Dose-dependent Hematological Effects of Green Tea (Camellia sinensis) Extract in Male Wistar Rats

Abstract

Background: Green tea (Camellia sinensis) is widely recognized for its antioxidant, metabolic, and cardiovascular benefits. However, its dose-dependent effects on hematological parameters remain unclear, particularly under non-pathological conditions. Aim: This study aims to evaluate the hematological response to graded doses of green tea extract in healthy male Wistar rats. Methods: In this study, Twenty-eight(28) male Wistar rats (180–220 g) were obtained from the animal facility of the Department of Physiology, Alex Ekwueme Federal University, Nigeria and randomly assigned to four groups (n = 7 each). Group I (control) received distilled water; Groups II, III, and IV received green tea extract orally at 100 mg/kg, 300 mg/kg, and 500 mg/kg body weight, respectively, for 21 days. Hematological parameters—including red and white blood cell indices, hemoglobin concentration, hematocrit, and platelet counts were assessed using an automated hematology analyzer. Data were analyzed using one-way ANOVA and Tukey’s post hoc test (*p* < 0.05). Results: No significant differences were observed in RBC count, hemoglobin concentration, hematocrit, WBC count, or platelet indices across groups (p > 0.05). However, mean corpuscular hemoglobin concentration (MCHC) significantly increased in all green tea-treated groups compared to the control (p = 0.003), suggesting enhanced intracellular hemoglobin concentration. Other parameters, including MCV and monocyte percentage, showed non-significant trends approaching statistical relevance. Conclusion: Green tea extract at doses up to 500 mg/kg does not adversely affect hematological parameters in healthy Wistar rats. The observed increase in MCHC may reflect improved erythrocyte function, potentially due to the antioxidant properties of green tea polyphenols. These findings support the hematological safety of green tea and provide a basis for further investigation in disease models or under oxidative stress conditions.