This paper studied the radiation protection effect of stevia, which is a known natural sweetener for health-conscious consumers. Seventy-eight male rats(aged 6 weeks) were divided into four experimental groups(control group, stevia oral administration group, radiation group, and irradiated group after oral administration of stevia), and stevia leaf powder was orally administered at a dose of 250 mg/kg for 14 days. Then, irradiation(10 Gy) was perfomed once using a linear accelerator. The results were obained 1, 3.5, 7, and 21 days after the rats were euthanized.

In experiments on the rats’ blood components, the lymphocyte and neutrophil counts were higher than those of the irradiated group (p<0.01 and p<0.05, respectively). We also found significant results regarding protection against radiation in the platelets (p<0.05) and erythrocytes (p<0.05) on the 7th and 14th days of the experiment. The administration of stevia leaf powder effectively reduced the damage of the hematopoietic/immune system caused by radiation.

Although statistical significance could not be observed in SOD activity after irradiation, the irradiated group had higher SOD activity after administration compared with the irradiated group. On the 21st day of the experiment, the recovery(29%) of the irradiated group after administration(81%) considerably differed from that of the radiation irradiation group(51%).

No significant differences in body weight and brain weight were observed. By contrast, there was a significant difference in the weight of the spleen. These results, such as those of the blood component test, indicated that the damage of the hematopoietic/immune system was alleviated.

In experiments involving the cerebral cortex, parenchymal cells, and liver parenchymal cells, cell death was not observed due to lack of radiation dose, and the protective effect of stevia leaf powder could not be confirmed. However, such protective effect against radiation was verifed in a small intestine observation experiment, which tested jejunum. The protective effect of stevia leaf powder was also validated by observing the length of the small villi from the small intestines. Finally, histological observation of the spleen showed the protective effect of stevia leaf powder.

In conclusion, stevia leaf powder protects the hematopoietic/immune system (lymphocyte, neutrophil, platelet, red blood cells) of rats from radiation, increases the activity of SOD as an antioxidant enzyme, and decreases the cell damage of the spleen and the small intestines. Therefore, stevia leaf powder can be utilized as a natural radiation protection agent for the human body