The Gut–Skin Connection: What New Research Says About Eczema

Originally published November 2025 · Updated April 2026 with the January 2026 BMC Microbiology washed microbiota transplantation trial and the December 2025 Pediatric Allergy and Immunology gut-skin axis mechanisms review

New 2025 and 2026 research confirms that eczema isn't just a skin-deep condition. Here's what the gut-skin axis research shows — and what it means practically.

Eczema can feel like a purely skin-level problem — dryness, redness, itch, inflammation, cracked patches. But a growing body of research over the past two years is painting a more complex picture: eczema does not always start with the skin.

For many people, the gut — and the trillions of microbes living inside it — plays a significant role in disease severity, flare frequency, and even the likelihood of developing eczema in the first place. Understanding this connection does not replace standard medical treatment, but it does open a set of practical, evidence-based approaches that can meaningfully support conventional care.

Here is what the latest science actually shows.

TL;DR

• Atopic dermatitis pathogenesis involves a combination of genetic, immune, and microbial factors. An imbalance in skin and gut microbiota — termed dysbiosis — may contribute to disease severity through overgrowth of pathogenic microbes and suppression of healthy commensal bacteria, promoting barrier disruption and pro-inflammatory responses.
• People with eczema consistently show reduced gut microbial diversity, lower levels of Bifidobacterium and Lactobacillus, and higher levels of inflammation-promoting bacteria.
• Early-life gut microbiome patterns predict eczema risk — infants with lower microbial diversity in the first months of life are more likely to develop eczema by age three.
• A 2026 BMC Microbiology trial found that washed microbiota transplantation in 23 patients with moderate-to-severe atopic dermatitis significantly improved disease severity scores, reduced itch, and enriched short-chain fatty acid-producing bacteria in the gut.
• Supporting gut health does not replace medical treatment — but the evidence for it as a complementary approach is now substantially stronger than two years ago.
• Specific dietary and lifestyle habits have good evidence for supporting the gut-skin axis in eczema.

What the Gut-Skin Axis Actually Is

The gut-skin axis describes the bidirectional communication network between the gut microbiome and the skin — a relationship mediated through immune signalling, inflammatory pathways, and metabolic compounds produced by gut bacteria.

The gut-skin axis theory describes a complex bidirectional communication network between the gut and the skin, providing mechanistic insights into the pathogenesis of certain cutaneous diseases. The gut microbiome influences skin health through the regulation of systemic immunity, inflammatory responses and metabolic pathways.

This bidirectionality is important to understand. It is not simply that gut problems cause skin problems. The relationship runs in both directions — disrupted skin barrier function can impair intestinal barrier integrity, and intestinal dysbiosis can worsen skin inflammation. Both systems are connected through shared immune pathways, and disruption in either amplifies disruption in the other.

The primary mediators of this connection are:

Short-chain fatty acids (SCFAs) — produced when gut bacteria ferment dietary fibre. Butyrate, propionate, and acetate have direct anti-inflammatory effects, support the gut barrier, regulate T-cell function, and influence skin keratinocyte differentiation. Microbial metabolites such as short-chain fatty acids and indole derivatives are emerging as critical regulators of skin homeostasis, modulating immune responses and barrier integrity through host receptors.

Systemic immune regulation — the gut microbiome trains and regulates the immune system. In people with eczema, a characteristic immune imbalance — a shift toward Th2-dominant responses — drives the allergic inflammation at the skin. Gut dysbiosis disrupts the Th1/Th2 balance and reduces T-regulatory cell populations that normally dampen excessive immune responses.

Intestinal permeability — a disrupted gut barrier allows bacterial products including lipopolysaccharide to enter systemic circulation, triggering low-grade inflammation that exacerbates skin disease. A 2025 Scientific Reports study of 50 adult atopic dermatitis patients found higher concentrations of leaky gut biomarkers — including Reg3A, I-FABP, IL-10, and IL-22 — in people with eczema compared to healthy controls, and these biomarkers correlated with higher disease activity scores.

What the Microbiome Research Shows

Reduced Diversity in People With Eczema

The most consistent finding across the gut-skin axis research in eczema is reduced gut microbial diversity — fewer different species present, with a less resilient and less functional microbial community.

Several studies have consistently demonstrated that alpha diversity of gut microbiota in atopic dermatitis patients is reduced compared to healthy individuals, indicating a lower contraction in species richness and skewed relative abundance distributions that may impair ecological stability and functional resilience of the microbial community. A cross-sectional study of 172 subjects found that gut microbiota diversity, particularly bifidobacteria, was significantly reduced in eczema patients aged 2 to 3 years compared to healthy controls. Another study revealed a decreased relative abundance of beneficial bacteria, including Bifidobacterium, Lactobacillus, and Faecalibacterium, in the gut microbiota of atopic dermatitis patients compared to healthy controls.

Lower microbial diversity does not cause eczema directly — but it is consistently associated with higher systemic inflammation, increased immune activation, and disrupted skin barrier function. It also means the gut ecosystem is less able to produce the SCFAs and immunomodulatory compounds that normally keep inflammatory responses in check.

Early-Life Gut Patterns and Eczema Risk

One of the most striking recent findings is the predictive relationship between early-life gut microbiome composition and subsequent eczema development.

In a prospective study involving 100 infants, researchers found that infants who developed atopic dermatitis within their first year exhibited lower gut microbiota diversity during the early months of life, with distinct differences in the abundance of specific bacterial taxa compared to infants without atopic dermatitis. Another prospective cohort study found that infants who later developed allergies had lower Bifidobacteria and higher Klebsiella levels at 3 months of age compared to infants who remained healthy. A higher Klebsiella/Bifidobacterium ratio at 3 months was linked to a greater risk of allergic diseases by age 3 years.

This does not mean parents should immediately supplement infants with probiotics — the evidence for that specific intervention is not yet strong enough for universal recommendation. What it does mean is that the gut microbiome's developmental trajectory in early life is meaningfully connected to immune development and atopic disease risk. Factors that support healthy early-life microbial diversity — breastfeeding, vaginal birth where possible, avoiding unnecessary antibiotics in infancy, diverse dietary introduction from six months — are worth supporting on this basis.

The Skin Microbiome: A Second Front

Beyond the gut, the skin itself has its own microbiome. In atopic dermatitis, there is disruption of the skin epithelial barrier and an overgrowth of pathogenic microbes like Staphylococcus aureus alongside reduced abundance of beneficial commensal bacteria.

Staphylococcus aureus colonisation is found in up to 90% of people with atopic dermatitis during flares — compared to approximately 5% of healthy skin. S. aureus produces toxins that directly damage the skin barrier, activate immune cells, and perpetuate the inflammation-barrier disruption cycle.

Importantly, improving the gut microbiome appears to influence the skin microbiome through systemic immune pathways — which is partly why gut-targeted interventions show skin-level effects. The two microbiomes are not independent systems.

The Most Significant Recent Study: Washed Microbiota Transplantation

The most striking recent development in gut-skin axis research for eczema is the application of microbiota transplantation — previously explored mainly for conditions like C. difficile infection — to atopic dermatitis.

A 2026 BMC Microbiology study followed 23 patients with moderate-to-severe atopic dermatitis who received at least two courses of washed microbiota transplantation between 2022 and 2023. The treatment significantly improved SCORAD scores, EASI scores, itch intensity, and dermatology-related quality of life. Gut microbiota analysis showed an increased Gut Microbiome Health Index, a decreased Microbial Dysbiosis Index, and enrichment of short-chain fatty acid-producing bacteria including the Eubacterium coprostanoligenes group.

This is not a widely available treatment — washed microbiota transplantation is a research-stage intervention — but it is among the most direct evidence to date that modulating gut microbiome composition can produce measurable improvements in eczema severity. It validates the gut-skin axis mechanism in a clinical setting rather than simply in observational studies.

What Actually Helps: Evidence-Based Approaches

Diet: The Foundation

Diet is the primary lever for influencing gut microbiome composition, and the evidence for its relevance to eczema is growing.

Dietary fibre and plant diversity — fibre is the substrate for SCFA production by gut bacteria. Higher fibre intake from diverse plant sources supports microbial diversity and SCFA production, both of which are reduced in people with eczema. Aim for 30 different plant foods per week — vegetables, fruits, whole grains, legumes, nuts, seeds, herbs, and spices each count. Even modest increases in plant diversity produce measurable changes in microbiome composition within weeks.

Omega-3 fatty acids — found in oily fish (salmon, mackerel, sardines), walnuts, and flaxseed — support both gut barrier integrity and skin barrier function through their role in cell membrane composition and inflammatory signalling. Two to three portions of oily fish per week, or supplementation at 1 to 2g of combined EPA and DHA daily, is the practical recommendation.

Reduction of ultra-processed foods — UPFs disrupt gut microbiome composition through emulsifiers, artificial sweeteners, and preservatives that alter the gut lining and microbial balance. Gradual reduction — not elimination, but reduction — produces meaningful microbiome benefits over weeks to months.

Fermented foods — yoghurt, kefir, kimchi, sauerkraut, and kombucha introduce live bacteria to the gut and have evidence for improving microbiome diversity. A 2021 Stanford trial found that a high-fermented food diet increased microbiome diversity and reduced inflammatory markers significantly faster than a high-fibre diet alone.

Probiotics: Promising but Strain-Specific

The probiotic evidence for eczema is promising but requires careful interpretation — not all probiotics are equivalent, and the evidence is strain-specific.

For early-stage persistent atopic dermatitis patients, priority can be given to supplementing with probiotics that regulate Th2 inflammation, such as Lactobacillus rhamnosus, to restore gut microbiota balance. Lactobacillus rhamnosus GG is the most studied strain in children with atopic dermatitis, with several trials showing reductions in eczema severity scores. Results in adults are less consistent.

The most honest summary of the probiotic evidence: some strains — particularly Lactobacillus rhamnosus and Bifidobacterium species — show meaningful benefit in some populations, particularly children with mild-to-moderate eczema. The evidence for specific strains in adults is improving but not yet definitive. Multi-strain formulations targeting both Lactobacillus and Bifidobacterium species are generally recommended over single-strain products, and consistent use for at least eight to twelve weeks is needed to assess response.

Skin Barrier Care: Still the Biggest Lever

Despite the compelling gut-skin axis research, skin barrier care remains the most evidence-backed intervention in eczema management and should not be deprioritised in favour of gut-focused approaches.

A disrupted skin barrier drives the inflammatory cascade that leads to flare-ups — and repairing it reduces the immune activation that also disrupts gut microbiome balance, working through the bidirectional relationship in the opposite direction.

Evidence-based skin barrier practices include: ceramide-rich moisturiser applied twice daily including immediately after bathing while skin is still slightly damp, gentle fragrance-free cleansing, short lukewarm showers rather than long hot baths, and avoiding scratching — which perpetuates the itch-scratch cycle and increases S. aureus colonisation.

Sleep and Stress

Sleep deprivation disrupts gut microbiome composition within days — studies have shown measurable changes in bacterial abundance after as little as two nights of poor sleep. Chronic psychological stress increases intestinal permeability and promotes pro-inflammatory immune states that exacerbate eczema.

Both of these create practical entry points: consistent sleep timing and adequate duration directly support the gut-skin axis, as does stress management through whatever means works sustainably — breathwork, exercise, social connection, nature exposure.

FAQ

Is eczema caused by poor gut health?

Not directly — eczema has multiple interacting causes including genetic factors, immune dysregulation, and environmental triggers. But gut microbiome dysbiosis is now consistently associated with both eczema prevalence and severity in the research, and the mechanisms through which gut health influences skin inflammation are well characterised. It is more accurate to say that poor gut health may worsen eczema and that improving it can support management, rather than that it causes eczema in a simple linear sense.

Do probiotics help eczema?

For some people — particularly children with mild-to-moderate atopic dermatitis — certain probiotic strains, particularly Lactobacillus rhamnosus, have shown meaningful reductions in eczema severity scores in clinical trials. The evidence in adults is improving but less definitive. Results depend heavily on the specific strain used, the duration of supplementation, and the individual's microbiome composition. Probiotics are best used as part of a broader gut-supportive approach alongside dietary changes and skin barrier care, not as a standalone treatment.

What foods trigger eczema through the gut?

Ultra-processed foods — through their emulsifiers, artificial additives, and low fibre content — consistently disrupt gut microbiome composition in ways that promote inflammation. Common food allergens including cow's milk protein, eggs, wheat, soy, and peanuts can trigger immune responses in people with food sensitivities that manifest in skin flares. If food-triggered flares are suspected, an elimination diet under dietetic supervision is the appropriate investigation — not self-directed elimination, which risks nutritional deficiency and is often inconclusive.

Can improving gut health reduce eczema flare-ups?

The evidence increasingly suggests yes — through improving SCFA production, reducing intestinal permeability, restoring immune balance, and supporting the skin microbiome through systemic pathways. A 2026 clinical trial of microbiota transplantation in moderate-to-severe eczema showed significant improvements in severity scores and itch. Dietary changes, fermented foods, and appropriate probiotic supplementation are the most accessible gut-targeted interventions, with effects typically emerging over weeks to months of consistent application.

Is there a link between eczema and irritable bowel syndrome?

Yes — people with atopic dermatitis show higher rates of IBS and other inflammatory gut conditions than the general population, reflecting the bidirectional gut-skin relationship. Both conditions involve gut barrier dysfunction and dysregulated immune responses. Addressing gut symptoms in people with eczema — and addressing skin symptoms in people with IBS — through a whole-system approach is increasingly supported by the research.

What is the best diet for eczema?

The most evidence-aligned dietary approach for eczema combines high fibre intake from diverse plant sources, regular consumption of omega-3-rich oily fish, daily fermented foods, and reduction of ultra-processed foods and common dietary triggers. This broadly resembles a Mediterranean dietary pattern, which also has the strongest evidence base for reducing systemic inflammation more generally. Individual food triggers vary — working with a dietitian to identify personal triggers while maintaining nutritional adequacy is the most effective personalised approach.

The Bottom Line

The gut-skin axis in eczema is no longer a fringe theory — it is supported by a growing and increasingly robust body of research, culminating in 2025 and 2026 studies showing that gut microbiome modulation produces measurable improvements in eczema severity. The bidirectional relationship between gut and skin means that supporting one system benefits the other.

The practical takeaway: gut-targeted approaches including dietary fibre diversity, omega-3s, fermented foods, and appropriate probiotic supplementation are evidence-backed complements to conventional eczema treatment. They do not replace emollients, topical steroids, or prescribed medications where these are needed — but they address a dimension of the condition that standard dermatological treatment does not.

For a structured approach to building a gut-supportive diet and lifestyle, the Gut Reset from the Reset Series covers the foundations of microbiome health that are most relevant to the gut-skin connection. The Sleep Reset addresses the sleep-microbiome relationship that directly influences both gut and skin health. For ongoing personalised guidance on applying these principles, the Reset Companion can help you build a sustainable, gut-supportive routine.

Related reading: Fibremaxxing: What It Is, Whether It Works, and How Much Is Too Much · Kimchi: What the 2025 Health Research Actually Shows · Diet, Microbiota and IBS Risk: What the Connection Means

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