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

UNLABELLED There is increasing evidence that tea and its non-caffeine components (primarily flavonoids) contribute to cardiovascular health. Randomized controlled trials have shown that tea can improve cardiovascular disease risk factors. We have previously reported a non-caffeine associated beneficial effect of regular black tea consumption on blood pressure and its variation. OBJECTIVE To explore the non-caffeine associated effects of black tea on body weight and body fat distribution, and cardiovascular disease related metabolic outcomes. DESIGN regular tea-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 black tea solids (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. RESULTS Compared to control, regular ingestion of black tea over 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. CONCLUSION Our study suggests that short-term regular ingestion of black tea over 3 months can improve body weight and body fat distribution, compared to a caffeine-matched control beverage. However, there was no evidence that these effects were sustained beyond 3 months.

[1]  M. Gross.  Flavonoids and Cardiovascular Disease , 2004 .

[2]  Xiao-jian Wang,et al.  Effect of oral isoflavone supplementation on vascular endothelial function in postmenopausal women: a meta-analysis of randomized placebo-controlled trials. , 2010, The American journal of clinical nutrition.

[3]  T. Dadd,et al.  Health effects of green tea catechins in overweight and obese men: a randomised controlled cross-over trial , 2011, British Journal of Nutrition.

[4]  R. Levy,et al.  Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge. , 1972, Clinical chemistry.

[5]  J. Hodgson,et al.  Acute effects of ingestion of black and green tea on lipoprotein oxidation. , 2000, The American journal of clinical nutrition.

[6]  B. Clevidence,et al.  Antihyperglycemic effect of oolong tea in type 2 diabetes. , 2003, Diabetes care.

[7]  C. Schwanke,et al.  Effect of green tea (Camellia sinensis) consumption on the components of metabolic syndrome in elderly , 2012, The journal of nutrition, health & aging.

[8]  Mingyuan Wu,et al.  Green Tea Supplementation Affects Body Weight, Lipids, and Lipid Peroxidation in Obese Subjects with Metabolic Syndrome , 2010, Journal of the American College of Nutrition.

[9]  C. Auger,et al.  The effect of black tea on risk factors of cardiovascular disease in a normal population. , 2012, Preventive medicine.

[10]  Paul Zimmet,et al.  The metabolic syndrome – Authors' reply , 2005, The Lancet.

[11]  P. Judd,et al.  The Effect of Consuming Instant Black Tea on Postprandial Plasma Glucose and Insulin Concentrations in Healthy Humans , 2007, Journal of the American College of Nutrition.

[12]  S. Grundy,et al.  The metabolic syndrome. , 2008, Endocrine reviews.

[13]  J. Hodgson.  Tea flavonoids and cardiovascular disease. , 2008, Asia Pacific journal of clinical nutrition.

[14]  D. Mela,et al.  Effects of Catechin Enriched Green Tea on Body Composition , 2010, Obesity.

[15]  Davide Grassi,et al.  Black tea consumption dose-dependently improves flow-mediated dilation in healthy males , 2009, Journal of hypertension.

[16]  W. Baker,et al.  Effect of green tea catechins with or without caffeine on anthropometric measures: a systematic review and meta-analysis. , 2010, The American journal of clinical nutrition.

[17]  G. Watts,et al.  Regular ingestion of black tea improves brachial artery vasodilator function. , 2002, Clinical science.

[18]  U. Engelhardt,et al.  Determination of flavanols, theogallin, gallic acid and caffeine in tea using HPLC , 1991 .

[19]  R. Turner,et al.  Homeostasis model assessment: insulin resistance and β-cell function from fasting plasma glucose and insulin concentrations in man , 1985, Diabetologia.

[20]  J. Hodgson,et al.  Comparison of the effects of black and green tea on in vitro lipoprotein oxidation in human serum , 1999 .

[21]  G. Watts,et al.  Endothelium-dependent and independent vasodilation studied at normoglycaemia in Type I diabetes mellitus with and without microalbuminuria , 2001, Diabetologia.

[22]  H. Minuk,et al.  Metabolic syndrome. , 2005, Journal of insurance medicine.

[23]  T. Tsai,et al.  Effect of green tea extract on obese women: a randomized, double-blind, placebo-controlled clinical trial. , 2008, Clinical nutrition.

[24]  S. R. Ferreira,et al.  Methods of estimation of visceral fat: advantages of ultrasonography. , 2003, Obesity research.

[25]  D. Corella,et al.  Nutrigenomics in Cardiovascular Medicine , 2009, Circulation. Cardiovascular genetics.

[26]  W. Marsden.  I and J , 2012 .

[27]  R. Lamuela-Raventós,et al.  Analysis of total phenols and other oxidation substrates and antioxidants by means of Folin-Ciocalteu reagent , 1999 .

[28]  D. Playford,et al.  Improved analysis of brachial artery ultrasound using a novel edge-detection software system. , 2001, Journal of applied physiology.

[29]  D. Baer,et al.  Black tea consumption reduces total and LDL cholesterol in mildly hypercholesterolemic adults. , 2003, The Journal of nutrition.

[30]  J. Lane,et al.  Effects of dietary supplementation with the green tea polyphenol epigallocatechin-3-gallate on insulin resistance and associated metabolic risk factors: randomized controlled trial , 2008, British Journal of Nutrition.

[31]  J. Keaney,et al.  Short- and Long-Term Black Tea Consumption Reverses Endothelial Dysfunction in Patients With Coronary Artery Disease , 2001 .

[32]  H. Urata,et al.  Improvements of mean body mass index and body weight in preobese and overweight Japanese adults with black Chinese tea (Pu-Erh) water extract. , 2011, Nutrition research.

[33]  J. Vita,et al.  Tea and cardiovascular disease. , 2011, Pharmacological research.

[34]  R. Draijer,et al.  Tea Consumption Enhances Endothelial-Dependent Vasodilation; a Meta-Analysis , 2011, PloS one.

[35]  J. Hodgson,et al.  Effects of black tea on blood pressure: a randomized controlled trial. , 2012, Archives of internal medicine.

[36]  M. C. Cesar,et al.  The effects of green tea consumption and resistance training on body composition and resting metabolic rate in overweight or obese women. , 2013, Journal of medicinal food.

[37]  Miss A.O. Penney.  (b) , 1974, The New Yale Book of Quotations.

[38]  J. Hodgson,et al.  Effects of tea and coffee on cardiovascular disease risk. , 2012, Food & function.

[39]  J. Hodgson,et al.  Black tea lowers the rate of blood pressure variation: a randomized controlled trial. , 2013, The American journal of clinical nutrition.

[40]  B. Thinkhamrop,et al.  Effectiveness of green tea on weight reduction in obese Thais: A randomized, controlled trial , 2008, Physiology & Behavior.

[41]  H. Pijl,et al.  No effect of consumption of green and black tea on plasma lipid and antioxidant levels and on LDL oxidation in smokers. , 1998, Arteriosclerosis, thrombosis, and vascular biology.

[42]  H. Ashida,et al.  Epigallocatechin gallate promotes GLUT4 translocation in skeletal muscle. , 2008, Biochemical and biophysical research communications.