Dermatitis and the Gut: How Dysbiosis and Leaky Gut Affect the Skin

The skin is the largest organ in the human body, and in addition to being a protective barrier against the environment, it also faithfully reflects what happens inside us. When we think about skin health, we often focus only on external factors, such as pollution, sun exposure, or the use of topical products. However, integrative and functional medicine has increasingly highlighted the connection between gut health and skin as a fundamental aspect for understanding and treating skin conditions. This link, known as the gut-skin axis , reveals how the balance of the gut microbiota is not only vital for digestion and immunity, but also for maintaining healthy, inflammation-free skin.

The concept of a gut-skin axis may seem complex, but it's essential to understand that the state of our gut microbiota directly influences the health of our skin. Recent studies have shown that when the gut suffers from an imbalance in microbiota , known as dysbiosis, it can trigger or worsen inflammatory skin conditions such as atopic dermatitis, acne, rosacea, and psoriasis. This connection is explained through a bidirectional mechanism, in which inflammation and intestinal permeability impact the immune response and, consequently, skin health.

This link between the gut and skin, known as the gut-skin axis , reveals how the balance of gut microbiota is not only vital for digestion and immunity, but also for maintaining healthy, inflammation-free skin.

The Role of Gut Microbiota in Skin Health

The gut microbiota is a complex ecosystem composed of trillions of microorganisms, including bacteria, viruses, fungi, and protozoa. These microbes play a crucial role in digestion, vitamin production, immune system modulation, and protection against pathogens. However, when the balance of the microbiota is disrupted—a condition known as dysbiosis—it can trigger a cascade of negative effects that affect the integrity of the gut barrier and, consequently, skin health.

Studies have shown that certain gut bacteria, such as Lactobacillus and Bifidobacterium , have a protective effect on the skin by regulating the immune response and reducing systemic inflammation. On the other hand, an overabundance of pathogenic bacteria or an imbalance in the proportion of beneficial bacteria can lead to chronic inflammation , a major cause of dermatitis and other skin disorders.

Atopic dermatitis and psoriasis are examples of inflammatory skin conditions associated with imbalances in the gut microbiome. In atopic dermatitis, elevated levels of bacteria such as Clostridium and Escherichia have been identified , which contribute to an inflammatory state and can increase intestinal permeability, triggering further inflammatory responses. In psoriasis, a lower presence of Bacteroides , bacteria with anti-inflammatory properties, is linked to increased inflammation. Furthermore, rosacea, which is characterized by facial redness, also shows a link with gut dysbiosis, the bacteria Helicobacter pylori, and small intestinal bacterial overgrowth (SIBO) , where treatment of the latter has resulted in the improvement of skin lesions. These conditions highlight the connection between gut health and skin, and how an imbalanced microbiome can trigger or exacerbate skin conditions.

An imbalance in the proportion of beneficial bacteria can lead to chronic inflammation , a major cause of dermatitis and other skin disorders.

Intestinal permeability and its impact on dermatitis

Increased intestinal permeability , commonly known as "leaky gut," is a condition in which the intestinal barrier weakens, allowing undigested food particles, toxins, and microbes to pass into the bloodstream. This phenomenon activates the immune system and generates a widespread inflammatory response that can manifest on the skin.

A leaky gut can lead to increased levels of pro-inflammatory cytokines , which contribute to the development of skin conditions such as atopic dermatitis. Systemic inflammation and immune system activation can also disrupt skin barrier function, making the skin more susceptible to irritation and breakouts.

Intestinal bacteria and their relationship with the skin

Different studies have identified intestinal bacteria that are closely related to skin health:

• Lactobacillus: The genus Lactobacillus , composed of lactic acid bacteria, stands out for its key role in skin health thanks to its anti-inflammatory capacity and its modulatory action on the cutaneous microbiome . Lactobacillus strains have been shown to reduce inflammation in keratinocytes and control the growth of Staphylococcus epidermidis , a microorganism linked to cutaneous imbalances. Furthermore, these probiotics help mitigate inflammatory responses induced by substance P and promote the restoration of the skin barrier. Clinical studies have shown that the intake of Lactobacillus rhamnosus improves the expression of genes associated with insulin signaling and contributes to the management of adult acne . Other findings suggest that the use of Lactobacillus acidophilus reduces wrinkle formation after exposure to UV radiation.
• Bifidobacterium : Oral supplementation with Bifidobacterium breve B-3 has shown significant benefits in skin by reducing transcutaneous water loss (TEWL), epidermal dryness and thickening, and improving the integrity of tight junctions and basement membranes following excessive UV radiation exposure. In addition, this strain helps inhibit UV-induced IL-1β production. In patients with atopic dermatitis, Bifidobacterium bifidum can reduce itching, and in trials with fermented milk, combined with galactooligosaccharides, an improvement in skin hydration and a decrease in pro-inflammatory compounds have been seen.
• Nitrobacter bacteria : Nitrobacter is a bacterium that produces nitrates, which can benefit the skin by improving circulation and lowering blood pressure. Nitrates, found in foods like green leafy vegetables, contribute to better blood circulation and more efficient use of oxygen during physical activity. Additionally, Nitrobacter helps protect the skin from infections thanks to its antifungal properties, fighting fungi and bacteria like Staphylococcus aureus , which can cause skin problems. The nitrates it generates have also been observed to protect skin cells from UV radiation damage, helping to maintain skin health.

Prebiotics and their importance in skin health

Prebiotics are non-digestible fibers that act as specific nutrients for beneficial bacteria in the gut, facilitating their growth and activity. These substances play a key role in the balance of the gut microbiome, which has implications not only for digestive health but also for other body systems, including the skin.

Types of prebiotics and their impact on the skin

1. Inulin : Inulin is a type of soluble fiber found in foods like asparagus, garlic, onions, and leeks . This compound is known to feed beneficial bacteria strains like Bifidobacterium and Lactobacillus . By improving the diversity of the gut microbiome, inulin helps reduce systemic inflammatory processes that can manifest in the skin, such as acne and dermatitis. Inulin also helps optimize the absorption of minerals like calcium and magnesium , which are essential for skin regeneration.
2. Fructooligosaccharides (FOS) : These compounds are found in foods like asparagus, leeks, and artichokes . FOS works by boosting healthy gut flora, which strengthens the gut barrier and reduces intestinal permeability . This is crucial because a compromised gut barrier can cause endotoxins and other substances to pass into the bloodstream, triggering inflammatory responses that negatively affect the skin. Therefore, consuming FOS may be beneficial for maintaining skin integrity and preventing inflammatory conditions like rosacea.
3. Galactooligosaccharides (GOS) : GOS are found primarily in breast milk and certain fermented dairy products . These compounds have been shown to support the growth of bacteria such as Bifidobacterium , which have immune-modulating properties. A robust gut microbiome that includes GOS can help regulate the production of pro-inflammatory cytokines, resulting in less reactive, more balanced skin. Additionally, by promoting a healthy gut environment, GOS support the production of short-chain fatty acids such as butyrate, which have anti-inflammatory properties.

Prebiotics play a key role in balancing the gut microbiome, which has implications not only for digestive health but also for other body systems, including the skin.

How to improve gut health to benefit your skin

To maintain a balanced microbiota and promote healthy skin, it is important to follow integrative strategies that include:

• Anti-inflammatory diet rich in prebiotic fibers : An anti-inflammatory diet rich in prebiotic fibers is key to promoting a healthy balance in our gut microbiota. Prebiotic fibers are food components that are not digested in the small intestine, but instead reach the colon, where they serve as food for the beneficial bacteria that reside there . Consuming foods rich in these fibers favors the growth of bacteria such as Bifidobacterium and Lactobacillus , which have positive effects on digestive health, modulate inflammation, and improve immune function.

Among the foods richest in prebiotic fibers are resistant starch , a type of carbohydrate resulting from refrigeration after cooking foods high in starch such as potatoes, sweet potatoes, cassava, plantains, or legumes.

• Avoid processed foods and refined carbohydrates : Avoiding processed foods and refined carbohydrates is essential for maintaining a balanced gut microbiota and a healthy intestinal barrier. This, in turn, impacts skin health. Processed foods are often loaded with additives, refined sugars, and trans fats , which can negatively alter the composition of the microbiota, promoting the growth of pathogenic bacteria and reducing the population of beneficial microorganisms.

Refined carbohydrates, such as those found in white bread, cakes, cookies, sugary cereals, and other processed baked goods, have a negative impact on the gut because they are digested quickly, causing blood glucose spikes. These spikes can induce chronic low-grade inflammation, which favors the growth of bacteria that promote inflammation and dysbiosis. Furthermore, foods high in sugars and refined carbohydrates can disrupt the production of short-chain fatty acids (such as butyrate), thus promoting inflammation and increased intestinal permeability.

Avoiding processed foods and refined carbohydrates is essential for maintaining a balanced gut microbiota and a healthy intestinal barrier, which in turn impacts skin health.

• Probiotic use : Supplements with Lactobacillus and Bifidobacterium may be an effective tool for reducing inflammation and strengthening the intestinal barrier . Probiotics have the ability to reduce the release of proinflammatory substances, helping to mitigate the risk of inflammatory skin conditions.

In addition to probiotic supplements, you can obtain these microorganisms through fermented foods that naturally contain high levels of probiotics. Some examples include yogurt, kefir, sauerkraut, and kimchi.

• Stress reduction : When the body is under constant stress, the nervous system responds, releasing hormones like cortisol. High levels of cortisol can alter the composition of the gut microbiota and promote increased intestinal permeability, producing systemic inflammation that impacts the skin . Reducing stress can be key to restoring gut health and, therefore, improving skin condition. Techniques like meditation, yoga, and deep breathing are effective in lowering cortisol levels and helping to balance the microbiota.

• Physical exercise: Physical exercise has a significant impact on the composition and diversity of the gut microbiota, which impacts our overall health. Moderate, regular exercise, such as running, cycling, or resistance training, can increase bacterial diversity, promoting microbial balance . It is also linked to increased production of butyrate fatty acids.

Reducing stress can be key to restoring gut health and, therefore, improving skin condition.

Conclusion

The connection between gut health and skin is undeniable, as imbalances in the gut microbiome and intestinal permeability can directly influence skin disorders such as dermatitis, acne, and rosacea. Gut dysbiosis generates inflammation that affects not only digestion and the immune system, but also the skin, where these internal problems are reflected.

An integrative approach that combines nutrition and PNIe can address the root causes of skin conditions, restoring intestinal balance. Through an anti-inflammatory diet, the use of prebiotics and probiotics, along with stress management and moderate exercise, we can improve intestinal flora and reduce systemic inflammation.

By approaching skin health from this holistic perspective, lasting improvements are achieved that go beyond topical treatments, promoting overall well-being that translates to healthier, more balanced skin.

Sources

Gao, T., Wang, X., Li, Y., & Ren, F. (2020). The role of probiotics in skin health and the related gut-skin axis: a review .

Gueniche, A., Benyacoub, J., Philippe, D., Bastien, P., Kusy, N., Bretón, L., Blum, E., & Castiel-Higounenc, I. (2010). Lactobacillus paracasei CNCM I-2116 (ST11) inhibits substance P-induced skin inflammation and accelerates the recovery of skin barrier function in vitro. European Journal of Dermatology , DOI: 10.1684/ejd.2010.1108, PMID: 20965806.

Fabbrocini, G., Bertona, M., Picazo, E., Pareja-Galeano, H., Monfrecola, G., & Emanuele, E. (2016). Lactobacillus rhamnosus SP1 supplementation normalizes cutaneous expression of genes involved in insulin signaling and improves adult acne . DOI: 10.3920/BM2016.0089, PMID: 27596801.

Bressa, C., Bailén Andrino, M., Pérez-Santiago, J., González-Soltero, R., Pérez, M., Montalvo Lominchar, M.G., Maté-Muñoz, J.L., Domínguez, R., Moreno, D., & Larrosa, M. (2020). Differences in the gut microbiota profile between women with an active lifestyle and sedentary women.

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