Basic nutritional investigationEffect of green tea in the prevention and reversal of fasting-induced intestinal mucosal damage
Introduction
An intact intestinal mucosa is essential for nutrient absorption and halting organisms and endotoxins from reaching the circulation. Surgical stress increases intestinal permeability and causes damage to the intestinal mucosa.1, 2 Most of these patients are kept fasting and are maintained on intravenous nutrition. Increased bacterial translocation has been seen in critically ill and nutritionally depleted patients and experimental animals,3, 4 and its clinical significance is not entirely known. Agents that would preserve the mucosal integrity and prevent bacterial translocation may have a positive effect on the management of patients undergoing surgery or fasting.
In the past 20 y epidemiologic and experimental studies have shown that polyphenols in tea reduce the risk of many diseases. Green and black teas have been reported to have a protective effect on chemically induced tumors in the gastrointestinal tract, liver, and mammary epithelium in rats.5, 6 In addition, population studies have shown that consumption of high quantities of green tea in certain parts of the world have beneficial effects on the gastric mucosa. Consumption of green tea has been associated with the prevention of chronic active gastritis7, 8 and with decreased risk of gastric cancer in Japan9, 10 and China.11, 12
The effects of black and green teas on the intestinal mucosa are unknown and have not been addressed. We studied the effects of green and black teas on the villous structure of the intestinal mucosa in control and fasting rats. Because some beneficial effects of tea have been attributed to the presence of potent antioxidants such as polyphenols, vitamin E was included for a comparative analysis of antioxidant effects.
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Experimental animals
Male Wister rats (weighing 250 to 300 g) were used for this study. Rats were bred locally in the animal facility of the Faculty of Medicine, Kuwait University Health Sciences Center and fed water and standard rat chow (France Nutris Company SA., Paris, France) ad libitum. The animals were exposed daily to a 12-h light-and-dark cycle and controlled normal room temperature at 25 ± 2°C. The animals were assigned randomly to one of nine groups (n = 4/group) and kept in separate cages. The study was
Histopathologic changes
In the control animals (group 1), the villi were packed, tall, well spaced, and of equal thickness. The villous stroma was abundant with stromal and inflammatory cells. The number of goblet cells, the covering enterocytes, and epithelial thickness of this group was used as the standard against which the other experimental groups were compared. The crypts were packed with thin lamina propria (Fig. 1a).
In the experimental groups, the histologic changes in the intestinal mucosa were uniform and
Discussion
To our knowledge, the effect of tea on normal intestinal mucosa has not been studied previously. In this fasting rat model, we found that the mucosal and villous atrophy induced by 3 d of fasting can be reverted to normal by the ingestion of green tea. This finding was not observed after black tea or water ingestion. Moreover, 2 wk of regular ingestion of green or black tea before fasting protected the intestinal mucosa from damage induced by subsequent fasting. Consumption of vitamin E, a
Acknowledgements
The authors greatly appreciate the expert technical help provided by Mr. K. I. Mathew from the Department of Surgery and Mrs. T. Saji from the Department of Pathology, Faculty of Medicine.
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