS: The EGCG pre-treatment abolished ethanol-induced lipid peroxidation of the cell membrane, loss of total superoxide dismutase (SOD) activity and suppressed ethanol-induced gene expressions of Mn- and Cu/Zn-SOD. EGCG also suppressed ethanol-induced p38 mitogen-activated protein (MAP) kinase phosphorylation, alpha-smooth muscle actin production in PSCs and activated transforming growth factor-beta1 secretion into the medium. Furthermore, EGCG inhibited ethanol-induced type-I procollagen production and collagen secretion. In addition, EGCG inhibited transformation of freshly isolated cells to activated myofibroblast-like phenotype. CONCLUSIONS: Our results suggest that green tea and polyphenols could prevent pancreatic fibrosis by inhibiting PSC activation through the antioxidative effect.

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American Gastroenterological Association


Volume 129, Issue 6, Pages 1928-1936 (December 2005)

Constance E. Ruhl, James E. Everhart


Coffee and Tea Can Reduce Risk of Chronic Liver Disease


National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland.


A study published today in the American Gastroenterological Association (AGA) journal Gastroenterology found that people at high risk for liver injury may be able to reduce their risk for developing chronic liver disease significantly by drinking more than two cups of coffee or tea daily. This preventative effect was only seen in people at higher risk for liver disease due to heavy alcohol intake, being overweight or having diabetes or iron overload.
This is the first study to take a prospective look at the relationship between coffee and tea consumption and chronic liver disease in the general U.S. population.

"While it is too soon to encourage patients to increase their coffee and tea intake, the findings of our study potentially offer people at high-risk for developing chronic liver disease a practical way to decrease that risk," said Constance E. Ruhl, MD, PhD, who conducted the study with colleague, James E. Everhart, MD, MPH. "In addition, we hope the findings will offer guidance to researchers who are studying liver disease progression."

Chronic liver disease is an ongoing injury to the cells of the liver, resulting in inflammation that lasts longer than six months. Its causes are numerous, including viruses, obesity, alcohol, metabolic or immunologic abnormalities, and side effects from various medications. Chronic liver diseases include cirrhosis, fibrosis and hepatitis. According to the most recent estimates from the NationalCenter for Health Statistics, nearly 28,000 people die of chronic liver disease each year and there are more than 5 million prevalent cases of chronic liver disease and cirrhosis in the United States.

Researchers at the National Institute of Diabetes and Digestive and Kidney Diseases and Social & Scientific Systems, Inc. conducted an analysis of patients using the first National Health and Nutrition Examination Survey (NHANES I) and the NHANES I Epidemiologic Follow-Up Study.

The study population included 9,849 participants whose coffee and tea intake was evaluated and who were followed for a median of 19 years. In this analysis, coffee and tea intake was measured in cups, ranging from 0 to 16 cups per day with a median of two cups per day. Findings showed that those who consumed more than two cups of coffee or tea per day developed chronic liver disease at half the rate of those who drank less than one cup each day.

Over the last few years, there has been a growing body of evidence that coffee decreases the risk of elevated liver enzymes, cirrhosis and liver cancer. This study provides support for a protective effect of coffee on chronic liver disease and cirrhosis, and extends these findings to the general U.S. population. However, the study does not provide evidence that coffee and tea protect against chronic liver disease from individual causes, such as fatty liver disease or viral hepatitis.

"In the analysis, we determined that caffeine was partly responsible for the protective effect found. We believe that investigations into the mechanism of action of caffeine for protecting the liver and its clinical application are needed," said Dr. Ruhl.


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