Toxicological safety evaluation of the human-identical milk oligosaccharide 6'-sialyllactose sodium salt.

Human milk oligosaccharides (HMOs) are abundant in breastmilk, but their presence in infant formula is negligible. Sialylated HMOs, such as 6 '-sialyllactose, constitute a significant portion of the HMO fraction of human milk and are linked to important biological functions. To produce infant formula that is more comparable with human milk, biosynthesized sialyllactoses known as human-identical milk oligosaccharides (structurally identical counterparts to their respective naturally occurring HMOs in breastmilk) are proposed for use in infant formula and other functional foods for the general population. To support the safety of 6 '-sialyllactose sodium salt (6 '-SL), a 90-day oral (gavage) toxicity study and in vitro genotoxicity tests were conducted. The 90-day study is the first to be conducted with 6 '-SL using neonatal rats (day 7 of age at the start of dosing), thus addressing safety of 6 '-SL for consumption by the most sensitive age group (infants). In the 90-day study, neonatal rats received 6 '-SL at doses up to 5000 mg/kg body weight (BW)/day and reference controls received 5000 mg/kg BW/day of fructooligosaccharide (an ingredient approved for use in infant formula) for comparison with the high-dose 6 '-SL group, followed by a 4-week recovery period. There was no evidence of genotoxicity in vitro. No test item-related adverse effects were observed on any parameter in the 90-day study, thus the high dose (5000 mg/kg BW/day) was established as the no-observed-adverse-effect level. These results confirm that 6 '-SL is safe for use in formula milk for infants and in other functional foods for the general population.