What Causes Psoriasis?

What Causes Psoriasis? A Functional Medicine Perspective

Psoriasis is more than just a skin condition—it’s a complex, chronic autoimmune disorder that affects millions of people worldwide. Characterised by red, scaly patches on the skin, it is often accompanied by discomfort, itching, and inflammation. While conventional treatments focus on managing symptoms through topical creams, medications, and biologics, functional medicine seeks to uncover and address the root causes of psoriasis.

This holistic approach considers the interconnectedness of the body’s systems, exploring how factors like gut health, immune function, stress, and nutrient balance contribute to the development and progression of psoriasis. In this article, we’ll dive deep into the functional medicine view of psoriasis, examining key contributors such as gut health (SIBO, dysbiosis, leaky gut, and bile acids), stress, the gut-skin axis, blood sugar imbalances, thyroid function, nutrient deficiencies, oxidative stress, and food sensitivities.

🦠 1. The Gut-Skin Connection: How Gut Health Drives Psoriasis

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The gut and skin are closely linked through what’s known as the gut-skin axis. You can read our blog on the gut-skin connection here which provides a deeper explanation. The simple take away is that when the gut is out of balance, it can trigger immune responses that lead to skin inflammation, a hallmark of psoriasis.

Key Gut Issues Linked to Psoriasis:

• Small Intestinal Bacterial Overgrowth (SIBO): SIBO occurs when bacteria overgrow in the small intestine. This can cause bloating, digestive issues, and systemic inflammation, which may worsen psoriasis (source). In fact, research has shown that trating SIBO leads to improvement in psoriasis (source).
• Gut Dysbiosis: Gut dysbiosis occurs when the balance between “good” and “bad” bacteria in the gut is disrupted. This imbalance can lead to chronic inflammation, which is at the heart of autoimmune conditions like psoriasis (source, source). A 2024 study published in PharmaNutrition found that people with psoriasis often have a reduced diversity of beneficial gut bacteria and an overgrowth of harmful bacteria (source). This imbalance can contribute to poor immune function, that may lead to skin inflammation.
• Leaky Gut (increased intestinal permeability): When the gut lining becomes compromised, toxins and undigested food particles can enter the bloodstream, causing widespread inflammation that may contribute to psoriasis flares (source). Another study in The Egyptian Journal of Hospital Medicine identified higher levels of gut permeability markers (a sign of “leaky gut”) in psoriasis patients compared to healthy individuals, linking gut barrier dysfunction directly to psoriasis severity (source).
• Bile Acids: Clinically, bile acids have promising potential in the management of psoriasis. In a trial of bile acid supplementation, 80% of patients treated with a synthetic bile acid, dehydrocholic acid, experienced resolution of symptoms compared to 25% of patients receiving conventional therapy (source). A supplement called Bile Acid Factors has been found to be helpful in psoriasis.

✅ Functional Medicine Approach:

• Comprehensive stool testing to assess gut microbiome health.
• SIBO breath tests to detect bacterial overgrowth in the small intestine.
• Healing leaky gut with nutrients like L-glutamine, zinc, and probiotics.
• Supporting bile acid production through liver health and dietary and supplement changes.

😰 2. Stress: The Psoriasis Trigger You Can’t Ignore

Chronic stress is one of the most common triggers for psoriasis flare-ups. Stress activates the hypothalamic-pituitary-adrenal (HPA) axis, leading to increased cortisol production and immune system dysregulation.

Research has shown that 72% of psoriatic patients had experienced significant stressful events about one month before the appearance of psoriasis. Moreover, those patients showed high levels of anxiety (source).

How Stress Affects Psoriasis:

• Increases inflammatory cytokines, which can worsen skin symptoms.
• Weakens the skin barrier, making it more vulnerable to irritation.
• Disrupts gut health, further fuelling inflammation.

✅ Functional Medicine Approach:

• Stress-reducing practices like mindfulness, meditation, yoga, and deep breathing.
• Adaptogenic herbs (e.g., ashwagandha, rhodiola) to support the stress response.
• Cognitive Behavioural Therapy (CBT) for managing emotional triggers.

🩸 3. Blood Sugar Imbalance: A Hidden Driver of Inflammation

Many people with psoriasis also experience insulin resistance or metabolic issues related to poor blood sugar control (source). High blood sugar levels trigger inflammation, which can worsen psoriasis symptoms.

How Blood Sugar Affects Psoriasis:

• Increases the production of advanced glycation end-products (AGEs), which promote inflammation.
• Fuels oxidative stress, damaging skin cells.
• Contributes to obesity, a known risk factor for psoriasis (source).

✅ Functional Medicine Approach:

• Implementing a low-glycemic, anti-inflammatory diet.
• Prioritising fiber-rich foods to stabilise blood sugar levels.
• Regular physical activity to improve insulin sensitivity.

🦋 4. Thyroid Health and Psoriasis: The Autoimmune Link

Psoriasis often coexists with other autoimmune conditions, including Hashimoto’s thyroiditis, an autoimmune thyroid disorder. Thyroid dysfunction can alter the immune response, increase systemic inflammation, and exacerbate skin symptoms (source).

Signs of Thyroid Dysfunction in Psoriasis Patients:

• Fatigue.
• Unexplained weight changes.
• Cold intolerance.
• Hair thinning.
• Constipation.
• Dry skin.

✅ Functional Medicine Approach:

• Comprehensive thyroid testing, including TSH, Free T4, Free T3, reverse T3, and thyroid antibodies.
• Supporting thyroid health through selenium, zinc, and iodine (when appropriate).
• Addressing gut health, as it plays a key role in thyroid hormone conversion.

🥦 5. Nutrient Deficiencies That Can Trigger Psoriasis

Certain nutrient deficiencies can weaken the skin barrier, impair immune function, and promote inflammation—all of which are central to psoriasis.

Common Deficiencies in Psoriasis:

• Vitamin D: Regulates immune responses and reduces skin inflammation. Many psoriasis patients have low vitamin D levels (source).
• Omega-3 Fatty Acids: Anti-inflammatory fats that help calm the immune system (source).
• Zinc-Copper Balance: Increased serum copper and decreased serum zinc levels were generally observed in patients with psoriasis (source).
• Vitamin B12 and Folate: Important for cell repair and reducing inflammation (source, source).
• Magnesium: Magnesium is thought to have an indirect relationship with psoriasis due to its role in Vitamin D absorption (source).

✅ Functional Medicine Approach:

• Testing for nutrient deficiencies through blood or urine panels.
• Personalised supplementation based on test results.
• A nutrient-dense, whole-foods diet rich in vegetables, healthy fats, and lean proteins.

🌿 6. Oxidative Stress: The Role of Free Radicals in Psoriasis

Oxidative stress occurs when there’s an imbalance between free radicals and antioxidants in the body. This leads to chronic inflammation and tissue damage, which can worsen psoriasis (source).

How Oxidative Stress Affects Psoriasis:

• Damages skin cells and accelerates the skin turnover process, leading to thick plaques.
• Triggers immune system overactivity.
• Increases the risk of co-morbid conditions like heart disease and diabetes.

✅ Functional Medicine Approach:

• Increasing antioxidant intake (vitamins A, C, E, selenium, glutathione).
• Incorporating antioxidant-rich foods like berries, leafy greens, nuts, and seeds.
• Reducing exposure to environmental toxins, processed foods, and pollutants.

🚫 7. Food Sensitivities: Could Your Diet Be Making Psoriasis Worse?

While psoriasis isn’t a food allergy, many people with the condition have food sensitivities that trigger inflammation and flare-ups. Common culprits include (source):

• Gluten: Linked to increased intestinal permeability (“leaky gut”) and autoimmune reactions. It’s important to note that not everyone with psoriasis needs to avoid gluten as shown in this study. I personally have found that gluten is only a trigger when stress levels are high. And as my health improved I was able to tolerate gluten even when experiencing high stress levels!
• Dairy: There is no clear evidence that dairy needs to be avoided by those with psoriasis, but it is clear that some do notice benefit by eliminating it. This should be no surprise as we are all unique.
• Nightshades (tomatoes, peppers, eggplants): May trigger symptoms in some people.
• Processed foods and sugars: Contribute to systemic inflammation and should be limited.

A case study published found that IgG testing led to improvement in psoriasis (source).

✅ Functional Medicine Approach:

• Elimination diets to identify food triggers.
• IgG food sensitivity testing (if appropriate).
• Transitioning to an anti-inflammatory diet rich in whole, unprocessed foods.

🌍 Other Contributing Factors in Psoriasis

• Infections: Recent research shows that various microorganisms may play an important role in triggering and worsening psoriasis. Bacteria like streptococci and staphylococci are thought to contribute to the condition, possibly by activating specific immune cells (T cells) that target the skin. Besides bacteria, certain fungi such as Candida and Malassezia, as well as viruses like HIV, hepatitis C, and human papillomavirus (HPV), have been linked to psoriasis flare-ups. More recently, infections from Helicobacter pylori, the Zika virus, and even scabies have been suggested as potential triggers for psoriasis in some individuals (source).
• Toxin Exposure: Heavy metals like cadmium (source), air pollution (source) mould (source), and environmental toxins can overwhelm the immune system.
• Hormonal Imbalances: The severity of psoriasis in a female patient may fluctuate with hormonal changes since psoriasis develops more frequently or gets worse at puberty, with another smaller peak at menopause. Often, there is a marked symptomatic improvement or even disappearance during pregnancy, only to reappear after childbirth. With such strong data linking hormones and psoriasis, estrogen and/or progesterone may be potentially useful in the treatment of psoriasis. (source).

✅ Key Takeaways: A Functional Medicine Approach to Psoriasis

1. Heal the Gut: Address SIBO, leaky gut, dysbiosis, and bile acid imbalances.
2. Manage Stress: Incorporate stress-reducing techniques to regulate the immune response.
3. Balance Blood Sugar: Improve insulin sensitivity through diet and lifestyle changes when appropriate.
4. Support Thyroid Health: Screen for thyroid dysfunction and optimise hormone levels when appropriate.
5. Correct Nutrient Deficiencies: Identify and replenish key vitamins and minerals.
6. Reduce Oxidative Stress: Boost antioxidants through diet and targeted supplements.
7. Identify Food Triggers: Use elimination diets or sensitivity testing to reduce inflammation.

💡 Final Thoughts

Psoriasis is a complex condition that goes beyond the skin. By addressing the underlying causes—gut health, immune dysfunction, nutrient imbalances, and lifestyle factors—functional medicine offers a comprehensive, personalised approach to managing psoriasis.