New Research Suggests The Microbiome Plays A Role In Helping The Skin Deal With The Sun

There’s little that feels better than the sun on your skin. Bright summer rays gently warming the body. The freedom of shedding layers. The relief of a cool breeze. These sun-soaked moments are meant to be savored.

We associate this warmth with vitality, improved mood, and even a certain radiance. And for good reason, as research shows us the sun can improve mental health, increase vitamin D, and is associated with a variety of long-term health benefits. But beneath this sunlit euphoria, your skin is engaged in quiet negotiation with the sun’s rays. 

For all that the sun gives us, it also damages your body’s largest organ. UV radiation affects DNA and RNA, breaks down collagen, triggers melanin overproduction, reduces our skin’s immune function, and encourages cancer cell growth.  

So here we are at a curious crossroads: for as life-giving as the sun is for our bodies, why is it as equally destructive for our skin? 

The skin microbiome, also called the skin flora, refers to the trillions of organisms 1that live on the skin. This includes over 1,000 different bacterial species, 80 different fungi species, viruses and more. 

In a thriving, diverse ecosystem, these organisms play a vital role in several skin functions. It communicates with our immune system, helps prevent infection, moderates inflammation, and protects against common concerns like acne, fine lines, dark spots, and sagging.

What makes the microbiome especially fascinating is its variability. It changes depending on the skin’s microenvironment or “eco-niche”2: whether an area is oily, moist, dry, or hairy. It also shifts with age, gender, habits, and environment.

And it’s changed dramatically over time. Due to modern living and environmental shifts, skin microbiome diversity has declined significantly. Some estimates suggest up to 80% of species have been lost. Much of this loss is tied to the reduction of the skin’s "biofilm," a once-abundant surface layer of microbial protection that humans have all but lost. 

The microbiome is made up of two parts: The surface of our microbiome (the biofilm) that’s fluid and malleable and the engrafted part that is not. In our youth, we become engrafted with a microbiome3 that lives in our tissues. This engrafted microbiome is responsible4 for dictating what strains are able to populate our skin and what are not, or what's known as colonization resistance. 

The biofilm, on the other hand, harmonized us with the world around us and they protected us from oxidative stress (or oxidization or inflammaging or free radical skin damage—whatever you want to call it). And this loss is something we deal with every single day. 

There is still a tremendous amount of information we don’t know about this biofilm and the microbiome in general. It’s an area of study that we’ve only just scratched the surface. But from our current understanding, this diverse ecosystem of organisms used to take in the environment around us, metabolise it, and create beneficial byproducts (often called postbiotics).

And it may have done this for UV rays too: The biofilm absorbed radiation, turned it into energy, and then drove metabolic pathways that supported the skin and full body health. 

“It created a path for high energy free radicals to cascade down and do constructive work rather than destructive work. So that when it reaches the deeper layers of the skin, it would be beneficial for us, such as helping produce vitamin D,” says biotech expert and physician Larry Weiss, M.D., founder of Symbiome. “The damage we talk about—free radicals, oxidative stress—is predominantly caused because the UV rays didn’t go through that biofilm.”

Interestingly, even without this biofilm, research shows that even our engrafted microbiome offers us some defense. 

For example, a 2025 study published in the Journal of Investigative Dermatology looked at how certain commensal microbes can mitigate UVB light, the type of ultraviolet radiation that causes sunburn and can affect the immune system. It does so because when our skin is exposed to UVB, it produces a molecule called cis-urocanic acid, which suppresses the immune response.

The study found that specific skin bacteria—like Staphylococcus epidermidis—contain an enzyme called urocanase that can break down this molecule. By doing so, these bacteria reduce the immune-suppressing effects of UVB exposure, helping the skin respond in a healthier way. 

Another recent study5 published in the journal Research in Microbiology in 2023 found that the skin microbiome actually adjusts to time in the sun. Researchers swabbed skin prior to and following periods of sun exposure, and they found that the microbiome changed accordingly. Interestingly, they saw an increase in two bacterial families—Sphingomonas and Erythrobacteraceae—which may have the ability to protect against UV radiation as they produce potentially protective compounds. 

This is all very exciting, promising research. It opens opportunities for radical, innovative ways to protect our skin from UV radiation, oxidative stress, and inflammaging. 

For example, Symbiome launched The Essence Rejuvenating Mist at the end of last year. This mist (which I use daily) is made with the brand’s signature Postbiomic™ microbial lysates and enzymes which help mitigate sunburn, cellular deterioration, and provide defense against reactive oxygen species (ROS). Essentially, the mist helps replenish what was lost with the biofilm, Weiss explains.  

We’re at the start of a major shift in how we care for skin. Instead of viewing sun exposure as a purely external threat, we can begin to understand it as part of a larger, microbiome-mediated interaction. New tools may even allow us to rebuild and support these ancient systems of protection.

This doesn’t mean abandoning sunscreen or basic sun safety. Instead, it means expanding our toolkit. It means supporting the skin’s microbiome with barrier-friendly products, nourishing lifestyles, and innovations that reconnect us with the evolutionary biology we’ve lost.