Oral toxicity study of kestose, a key prebiotic component of fructooligosaccharide, in Sprague-Dawley rats: A 90-day repeated dose study.

Kestose, a major component of short-chain fructooligosaccharide, is a prebiotic modulating intestinal microbiota and regulating immune functions. No toxicological studies have been reported on repeated-dose oral intake of kestose produced from sucrose via enzymatic epimerization as a single ingredient. This study evaluated the oral toxicity of kestose upon 90-day repeated administration at doses of 1250 (low dose), 2500 (middle dose), and 5000 (high dose) mg/kg body weight each day in Sprague-Dawley rats. It was performed following OECD TG 408. There were no specific clinical signs associated with kestose administration, as determined by clinical observations, ophthalmology, and a functional observational battery. No significant alterations related to kestose administration were detected by hematology, clinical biochemistry, and urinalysis, except that urine specific gravity was higher in the middle and high dose groups than in the vehicle control. This difference was considered to be unrelated to kestose administration because no changes related with kestose administration in clinical biochemistry, gross necropsy, and histopathological observations were detected. No toxicological lesions related to kestose administration were observed upon gross necropsy and histopathological evaluation. Water consumption in males was sporadically increased primarily in the high dose group at various time points. However, kestose administration had no effects on clinical biochemistry parameters and histopathological observations associated with increased water consumption. Under the present experiment, oral administration of kestose for 90 consecutive days does not elicit toxic effects associated with kestose administration at any doses employed. Thus, the no-observed-adverse-effect level is estimated at 5000 mg/kg body weight for both sexes.