Over the last five years, the brains behind big beauty brands have become acutely aware of the importance of the skin microbiome—the ecosystem of bacteria that lives on the surface of your skin and helps to protect it from the outside world. “We know that skin has its own natural flora of bacteria, and if you can keep that intact or enhance that, you can [coax] your skin into doing a lot of other healthy things like calming inflammation, helping acne, eczema, and rosacea,” says Rachel Nazarian, MD, a board-certified dermatologist based in New York City. And that’s where fermented ingredients come in. Keep reading to find out how.

Fermentation delivers more potent ingredients

Before we dive into exactly how fermented ingredients work to benefit the skin, it’s important to understand what, exactly, they are. “Fermentation is a process where you introduce a microbe, bacteria, or yeast into an ingredient, and the process changes the chemical structure of the ingredient by breaking it down into the basic building blocks,” says Caroline Chang, MD, a board-certified dermatologist with The Rhode Island Dermatology Institute. In the food world, this is how you wind up with things like kimchi (or wine), but in the skin-care world, you get more potent ingredients.

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These “basic building blocks” include vitamins, essential minerals, and amino acids in their purest form. Because they’ve been broken down by the microbes, bacteria, and yeast (in a lab, long before you actually apply them to your face), you’re left with smaller, more concentrated molecules that are ready to get to work in skin. “Given the fact that fermentation causes the molecules to be smaller, they tend to absorb better,” says Dr. Chang. In other words, the fermented versions of some of your favorite ingredients will give you more bang for your buck.

“Because of this natural process, fermented skin-care products generally contain higher, more potent concentrations of vitamins and antioxidants, which help to fight free-radical damage and protect against UV damage,” says Dr. Chang. Fermentation can also produce fruit and sugar acids, which exfoliate skin for a healthy glow, plus amino acids, which act as the building blocks of peptides to help fight fine lines and wrinkles.

The link between fermentation and the skin microbiome

Aside from the fact that they tend to deliver a laundry list of potent ingredients, what’s really exciting about fermented products is their ability to help balance the skin microbiome. The fermentation process creates something called postbiotics, or the chemical byproducts of bacteria, which show up in the form of peptides, enzymes, and acids. “The side effects in these chemical reactions create postbiotics that also have anti-inflammatory benefits,” says Dr. Nazarian. “You’re enhancing your skin with a better environment for calmer, less inflamed skin, and a more intact skin barrier.” A postbiotic ingredient you’re likely already familiar with? Lactic acid, which comes from fermented milk and is known for being one of the gentlest chemical exfoliants money can buy.

In addition to postbiotics, fermentation also leaves you with probiotics, another member of the “biotics” family (which refers to “living organisms,” like bacteria)  believed to help balance the microbiome. “These are the environmental substances that help support the health and strength of the microorganisms that make up skin’s microbiome, allowing them to do their job more effectively,” says Tiffany Masterson, Drunk Elephant founder. While more research needs to be done to confirm the effectiveness of topical probiotics, it’s purported that they help to make your microbiome a more hospitable home for the good bacteria it needs to function properly.

Fermented ingredients to look for

Since there are many different kinds of fermented ingredients, the one that’s best suited for your routine comes down to what skin issues you’re looking to treat.

For fighting fine lines and wrinkles: Amino acids

“If you have fine lines, look for products with amino acids which help to firm skin,” says Dr. Chang. Amino acids are the building blocks of protein (you may remember that from high school chem), and applying them topically will help build collagen beneath the surface while also boosting hydration and calming inflammation. The result, as Dr. Chang notes, is a firmer and tighter complexion overall. Most amino acids in skin care come by way of the fermentation process, so if you see the term on the label, it’s safe to assume you’re getting all of the skin-supporting benefits of a fermented product.

1. The Ordinary Amino Acids + B5, $7

This serum  combines ingredients that are already found in your skin’s natural moisturizing factors—aka amino acids and niacinamide—to enhance barrier support while balancing your complexion and improving elasticity. It helps to tighten up your skin while also boosting hydration, and will aid in smoothing out fine lines and wrinkles all over.

Shop now: The Ordinary Amino Acids + B5, $7

2. Benton Fermentation Essence, $27

Anything with two or more amino acids is known as a peptide, and this ferment is packed with them. It’s made with a fermented yeast called “galactomyces ferment filtrate,” which has brightening and plumping effects. It’s also got bifida ferment lysate, another yeast-derived ferment that helps to balance the skin’s microbiome to protect it from environmental stressors.

Shop now: Benton Fermentation Essence, $27

For brightening: Sugar acids

Though you may not realize it, many of the chemical exfoliants that are already in your routine come from fermented ingredients: Alpha-hydroxy acids are actually a byproduct of plant fermentation. Glycolic acid is fermented sugar, mandelic acid comes from almonds, and (as mentioned) lactic acid comes from milk. “If a brightening effect is what you’re after, look for products with fruit and sugar acids,” says Dr. Chang. These acids work to weaken the bonds between dead skin cells and the surface of your skin, whisking them away to allow fresh, new cells to shine.

1. Biossance Squalane + 10% Lactic Acid Resurfacing Night Serum, $62

This gentle exfoliating serum combines vegan lactic acid with clover, which encourages cell renewal and calms stressed skin, plus moisture-locking squalane. It’s great for all skin types including dry, sensitive, and acne-prone, thanks to its gentle nature, and won’t irritate skin as it exfoliates.

Shop now: Biossance Squalane + 10% Lactic Acid Resurfacing Night Serum, $62

2. Maelove Night Renewer Glycolic Acid Cream, $28

The formulators at Maelove spent years trying to formulate a peel that was gentle enough to be used on sensitive skin, and this overnight cream was the fruit of their labors. It’s made with nourishing ingredients like vitamin E, squalane, shea butter, arnica, and aloe, plus hydrating hyaluronic acid. These ingredients, plus glycolic acid (aka fermented sugar) work together to resurface your complexion without any harsh side effects.

Shop now: Maelove Night Renewer Glycolic Acid Cream, $28

For environmental protection: Fermented antioxidants

Antioxidants are an important part of any a.m. routine, thanks to the fact that they help defend against environmental factors, like pollution and UV rays, which cause free radical damage. While antioxidants in any form are great, using a fermented version can offer even more protection. “The fermentation process cultivates and increases antioxidant compounds significantly, specifically phenolics and flavonoids, by breaking down and potentiating the plant or fruit material,” says Masterson. Black tea, for example, is rich in antioxidant compounds, but when it’s fermented into kombucha, its antioxidant power becomes even more potent… and that translates into skin care. “Phenols, [one of the antioxidants in black tea that increases in the fermentation process], are particularly beneficial to skin due to their broad-spectrum antioxidant activity, helping to defend and ward off multiple forms of oxidative damage,” she says.

1. Drunk Elephant Sweet Biome Fermented Sake Hydrating Spray, $42

When creating this antioxidant-packed product, Masterson was inspired by—wait for it—sweat. “Sweat is full of lipids, amino acids, electrolytes, and minerals that your skin barrier needs” says Masterson. “I thought, ‘what if we make a spray that has all of those healthy, nourishing components so that it strengthens the acid mantle and also nourishes your microbiome?'” The formula combines sake (fermented rice water, which is known to be hydrating) with kombucha (a black tea ferment that’s rich in antioxidants) and electrolyte-packed sodium PCA to act as a “nutritional booster for your skin,” says Masterson, adding that “the skin will recognize the ingredients, and your acid mantle and microbiome will be healthier for it.” In addition to giving your complexion a spritz of hydration, this product’s antioxidant prowess helps it to fend off environmental stressors, including blue light.

Shop now: Drunk Elephant Sweet Biome Fermented Sake Hydrating Spray, $42

2. Fresh Kombucha Cleansing Treatment, $44

This no-rinse cleanser serves double duty in fighting off oxidative stress from the environment. For starters, it helps wipe away any remnants of dirt and pollution on your skin (the way any good cleanser does), but then also delivers powerful antioxidant protection to keep your complexion protected throughout the day. It’s made with a plant-based extract called prebiotic insulin, which feeds the bacteria living on your skin. This serves to better balance your microbiome, which better fortifies it to be able to fend off environmental stressors. The formula has also got kombucha, one of the antioxidant stars of the ferment world, which helps to further strengthen your skin’s defense system.

Shop now: Fresh Kombucha Cleansing Treatment, $44

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