Evaluation of Subchronic Oral Stevia Supplementation on Haematological Parameters and Serum Metabolic Profile in Male Wistar Rats

Abstract

The rising global burden of metabolic disorders has driven increased consumption of non-nutritive sweeteners like stevia as sugar substitutes. While purified steviol glycosides are generally recognised as safe, commercially available stevia products often contain multiple additional ingredients whose combined effects remain inadequately characterised. This study evaluated the subchronic effects of a commercial stevia sweetener on haematological and metabolic parameters in healthy male Wistar rats. Fifteen (15) adult male Wistar (180-200 g) rats were randomly assigned to three groups (n=5 per group): control (distilled water), low-dose stevia (200 mg/kg), and high-dose stevia (400 mg/kg). Treatments were administered daily by oral gavage for eight weeks. Haematological parameters were analysed using an automated haematology analyser, while lipid profile, fasting blood glucose, and insulin were measured spectrophotometrically using standard kits. Stevia supplementation significantly reduced packed cell volume at both doses (p<0.05). The 400 mg/kg dose increased total white blood cell count and reduced platelet count (p<0.05). Monocyte and eosinophil percentages increased at 400 mg/kg and 200 mg/kg, respectively (p<0.05). Metabolically, both doses significantly reduced insulin levels and HOMA-IR values while paradoxically elevating fasting blood glucose (p<0.05). The 400 mg/kg dose significantly increased total cholesterol, triglycerides, and low-density lipoproteins (p<0.05). Evidence from the present study has shown that subchronic commercial stevia supplementation improved insulin sensitivity in healthy rats but concurrently induced haematological and metabolic stress, manifesting as reduced packed cell volume, leukocytosis, hyperglycaemia, and dyslipidaemia. These findings underscore the critical influence of dose and duration context and highlight the need for stevia-based products formulated with fewer potentially harmful additives. The dissociation between improved insulin sensitivity and worsened metabolic control suggests that multiple ingredients may exert opposing effects, warranting further investigation into commercial formulations rather than assuming equivalence to purified steviol glycosides.