Genes, Guts, and Fungi: New Study Reveals How Our DNA Shapes the Gut Mycobiome and Chronic Disease Risk

According to NEWS MEDICAL LIFE SCIENCES

The Overlooked World in Our Guts

We often hear about the gut microbiome — the teeming population of bacteria that shapes digestion, immunity, and even mental health. But nestled alongside those bacteria is a less familiar community of microorganisms: the mycobiome, made up of fungi that quietly inhabit the digestive tract.

For years, this fungal presence was treated as incidental — passive passengers in a bacterial world. But new research is now painting a different picture. Not only does the gut mycobiome play an active role in human health, but it may also be shaped by our genes — and, in turn, linked to the development of chronic diseases.

A landmark study published by researchers from the University of Trento, the European Bioinformatics Institute (EMBL-EBI), and collaborators across multiple institutions has uncovered associations between human genetic variation, gut fungi, and disease markers — ushering in a new chapter in the science of host-microbe interactions.

The Study at a Glance

In the most comprehensive investigation of its kind, scientists analyzed multi-omics data from over 600 healthy individuals in the Dutch Microbiome Project, including:

• Whole-genome sequencing (human genetics)
• Fecal fungal DNA profiling (gut mycobiome composition)
• Dietary data
• Blood biomarkers related to immunity and inflammation

The researchers found that certain human gene variants correlate with the presence or abundance of specific fungal genera in the gut. These genetic–fungal links, in turn, were associated with risk factors for chronic diseases, including:

• Inflammatory Bowel Disease (IBD)
• Type 2 Diabetes
• Allergies and autoimmune disorders
• Elevated inflammatory markers

This multi-dimensional approach — connecting the dots between DNA, fungi, and disease risk — opens up entirely new paths for understanding human health.

Fungal Players in the Gut

Among the fungi highlighted in the study were genera such as:

• Candida (including Candida albicans) – known for both its commensal and pathogenic roles
• Saccharomyces – used in fermentation but also present in human intestines
• Malassezia – more often associated with the skin, but increasingly found in the gut
• Debaryomyces and Pichia – yeast species that may influence gut metabolism

These fungi are not always harmful. In fact, in healthy individuals, they may play roles in nutrient processing, immune training, and competition with pathogens. However, imbalances — or dysbiosis — in the mycobiome have been linked to gut inflammation and systemic disease.

Genes and Fungi: The Hidden Dialogue

The study identified specific human genetic variants that were associated with the abundance of gut fungi. Notably:

• Variants near the TLR genes (Toll-like receptors), which are involved in immune system recognition of microbes, correlated with fungal diversity.
• Genes related to intestinal barrier function influenced the abundance of Candida.
• Variants in HLA regions, key for immune response, were linked to differential fungal colonization.

This suggests that our innate immunity and mucosal defense mechanisms — determined in part by our genes — help shape which fungi thrive inside us.

More intriguingly, certain combinations of human and fungal genetic markers were associated with blood biomarkers related to chronic inflammation — offering early clues about how fungi might contribute to, or result from, disease processes.

Beyond Bacteria: A Paradigm Shift

The human microbiome field has been dominated by bacteria-focused research for the past two decades. But this study reinforces what many microbiologists have long suspected: fungi are not just side characters in the microbiome story — they are key actors, especially in immune-modulated diseases.

One reason fungi have been overlooked is their lower abundance in the gut compared to bacteria. But what they lack in numbers, they may make up for in potency. Fungal cells are structurally complex, contain immunogenic components like β-glucans, and interact with both host tissue and other microbes in unique ways.

The fact that human genetics shape these fungal populations — and that this relationship connects to disease — demands a new, multi-kingdom approach to microbiome science.

Chronic Disease Connections

The implications of the study touch on several key conditions:

• Inflammatory Bowel Disease (IBD): Variants linked to fungal colonization overlapped with genes known to predispose individuals to IBD. Certain fungi may aggravate gut inflammation in genetically susceptible individuals.
• Metabolic Disease: A higher abundance of Candida and Saccharomyces species was associated with insulin resistance and pro-inflammatory markers, suggesting a potential role in type 2 diabetes risk.
• Allergies and Autoimmunity: The study supports previous findings that fungal exposure shapes immune tolerance — and that genetic variation determines who reacts pathologically.

This aligns with emerging research that the mycobiome may influence the onset and severity of immune disorders, particularly when early-life exposures or antibiotics disrupt fungal–host equilibrium.

Personalized Medicine and the Mycobiome

One of the most promising aspects of this research is its relevance to personalized health.

By mapping the interaction between host genetics and gut fungi, researchers are laying the groundwork for:

• Predictive models for disease susceptibility
• Customized microbiome therapies that consider not just bacteria but fungi
• Targeted dietary interventions to support beneficial fungal populations
• New antifungal or probiotic treatments for chronic inflammation

As sequencing becomes cheaper and more accessible, integrating fungal profiling into routine microbiome analysis could help clinicians offer more tailored advice — especially for individuals with autoimmune or metabolic conditions.

Open Questions and Future Directions

While this study is a milestone, it also raises many important questions:

• What drives fungal colonization in early life — birth mode, breastfeeding, antibiotics, or diet?
• How stable is the mycobiome over time, and how does it change with age or illness?
• Can mycobiome-targeted therapies — such as yeast probiotics or antifungals — meaningfully alter disease progression?

The research team hopes to expand their work into longitudinal studies, looking at how gene-fungus interactions evolve over time and whether interventions can shift health outcomes.

The Takeaway: A New Era of Gut Science

This groundbreaking research offers a clear message: to fully understand human health, we must look not just at bacteria or genes in isolation, but at their complex interplay with the fungal world inside us.

The gut mycobiome, once considered an afterthought, may be a critical player in disease development, immune balance, and even therapeutic success.

For scientists, it means embracing a multi-omics, multi-kingdom approach. For clinicians, it may soon mean adjusting how we assess and manage chronic conditions. And for all of us — it’s a reminder that the ecosystems inside us are far more intricate, intelligent, and interconnected than we ever imagined.

References

University of Trento.

European Bioinformatics Institute (EMBL-EBI).

According to NEWS MEDICAL LIFE SCIENCES

Frequently Asked Questions

What is the gut mycobiome and why does it matter for health?

The gut mycobiome refers to the community of fungi inhabiting the human gastrointestinal tract. While fungi constitute less than 0.1% of gut microbial cells (vastly outnumbered by bacteria), they are not inert passengers—they interact with the host immune system, with bacteria and other microorganisms, and with the intestinal epithelium in ways that can significantly influence health and disease. The gut mycobiome has been implicated in inflammatory bowel diseases (IBD), colorectal cancer risk, type 2 diabetes, asthma, and food allergies—predominantly through its effects on intestinal immune regulation. Research in this field has been enabled by DNA metabarcoding of stool samples using fungal ITS (internal transcribed spacer) sequencing, which can characterise the full mycobiome community from a non-invasive sample.

How does host genetics shape the gut mycobiome?

Genome-wide association studies (GWAS) of gut mycobiome composition have identified several human genomic regions associated with mycobiome variability. Genes in the pattern recognition receptor family—particularly CARD9, Dectin-1 (CLEC7A), and FUT2—affect how effectively the host immune system recognises and responds to fungal cell wall components, influencing which fungi can colonise and persist in the gut. FUT2 status (fucosyltransferase 2, which affects mucus layer composition) influences the carbohydrate substrates available for fungal attachment and fermentation. CD44 and other immune regulatory genes affect fungal colonisation resistance. The twin studies estimating 30–40% heritability of gut mycobiome composition use both identical and fraternal twin pairs to partition variance into genetic, shared environmental, and unique environmental components.

What role does the gut mycobiome play in inflammatory bowel disease?

Research has identified specific gut mycobiome changes associated with Crohn’s disease and ulcerative colitis. Patients with Crohn’s disease show elevated ratios of Candida tropicalis and Saccharomyces cerevisiae compared to healthy controls, along with reduced diversity of other fungal genera. The Sartor laboratory at UNC Chapel Hill demonstrated that C. tropicalis combined with Escherichia coli and Serratia marcescens forms a polymicrobial biofilm on gut mucosal surfaces that induces sustained intestinal inflammation in mouse models—a potential mechanism for driving Crohn’s pathogenesis. Anti-Saccharomyces cerevisiae antibodies (ASCA) are a clinical biomarker used in IBD diagnosis, reflecting altered immune response to gut fungi. Antifungal treatment has shown benefit in some Crohn’s disease trials, though evidence for routine antifungal use in IBD is not yet sufficient for standard clinical recommendation.

How does diet influence the gut mycobiome?

Diet is among the most powerful modifiers of gut mycobiome composition that can be influenced at individual level. Refined carbohydrates and simple sugars provide fermentable substrate for Candida species, and high-sugar diets consistently associate with Candida abundance in gut studies. Dietary fibre supports bacteria that competitively suppress fungal overgrowth; high-fibre diets are associated with lower gut Candida and higher mycobiome diversity in population studies. Fermented food consumption introduces live fungi (Saccharomyces cerevisiae from bread and beer; various non-Saccharomyces yeasts from traditional fermented foods) and bacteria (Lactobacillus, Bifidobacterium) that compete with and regulate existing gut fungi. A Stanford University study showed that a high-fermented food diet for 10 weeks measurably increased gut microbiome diversity and reduced inflammatory markers compared to a high-fibre diet.

Can you improve your gut mycobiome and how would you know if it’s unhealthy?

Practical strategies to support a healthy gut mycobiome include: maintaining dietary diversity with plenty of vegetables, legumes, and whole grains; incorporating fermented foods (yogurt, kefir, kimchi, sauerkraut, kombucha); moderating refined sugar and highly processed food intake; using antibiotics only when medically necessary (antibiotic courses reliably disturb gut mycobiome balance and can trigger Candida overgrowth); and managing stress (gut microbiome composition is sensitive to psychological stress). Consumer gut mycobiome testing is available through companies including Viome, Thryve, and others, though the clinical interpretation of results is still limited by incomplete understanding of what constitutes an ‘optimal’ mycobiome. Symptoms that may indicate mycobiome disruption include persistent digestive discomfort, recurrent vaginal or oral Candida infections, and skin conditions associated with gut dysbiosis.