The Gut–Skin Axis: A Hidden Factor of Healthy Skin

Šárka Kůrková
2026-04-30T16:01:23+02:00

The condition of our skin is not just a matter of cosmetics. Gut health and the composition of the gut microbiome play a key role. How exactly digestion, immunity, and skin health are connected—and why the solution to skin problems may lie much deeper than it seems.

What you will learn in this article?

1. The "Gut-Skin Axis"

2. Microbiom: the invisible player of healthy skin

3. The gut as a barrier

4. Why stress worsens the skin more than we think

5. Which diet harms the skin

6. Key nutrients for skin and gut

7. Key takeaways

The "Gut-Skin Axis"

At first glance, it may seem that the skin is influenced mainly by external factors. In reality, however, it is closely connected to the health of the gastrointestinal tract, as well as the hormonal and nervous systems. This connection is therefore referred to as the “gut–skin axis.”

The gut plays a crucial role in this system—approximately 70% of immune cells are located there. This means that any imbalance in the gut environment can also manifest on the skin, which is in fact an “output organ” of many internal processes. When balance in the gut is disrupted, it is often reflected in the skin.

Many studies show that changes in the gut microbiome (so-called dysbiosis) are associated with skin conditions such as acne, atopic dermatitis, rosacea, and increased skin sensitivity.

This axis operates through several key mechanisms and influences:

the immune system (most immune cells reside in the gut)

metabolites of gut bacteria

the nervous system (gut–brain axis)

hormonal regulation [1]

Microbiome: the invisible player of healthy skin

The gut microbiome is not just a passive community in our digestive tract; it is a complex ecosystem of trillions of microorganisms that functions as an independent metabolic organ, often referred to as the “second brain.” Its impact on the skin is fundamental, as it modulates systemic immunity, reduces chronic inflammation, and directly influences hormone synthesis and the metabolism of key nutrients (e.g., B vitamins, vitamin K, iron, zinc) [2].

When the microbiome is balanced, it acts as a barrier against pathogens. Problems arise in dysbiosis—a state in which pathogenic bacteria begin to dominate over beneficial ones.

A key role is also played by short-chain fatty acids (SCFAs), especially butyrate, which is produced by the fermentation of fiber by beneficial bacteria and strengthens the integrity of both the gut and skin barrier.

These fatty acids also help maintain the skin’s optimal acidic pH and stimulate the production of ceramides, which prevent transepidermal water loss. As a result, the skin remains hydrated and more resistant to external factors.

A healthy microbiome also acts as an internal shield. It modulates the body’s response to oxidative stress caused by UV radiation. By reducing sun-induced inflammatory mediators, it may actively mitigate the effects of photoaging, such as premature wrinkles and pigmentation spots [3].

The gut as a barrier

The gut is not only responsible for digestion but also functions as a highly sophisticated barrier that determines what enters the body and what does not.

When the intestinal lining is healthy, it acts as a fine sieve—allowing nutrients to pass through while blocking harmful substances.

In dysbiosis (often due to stress, poor diet, or infections), the tight junctions in the intestinal lining become disrupted, leading to increased intestinal permeability (leaky gut). Endotoxins and “food residues” then enter the bloodstream. These substances trigger an immune cascade that results in systemic inflammation, which externally manifests through the skin as acne, atopic dermatitis, rosacea, or psoriasis [4].

Why stress worsens the skin more than we think

Stress acts as a trigger for a cascade of biochemical reactions that affect the skin on multiple levels.

Impact on gut health: Hormones released during stress can promote the growth of pathogenic bacteria at the expense of beneficial ones. This imbalance leads to the production of toxic substances that travel through the bloodstream to the skin [5].

Chronic stress also weakens tight junctions in the intestinal wall, contributing to the development of leaky gut.

Hormonal response and cortisol: During stress, the adrenal glands release cortisol (“the stress hormone”), which increases sebaceous gland activity and makes the skin more sensitive and prone to inflammation [6].

Stress also activates mast cells in the skin, which release histamine and other inflammatory mediators. This explains why stressful periods are often accompanied by flare-ups of rosacea, worsening psoriasis, and atopic dermatitis [7].

Which diet harms the skin

What we eat has a direct impact on digestion and the microbiome—and therefore on the skin. Some foods promote inflammation, while others reduce it.

A diet high in processed foods and sugars leads to a process called glycation, which damages collagen fibers and accelerates skin aging [8]. We have discussed how blood sugar fluctuations affect the body in one of our previous articles Blood sugar under control.

What harms the skin:

High sugar intake: increases insulin levels, stimulates androgen production and sebum; also promotes pathogenic bacteria and inflammation

Ultra-processed foods: contain additives that may disrupt gut barrier integrity

Lack of fiber: leads to starvation of beneficial bacteria and dysbiosis

Frequent alcohol consumption: dehydrates the skin and disrupts the microbiome

What supports the skin:

A diverse, fiber-rich diet: fiber acts as a prebiotic and is fermented into butyrate, reducing inflammation and supporting gut barrier health

Vegetables and legumes: sources of antioxidants that protect against oxidative stress

Fermented foods: sources of probiotics that help suppress pathogenic bacteria

Healthy fats: especially omega-3 fatty acids (fish oil, flaxseed), which reduce inflammation in the dermis [9]

Targeted probiotics: different bacterial strains have different effects; some may reduce inflammation, improve eczema, and support the skin barrier, while others may have little effect—strain selection matters [10]

Key nutrients for skin and gut

For the skin to glow, it needs specific “building blocks” that support both the gut barrier and skin regeneration:

Zinc: essential for maintaining the intestinal lining and its function; also important for wound healing and sebum regulation.

Vitamin D: acts more like a hormone and is crucial for proper immune barrier function in both skin and gut.

Vitamin A: key for the renewal of skin and intestinal cells; the microbiome influences its metabolism and utilization.

Polyphenols and antioxidants: found in green tea, wild blueberries, or dark chocolate; they also act as substrates for the microbiome and help reduce inflammation.

Omega-3 fatty acids: reduce pro-inflammatory cytokines and support gut lining integrity, helping prevent leaky gut.

Collagen: contains specific amino acids (glycine, glutamine, proline) essential for intestinal lining regeneration and tightening junctions in the gut wall. We have written more about collagen in articles such as The Role of Collagen in the Human Body and Comparing of Beauty vs. Beef Collagen: Which to Choose and Why.

Key takeaways

Skin as a reflection of internal health: Skin health is not about quick external fixes but about overall internal balance.

Gut as the foundation: Controlling inflammation and supporting the microbiome is key.

Mind–microbiome balance: Stress management is as important as diet. Chronic stress disrupts the intestinal barrier and, through a hormonal cascade, directly triggers inflammatory processes in the skin.

Nutritional support: Key nutrients include zinc, vitamins D and A, and omega-3 fatty acids.

Sustainable approach: Focus on prevention rather than symptom masking. A combination of proper nutrition, digestive health, and stress management provides a solid foundation for healthy, beautiful skin.

Sources:
[1] https://thenaturopathic.co/the-gut-skin-connection-a-gut-naturopath-explains/

[2] https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.01459/full

[3] https://pmc.ncbi.nlm.nih.gov/articles/PMC2836434/

[4] https://pubmed.ncbi.nlm.nih.gov/30472851/

[5] https://pubmed.ncbi.nlm.nih.gov/24997027/

[6]https://www.researchgate.net/publication/263287535_Brain-Skin_Connection_Stress_Inflammation_and_Skin_Aging

[7] https://pubmed.ncbi.nlm.nih.gov/20113345/

[8] https://pmc.ncbi.nlm.nih.gov/articles/PMC2836431/

[9] https://pmc.ncbi.nlm.nih.gov/articles/PMC6048199/

[10] https://pubmed.ncbi.nlm.nih.gov/22099848/