TREVOR STEYN

5 MINUTES WITH… TREVOR STEYN

WHEN DID YOUR FASCINATION WITH THE MICROBIOME BEGIN?

“My obsession really started around 2010, when the Human Microbiome Project released its first findings. It showed that there are more microbes living in and on the human body than there are human cells.

“Coming from a chemistry and drug discovery background, that was a complete shock. It meant we weren’t treating a single organism anymore, but an entire ecosystem. Once that penny dropped, it was impossible not to become fascinated by it.”

HOW EARLY DID YOU START TO SEE THE CONNECTION BETWEEN THE GUT AND THE SKIN?

“Pretty much straight away. At that time, people were already talking about the gut-brain axis, and it quickly became clear that all microbiomes are interconnected. What’s interesting is that while we talk a lot about the gut-skin axis, we’re only just beginning to understand the skin-gut axis, and how what happens on the skin can influence the rest of the body. Skin microbiome research is about a decade behind gut research, largely because it’s much harder to sample.”

WHAT SIGNS DO YOU SEE ON THE SKIN WHEN THE GUT MICROBIOME IS DISRUPTED?

“Dysbiosis is a disrupted microbiome that often shows up on the skin through inflammation. Rosacea is a good example; it’s frequently treated with oral antibiotics, which points to a gut connection. The immune system is the key driver, if the gut microbiome is out of balance, the immune system goes on high alert, and that heightened state isn’t localised – it affects the entire body, including the skin. What many people don’t realise is just how large the skin’s surface area actually is. When you take into account hair follicles, sebaceous units and sweat glands, the skin’s microbial surface area is closer to 100 square metres, which is far larger than the gut.”

WHAT RECENT RESEARCH DEVELOPMENTS HAVE REALLY SURPRISED YOU?

“One fascinating area is research coming out of San Diego, where they’ve shown that skin injury can alter the gut microbiome. There’s also research showing that sun exposure can meaningfully change the gut microbiome, whether that’s driven by vitamin D or another mechanism is still being explored. We’re also seeing exciting developments with live biotherapeutics – what people often loosely call probiotics. These are live microbes used as treatments, and we’re now seeing scheduled drugs that contain live bacteria, not just for gut conditions like IBS, but even topical treatments being trialled for inflammatory diseases such as rheumatoid arthritis.”

WHY HAS THERE BEEN A MOVE AWAY FROM THE TERM ‘PROBIOTICS’?

“The term was badly diluted. True probiotics are live microbes, but most skincare products contain preservatives that kill bacteria. As a result, many brands used dead bacteria, fragments of bacteria or fermented broths and still called them probiotics, which is misleading. It took us two and a half years to develop a topical product that could keep live bacteria alive for 18 months without refrigeration. Very few companies in the world have managed that. The industry is now moving towards clearer terminology, like ‘postbiotics’ and ‘live biotherapeutics’, partly due to lawsuits that forced brands to be more honest.”

HOW POWERFUL IS PERSONALISED SEQUENCING?

“Personalised sequencing has completely changed the game. Early sequencing methods could only tell us the genus of a bacterium, not the exact species or strain. With newer shotgun metagenomic sequencing, we can identify microbes down to strain level.

“We recently worked with someone who had severe cystic skin issues for months and had been put on long-term antibiotics. Sequencing revealed that 72% of her skin microbiome was made up of a bacterium that normally causes mastitis in cows and isn’t a known human pathogen. It was clear the antibiotic she’d been prescribed was wrong. With the correct treatment, it could be resolved in days. This is the future of precision skincare.”

WHAT CAN WE LEARN FROM HUNTER-GATHERER POPULATIONS?

“We’ve studied groups like the Hadza and Himba, and they have incredibly diverse microbiomes, with virtually no acne, eczema or inflammatory skin disease.If you compare that to the Western world, where around 85% of teenagers experience acne.

“The difference comes down to their lifestyle: whole-food diets, daily movement, constant contact with nature and microbes, and minimal exposure to processed foods and antibiotics.

“As populations become more urbanised, microbial diversity drops and inflammatory skin conditions rise.”

HOW DOES MODERN HYGIENE AFFECT OUR MICROBIOME?

“We’ve become too sterile. Research has shown that pathogens like E. coli survive far longer on sanitised surfaces than on healthy skin with an intact microbiome.

“The microbes on our skin fight for their space, because they don’t want bad actors moving in. When we over-sanitise, we remove that natural defence and create an environment that actually favours opportunistic pathogens. There’s a balance to be struck between hygiene and over-sterilisation, especially outside of medical settings.”

WHY DO CONVENTIONAL ACNE TREATMENTS OFTEN FAIL LONG-TERM?

“Conventional acne treatments are blunt tools. Most acne treatments aim to kill Cutibacterium acnes (C. acnes) or suppress sebum production, but C. acnes makes up 60–70% of a healthy skin microbiome. Wiping C. acnes out destabilises the system.

“Only a handful of C. acnes strains are actually linked to acne. Acne is a strain-level problem, not a single-bacteria problem. That’s why many treatments work temporarily, but acne returns once the skin tries to rebalance itself.”

WHAT ADVICE WOULD YOU GIVE PRACTITIONERS DEALING WITH ACNE OR SENSITIVE SKIN?

“First, back off harsh surfactants. Over-cleansing strips sebum, which triggers rebound oil production and worsens acne. Mild cleansing, and even just water in the morning, is often better.

“Secondly, feed the microbiome. Skin microbes primarily eat sebum and fatty acids, not sugar-based prebiotics designed for the gut. Supporting the skin’s natural lipids helps restore balance and barrier function. Around 70% of people now identify as having sensitive skin, pointing to a compromised barrier. A healthy microbiome is the skin’s first line of defence and plays a constant role in calming the immune system.”

WHERE DO YOU SEE SKIN MICROBIOME RESEARCH HEADING IN THE NEXT FIVE YEARS?

“Towards precision and targeted therapies. Sequencing will become a diagnostic tool, allowing us to identify the exact strain causing a problem and treat it directly, potentially with bacteriophages instead of broad-spectrum antibiotics. We’re also working on skin microbiome transplants, where microbes from a healthy area of a person’s skin are reintroduced to a problem area. It’s an exciting space, and I believe that in the near future, healthy skin microbes will be seen as just as essential as healthy gut microbes.”

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Trevor Steyn sadly passed away on November 1, 2025. He was a visionary chemist and entrepreneur, at the forefront of probiotic and microbiome research and, through Esse, he helped pioneer a new era of personalised, microbiome-focused skincare.