For a long time, the word “biotics” lingered around probiotics; live bacteria aimed at colonizing the skin and prebiotics, ingredients that feed and support the growth of beneficial skin or gut bacteria. Recently, cosmetic chemists are now pivoting towards postbiotics.
What are Postbiotics?
Postbiotics are bioactive molecules or metabolic complexes derived from the fermentation or activity of microorganisms. As the inanimate functional components of bacteria, they’re proving to be a more stable, scalable and scientifically sound shift for the future of microbiome skincare. Made from inactivated microbes, they don’t need to be alive unlike probiotics which are live cultures, or prebiotics, which act as the “food” for those cultures. They are the beneficial by-products or inactive versions of bacteria which include metabolites like short-chain fatty acids, cell fragments known as lysates and secreted proteins.
Understanding Postbiotics in Formulations
Ashley Kuczynski, the chief operating officer and cosmetic chemist at Pensive Beauty notes, “What genuinely stood out for me about postbiotics wasn’t their biology. It was how cleanly they behaved once we stopped forcing them into traditional HLB-based formulation systems. HLB logic was never designed for biological signaling. It was built to keep oil and water from separating on a shelf. When modern actives or probiotics are dropped into that framework, chemists end up compensating, more emulsifiers, higher loads, penetration boosters and instability that gets mislabelled as ingredient sensitivity. Postbiotics expose that flaw immediately because they’re already metabolically complete, they don’t need protection from life or oxygen. They need controlled spatial placement.”
To master postbiotic formulations, one must understand the limitations of the Hydrophilic-Lipophilic Balance (HLB), this is the traditional scale used to select emulsifiers. While HLB is excellent for achieving mechanical stability, (preventing phase separation), it does not account for biological signaling.
In high-performance skincare, postbiotics must physically interact with specific skin receptors to trigger repair processes. If a chemist follows HLB logic too strictly, the resulting emulsion can trap these bioactives within internal micellar or oil droplet structures. This is where spatial placement becomes critical. Instead of simply balancing the oil and water phases, the chemist must strategically ensure the postbiotics reside in the continuous phase which is the outer water phase of the cream. This positioning ensures that upon application, the bioactives are immediately available to signal the skin’s receptors instead of remaining trapped inside internal droplets.
Postbiotics vs Probiotics
The distinction between probiotics and postbiotics is viability versus functionality. While probiotics are live bacteria that often perish in the presence of cosmetic preservatives or heat, postbiotics are the inactive, stable byproducts of those bacteria. In the lab, cosmetic chemists treat postbiotics as a versatile class of “biotech actives.” Because they are inactive, chemists can use specific strains and fractions to target precise skin concerns without the stability risks of live bacteria.
Postbiotics vs Prebiotics
While postbiotics provide the final ‘functional output’ of bacterial activity, prebiotics act as the selective fuel source that precedes it. Prebiotics are typically non-digestible complex sugars or fibers, such as inulin designed to be consumed exclusively by beneficial skin commensals. The goal of a prebiotic is to encourage the skin’s existing microbiome to produce its own beneficial metabolites naturally over time. In contrast, postbiotics bypass this ‘feeding and waiting’ phase by delivering those exact metabolic benefits directly to the skin barrier.
Mechanism and Safety of Postbiotics
Postbiotics such as Lactococcus ferment lysate are used to accelerate epidermal renewal while Bifida ferment lysate aids in stimulating the skin’s natural DNA repair and enzymatic process. These ingredients offer high heat stability, meaning they can be incorporated into the water phase before emulsification without losing their potency.
The effectiveness of postbiotics lies in their ability to communicate with the skin’s innate immune system and structural proteins. Unlike traditional moisturizers that merely provide an occlusive seal, postbiotics function as biological rheostats that actively re-engineer the barrier from within. Components such as peptidoglycans and lipoteichoic acids found in bacterial cell walls, specifically lysates, signal the skin to increase the production of tight junction proteins like Claudin and Occludin. These proteins act as the mortar between skin cells, preventing trans-epidermal water loss and maintaining a resilient surface.
Safety, being the strongest voucher for postbiotics, ensures there is virtually no risk of microbial overgrowth or infection, even for users with compromised skin barriers or those who are immunocompromised which makes them the much safer option.
The Future of Postbiotics in Skincare
Kelly Dobos, a consultant cosmetic chemist and adjunct professor of cosmetic science at the University of Cincinnati, sees the use of postbiotics, or in this case fermented ingredients as part of a broader shift towards using biotechnology as a manufacturing platform, “I see the use of fermented ingredients as part of a broader shift toward using biotechnology as a manufacturing platform for efficacious and functional beauty ingredients because fermentation lets us produce consistent, high purity materials that would be hard or inefficient to make through natural extraction. Fermentation isn’t new, some of the ingredients produced by biotech certainly aren’t new to us, and not every novel postbiotic will have meaningful clinical benefits.”
By focusing on the metabolic output of bacteria rather than the unstable survival of live cultures, chemists can finally deliver on the promise of microbiome health without compromising on product safety or shelf-life. As biotech manufacturing matures, postbiotics are likely to move from being niche hero ingredients to the fundamental building blocks of modern resilient skincare.
