Dahlia Devkota does not exfoliate. She does not apply acid peels or retinols. She does not coat her face with sunscreen on a blazing summer day. She prefers no chemical interference between her skin and the wild, filthy, chaotic world. As she sits across from me on a Saturday morning, she looks as dewy and fresh as a well-rested, not-hungover 29-year-old. “As I’ve aged, I’ve done less to my skin, but still I have the best skin of my life.” She’s 48. I’m sold.

What she’s selling is a collection of skin-care products that aim to help support the skin’s microbiome. You know, germs. Bugs. It’s the hottest territory in skin-care today, and among the most confusing.

You’ve heard of the microbiome, but probably only in connection with the gut, which hogs all the attention, the way the stomach tends to do.

“The microbiome is the skin’s healthy bacteria,” says Ron Robinson, a cosmetic chemist and creator of a skin-care line called BeautyStat. “It’s getting a lot of attention because people are talking about the gut microbiome. The microbiome helps skin function at its best.”

The bacteria living on the skin produces a compound that has numerous benefits, protecting the skin barrier from moisture loss, and the dryness, irritation, and inflammation that follow. It helps the skin develop its own defenses against rashes, rosacea, and acne.

Want to know something fun? All of these natural benefits decrease with age.

Ah, but the gut microbiome would like a word (again). When it’s impaired—thanks in part to the trash Western diet—trouble often shows on the skin. Researchers have already connected problems in the gut microbiome with acne, atopic dermatitis, eczema, psoriasis, and rosacea. “In the future, we may be taking supplements for the gut, which will then help the skin,” says Dr. Leslie Baumann, a dermatologist, the founder of the University of Miami’s Cosmetic Medicine and Research Institute, and the author of The Skin Type Solution.

Just as we destroy the gut microbiome with processed food, we also destroy the skin microbiome with products intended to clear, smooth, and soothe it. If you grew up in the 80s, that might have meant Sea Breeze astringent followed by scouring with a Buf-Puf, as Dr. Baumann used to do. If you’re a proud skin-care consumer today, it’s face scrubs, acid peels, toners, pimple patches, lasers, and so much more.

“People use products to fix problems they don’t have, and then they cause more problems they didn’t have,” says Dr. Baumann. As Robinson says, “Consumers think if one product is good then two or three things at a time are better. And then they see how that disrupts the microbiome and the barrier. As brands and marketers, we create all these products not realizing consumers would use them all at once.”

For years, Dr. James Hamblin, a lecturer at the Yale School of Public Health, gave up shampoo, conditioner, exfoliants, moisturizers, deodorants, and soap—except on his hands. Also showers. His aim was to examine the emphasis on cleanliness in our culture and our overdependence on soap and skin-care products for his book, Clean: The New Science of Skin. His microbiome triumphed. And his marriage survived. Now, he uses soap “strategically” on an “as-needed basis,” he says.

Devkota also makes a plea for simplicity, but one with slightly more products. “When you’re constantly washing the face and putting on too much makeup you’re confusing the microbiome and reducing biodiversity,” she says. “It’s better to do nothing than to do all these things.”

Well, maybe not exactly nothing. After all, she created Editrix, four skin-care products intended to “facilitate the environment so your microbiomes are actually able to do the work,” she says.

It sounds so easy, and yet “we still do not know what the optimal bacteria on the skin are,” says Dr. Baumann. “We do not know what a ‘balanced’ microbiome is. We do know that diversity of bacteria is important.”

The best way to encourage a robust, diverse population of skin microbes doesn’t sound like a party, but maybe that’s me. Step one: pack your gunnysack. Step two: hop in a horse-drawn buggy. Step three: head to Amish country. Step four: plant some crops and milk some cows. Numerous studies have shown that exposure to soil and farm animals may contribute to the wonderfully clear skin and remarkably few allergies seen in Amish communities.

It’s the hottest territory in skin-care today, and among the most confusing.

I’m happy for them. And still, I prefer to get my microbiomes at Knockout Beauty.

Many of these new products on the shelves try to add probiotics to the skin, but that’s not the answer. “It’s like putting a drop of dye in the ocean and expecting it to change color,” says Devkota. “The moment you have a living bug in a formula with a preservative, the preservative will kill it immediately.” Instead, you want to protect the skin’s acid mantle—the fine film on its surface—and re-populate the skin with living bacteria.

First, pick a cleanser with a low pH and no surfactants, which means it doesn’t strip the skin of healthy bacteria or compromise its acid mantle. From there, Devkota adds a face spray containing postbiotics made of what she calls, deliciously, a “biodiversity broth.” Working under the guidance of her sister Dr. Suzanne Devkota, the director of the Human Microbiome Institute at Cedars-Sinai Medical Center, in Los Angeles, she extracted staphylococcus epidermidis from human skin and purified it in a lab, then fermented it to yield a multitude of postbiotics. Got it? The by-product of this bacteria includes amino acids, lactic acid, salicylic acid, proteins—“hundreds of beneficial ingredients that human skin needs to thrive,” says Devkota.

You have not heard the end of this delightful bacteria, and already some of the claims made by some of the products are fantastical. One Web site for a new probiotic skin-care line says its serums “prevent premature aging in skin … and even protect against cancer.” I can almost feel Dr. Baumann’s eyes rolling over the phone. “Seems very far-fetched to me,” she says.

Dr. Baumann believes the microbiome is the future of skin care. “But I think we’re 10 years away before we know anything,” she says. One day, just maybe, we’ll find that the skin microbiome benefits the gut as much as the gut helps the skin. Perhaps we’ll also discover, as some scientists suspect, that these microbiomes have positive effects on our immunity and our mental health. It almost makes you want to get a little dirty.

Linda Wells spent 25 years as Allure magazine’s founding editor, served as Revlon’s chief creative officer, and currently consults and sits on the boards of several beauty and apparel companies