Abstract
Water-soluble black Chinese (Pu-Ehr) tea extract has been demonstrated to elicit antiobese effects in animals. We investigated the effects of black Chinese tea extract intake in 36 preobese Japanese adults in a 12-week double-blind randomized placebo-controlled group comparison study using powdered barley tea with or without black Chinese tea extract. All subjects ingested barley tea with (333 mg) or without (0 mg) black Chinese tea extract before each of three meals daily. In the black Chinese tea extract-treated group, the mean pretreatment values of body weight and body mass index significantly decreased from 8 weeks after intake (versus controls). Black Chinese tea extract intake may be useful for weight control and prevention of obesity development in humans.
INTRODUCTION
Foods that reduce body fats, such as medium-chain triacylglycerol,[Citation1,Citation2] diacyl glycerol,[Citation3] epigallocathechin-3-gallate (EGCG),[Citation4,Citation5] and fucoxithantin,[Citation6] have been identified. Apart from reducing abdominal fats and eliciting antioxidative effects,[Citation7,Citation8] green tea suppresses cholesterol levels (probably attributable to catechins, such as EGCG).[Citation9] EGCG strongly precipitates mixed bile salt micelles in vitro and lowers blood cholesterol levels in rats.[Citation10] We previously studied the effects and safety of long-term black Chinese tea extract (BTE) ingestion on body mass index (BMI) and visceral fat areas in Japanese adults with a preobese condition in a randomized, double-blind, placebo-controlled study.[Citation11] Data were assessed statistically using the two-way (each group × period) ANOVA method, significant differences between the groups for the respective same ingestion interval were compared with the unpaired Student t-test (two-tailed, Stat View, SAS, Cary, NC, USA), and differences where P < 0.05 were considered significant. However, in this study, we focused on the body weight analysis, and differences were found to be more reliable when we verified the data at first interaction with ingestion period and placebo-BTE group at each time interval using the two-way repeated ANOVA followed by Bonferroni post hoc group comparisons.
MATERIALS AND METHODS
BTE Preparation
BTE was prepared by a previously reported method.[Citation12] Briefly, leaves from fenhai broad-leaf tea trees cultivated in the Yunnan Highlands of China were harvested and subjected to heating and drying before being dampened and fermented with Aspergillus niger. The fermented black tea leaves (100 g) were milled, suspended in 900 mL water, and boiled for 60 min at 100°C before centrifugation at 2050× g for 30 min at room temperature. The supernatant was filtered (filter paper No. 5C; Toyo Roshi Co., Kawasaki, Japan), and the filtrate was then concentrated and dried as a BTE powder under a stream of air. BTE powder contains >2.9% (w/w) gallic acid by HPLC analysis.[Citation13] We buffered the unpleasant taste and odor of BTE with barley tea for good compliance. Barley tea, prepared with or without BTE, was packed in single-serving aluminum pouches with each pouch containing 333 mg or 0 mg (placebo) BTE, respectively. Each BTE or placebo pouch (1 g) respectively contained BTE (33.3%) or dexstrin (33.3%) blended with various bulking agents, including barley tea extract (21.1%), polysaccharides (19.3%), and glossing agents (26.3%).
Subjects and Clinical Study
The randomized, double-blind, placebo-controlled study was conducted between April 2007 and October 2008 at Fukuoka University Chikushi Hospital, Japan. Subjects (male: 24; female: 12) with a body mass index (BMI: kg/m2) ranging from 25 to 30 (grade I obese: the status of preobesity or overweight as categorized according to the Japan Society for the Study of Obesity[Citation14]) were enrolled in the study. Exclusion criteria of subjects included those: (i) under treatment for serious cardiac, renal, or hepatic diseases; (ii) with a history of gastrectomy, enterectomy, unrelated gastrointestinal surgeries, or hypothyroidism; and (iii) judged to be inappropriate by the attending physicians for the study. In addition, subjects with previous or preexisting alcohol abuse, insulin-dependent diabetes, or secondary causes of hyperglycemia, pancreatitis, or severe hypertension (systolic/diastolic blood pressure of >180/>110 mmHg) were also excluded. All subjects consented to participate in the study with a written consent after being briefed on the nature and purpose and possible side-effects of the study. The study was approved by the Institutional Review Board of the Fukuoka University Chikushi Hospital in April 2007. All procedures were performed in accordance with the Declaration of Helsinki of 1975 (revised in 1983; http://www.wma.net/e/policy/b3.htm). Other details were described in detail previously.[Citation11] Body weights, BMI, and waistline circumference of subjects were monitored before, and 4, 8, and 12 weeks after treatment as well as 4 weeks after withdrawal of BTE consumption. At each time interval prior to blood-sampling, subjects were starved for 12 h. All subjects ingested three pouches daily; they were asked to take one pouch with lukewarm water before each meal for efficacy and good compliance. In short, 333 mg BTE/pouch/meal or total 1 g/day dose was given to the BTE-treated group.
Statistical Analyses
Results of body weights and BMI were expressed as the mean ± SE. Comparisons between placebo- and BTE-treated groups were made by Two-Way Repeated-Measures ANOVA, and Bonferroni post hoc group comparisons (α = 0.05 level of significance) were used to determine differences between two groups at each time interval (JMP9.0.2; SAS, Cary, NC, USA).
RESULTS
Findings on the body weight showed the post hoc values for the respective time-points () were significant (P < 0.05): viz., BTE-treated subjects showed significant decreases at 4, 8, 12, and 16 weeks after intake compared to non-treated controls. Similar time-related decreasing tendencies were portrayed by the BMI values () as well. After 4-week treatment, the mean values of body weight () and BMI () in the BTE-ingested subjects tended to be lower than their respective baseline values. The trend was time-related; significant improvements in the mean BMI and body weight values were established 4, 8, and 12 weeks after BTE treatment, and 4 weeks after BTE withdrawal when compared to pretreatment values: the mean values of body weight () indicated −0.15 ± 0.09 (P < 0.05), −0.87 ± 0.21 (P < 0.01), −0.79 ± 0.22 (P < 0.05), and −1.10 ± 0.25 (P < 0.05), while those of BMI () registered −0.20 ± 0.08 (P < 0.05), −0.40 ± 0.11 (P < 0.05), −0.29 ± 0.11(P < 0.01), and −0.39 ± 0.10 (P < 0.01), respectively. When compared with the placebo-treated group, the mean body weight values were significantly reduced 8 (P < 0.05) and 12 (P < 0.01) weeks after intake, and 4 weeks (P < 0.01) after BTE withdrawal. In a similar tendency, the mean BMI values (kg/m2) of the BTE-treated group indicated significant improvements 8 (P < 0.01) and 12 (P < 0.01) weeks after intake and 4 weeks after BTE withdrawal (P < 0.05).
FIGURE 1 Inhibitory effects of the water extract of black Chinese tea (BTE) on the body weight (a) and body mass index (BMI; b) in preobese human subjects (n = 36) after ingesting BTE (333-mg/meal × 3 meals/day: closed circles) or placebo (closed diamonds) before each meal for a 12-week period with a follow-up 4-week withdrawal period. All parameters were monitored at 0 (preingestion), 4, 8, and 12 weeks after BTE ingestion as well as 4 weeks after withdrawal. Values are expressed as the mean ± standard error. Differences between post- and pre-ingestion levels in each group were compared with the two-way repeated ANOVA followed by Bonferroni post hoc test at each time interval, where differences with P < .05 (*) or .01 (**) were considered significant. Differences between the placebo- and BTE-treated groups at the respective time intervals were compared with the two-way repeated ANOVA followed by the Bonferroni post hoc group comparisons. Differences where P < .01 (†), or P < .05 (§) were considered significant.
In contrast, the corresponding time-related mean body weight and BMI values of the placebo group did not show any significant changes during the same study period. BTE was intake-dependent and non-addictive (or safe) in both groups. Neither BTE-induced side effects, such as abdominal distension, abdominal pain, diarrhea, retching, increased flatulence frequency, and allergic symptoms, nor other abnormalities in the monitored hematologic or biochemical parameters were observed (data not shown).
DISCUSSION
Although the tendencies were similar to previous published data,[Citation11] our present use of a different statistical verification yielded more detail and useful effects of BTE ingestion in body weight loss and BMI values versus time. Pu-Ehr (black Chinese) tea lowers the body weight in rats.[Citation12,Citation15] The present findings indicated that BTE exhibited weight-reducing effects in preobese Japanese patients. BTE (333 mg/meal × 3:1 g/day) significantly elicited antiobesity effects within a 4-week ingestion period () in terms of body weight. Note that BTE ingestion did not induce any side effects or addiction in the treated subjects. Thus, BTE elicited moderate yet significant time-related reductions in body weight, and may, therefore, be a useful food for preventing obesity development, especially for subjects in the overweight category (BMI: >25 kg/m2).
This is the first randomized, double-blind, placebo-controlled study of BTE intake attempted in humans, and the results revealed the suppressive effects of BTE on the mean body weight and BMI values in preobese or overweight Japanese subjects from 4–12 weeks after intake and 4 weeks after BTE termination without any side-effects or addiction. These useful results indicate that follow-up studies are warranted to examine possible favorable effects on relevant pathological phenomena, such as metabolic syndrome-induced obesity and/or arteriosclerosis in humans.
ABBREVIATIONS
| BMI | = | Body mass index |
| BTE | = | Black Chinese tea extract |
| CT | = | Computed tomography |
ACKNOWLEDGMENT
The authors would like to thank Harumi Ide and Narumi Yamauchi from the Department of Radiology of Fukuoka University Chikushi Hospital for their technical expertise in this study. Thanks are also due to Dr. Ryuji Takeda from the Department of Agriculture of Kinki University, Osaka, Japan for statistical analysis and to Professor Anthony Foong of Kyoto Pharmaceutical University, Kyoto for reading the manuscript.
FUNDING
This project was funded by Nippon Supplement, Inc.
Additional information
Funding
REFERENCES
- Tsuji, H.; Kasai, M.; Takeuchi, H.; Nakamura, M.; Okazaki, M.; Kondo, K. Dietary medium-chain triacylglycerols suppress accumulation of body fat in a double blind, controlled trial in healthy men and women. Journal of Nutrition 2001, 131, 2853–2859.
- Marie-Pierre, S.O.; Aubrey, B. Weight-loss diet that includes consumption of medium-chain triacylglycerol oil leads to a greater rate of weight and fat mass loss than dose olive oil. The American Journal of Clinical Nutrition 2008, 87, 621–626.
- Nagao, T.; Watanabe, H.; Goto, N.; Onizawa, K.; Taguchi, H.; Matsuo, N.; Yasukawa, T.; Tsushima, R.; Shimasaki, H.; Itakura, H. Dietary diacylglycerol suppresses accumulation of body fat compared to triacylglycerol in men in a double-blind control trial. Journal of Nutrition 2000, 130, 792–797.
- Michael, B.; Frank, T. The effects of epigallocatechin-3-gallate on thermogenesis and fat oxidation in obese men: A pilot study. Journal of the American College of Nutrition 2007, 26, 389S–395S.
- Sabu, M.C.; Priya, T.T.; Ramadasan, K.; Nishigaki, I. Beneficial effects of green tea: A literature review. Chinese Medicine 2010, 5, 13–22.
- Hosokawa, M.; Miyashita, T.; Nishikawa, S.; Emi, S.; Tsukui, T.; Beppu, F.; Okada, T.; Niyashita, K. Fucoxanthin regulates adipocytokine mRNA expression in white adipose tissue of diabetic/obese KK-Ay mice. Archives of Biochemical and Biophysics 2010, 504, 17–25.
- Rababah, T.M.; Ereifej, K.I.; Al-Qudah, K.M.; Al-Mahasneh, M.A.; Al-u’datt, M.H.; Yang, W. Effects of green tea and grape seed TBHQ on physicochemical properties of Baladi goat meats. International Journal of Food Properties 2011, 14, 1208–1216.
- Pekal, A.; Drozdz, P.; Pyrzynska, K. Comparison of the antioxidant properties of commonly consumed commercial teas. International Journal of Food Properties 2012, 15, 1101–1109.
- Tsuchida, T.; Itakura, H.; Nakamura, H. Reduction of body fat in humans by long-term ingestion of catechins. Progress in Medicine 2002, 22, 2189–2203.
- Ikeda, I.; Imasato, Y.; Sasaki, E.; Nakayama, M. Tea catechins decrease micellar solubility and intestinal absorption of cholesterol in rats. Biochemical Biophysical Acta 1992, 1127, 141–146.
- Kubota, K.; Sumi, S.; Tojo, H.; Sumi-Inoue, Y.; Hou, I.-C.; Oi, Y.; Fujita, H.; Urata, H. Nutrition Research 2011, 31, 421–428.
- Fujita, H.; Yamagami, T. Extract of black tea (Pu-Ehr) inhibits postprandial rise in serum cholesterol in mice, and with long term use reduces serum cholesterol and low density lipoprotein levels and renal fat weight in rats. Phytotherapy Research 2008, 22, 1275–1281.
- Lin, J.K.; Lin, C.L.; Liang, Y.C. Survey of catechins, gallic acid, and methylxanthines in green, oolong, pu-erh, and black teas. Journal of Agriculture and Food Chemistry 1998, 46, 3635–3642.
- The Examination committee of criteria for “Obesity disease” in Japan. Japan society for the study of obesity. New criteria for “Obesity disease”. Circulation Journal 2002, 66, 987–992.
- Kuo, K.L.; Weng, M.S.; Chiang, C.T.; Tsai, Y.J.; Linshiau, S.Y.; Lin, J.K. Comparative studies of the hypolipidemic and growth suppressive effects of oolong, black, Pu-Ehr, and green tea leaves in rats. Journal of Agriculture and Food Chemistry 2005, 53, 480–489.