Psoriasis, Psoriatic Arthritis and the Gut: How Diet and the Microbiome Influence Inflammation
Psoriasis and psoriatic arthritis are complex immune-mediated conditions. They are not caused by diet, nor are they simply “skin” or “joint” problems. Instead, they involve an interplay between genetics, the immune system and environmental triggers — including the gut microbiome.
Increasing evidence suggests that what happens in the gut can influence inflammation elsewhere in the body, helping explain why some patients notice that diet affects their symptoms. This growing understanding has transformed how we approach care, particularly in clinics that look at psoriasis and psoriatic arthritis holistically rather than through a single specialty lens.
The Gut–Skin–Joint Axis: Why the Microbiome Matters
The gut microbiome — the diverse ecosystem of bacteria, fungi and viruses within the intestine — plays a central role in regulating immune activity. When the microbiome becomes imbalanced (dysbiosis), immune pathways can become overactive, including those involved in psoriatic disease such as IL-17, IL-23 and TNF-α.
Research has shown:
Reduced levels of beneficial anti-inflammatory bacteria
Increased levels of species linked with metabolic and immune activation
Greater intestinal permeability (“leaky gut”) allowing inflammatory molecules to reach the bloodstream
These changes do not cause psoriasis or psoriatic arthritis, but they can influence severity, flares and systemic inflammation.
How Diet Shapes the Microbiome — and Why It Matters
Diet is one of the most powerful modulators of the gut microbiome. Certain foods help beneficial bacteria thrive, while others promote inflammation.
Foods that support gut and immune health
✔ Fibre-rich foods
Vegetables, fruits, legumes and whole grains feed beneficial microbes and promote anti-inflammatory short-chain fatty acids.
✔ Omega-3 fats
Found in oily fish, flaxseed and chia, omega-3s shift the immune response away from inflammatory pathways and may reduce joint symptoms.
✔ Polyphenol-rich foods
Berries, olive oil, nuts and herbs provide antioxidants that support beneficial bacteria.
✔ Fermented foods
Kefir, yogurt, sauerkraut and kimchi can help restore microbial diversity.
✔ Weight optimisation
Excess weight independently worsens psoriasis and psoriatic arthritis due to increased inflammatory signalling. Sustainable dietary changes can meaningfully improve disease activity.
Gluten and Dairy: What Do We Know?
Gluten
People with psoriasis have a higher rate of coeliac disease
Those with positive coeliac or anti-gliadin antibodies often improve on a gluten-free diet
Evidence is mixed for people without these markers, though some still choose a trial
Dairy
No strong evidence that dairy directly triggers psoriasis
Some patients feel better reducing high-fat or highly processed dairy
Important to maintain calcium and vitamin D if restricting
Dietary triggers are highly individual — what helps one person may not help another
The Mediterranean Diet: The Strongest Evidence
Across multiple studies, the Mediterranean diet consistently reduces systemic inflammation and can improve psoriasis and psoriatic arthritis activity.
This dietary pattern emphasises:
Vegetables, fruit and whole grains
Olive oil and nuts
Legumes
Fish and lean protein
Minimal processed foods
Patients often report:
Improved skin
Reduced joint pain
Better energy
Weight loss
Improved cardiovascular health (important in psoriatic disease)
How This Integrates Into My Joint Dermatology–Rheumatology Clinic
I run a combined Dermatology–Rheumatology Psoriasis & Psoriatic Arthritis Clinic, where patients benefit from a coordinated approach across both specialties. This allows us to look at psoriasis as a whole-system condition rather than as separate skin and joint problems.
In this clinic, we focus not only on choosing the right medication, but also on the wider lifestyle factors that influence inflammation, including:
diet and the gut microbiome
weight management
cardiovascular risk reduction
sleep
stress
physical activity
smoking and alcohol habits
Patients often value the chance to discuss these aspects in detail, and to receive aligned advice from two consultants working together. Many find that combining medical treatment with sustainable lifestyle changes leads to better long-term control of their condition.
Can Diet Replace Medication?
No — diet is supportive, not curative.
For many patients, the most effective care comes from:
medical therapy (topicals, DMARDs or biologics)
lifestyle interventions
cardiovascular risk management
treating psoriasis and PsA together, not separately
Diet should complement, not substitute, appropriate medical treatment — especially for joint disease where early control prevents long-term damage.
Final Thoughts: A True Whole-Person Approach
Psoriasis and psoriatic arthritis are systemic immune conditions. The gut microbiome, diet and lifestyle do not cause them, but they can influence how active the disease feels and how well-controlled symptoms become.
In my clinic, we integrate these elements into a personalised care plan — combining effective medication with whole-person strategies that support long-term wellbeing.
Please note, these posts are for general information only and do not constitute medical advice. Dr Singh would encourage you to speak to your healthcare professional to be assessed and managed for your specific symptoms.