Consumption of green tea infusion causes loss of nutrients through faeces in Wistar rats

Relationship between consumption of green tea infusion and faecal nutrient content was studied. Twelve male Wistar rats (aged 10 to 12 weeks and weighed 87 to 120 g) were divided into two groups of six rats each. The control group was placed on tap water, while the test group was placed on green tea infusion (0.20 g/50 ml) daily as the only source of fluid; for 28 days. Both groups consumed rat feed ad libitum. Phytochemicals detected in the infusion were tannins, saponins, alkaloids, flavonoids and phytosterols. The infusion increased test animals’ appetite for food (% coefficient of variation, % CV = 5.44) but decreased their appetite for the infusion (% CV = 72.41). Animals placed on the infusion (test group) did not gain more weight (% CV = 3.86) nor had better feed conversion ratio (% CV = 1.41). Faecal ash and fibre contents were not affected by tea consumption (% CV = 3.38 and 2.03, respectively). Control rats lost more carbohydrate and moisture (% CV = 27.58 and 9.58, respectively) but test rats lost more protein and lipids. Energy lost by test rats through faecal matter was not appreciably higher (101.31 vs 96.24 kcal/ 100 g sample; % CV = 2.56). Loss of certain nutrients in the test rats may have been triggered by the inhibitory action of polyphenols such as tannins present in the infusion on their digestive enzymes. In conclusion, the tea infusion elicited increased feacal excretion of proteins and lipids in treated animals.