2′-Fucosyllactose (2′-FL) is a fucosylated neutral trisaccharide composed of L-fucose, D-galactose, and D-glucose units.

It is the most prevalent human milk oligosaccharide (HMO) naturally present in human breast milk, making up about 30% of all of HMOs.

[3][4][5][6] As with many other oligosaccharides, a characteristic of 2′-FL is its ability to protect against infectious diseases[7] by preventing epithelial-level adhesion of toxins and pathogens.

[8] 2′-FL stimulates the growth of certain bifidobacteria and upregulation of receptors[citation needed] which collectively lend to toxic and pathogenic protection;[citation needed] this is most prevalent in infants.

Among the pathogens that 2′-FL is known to protect against are Campylobacter jejuni, Salmonella enterica (serotype Typhimurium), and Helicobacter pylori.