Glycans are complex carbohydrates made of sugar units, but unlike simple sugars, they don't act as energy. Instead, they play regulatory roles: coating proteins, cells, and tissues to influence immunity, microbiome composition, and cellular signaling. In essence, they’re not “fuel”, they’re “instructions”.

Glycans are naturally present in whole foods like legumes, whole grains, and some fermented products. However, bioactive glycans like HMOs (human milk oligosaccharides) are unique to breast milk. They're not typical dietary carbohydrates, they're biologically active molecules with targeted effects.

Glycans are carbohydrates, but they often attach to proteins (as glycoproteins) or lipids (as glycolipids). This combination alters how those proteins behave, influencing everything from immune signaling to cell recognition. In the body, this glycan “code” is critical to function.

Glycans, including HMOs, act as selective substrates for beneficial bacteria like Bifidobacteria. They shape early-life microbial colonization, influence immune tolerance, and help block pathogen adhesion. In adults, glycan-based ingredients are growing in their use by food and supplement brands.