How the Microbiome Shapes Glycan Expression — and Your Inflammation Profile

Gut bacteria and inflammation are more tightly linked than most people realise, and the connection runs through a molecular signal most of us have never heard of: glycans. The colon hosts a dense, largely stable population of commensal, symbiotic, and pathogenic microorganisms. That balance can shift, and conditions like inflammatory bowel disease show how disruptive an unstable microbiome can become. But the more useful question for someone tracking their own health isn't what disease might develop. It's what your gut bacteria are doing to your inflammation levels right now.

New to the science behind this? Glycans: the sugars that reveal your biological age and immune health breaks down what glycans are and why they matter before we get into how your gut fits into the picture.

A brief look at the gut's microbial environment

The human colon is colonised by billions of bacteria, fungi, and viruses that typically coexist with the body in a stable equilibrium. This equilibrium can be disturbed by disease, such as inflammatory bowel disease, and by environmental factors including diet and antibiotic use. Research has shown that gut microbiota is measurably less stable in people with inflammatory bowel disease than in healthy individuals. That's useful context, but the more actionable story is what happens next: how gut bacteria communicate with the rest of the immune system, and how that communication shows up as measurable inflammation.

From microbial signalling to immune signalling

Gut bacteria don't just sit behind a mucus barrier. They actively shape immune signalling well beyond the gut wall. The mucus layer lining the gastrointestinal tract, built from glycoproteins called mucins, still matters here. Mucins are coated in O-glycans that lubricate the digestive tract, feed resident bacteria, and stop microorganisms from crossing the epithelial barrier and triggering inflammation. But this layer is a checkpoint, not the whole story.

This relationship extends beyond the mucus layer. Plasma N-glycan signatures, including those on antibodies circulating in the bloodstream, have been shown to correlate with clinical features of inflammatory bowel disease, indicating that gut-level inflammation registers as a systemic, measurable signal rather than staying contained to the gut. This bidirectional relationship, gut bacteria shaping local glycan structures and glycan structures in turn shaping the microbial environment, is what makes gut bacteria and inflammation such a tightly coupled system.

"If we change the glycosylation profile at the level of the mucosa, this will consequently have an impact on the microbiota composition."
— Prof. Salomé Pinho, GlycanTrigger Coordinator, i3S, University of Porto

The inflammation profile: what your glycans reveal

Here is where the connection becomes measurable. IgG antibodies carry glycan structures that shift in predictable ways with inflammation. A reduction in galactosylation, the attachment of galactose sugars to IgG glycans, has been studied as a marker of disease activity in inflammatory bowel disease and other inflammatory conditions for decades. A 2026 multi-cohort study of newly diagnosed inflammatory bowel disease patients found that reduced IgG galactosylation was accompanied by consistently accelerated biological aging, as measured by the GlycanAge index, across all cohorts studied. When galactosylation drops, IgG antibodies are more likely to activate inflammatory pathways rather than suppress them.

GlycanAge tracks this pattern through its glycan indexes. The Glycan Mature and Glycan Bisection indexes track pro-inflammatory structures, and elevated levels reflect antibodies that have lost protective sugars. The Glycan Youth and Glycan Shield indexes track anti-inflammatory structures, and higher levels reflect antibodies rich in protective galactose and sialic acid. Together, this glycan expression pattern has been identified as a biomarker of biological age distinct from your chronological age, acting as a dynamic readout of your current inflammatory status.

The invisible impact of your gut on your immune age

Gut bacteria and inflammation interact quietly. You will not feel a shift in microbial diversity or a drop in galactosylation. Fatigue, brain fog, and slower recovery tend to show up only once inflammation has been building for a while.

"Inflammation is the new currency of medicine, and we all need to understand it more."
— Dr. Mohammed Enayat, Founder, HUM2N

This is the practical value of measuring your glycan expression pattern. It reveals the inflammatory consequences of what's happening in your gut before symptoms surface, giving you a concrete number to act on rather than a guess.

Tracking dietary change through your glycan profile

Since gut bacteria and inflammation move together, changes to the microbiome tend to register in your glycan profile too, just not immediately. Diet, fibre intake, and antibiotic use are among the biggest levers on microbial diversity, and our guides on how to reduce gut inflammation and ways to improve gut health cover the specific changes worth prioritising.

The timeline matters when you're tracking results. Lifestyle-based changes, including diet and gut-focused interventions, typically take six to twelve months to produce a measurable shift in glycan structures. Pharmaceutical or more aggressive interventions can show changes in as little as three to four months. Retesting within the right window is what turns a dietary change into a confirmed result instead of a guess.

Measure the invisible impact of your gut on your immune system

Gut bacteria and inflammation leave a signature that finger-prick testing can reveal. GlycanAge measures your glycan expression pattern to show your immune system's biological age, giving you a way to confirm whether the changes you're making to your gut health are actually reducing your inflammatory load. Ready to see your own results? Shop GlycanAge tests to get started.

External sources

• Halfvarson J, Brislawn CJ, Lamendella R, Vazquez-Baeza Y, Walters WA, Bramer LM, et al. Dynamics of the human gut microbiome in inflammatory bowel disease. Nat Microbiol. 2017;2:17004. doi:10.1038/nmicrobiol.2017.4. PMID: 28191884. PMC: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5319707/

• Clerc F, Novokmet M, Dotz V, Reiding KR, de Haan N, Kammeijer GSM, et al. Plasma N-glycan signatures are associated with features of inflammatory bowel diseases. Gastroenterology. 2018;155(3):829-843. doi:10.1053/j.gastro.2018.05.030. PMID: 29792883. Link: https://pubmed.ncbi.nlm.nih.gov/29792883/

• Nakajima S, Iijima H, Shinzaki S, Egawa S, Inoue T, Mukai A, et al. Functional analysis of agalactosyl IgG in inflammatory bowel disease patients. Inflamm Bowel Dis. 2011;17(4):927-936. doi:10.1002/ibd.21459. PMID: 20824817. Link: https://pubmed.ncbi.nlm.nih.gov/20824817/

• Flevaris K, Trbojević-Akmačić I, Goh D, Lalli JS, Vučković F, Ćapin Vilaj M, et al. A multi-cohort study of immunoglobulin G glycans in newly diagnosed inflammatory bowel disease patients reveals accelerated biological aging. medRxiv. 2026. doi:10.64898/2026.04.10.26349930. Link: https://www.medrxiv.org/content/10.64898/2026.04.10.26349930v1

• Krištić J, Vučković F, Menni C, Klarić L, Keser T, Beceheli I, et al. Glycans are a novel biomarker of chronological and biological ages. J Gerontol A Biol Sci Med Sci. 2014;69(7):779-789. doi:10.1093/gerona/glt190. PMID: 24325898. PMC: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4049143/