As the body’s largest organ, the skin is often described by dermatologists as a ‘mirror’ of internal health. This means that many troublesome yet common skin conditions, such as acne, eczema, psoriasis and rosacea can be related to health issues inside the body. Furthermore, in recent years, an ever-growing amount of clinical evidence has proven a link between gut microbiome dysbiosis and the development of these kinds of skin disorders.
However, new research on this gut-skin axis has also shown that this relationship is bidirectional, which means that the condition of the skin is not just affected by the state of the gut microbiome, but that products applied directly to the skin can also have an impact on gut health.
To find out more about this emerging discovery, CosmeticsDesign-Europe spoke to microbiome testing company Sequential, which participated in a recent study on the bidirectional gut–skin axis that was published in the Journal of Cosmetic Science in December 2024.
“The most interesting thing we’ve discovered is that the gut and skin work together in two ways,” said Pétronille Houdart, PharmD, Skincare Director at Sequential.
“We already knew the gut affects the skin, but now we also know that skin conditions can affect the gut.,” she said “This idea helps us think differently about how to care for the skin and the whole body.”
Houdart explained that certain gut bacteria produce small molecules (such as SCFAs and tryptophan metabolites) that can support or damage the skin, influencing inflammation, hydration, and even pigmentation.
Gut–skin axis: a whole-body perspective
Houdart said she believes this new understanding will transform how we treat skin problems.
“Instead of just focusing on the skin, we’ll also look at how the whole body works together,” she shared. “For example, specific live bacteria can help with skin issues like acne or eczema by restoring the balance of beneficial gut bacteria and reducing inflammation.”
While ingestible beauty supplements – including probiotics, prebiotics, postbiotics, and synbiotics – can support the immune system and reinforce the skin barrier, topical products can also play a role in this.
“Topical formulations not only maintain the skin microbiome but also enhance microbial resilience, possibly influencing the gut indirectly through the skin–gut axis,” she explained.
These recent findings make a stronger case for taking a more holistic approach to treating skin conditions such as acne and rosacea.
“These conditions aren’t just about the skin’s surface,” Houdart explained. “They’re also connected to internal factors like gut health, the immune system, hormone levels, and stress. Many people treat acne or rosacea with only creams or antibiotics, but that often doesn’t address the root cause.”
For example, in the case of acne vulgaris, research shows that a diet high in sugar and saturated fats and low in omega-3 fatty acids can worsen symptoms. “This kind of diet causes gut dysbiosis, increases insulin and IGF-1 levels, and stimulates sebum production and inflammation via the mTORC1 pathway,” Houdart said. “More sebum creates the ideal environment for C. acnes to thrive.”
Skin injury and the gut microbiome
Research has also shown that skin injury may negatively affect the gut microbiome, leading to a loss of beneficial bacteria, an increase in pathogenic bacteria, and an overall reduction in microbial diversity.
“However, it’s important to note that this area of research is still in its infancy, and further investigation is needed to understand the mechanisms and potential applications,” Houdart cautioned.
For her, the key takeaway from the research is that skin injury – whether from trauma, chronic inflammation, or even topical products – can trigger systemic inflammatory responses.
“Conversely, gut dysbiosis, whether caused by antibiotics or poor diet, may influence the skin through circulating microbial metabolites, immune signalling, or increased intestinal permeability,” she added.
Houdart also said this bidirectional axis suggests that treating skin conditions may also require supporting gut health – and vice versa.
“A holistic approach involving topical and oral probiotics, dietary interventions, or anti-inflammatory regimens is needed,” she stated.
Going forward, Houdart said that future research in this space will likely focus on:
- Strain-specific therapies (eg engineered probiotics, microbiome transplants)
- Microbiome signatures as diagnostic markers
- Integration of AI and omics data to create personalised skincare products
“We’re entering an age where formulating with the microbiome in mind is not just a trend – it’s becoming a scientific necessity,” Houdart concluded.
“The more we respect the skin and the whole body as a living ecosystem, the more precise and effective our dermatological and cosmetic solutions will become.”