Science Reviewed · Boldpurity Science Team
Last reviewed: July 2026
Quick Answer
Fermented ingredients — like Saccharomyces (yeast) ferment — are a gentle, modern approach to skincare. Paired with N-Acetylglucosamine (NAG), they can offer mild, kind exfoliation that helps with the appearance of texture and tone, without the harshness of strong acids. NAG works differently from acids: instead of dissolving the bonds between dead cells, it gently discourages them from clumping — so skin sheds more naturally. Fermented ingredients are gentle enough for most skin types, including sensitive skin, and sit in the Prep step.
Key Facts About Fermented Ingredients & NAG
- Fermented ingredients are made using microorganisms (like yeast) — a biotechnology approach.
- Saccharomyces ferment is a popular fermented skincare ingredient.
- N-Acetylglucosamine (NAG) is a gentle exfoliant — part of hyaluronic acid's natural structure.
- NAG works gently — it doesn't dissolve cell bonds the way strong acids do.
- Fermentation lets brands make ingredients (like squalane, NAG) without harming animals or intensive farming.
- Gentle enough for most skin types, including sensitive skin.
- Don't layer with other exfoliants (acids, scrubs) — risk of over-exfoliation.
Key Takeaways
- Fermented ingredients offer a gentle, modern route to smoother-looking skin.
- NAG gently exfoliates by discouraging dead cells from clumping — kinder than acids.
- Suitable for most skin types, including sensitive.
- Sits in the Prep step, after cleansing.
- Don't combine with other exfoliants to avoid over-exfoliation.
- Fermentation is also a more sustainable, animal-friendly way to make ingredients.
What Are Fermented Ingredients?
Fermented ingredients are made using microorganisms — like yeast or bacteria — in a process similar to how bread, yoghurt, and wine are made. In skincare, fermentation (a form of biotechnology) is used to create or transform ingredients gently and sustainably. Saccharomyces ferment is a yeast-based ferment popular for its skin-conditioning qualities. Fermentation is also how modern skincare produces ingredients like N-Acetylglucosamine (NAG) and squalane without relying on animal sources or intensive farming.
Fermentation isn't new — humans have used it for thousands of years to make food and drink. But in skincare, fermented ingredients have become one of the most interesting modern developments: a way to deliver gentle, effective results using biotechnology instead of harsh chemistry.
Let's look at what fermented ingredients do, how the gentle exfoliant NAG works, and why fermentation is also a more sustainable choice.
How NAG Gently Exfoliates
N-Acetylglucosamine (NAG) is a naturally occurring molecule — in fact, it's part of the structure of hyaluronic acid in the body. As a skincare ingredient, it offers a notably gentle form of exfoliation.
The "Key in a Keyhole" Idea
Dead skin cells are held together by tiny links (corneodesmosomes). Strong acids dissolve these links forcefully. NAG works differently — it gently occupies the space and discourages cells from forming those links in the first place, like a key sitting in a keyhole. This helps the skin shed dead cells more naturally and kindly — supporting the appearance of smoother, brighter skin.
NAG vs. Direct Acids
| Feature | NAG (Gentle) | Direct Acids (AHA/BHA) |
|---|---|---|
| How it works | Discourages dead cells from clumping | Dissolves the bonds between dead cells |
| Intensity | Gentle, gradual | Stronger, faster |
| Sensitive skin | Usually well-tolerated | Can be irritating |
| Frequency | Often suitable for daily use | Usually 2–3× per week |
Gentle Doesn't Mean "Do Both"
Because NAG is gentle, it's tempting to layer it with acids for "extra" exfoliation. Don't. Combining exfoliants — even gentle ones — risks over-exfoliation and barrier damage. Pick one approach. (See our exfoliation guide.)
What Fermented Exfoliation May Help With
Smoother-Looking Texture
Gently encouraging natural cell turnover may support the appearance of a smoother surface.
Brighter Appearance
Clearing dead-cell buildup may reveal a fresher, more radiant-looking complexion.
More Even-Looking Tone
NAG may help with the appearance of uneven tone and the look of dark spots over time.
Hydration Support
Fermented toners are often paired with hydrating ingredients like squalane for a comfortable, non-stripping feel.
The Sustainability Angle
Kinder to Animals and the Planet
Fermentation and biotechnology let modern skincare replicate ingredients that were historically sourced in less sustainable ways:
- Squalane — once derived from shark liver, now made sustainably via fermentation or plants
- NAG — historically from algae or plants, now produced through bacterial fermentation
This means effective ingredients without unnecessary harm to animals or intensive farming.
How to Use Fermented Exfoliating Toners
- Cleanse first — apply after cleansing, in the Prep step
- Apply with hands or a cotton pad — a few drops, patted or swept gently
- Use as directed — many gentle fermented toners are suitable for AM and PM, but follow the product's guidance
- Don't layer with other exfoliants — no acids or scrubs in the same routine
- Follow with serums and moisturiser — continue your Treat and Seal steps
- Use SPF in the AM — any exfoliation can increase sun sensitivity; daily sunscreen is essential
- Patch test first — as with any new active
Where It Fits in Your Routine
1. Prep
Cleanser → fermented toner (generic) / AquaBlur™
3. Seal
Moisturiser → SPF 30+ (AM)
A Note on Products
Boldpurity does not currently manufacture a fermented or NAG-based exfoliating toner. All fermented-toner recommendations here are generic. Our AquaBlur™ Bubble Toner Serum sits in the same Prep step but is a hydrating toner serum, not a fermented exfoliant — the two are different products. If you use a fermented exfoliating toner, you likely don't need an additional exfoliant. Note: AquaBlur™ contains fragrance and is not labelled fragrance-free.
Your Questions, Answered
What are fermented skincare ingredients?
Ingredients made using microorganisms like yeast or bacteria — a biotechnology process similar to making yoghurt or wine. Saccharomyces (yeast) ferment is a popular example. Fermentation is a gentle, sustainable way to create skincare ingredients.
What is NAG (N-Acetylglucosamine)?
A gentle exfoliating molecule that's naturally part of hyaluronic acid's structure. Unlike acids, it discourages dead cells from clumping rather than dissolving their bonds — a kinder form of exfoliation suitable for most skin types.
Is fermented exfoliation good for sensitive skin?
Generally yes — NAG and fermented toners are usually gentler than direct acids, making them a good option for sensitive skin. As always, patch test first and stop if irritation occurs.
Can I use it with other exfoliants?
No — don't layer it with acids or physical scrubs. Even though it's gentle, combining exfoliants risks over-exfoliation and barrier damage. Choose one exfoliating approach.
Is fermented skincare more sustainable?
It can be. Fermentation lets brands make ingredients like squalane (historically from shark liver) and NAG (historically from algae/plants) without animal sourcing or intensive farming.
Do I still need sunscreen if I exfoliate gently?
Yes — any exfoliation can increase sun sensitivity. Daily broad-spectrum SPF 30+ is essential, especially when using any exfoliating product, gentle or not.
Gentle, Modern, Sustainable
Fermented ingredients and gentle exfoliants like NAG represent a kinder, more modern approach to smoother-looking skin. They work with your skin's natural processes rather than against them — suitable for most skin types, gentle enough for sensitive skin, and often more sustainable too. Just remember: gentle still counts as exfoliation, so don't double up, and always wear your SPF.
References
- India Cosmetics Rules, 2020 — CDSCO
- ASCI Code for Self-Regulation in Advertising, 2021
- Bissett DL. "Common cosmeceuticals." Clin Dermatol. 2009;27(5):435–445.
- Mukherjee S, et al. "Retinoids and other cell-turnover agents." Clin Interv Aging. 2006;1(4):327–348.
Disclaimer
This article is for informational purposes only and is not medical advice. Boldpurity does not currently manufacture a fermented or NAG-based product; all such recommendations are generic. AquaBlur™ is a hydrating toner serum, not a fermented exfoliant, and contains fragrance. All cosmetic claims refer to the appearance of the skin. In line with ASCI Code 2021 and India Cosmetics Rules, 2020. Results may vary. Patch test before use.
