2'-Fucosyllactose

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2'-Fucosyllactose (2'-FL)

What it is
2'-FL is a small sugar made of three units: L-fucose, D-galactose, and D-glucose. It is a fucosylated neutral trisaccharide and is the most common human milk oligosaccharide (HMO) found in breast milk, making up about 30% of HMOs. It helps give breast milk its unique health benefits.

Structure in simple terms
2'-FL is built from a fucose sugar attached to a galactose sugar, which is attached to a glucose sugar. The bonds create a specific arrangement (α and β configurations) that helps determine how it behaves in the body.

Where it comes from
- In human milk: 2'-FL occurs naturally and is abundant in breast milk.
- In the lab: scientists can produce 2'-FL in large amounts using engineered bacteria (such as E. coli) for research and potential use in products.

How it is processed by the body
Humans do not digest 2'-FL in the upper gut. Instead, it travels to the colon mostly intact, where gut bacteria break it down. Bacteria such as Bifidobacterium and Akkermansia release enzymes to cut off the fucose part and further break down the remaining sugars. This microbial processing can lead to the production of substances like short-chain fatty acids (for example, acetate and butyrate) that can benefit the gut environment.

What it does (uses and health effects)
- Supports gut health: by acting as a prebiotic, it encourages beneficial bacteria to grow.
- Protects against infections: 2'-FL can help prevent certain pathogens from sticking to gut cells, reducing the risk of infections.
- Reduces pathogen impact: it is associated with protection against bacteria such as Campylobacter jejuni, Salmonella (Typhimurium), and Helicobacter pylori.
- Infant formula: because of its beneficial properties, 2'-FL is sometimes added to infant formulas to better resemble the natural components of breast milk.

In short, 2'-FL is a key, naturally occurring sugar in human milk that supports infant gut health and infection protection, while also being producible for research and potential use in baby formula and other products.