Difucosyllactose (DiFL) is a tetrasaccharide formed of lactose, and two fucose units. One fucose is linked to the 3‑position of glucose; one fucose is linked to lactose (Fuc α1‑2 Gal β1‑4 (Fuc α1‑3) Glc) (Kunz et al. 2000). DiFL is one of the most abundant human milk oligosaccharides in human milk with approx. 0.46 g/l (Erney et al. 2000). In combination with 2'-FL, DiFL is approved for addition to infant formulas in the European Union since 2019 (EU/2019/1979).