Microbiome and Psoriasis: The Gut-Skin Connection

Psoriasis is widely understood as an immune-driven skin condition, but a growing body of research points to an unexpected participant: the trillions of microbes living in and on your body. The relationship between the microbiome and psoriasis is now one of the most actively studied areas in dermatology and immunology, with evidence suggesting that gut bacteria, skin microbes, and their metabolic byproducts may influence the inflammation that drives this condition. In this article, you'll learn how the gut-skin axis works, what studies have found in people with psoriasis, how treatments like probiotics and biologics interact with the microbiome, and what this emerging science could mean for your daily life.

Understanding the Microbiome and Psoriasis Connection

The human microbiome is the vast community of bacteria, fungi, viruses, and other microorganisms that live primarily in the gut, but also on the skin, in the mouth, and elsewhere. Far from being passive passengers, these microbes play an active role in training the immune system, producing vitamins and signaling molecules, and maintaining the barriers that separate your body from the outside world.

Psoriasis is a chronic inflammatory condition characterized by accelerated skin cell turnover, resulting in red, scaly, often itchy plaques. It affects roughly 2–3% of people globally and is now understood to be an immune-mediated disease rather than simply a skin problem. Key immune players, particularly T cells and inflammatory signaling molecules like interleukin-17 (IL-17) and interleukin-23 (IL-23), drive the visible changes in the skin as well as systemic inflammation that can affect joints and cardiovascular health.

What Is the Gut-Skin Axis?

The gut-skin axis is the term researchers use to describe the bidirectional communication between the gastrointestinal tract and the skin. This communication happens through several channels: immune cells that circulate between gut and skin, microbial metabolites absorbed into the bloodstream, the nervous system, and hormones. The concept helps explain why gut health and skin health so often change together, and why people with psoriasis show higher rates of gastrointestinal conditions such as Crohn's disease, celiac disease, and non-celiac gluten sensitivity.

Dysbiosis: When the Microbial Balance Breaks Down

A healthy microbiome is diverse, resilient, and dominated by bacteria that support immune tolerance. Gut dysbiosis describes a state in which this balance is disrupted, often marked by reduced diversity, a loss of beneficial bacteria that produce anti-inflammatory compounds, and an overgrowth of microbes that promote inflammation. In the context of psoriasis, dysbiosis is thought to contribute to the low-grade systemic inflammation and overactive immune responses that characterize the disease. It's important to note, however, that most evidence in this area is associative. Studies can show that dysbiosis and psoriasis occur together, but proving that one causes the other is far more difficult, and researchers are still working to untangle directionality.

Why the Immune System Sits at the Center

A large proportion of the body's immune cells reside in and around the gut. Gut microbes constantly interact with these cells, helping to educate them about which threats to respond to and which to tolerate. When this education is disrupted by dysbiosis, the immune system may become more prone to inappropriate activation, a hallmark of psoriasis. This framework, known as the "old friends" or hygiene hypothesis in its broader form, underpins much of the scientific interest in microbiome-based approaches to inflammatory disease.

Ontdek de microbioom test

ISO-gecertificeerd EU-laboratorium • Monster blijft stabiel tijdens verzending • GDPR-veilige gegevens

Microbioom test kit

The Gut Microbiome: Key Differences in Psoriasis Patients

Research comparing the gut microbiomes of people with psoriasis to those of healthy controls has revealed several recurring patterns, though findings vary between studies due to differences in study design, populations, sequencing methods, and disease severity.

Changes at the Phylum Level: Firmicutes and Bacteroidetes

The two most abundant bacterial phyla in the human gut are Firmicutes and Bacteroidetes. Systematic reviews of psoriasis microbiome studies have reported a general pattern of increased Firmicutes and decreased Bacteroidetes in people with psoriasis compared to healthy individuals. This shift is notable because different phyla produce different metabolites and interact with the immune system in distinct ways. However, individual studies do not always agree, and some report no significant difference at this level, which highlights the heterogeneity in this research area.

Genus-Level Findings: Akkermansia and Phocaeicola

Two genera have received particular attention in recent research:

• Akkermansia muciniphila: This bacterium degrades the mucus layer lining the gut and has been associated with metabolic health and immune regulation. Findings in psoriasis have been inconsistent, with some studies reporting reduced levels and others finding increased abundance, possibly related to disease activity or treatment status.
• Phocaeicola: A newer area of interest, some research has identified lower levels of Phocaeicola, a butyrate-producing bacterium, in people with psoriasis. Because butyrate is a short-chain fatty acid with well-documented anti-inflammatory properties, reduced Phocaeicola levels could theoretically contribute to a more pro-inflammatory gut environment.

Fungal Dysbiosis: The Role of Candida

Most microbiome research has focused on bacteria, but fungi also matter. Several studies have found elevated levels of Candida species in the gut of people with psoriasis. Because Candida can activate immune pathways relevant to psoriasis, including those involving IL-17, some researchers have proposed that fungal overgrowth may contribute to disease activity, although this remains an emerging and debated area.

Microbiome Diversity and Disease Severity

Researchers assess microbiome patterns using measures such as alpha diversity (the number and variety of species within one person's microbiome) and beta diversity (how different one person's microbiome is from another's). Some studies in psoriasis have found reduced alpha diversity, and some have observed correlations between microbial composition and disease severity scores such as the PASI (Psoriasis Area and Severity Index). However, these correlations are not consistent across all studies, and a lower score does not necessarily mean more severe disease in every individual.

Bekijk voorbeeldaanbevelingen van het InnerBuddies-platform

Bekijk alvast de aanbevelingen voor voeding, supplementen, het voedingsdagboek en recepten die InnerBuddies kan genereren op basis van je darmmicrobioomtest

Bekijk voorbeeld aanbevelingen

Limitations of Current Research

It's worth pausing here to note some important caveats. Much of the existing research is cross-sectional, meaning it captures a single moment in time and cannot establish cause and effect. Sample sizes are often small, sequencing techniques vary, and confounding factors such as diet, medications, body weight, and geography can influence microbiome results. These limitations don't diminish the significance of the findings, but they do mean conclusions should be interpreted cautiously.

The Skin Microbiome's Role in Psoriasis

While gut-focused research dominates the conversation, the skin itself hosts a distinct microbiome that plays a direct role in local immune responses and barrier function.

How the Skin Microbiome Differs in Psoriasis

Studies of lesional skin (areas with plaques) in people with psoriasis have found notable differences compared to healthy skin. Commonly reported changes include shifts in the relative abundance of bacteria such as Cutibacterium acnes and various Staphylococcus species. Interestingly, some research suggests that the microbiome of non-lesional skin in psoriasis patients may also differ from that of healthy controls, indicating that microbial changes extend beyond visible plaques.

Skin Barrier Function and Antimicrobial Peptides

In psoriasis, the skin barrier is structurally and functionally altered. Immune-driven inflammation disrupts normal skin cell maturation, which affects the skin's ability to retain moisture and resist microbial invasion. In response, the skin produces antimicrobial peptides such as cathelicidins and beta-defensins, which help control microbial overgrowth but can also amplify inflammation. This creates a feedback loop in which barrier damage, immune activation, and microbial changes reinforce one another.

Local Microbial Interactions and Flare-Ups

Some evidence suggests that the composition of the skin microbiome may influence the severity or behavior of psoriatic lesions. For example, certain Staphylococcus species have been associated with more pronounced inflammation in some studies. However, like gut microbiome research, this field is young, and most findings are associative rather than causal. What is clear is that the skin microbiome is not merely a passive bystander but an active participant in the local immune environment.

Mechanisms: How Gut Microbes Influence Skin Inflammation

Understanding how changes in gut microbes could affect skin inflammation requires looking at the specific biological pathways involved.

Short-Chain Fatty Acids and Immune Regulation

When gut bacteria ferment dietary fiber, they produce short-chain fatty acids (SCFAs), including acetate, propionate, and butyrate. SCFAs have several immune-relevant effects: they help maintain the integrity of the gut lining, support the development and function of regulatory T cells (Tregs), and can dampen inflammatory signaling. Butyrate, in particular, has been studied for its ability to reduce the production of pro-inflammatory molecules, including IL-17, which plays a central role in psoriasis pathogenesis. A microbiome with fewer SCFA-producing bacteria, as has been observed in some psoriasis studies, could theoretically result in a less anti-inflammatory gut environment.

Intestinal Permeability ("Leaky Gut")

The intestinal lining acts as a selective barrier, allowing nutrients to pass through while keeping bacteria and their components contained. Dysbiosis and certain dietary patterns may increase intestinal permeability, sometimes referred to as "leaky gut," allowing bacterial components such as lipopolysaccharide (LPS) to enter the bloodstream. Once in circulation, these components can activate immune cells and contribute to the systemic inflammation seen in psoriasis. While increased intestinal permeability has been observed in some people with psoriasis, its precise role and reversibility remain areas of active investigation.

Immune Cell Trafficking Between Gut and Skin

Immune cells activated in gut-associated lymphoid tissue can circulate and, in some cases, home to other tissues including the skin. This concept, known as the gut-lymphocyte axis, provides a plausible route by which gut-derived immune signals could influence skin inflammation. Some researchers have proposed that this pathway may help explain the overlap between psoriasis and inflammatory bowel disease.

In summary: the gut microbiome may influence psoriasis through SCFA-mediated immune regulation, intestinal barrier integrity, and immune cell trafficking. These mechanisms are biologically plausible and supported by animal and early human studies, but direct causal evidence in humans is still developing.

The Impact of Psoriasis Treatments on the Microbiome

An intriguing question in this field is whether psoriasis treatments themselves affect the microbiome, and if so, whether these changes contribute to how well treatments work.

2-minuten zelfcheck Is een darmmicrobioomtest nuttig voor jou? Beantwoord een paar korte vragen en ontdek of een microbioomtest echt nuttig is voor jou. ✔ Duurt slechts 2 minuten ✔ Gebaseerd op je klachten & leefstijl ✔ Duidelijke ja/nee aanbeveling Check of een test bij mij past →

Biologics and Microbiome Changes

Research on biologic therapies, including IL-17 inhibitors such as secukinumab, has found that successful treatment is associated with shifts in gut microbiome composition. Some studies have observed that as psoriasis improves clinically, the gut microbiome becomes more similar to that of healthy controls, with increases in bacteria associated with anti-inflammatory activity. Secukinumab, which targets IL-17A, has been the subject of several such studies.

Mechanism or Side Effect?

A key question is whether microbiome changes are part of how these treatments work, or simply a downstream consequence of reduced inflammation. Some evidence suggests that microbiome recovery may lag behind clinical improvement, which raises the possibility that inflammation itself shapes microbial composition rather than the reverse. Alternatively, treatment-induced microbiome changes could feed back to support sustained remission. Currently, the evidence doesn't allow a definitive answer, and this remains an active area of research.

Other Treatments and Microbiome Effects

Traditional systemic treatments such as methotrexate may also influence the gut microbiome, though research in this area is less extensive. Some studies in other contexts have found that methotrexate can alter gut bacterial composition, raising questions about whether microbiome changes contribute to some of its effects, including gastrointestinal side effects. More research is needed to understand these interactions fully.

Can Diet and Probiotics Help?

Given the connections between gut microbes and psoriasis-related inflammation, it's natural to wonder whether dietary strategies and probiotics could make a difference. Here's what the current evidence suggests.

The Evidence for Probiotics

A 2024 systematic review of probiotic interventions in psoriasis found promising, though not conclusive, results. Probiotics were associated with significant improvements in clinical measures of psoriasis severity, including a higher proportion of patients achieving clinically meaningful responses such as PASI75. Interestingly, however, the same review noted that probiotics did not significantly change overall microbiota composition in the studies analyzed. This disconnect, clinical improvement without major microbial shifts, suggests that probiotics may work through other mechanisms, such as modulating immune signaling or gut barrier function, rather than by permanently reshaping the microbiome. It also underscores that "probiotics help" and "probiotics change your microbiome" are not the same claim.

Strain specificity matters as well. Different probiotic strains have different properties, and results from one strain cannot be generalized to all. Study quality in this area is variable, with many trials being small and short in duration.

Dietary Patterns That Support a Healthier Gut Microbiome

Diet is one of the most significant factors influencing the gut microbiome. While no diet has been proven to treat psoriasis, research on gut health and inflammation suggests that certain patterns may be beneficial as complementary strategies:

• Fiber-rich foods: Vegetables, fruits, legumes, and whole grains provide the substrate gut bacteria need to produce SCFAs like butyrate.
• Fermented foods: Yogurt, kefir, sauerkraut, and other fermented foods introduce live microbes and may support microbiome diversity.
• Omega-3 fatty acids: Found in fatty fish and some plant sources, omega-3s have documented anti-inflammatory properties and may positively influence the gut microbiome.
• Limiting ultra-processed foods: Diets high in processed foods, added sugars, and unhealthy fats have been associated with dysbiosis and increased inflammatory markers.

Some people with psoriasis report that specific dietary changes, such as reducing gluten or alcohol, seem to help their symptoms, particularly if they have underlying gluten sensitivity. However, individual responses vary considerably, and large, high-quality dietary intervention trials in psoriasis remain limited. Any significant dietary change should ideally be discussed with a healthcare provider or registered dietitian.

Prebiotics and What They Offer

Prebiotics are compounds, typically certain types of fiber, that selectively feed beneficial gut bacteria. Unlike probiotics, which introduce live organisms, prebiotics work by nourishing the microbes already present. Prebiotic fibers such as inulin and resistant starch have been shown to increase SCFA production in research settings. Their specific role in psoriasis has not been well studied, but they represent a plausible supportive strategy within a broader gut-healthy eating pattern.

Does Drinking Water Help Psoriasis?

This is a common question, and the honest answer is that there is no direct evidence that water intake treats psoriasis. Staying adequately hydrated supports skin barrier function and overall health, but hydration alone is unlikely to meaningfully alter the immune processes driving psoriasis. It's a reasonable healthy habit, but not a substitute for medical treatment.

Future Directions in Microbiome-Based Psoriasis Therapies

The growing recognition of the microbiome's role in psoriasis is fueling research into new therapeutic approaches.

Word lid van de InnerBuddies-community

Voer elke paar maanden een darmmicrobioomtest uit en volg je vooruitgang terwijl je onze aanbevelingen opvolgt

Neem een ​​InnerBuddies-lidmaatschap

Fecal Microbiota Transplantation (FMT)

FMT, the transfer of processed stool from a healthy donor to a recipient, is an established treatment for recurrent C. difficile infection and is being explored for other conditions. A small number of case reports and early studies have examined FMT in psoriasis and psoriatic arthritis, with some reports of improvement. However, evidence remains limited to small studies and individual cases, and larger controlled trials are needed. FMT also carries safety considerations, including infection risk, and is not currently an approved treatment for psoriasis.

Next-Generation Probiotics and Targeted Strains

Researchers are working toward "next-generation" probiotics designed to address specific microbial deficits. If reduced Phocaeicola or other butyrate-producing bacteria prove to be consistent features of psoriasis dysbiosis, targeted supplementation with such strains could become a more precise intervention. This approach remains largely experimental, as live biotherapeutic products must clear substantial regulatory and safety hurdles.

Personalized Microbiome Medicine

Perhaps the most promising long-term direction is personalization. Microbiome composition varies significantly between individuals, influenced by genetics, diet, environment, and life history. In the future, microbiome profiles could potentially help predict treatment responses or guide tailored interventions. Tools like microbiome testing already allow individuals to gain a snapshot of their own gut microbial composition, which can be a useful starting point for understanding personal patterns, though such tests are educational rather than diagnostic.

Practical Takeaways and How to Discuss With Your Doctor

So what does all of this mean if you're living with psoriasis? Here are practical, evidence-informed considerations.

Questions to Bring to Your Healthcare Provider

If you're curious about the microbiome's role in your psoriasis, consider asking your dermatologist or primary care provider:

• Are there dietary changes that might support my overall treatment plan?
• Is there any evidence for probiotics in my specific situation?
• Could any of my current medications be affecting my gut health?
• Do I have symptoms that suggest an accompanying gastrointestinal issue worth evaluating?

A Holistic Approach to Psoriasis Management

While microbiome research is exciting, it's important to keep it in perspective. Psoriasis is a complex condition influenced by genetics, immune function, environment, stress, sleep, diet, and other factors. A holistic approach, one that combines prescribed medical treatments with healthy lifestyle habits like a fiber-rich diet, regular physical activity, stress management, and adequate sleep, offers the best foundation. The microbiome may be one meaningful piece of this puzzle, but it is not the only piece, and dietary or supplement-based strategies should complement, not replace, medical care.

Why Measuring Beats Guessing

Because microbiome composition varies widely from person to person, general recommendations about gut health may not reflect your individual situation. Symptoms alone also provide incomplete information; two people with similar skin symptoms may have very different underlying microbial and immune patterns. Understanding your own gut microbiome through testing, such as an at-home gut microbiome test, can offer personalized insight into which bacteria are abundant or scarce in your gut. This kind of information doesn't diagnose psoriasis or any other condition, but it can help you and your healthcare providers make more informed decisions about diet and lifestyle strategies. If you're curious what your gut microbial landscape looks like, you can learn more about personalized microbiome analysis and what the results can and cannot tell you.

Key Takeaways

• Psoriasis is an immune-mediated condition, and research increasingly points to the gut-skin axis as a pathway through which gut microbes may influence skin inflammation.
• Studies have found patterns of gut dysbiosis in psoriasis, including reduced Bacteroidetes, increased Firmicutes, lower levels of the butyrate-producing genus Phocaeicola, and inconsistent findings for Akkermansia.
• Fungal changes, particularly elevated Candida, have been reported in some people with psoriasis.
• Short-chain fatty acids like butyrate may help regulate immune responses relevant to psoriasis, including Treg function and IL-17 signaling.
• The skin microbiome also differs in psoriasis, with reported changes in bacteria such as Cutibacterium acnes and Staphylococcus, and may participate in local inflammation and barrier disruption.
• A 2024 systematic review found that probiotics were associated with improved psoriasis severity, but did not significantly change overall microbiome composition, suggesting effects may work through other mechanisms.
• Biologic treatments like secukinumab are associated with microbiome changes, though whether these changes are a cause or consequence of clinical improvement remains unclear.
• A fiber-rich diet with fermented foods supports SCFA-producing bacteria and is a reasonable complementary strategy, though no diet has been proven to treat psoriasis.
• Emerging therapies such as FMT and targeted next-generation probiotics show promise but remain experimental.
• Most microbiome evidence is associative, and individual variation means personal testing may provide more relevant context than general assumptions.

Frequently Asked Questions

What is the gut-skin axis in psoriasis?

The gut-skin axis is the proposed communication pathway through which signals from the gut microbiome influence skin health and immunity. In psoriasis, gut dysbiosis is thought to contribute to systemic inflammation that may drive or worsen flare-ups. Key players include short-chain fatty acids that support immune regulation and the integrity of the gut lining, which can affect how much bacterial material enters circulation.

Are there specific gut bacteria linked to psoriasis?

Yes, several recurring patterns have been reported. Systematic reviews indicate decreased Bacteroidetes and increased Firmicutes in people with psoriasis. Recent research has also highlighted lower levels of Phocaeicola, a butyrate-producing bacterium, and inconsistent findings for Akkermansia muciniphila. Additionally, some studies have found higher levels of the fungus Candida in people with psoriasis.

How do probiotics affect psoriasis?

The evidence is promising but not conclusive. A 2024 systematic review found that probiotics were associated with significant improvement in psoriasis severity, including a higher proportion of patients achieving clinically meaningful response thresholds. Notably, the same review found that probiotics did not significantly change overall microbiota composition, suggesting their benefit may come from immune or barrier effects rather than lasting microbial shifts.

Can changing your diet improve your gut microbiome and psoriasis?

Potentially, yes. Diet is one of the biggest drivers of gut microbiome composition, and a diet rich in fiber, fruits, vegetables, and fermented foods can promote beneficial bacteria that produce anti-inflammatory SCFAs like butyrate. This could theoretically help modulate the inflammation associated with psoriasis. However, diet should be viewed as a complementary strategy alongside medical treatment, and a direct causal link has not been established.

2-minuten zelfcheck Is een darmmicrobioomtest nuttig voor jou? Beantwoord een paar korte vragen en ontdek of een microbioomtest echt nuttig is voor jou. ✔ Duurt slechts 2 minuten ✔ Gebaseerd op je klachten & leefstijl ✔ Duidelijke ja/nee aanbeveling Check of een test bij mij past →

Is psoriasis caused by an unhealthy gut?

No. Psoriasis is a complex immune-mediated condition with strong genetic components, and gut dysbiosis is best viewed as one of many potential contributing factors rather than the sole cause. Many people with dysbiosis never develop psoriasis, and many people with psoriasis may have relatively typical gut microbiomes. The relationship is likely bidirectional and influenced by genetics, environment, and lifestyle.

Does drinking more water help psoriasis?

There is no direct evidence that water intake treats psoriasis. Adequate hydration supports general health and skin barrier function, which may help skin feel and look better, but it won't change the underlying immune processes driving the condition. It remains a sensible healthy habit, but not a treatment on its own.

Can gut issues make psoriasis worse?

There is a well-documented association between psoriasis and gastrointestinal conditions such as Crohn's disease and celiac disease, and some people with psoriasis report symptom changes related to gut health. The mechanisms may involve shared inflammatory pathways and the gut-skin axis. If you have significant digestive symptoms alongside psoriasis, it's worth discussing with your healthcare provider, as coexisting conditions may need their own evaluation.

What foods should I avoid if I have psoriasis?

There is no single "psoriasis diet," and individual triggers vary widely. Some research and patient reports suggest that alcohol, highly processed foods, and, for a subset of people with gluten sensitivity, gluten-containing foods may worsen symptoms. Rather than eliminating many foods at once, it's generally more sustainable to focus on an overall anti-inflammatory, fiber-rich eating pattern and to discuss any major changes with a healthcare provider or dietitian.

Do biologics change the gut microbiome?

Yes, research has found that biologic treatments, including IL-17 inhibitors like secukinumab, are associated with shifts in gut microbiome composition, often moving toward a pattern more similar to healthy controls. Whether these changes contribute to treatment efficacy or are simply a consequence of reduced inflammation is not yet clear. Some evidence suggests microbiome recovery may lag behind clinical improvement.

What is a PASI score and why does it matter in microbiome research?

PASI stands for Psoriasis Area and Severity Index, a standardized measure doctors use to quantify psoriasis severity based on plaque extent, redness, thickness, and scaling. In microbiome research, PASI scores allow researchers to explore whether microbial patterns correlate with disease severity. Some studies have found such correlations, though findings are not consistent across all research.

Can a gut microbiome test help with psoriasis?

A microbiome test can provide a personalized snapshot of the bacteria in your gut, which may offer useful context for understanding your overall gut health and guiding dietary discussions. However, microbiome testing is not a diagnostic tool for psoriasis or any other disease, and results should be interpreted alongside professional medical advice rather than as a substitute for it.

Is fecal microbiota transplantation a treatment for psoriasis?

Not currently. While a small number of case reports and early studies have described psoriasis improvement after FMT, the evidence is too limited to support its use, and FMT carries safety risks including infection. Larger controlled trials would be needed before FMT could be considered an established psoriasis therapy. It remains an area of active research interest.

Conclusion

The science of the microbiome and psoriasis reveals a compelling picture: psoriasis is not merely a skin condition but part of a broader immune landscape in which gut microbes, skin microbes, and their metabolites may play meaningful roles. Patterns like reduced butyrate-producing bacteria, altered diversity, and fungal overgrowth have emerged consistently enough to warrant serious scientific attention, and mechanisms involving SCFAs, intestinal permeability, and immune cell trafficking offer plausible explanations for how the gut could influence the skin. At the same time, most of this evidence is associative, individual microbiomes vary widely, and symptoms alone can't tell you what's happening in your gut. That's why measuring, rather than guessing, can add real value: understanding your own gut microbiome may provide personalized context that supports smarter, more informed conversations about diet and lifestyle with your healthcare team. As research advances, the microbiome is likely to become an increasingly important part of how we understand and manage psoriasis, one piece of a much larger, deeply interconnected puzzle.

Keywords

microbiome and psoriasis, gut-skin axis, gut dysbiosis, psoriasis gut health, skin microbiome psoriasis, probiotics for psoriasis, short-chain fatty acids, butyrate, IL-17, Treg cells, Firmicutes, Bacteroidetes, Akkermansia, Phocaeicola, Candida, intestinal permeability, microbiome diversity, PASI score, diet and psoriasis, prebiotics, fermented foods, fecal microbiota transplantation, secukinumab, Cutibacterium acnes, Staphylococcus, skin barrier function, next-generation probiotics, microbiome testing