Skin Microbiome 101: How To Nurture Good Bacteria & Glowing Skin

We typically think of skin only as it relates to beauty—but it's essential to our overall health, too. After all, it's the largest organ in the body and the major interface between us and pretty much everything outside of us. Our skin is also home to a vast array of microbes, and research has just begun to piece together the important role they play in our health and more exciting research is on the horizon.

Here's the 101 on the skin microbiome and how to care for yours.

The skin microbiome1, sometimes called the skin flora, is the term for the trillions of bugs2 that live on our skin. There are 1,000 different bacterial species and up to 80 different fungi species. Some of these are also residents of your gut microbiome, including Staph, Strep, and Candida species. There are also a few Bifidobacterium and Lactobacillus species on certain areas of the skin but much less so than in the gut.

The skin microbiome changes depending on the "eco-niche3," or location. The critters also vary depending on the amount of light and whether the area is moist, dry, hairy, or oily. And the microbiome differs with age and gender. For instance, a hormonal, sweaty teenage boy sports a very different microbiome than a sedentary, postmenopausal woman.

We once thought that our microbiome only existed on the surface of the skin and that the deeper dermal layers were sterile. We now know that's not true. In 2013, scientists did a deep dive4 into the dermis looking for microbes, which were found all the way to the subcutaneous fat layer. While the researchers noted that more studies are needed, it appears that the most intimate communication between the microbiome and our immune system takes place at this layer.

From what we can tell, a healthy skin microbiome protects against infection in much the same way a good gut microbiome does: by crowding out overgrowth of pathogenic organisms. The skin microbiome prefers a relatively acidic environment (pH is around 5.0), which also inhibits the growth of pathogens.

The microbiome and skin immune system "talk" to each other regularly, dampening inflammation. When the microbiome is out of line, the immune system can release various antimicrobial peptides5 such as cathelicidin to help balance things out. Likewise, our good bacterial residents can inhibit the release of inflammatory compounds from the immune system.

The microbiome also aids in wound healing, limits exposure to allergens, minimizes oxidative damage, and keeps the skin plump and moist. In fact, new research shows that it can protect us from harmful UV rays. The study found that when mice with the bacteria Staphylococcus epidermidi were exposed to UV rays, they developed significantly fewer tumors than the mice without it.

You're probably familiar with the idea that loads of antibiotics, other medications, and a poor diet can damage the gut microbiome. This is called the "hygiene hypothesis," and there's a lot of research6 to support this important concept.

Ditto for the skin microbiome. Use of antimicrobial hand sanitizers and soaps are important for hygiene and protecting us against sickness—but it does contribute to skin dysbiosis and antibiotic resistance, thus stoking various skin conditions7, research shows. An imbalanced microbiome, or skin dysbiosis, is associated with many health conditions, including psoriasis, allergies, eczema, contact dermatitis, acne, poor wound healing, skin ulcers, dandruff, yeast and fungal infections, rosacea, and accelerated skin aging.

It's compromised by way of two factors: what you put on our skin, and what you put in your body.

So if you're addicted to "clean," you could be damaging your skin microbiome. Take soap and sulfates, for example: By their very nature, it's alkalinizing. That's how it works to remove dirt and microbes. But recall that our skin microbiome prefers a pH of about 5. At this relatively acidic pH, the healthy microbiome thrives. It's also understood that the opportunistic bacteria—the dysbiotic players—do better at a higher, more alkaline pH. And soap has a pH of up to about 10. Thus, we may actually be damaging our microflora with soap or other alkaline topical products and setting the stage for increased risk for skin issues.

Also interesting: A recent study showed that kids who hand-wash dishes have a lower incidence of allergies compared to those in families that use a dishwasher. That sounds paradoxical given what I've just mentioned about soap, but the authors speculate this has to do with the benefits of skin exposure to the microbes on the dirty plates.

New research shows that anything damaging to your gut microbiome8 also influences what's happening to the skin. It's called the gut-skin axis, and scientists are just beginning to understand the connection. To date, much of the research has been done on the gut-acne connection, but the connection is strong: "The lines of communication, as mediated by gut microbes, may be direct and indirect, but ultimately influences the degree of acne by a systemic effect on inflammation, oxidative stress, glycemic control, tissue lipid levels, pathogenic bacteria, as well as levels of neuropeptides and mood-regulating neurotransmitters."

While this is a very recent area of study and hypothesis, most dermatologists and experts are coming to the understanding that the very act of applying too many skin care products has the potential to damage our skin barrier and throw our biomes out of whack. This is likely because potent actives in topicals change the behavior of the skin, and therefore the bugs that live on it.

It's good to get outdoors and in nature for your physical health, mental health, and it turns out, your microbiome. And unfortunately, people are increasingly living in urban environments—some without regular access to green parks, meaning human micro floras are becoming less diverse overtime.

In fact, research finds that contact with nature—or the lack of contact—directly influences your microflora diversity. "In industrialized countries, non-communicable diseases have been increasing in prevalence since the middle of the 20th century," the study elaborates. "While the causal mechanisms remain poorly understood, increased population density, pollution, sedentary behavior, smoking, changes in diet, and limited outdoor exposure have all been proposed as significant contributors."

The study went on to show that exposing yourself to greenery—be it the rugged outdoors or even urban green landscapes—improves the diversity of your microflora9 in a beneficial way. And what's happening is actually simple: The microbes found in nature literally transfer to your skin (and nasal) biomes through the simple act of touch and breathing. (While this is exciting to understand how closely human and earth biomes can be connected—the researchers couldn't draw any conclusions on long-term benefits of this exposure yet, and noted more research should be done in this area so we can better understand how to improve our skin microbiomes.)

If you think you might have done some damage to your microbiome over the years, the good news is you can help support its function. Here's how:

I recommend good fats, proteins, carbohydrates, colorful vegetables, and clean water. Keep processed foods and extra sugar out of the diet. Research shows that what you put in your mouth indeed influences your skin10 and skin microbiome in many ways.

Since we know that your skin microbiome may be influenced by internal inflammation, look to limit foods that are known skin irritants. For example, dairy and gluten are both associated with exacerbating a range of skin issues, including eczema and acne.

As we know that skin issues are influenced by the gut microbiome and gut health in general, I recommend taking a daily high-quality probiotic. Much research exists on the use of probiotics in supporting a healthy gut and therefore skin microbiome.*

Let your microbiome thrive. While, yes, it's critical to practice good hygiene, it's also important to make sure you are still letting the good bacteria stick around on your skin. While easier said than done right now, you can tend to your skin by using more gentle surfactants (look for coconut derived surfactants, rather that sulfates and detergents), as well as hand sanitizers that are buffered with ingredients like aloe vera to help keep your skin barrier in check. Finally, make sure you moisturize your hands regularly after washing and sanitizing.

If you're eating well, the sweat you produce is likely a fortifying prebiotic for the skin microbiome. Not to mention, working out leads to better skin health overall, as board-certified dermatologist Whitney Bowe, M.D., tells mbg, "When you exercise, you increase the blood flow to your skin, nourishing your skin with vital nutrients and oxygen."

Just as elsewhere in the body, stress likely negatively influences what's happening with your skin. Find a stress management method that works best for you, such as yoga or meditation.

However, it's just about using topical biotics—in conjunction with these, you must also use hydrating and barrier supporting ingredients, as well as skipping harming ingredients (like the surfactants mentioned above.) Finally, if you are one to DIY, research also shows that kefir or yogurt on skin also may benefit the microbiome.

With each passing year, we come to realize more and more how important our skin microbiome is for our overall health. Not only will it help our skin aesthetically, it helps protect our body. If you want to make sure your microflora is flourishing, just be mindful of harsh products and keep your skin moisturized.