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Human Nutrition and Metabolism
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Short Description: Human Nutrition and Metabolism. Oolong Tea Increases Metabolic Rate and Fat .... Abbreviations used: BHNRC, Beltsville Human Nutrition Research Center; ...
Content Inside: Human Nutrition and Metabolism Oolong Tea Increases Metabolic Rate and Fat Oxidation in Men William Rumpler,1* James Seale,* Beverly Clevidence,* Joseph Judd,* Eugene Wiley,* Shigeru Yamamoto, Tatsushi Komatsu, Tetsuya Sawaki, Yoshiyuki Ishikura and Kazuaki Hosoda *Beltsville Human Nutrition Research Center, Beltsville, MD 20705; Department of Nutrition, University of Tokushima, Tokushima, Japan; and Suntory Research Center, Suntory Ltd., Osaka, Japan ABSTRACT According to traditional Chinese belief, oolong tea is effective in the control of body weight. Few controlled studies, however, have been conducted to measure the impact of tea on energy expenditure (EE) of humans. A randomized cross-over design was used to compare 24-h EE of 12 men consuming each of four treatments: 1) water, 2) full-strength tea (daily allotment brewed from 15 g of tea), 3) half-strength tea (brewed from 7.5 g tea) and 4) water containing 270 mg caffeine, equivalent to the concentration in the full-strength tea treatment. Subjects refrained from consuming caffeine or flavonoids for 4 d prior to the study. Tea was brewed each morning; beverages were consumed at room temperature as five 300 mL servings. Subjects received each treatment for 3 d; on the third day, EE was measured by indirect calorimetry in a room calorimeter. For the 3 d, subjects consumed Downloaded from a typical American diet. Energy content of the diet was tailored to each subject's needs as determined from a preliminary measure of 24-h EE by calorimetry. Relative to the water treatment, EE was significantly increased 2.9 and 3.4% for the full-strength tea and caffeinated water treatments, respectively. This increase over water alone represented an additional expenditure of 281 and 331 kJ/d for subjects treated with full-strength tea and caffeinated water, respectively. In addition, fat oxidation was significantly higher (12%) when subjects consumed the full-strength tea rather than water. J. Nutr. 131: 2848 2852, 2001. jn.nutrition.org KEY WORDS: Tea metabolic rate fat oxidation caffeine catechins The Chinese belief that drinking tea promotes good health constituents such as polyphenolic compounds is unclear (8). This and longevity is gaining scientific merit (1). Oolong tea is one of study was designed to assess under controlled conditions whether by on August 3, 2008 the three types of tea that is manufactured from tea leaves; the consumption of oolong tea increases EE or modulates substrate others are black and green teas. Green tea, which is consumed oxidation relative to control beverages. largely in Asia, is processed to minimize fermentation, whereas black tea, which is popular in western countries, is fermented to METHODS produce the characteristic flavor components. Oolong tea is less fermented than black tea. It is sold commercially in the United Subjects. Twelve men ages 25 60 y were recruited from the States and is often served in Chinese restaurants. general population with an average age, weight and height of 44 Oolong tea has been studied for its antioxidant properties (2) 9 y, 83 10 kg and 179 6 cm, respectively. Body composition, and its effects on cardiovascular disease (3), cancer (4) and as determined by dual-energy X-ray absorptometry (DEXA) averaged obesity (5). In a recent study, 102 Chinese women who drank 60 8 kg lean body mass and 23 7 g/100 g fat. To minimize within-subject variation, the study was designed to complete all four cups of oolong tea per day (the brew from four 2 g tea bags) measurements on a single subject within a month. Males were studied lost over a kilogram of body weight during a 6-wk period (6). to avoid masking the expected response by the variation in EE known These data suggest that oolong tea may promote weight loss by to occur in premenopausal women across their menstrual cycle. increasing energy expenditure (EE)2 10 20%. Caffeine has been All volunteers participated in an initial screening that involved shown to increase EE for several hours following ingestion de- completion of questionnaires related to diet, physical activity, family pending on the level of intake. Oolong tea contains caffeine and and personal health history and availability for participation in the the 102 Chinese women received 125 mg/d. Studies show that study. A cooperating physician performed a simple medical evalua- consuming this amount of caffeine causes a 16% increase in tion. A 20 mL blood sample was collected from fasting subjects, and resting EE (7). Whether the increase in EE that accompanies the height and weight were recorded. The blood sample was analyzed for consumption of oolong tea is due solely to caffeine or to other routine blood chemistry. All men selected were in basic good health, had a BMI between 18 and 30 kg/m2 and had no history of cancer, heart disease, hypertension, diabetes, liver or kidney disease, endo- crine disorders or food allergies. Multiple selection criteria (height, 1 To whom correspondence should be addressed. weight, age, body composition, medical evaluation, blood chemistry E-mail: rumpler@bhnrc.arsusda.gov. 2 and normal level of physical activity) were used to select a homoge- Abbreviations used: BHNRC, Beltsville Human Nutrition Research Center; BMR, basal metabolic rate; DEXA, dual-energy X-ray absorptometry; EE, energy neous group of participants. Self-reported daily caffeine consumption expenditure; EGCG, epigallocatechin gallate; RQ, respiratory quotient. was recorded and used as a selection criterion. The target population 0022-3166/01 $3.00 © 2001 American Society for Nutritional Sciences. Manuscript received 8 February 2001. Initial review completed 30 March 2001. Revision accepted 16 August 2001. 2848
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