Chronic Toxicity Study of Dietary Stevia Extracts in F344 Rats

We fed 0 (control), 0.1, 0.3 and 1% stevia extracts (95.2% purity) to 480 F344 rats for 22 months in the case of males and 24 months in the case of females. At 6 and 12 months, 10 animals of each sex from each group were sacrificed for clinical and pathological tests. The middle dose induced a slight growth retardation in both sexes, but at the high-dose the growth was reduced only transiently. General appearance and behavior were the same in all groups, including the control. Mortality at the end of the study in rats given stevia extracts was not significantly different from that in the controls. At 6 months, a variety of changes were found in the results of urinary, hematological and blood biochemical examinations and in organ weights, but there were no such differences at 12 months or at the end of the experiment. The incidence and severity of non-neoplastic and neoplastic changes were unrelated to the level of stevia extracts in the diet. The highest level of stevia extracts that causes no effects in rats was 550mg/kg, under the conditions of our experiments.