The world of skincare has seen rapid innovation beyond classic hydrating serums and exfoliants. Among the newest frontiers is the use of postbiotics and fermentation filtrates — ingredients derived from microbial fermentation that support the skin’s natural barrier function, help reduce transepidermal water loss (TEWL), and encourage a balanced skin microbiome.
But what exactly are postbiotics, and how do they scientifically support skin health? Let’s break this down.
What Are Postbiotics and Fermentation Filtrates?
Postbiotics are defined as preparations of inanimate microorganisms and/or their components that confer a health benefit on the host — in this case, your skin. They include metabolites like short-chain fatty acids (SCFAs), peptides, polysaccharides, and other bioactive compounds produced during fermentation of probiotic bacteria like Lactobacillus and Bifidobacterium or yeasts like Saccharomyces cerevisiae.
Fermentation filtrates are the liquid extracts collected after fermentation. They contain vitamins, amino acids, enzymes, antioxidants, and microbial metabolites that can act on skin barrier mechanisms and hydration pathways.
Together, they are increasingly featured in serums, essences, and creams targeted at barrier repair, hydration, and microbiome support.
- Reducing TEWL and Improving Hydration
Transepidermal water loss (TEWL) measures how much water escapes from the skin — an indicator of barrier integrity. Lower TEWL means better retention of moisture and a stronger barrier.
Clinical and lab evidence shows that postbiotic-rich filtrates can significantly reduce TEWL and increase hydration:
- Bifida ferment filtrate in topical essence was associated with a statistically significant decrease in TEWL and improved stratum corneum hydration in human tests over 28 days.
- Research indicates that lysates or filtrates from Lactobacillus species can support hydration and barrier function by increasing expression of structural proteins like filaggrin, involucrin, and loricrin — all key for tight SC integrity.
These effects align with what scientists observe when barrier-strengthening molecules enhance lipid synthesis and structural cohesion in the epidermis, slowing water loss and improving resilience.
- Stratum Corneum Lipid Synthesis and Structural Support
Postbiotics don’t just preserve moisture — they can actively support the biochemical pathways that rebuild the barrier.
In vitro studies show that filtrates from Bifidobacterium fermentation upregulate genes related to:
- Barrier structure (e.g., FLG, TGM1),
- Antimicrobial peptides that help fend off harmful microbes,
- Antioxidant systems that guard against oxidative stress.
These genes are central to producing ceramides, fatty acids, and natural moisturizing factors that make the stratum corneum more cohesive and effective.
- Microbiome Balance and Immune Modulation
The skin’s microbiome — the community of bacteria and fungi living on the surface — is crucial for barrier defense. Pathogenic overgrowth (like Cutibacterium acnes or Malassezia) can contribute to inflammation and barrier breakdown.
Fermentation filtrates and postbiotic extracts have been shown to:
- Reduce proportions of harmful microbes like Cutibacterium acnes and Malassezia while preserving commensal bacteria.
- Display antioxidant and anti-inflammatory activities that mitigate irritation while maintaining microbial balance.
By influencing pH and delivering metabolites such as organic acids and polysaccharides, postbiotics can help nurture beneficial microbes and suppress pathogens — a balancing effect that supports barrier function and reduces inflammatory stress.
Putting It All Together: What This Means for Your Skin
This combination of effects creates a synergistic path to barrier recovery — not just symptomatic moisturizing, but biochemical reinforcement of the skin’s natural defenses.
Skincare postbiotics and fermentation filtrates are more than marketing buzzwords. Emerging scientific evidence shows that they interact with the skin’s structural, microbiological, and immune systems to enhance barrier function and resilience. From improving hydration and reducing TEWL to promoting structural lipid synthesis and microbiome balance, these bioactive ingredients represent a promising evolution in barrier-focused skincare.
As research continues, we expect even deeper insights into the specific metabolites and mechanisms that make these ingredients so effective — and tailored formulations to maximize benefits for different skin types and concerns.
References (APA Style)
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