Toxicological evaluation of 6′-sialyllactose (6'-SL) sodium salt

We performed a series of toxicity studies on the safety of 6′-sialyllactose (6′-SL) sodium salt as a food ingredient. 6′-SL sodium salt, up to a maximum dose of 5000 μg/plate, did not increase the number of revertant colonies in five strains of Salmonella typhimurium in the presence or absence of S9 metabolic activation. A chromosomal aberration assay (using Chinese hamster lung cells) found no clastogenic effects at any concentration of 6′-SL sodium salt in the presence or absence of S9 metabolic activation. An in vivo bone marrow micronucleus test in Kunming mice showed no clastogenic activities with 6′-SL sodium salt doses up to 2000 mg/kg body weight (bw). In an acute toxicity study, the mean lethal dose of 6′-SL sodium salt was greater than 20 g/kg bw in rats. In a 13-week subchronic toxicity investigation, no effects were found at doses up to 5.0 g/kg bw of 6′-SL sodium salt in food consumption, body weight, clinical signs, blood biochemistry and hematology, urinalysis, or ophthalmic and histological macroscopic examination of organs. The no-observed-adverse-effect level (NOAEL) was 5.0 g/kg bw/day in rats.