Metabolic Fate and Distribution of 2′-Fucosyllactose: Direct Influence on Gut Microbial Activity but not on Brain

Scope 2 '-Fucosyllactose (2 ' FL) is an abundant oligosaccharide in human milk. It is hypothesized that its brain enrichment is associated with improved learning. Accumulation of 2 ' FL in organs, biological fluids, and feces is assessed in wild-type and germ-free mice. Methods and results C-13-labelled 2 ' FL is applied to NMRI wild-type mice intravenously (0.2 g kg(-1)) or orally (1 g kg(-1)), while controls receive saline. Biological samples are collected (0.5-15 h) and C-13-enrichment is measured by elemental analysis isotope ratio mass spectrometry (EA-IRMS). After oral application, 2 ' FL is primarily eliminated in the feces. C-13-enrichment in organs including the brain follows the same pattern as in plasma with a maximum peak after 5 h. However, C-13-enrichment is only detected when the C-13-2 ' FL bolus reaches the colon. In contrast, in germ-free mice, the C-13-bolus remains in the intestinal content and is expelled via the feces. Furthermore, intravenously applied C-13-2 ' FL is eliminated via urine; no C-13-enrichment of organs is observed, suggesting that intact 2 ' FL is not retained. Conclusions C-13-enrichment in brain and other organs after oral application of C-13-2 ' FL in wild-type mice indicates cleaved fucose or other gut microbial 2 ' FL metabolites may be incorporated, as opposed to intact 2 ' FL.