A new study out of the University of Liverpool – funded by CPG giant Unilever – suggests that the bacteria on your skin might have a deeper influence. In fact, the researchers claim that those microscopic overachievers aren’t just maintaining your complexion. They also could be shaping your mood.
Published in the British Journal of Dermatology, the paper serves up some of the first empirical evidence for what the authors call a “skin-brain axis.” While there’ve been reams of research papers dedicated to the gut-brain axis, this study instead shows that bacteria living on the skin, influence our stress levels, emotional responses, and overall mood.
From Gut to Skin
Looking past the gut microbiome that’s garnered so much attention of late, lead author Jamie Tyson-Carr and colleagues wondered whether a much larger organ — the skin — might play a part, tool.
In a bid to find out, the team recruited 53 healthy participants between 18 and 45 years old, none of whom had active skin conditions or had taken antibiotics recently. Each person self-swabbed four body sites — the face, forearm, armpit, and scalp — to provide skin microbiome samples.
Participants also completed a battery of psychological assessments, including standardized measures of stress (PSS-10), mood (PANAS), and sleep quality (PSQI). Finally, they took more region-specific evaluations to find out how they felt about the appearance and feel of their skin in those areas.
Cutibacterium Makes a Strong Case
After sequencing the microbial DNA culled from the samples, one genus stood out: Cutibacterium – Cutibacterium acnes in particular. Specifically, the researchers reported that:
- On the face, a higher relative abundance of Cutibacterium correlated with lower perceived and daily stress, and better sleep quality.
- In the armpit, elevated Cutibacterium counts lined up with lower stress and a more positive mood.
- And on the forearm, a greater correlated presence corresponded with more positive feelings about the one’s skin condition and appearance.
Notably, the overall diversity of microbes — a popular metric in gut microbiome research — didn’t appear to make any difference. Simply put, it wasn’t how many different types of microbes were present, but rather the dominance of Cutibacterium that mattered.
But How?
The researchers offered up a few theories that might explain what they discovered.
Cutibacterium helps regulate skin pH and produces short-chain fatty acids, such as propionic acid, which may reduce inflammation, a process increasingly linked to our mental health. Its abundance might also signal healthier skin, which could improve self-esteem and spill over into our sense of emotional wellbeing.
Another possibility, they suggest, might lie in the broader idea of the skin-brain axis. Just as stress can trigger skin flare-ups, the condition of the skin — and maybe even the microbes camping out there — might influence stress in return. Though the exact mechanisms remain uncertain, the research team argued that microbial interactions with the immune and nervous systems could be at play.
While the study doesn’t establish causation, the consistent links between Cutibacterium and positive psychological indicators across multiple parts of the body seems to suggest that the skin microbiome deserves a closer look.
A Few Caveats
Like any pilot study, this one comes with caveats. It was a small, observational, study. And it included mostly healthy adults without clinical skin or mental health conditions. Participants self-collected swabs, which could introduce variability. And the research didn’t control for other factors such as diet, pet ownership, or travel history.
It’s also worth noting that while Unilever funded the research, and a few of the team members worked at the UK company, the study didn’t include any Unilever products.
All of that being said, the authors argue that the strength and consistency of the findings at least justify further investigation. Future studies, they propose, might test whether boosting Cutibacterium levels through skincare interventions or probiotic treatments might meaningfully impact stress or mood.
The Potential for Skin-Based Mental Health Support
This study adds to a growing body of data that reframes mental health as a system-wide phenomenon, and not some condition limited to the brain. If follow-up research backs up these results, skincare could become part of the mental wellness toolkit.
Further Reading
Gut Microbiome Breakthroughs Revolutionize Schizophrenia Treatment
Psychiatric and Psychological Impact of Chronic Skin Disease
