Pre-clinical safety assessment of the synthetic human milk, nature-identical, oligosaccharide Lacto-N-neotetraose (LNnT)

•We present the safety data generated on a potential new human milk oligosaccharide.•The HMO in question is Lacto-N-neotetraose (LNnT) produced by chemical synthesis.•LNnT was non-mutagenic in two in vitro assays.•Oral administration to rats over 90days was not associated with any adverse effects.•A No Observed Adverse Effect Level (NOAEL) of 5000mg/kgbw/day was identified. Lacto-N-neotetraose (LNnT) is a tetrasaccharide naturally occurring in human breast milk, but not in cow’s milk. The safety data generated on a potential new LNnT ingredient produced by chemical synthesis is presented. Standard in vitro genotoxicity tests were performed. LNnT was also administered via gavage in 14-, 28- and 90-day studies at levels corresponding to 0 (control), 1000, 2500 and 5000mg/kgbw/day in juvenile rats. Fructooligosaccharide (FOS) currently approved for use in infant formulae was used as a reference control at one dose level of 5000mg/kgbw/day. LNnT was non-mutagenic in in vitro assays. Oral administration up to 5000mg/kgbw/day to rats over 90days was not associated with any adverse effects, based on clinical observations, body weight gain, feed consumption, clinical pathology, organ weights and histopathology findings. Regarding gastrointestinal effects, LNnT was better tolerated than FOS during the first 2weeks of treatment. A No Observed Adverse Effect Level (NOAEL) of 5000mg/kgbw/day for both male and female rats was identified for LNnT when administered by gavage for 90days. These findings in the juvenile rat support the safety of LNnT for possible use in infant foods and allow further investigation in clinical studies.