## 4 Discussion  
Different climatic, soil and agotechnical conditions affect the differences in composition of plants, i.e., Stevia leaves. Therefore, it was assumed that the sum of plant components that interfere with each other weakening or strengthening the response will have an unequal effect on the evaluated parameters [26]. Figure 1: Histological evaluation of the liver of Wistar rats. AIN-93G—semi-synthetic diet; CHOL—Hypercholesterolic diet; GS—Hypercholesterolic diet with steviol glycosides; 10%PL—Hypercholesterolic diet with 10% of dried leaves of _Stevia reboundiana_ Bertoni from Polish cultivation; 17%BR—Hypercholesterolic diet with 17% of dried leaves of _Stevia reboundiana_ Bertoni from Brazilian cultivation; 18%PR—Hypercholesterolic diet with 18% of dried leaves of _Stevia reboundiana_ Bertoni from Paraguayan cultivation. Yellow arrow—infiltration of inflammatory cells with necrosis of hepatocytes; Green arrow—infiltration of inflammatory cells; Blue arrow—extravasation with inflammatory cell infiltration; Black arrow—small and large cell steatosis. The results concerning the effect of steviol glycosides obtained in this study generally differ from those available in the literature. It could be due to the fact that non-diabetic rats were used in our research, as opposed to the below-cited data reported by other authors. In our study, both the addition of steviol glycosides and Stevia leaves to the hypercholesterol diet resulted in a significant reduction in body gain. The weight of kidneys, heart and liver did not change significantly in rats fed the diet with the addition of steviol glycosides. However, in rats fed the diet with the addition of Stevia leaves, the heart weight decreased, the kidney weight did not change, and the liver weight increased only after adding Stevia leaves of Polish and Paraguayan origin. Significant differences in the reduction in the body weight of experimental animals were noted in [PERSON] et al. [27] and [PERSON] et al. [28] studies. However different results were obtained by [PERSON] [29], who observed a small but significant (\(p<0.05\)) increase in body weight of the animals fed a diet with a water extract of _Stevia rebaudiana_. In a 21-day experiment, [PERSON] et al. [30] administered pure stevioside in the amount of 2.5 g/kg b.w. to diabetic rats, as an addition to the basic diet. The researchers showed a significant reduction (\(p\leq 0.05\)) in the concentration of glucose in the animal blood compared to the control group of diabetic rats. In the study by [PERSON] et al. [31], a 10-times-lower (0.25 g/kg b.w.) dose of stevioside significantly increased glucose levels in healthy rats, but did not cause changes in sick diabetic animals. [PERSON] et al. [32] conducted research on Wistar and Goto-Kakizaki rats. The Goto-Kakizaki animals are characterized by induced diabetes. It was shown that the addition of stevioside to the diet in rats with impaired carbohydrate metabolism did not significantly affect blood glucose levels. The study showed that stevioside increased insulin secretion and lowered glucagon concentration. The same effect was not observed in Wistar rats, proving that stevioside had hypoglycemic activity only in rats with impaired carbohydrate metabolism. [PERSON] et al. [33] analyzed the effect of stevioside administered orally for 90 days, in the amount of 50 mg/day, on selected biochemical parameters of people with hyperlipidemia. In a study conducted by [PERSON] et al. [34] on a group of chickens fed dried leaves of _Stevia rebaudiana_ [PERSON]. as an addition to the diet (2 g/100 g of diet) or stevioside (0.013 g/100 g of diet), a significant reduction in glucose concentration from 265.6 mg/100 mL to 228.5 mg/100 mL was observed in the group of animals receiving a diet with the addition of dried _Stevia rebaudiana_ leaves. The addition of stevioside to the diet did not cause a significant difference in the level of glucose in the blood of chickens.