Our skin is host to diverse bacteria ecosystems. The composition of microbe species living on the skin is relatively stable over time including some microbes which are beneficial and responsible for reinforcing the skin barrier against bad bacteria, infections, environmental damage and balance the skin pH levels. The problem begins when the microbiome is out of balance, the bad bacteria gets a chance to cause troubles and the good bacteria starts acting in reverse threatening your skin health and causing disease such as acne, eczema, psoriasis, or dandruff. Probiotics-infused skincare products have been proven to be helpful in maintaining the microbiome’s balance, improving some skin issues and eliminating the signs of aging. In order to find out if and how probiotics work we have to understand:
a. what the skin microbiome is
b. what are probiotics-infused skincare products and how they work
a. The skin microbiome
The skin is host to many bacteria ecosystems. There are two main types of bacteria living on the skin:
1. Resident bacteria: are capable of reproducing and are commensal with the host when skin is healthy. “When skin is compromised resident bacteria can become pathogens (infectious agent) as is seen in acne and folliculitis”.
2. Transient bacteria: are contaminants that are acquired from the environment which are incapable of sustained growth under normal skin conditions.
** The composition of microbe species on the skin changes during various times of life for instance an oil-loving bacteria such as the p.acne predominates in puberty. Also different microbial species prefer particular regions of the skin such as the stratum corneum of the epidermis, sweat glands or hair follicles. For example, p-acne bacteria is more plentiful where sebaceous glands are present.
The microbiome constantly determines which organisms are friend or foe. Its goal is to maintain the delicate balance that keeps things in harmony, trying not to let the bad bugs cause trouble and to let the good bugs do their job. In order to keep the skin’s microbiome in balance we should adopt a healthy diet, wear SPF, use suitable cleansers and skincare products; However, In some conditions the microbiome is not able to balance the skin by itself and might need some help; that is when the probiotic-infused skincare products are helpful.
b. How probiotics work on skin
The main benefits of topical probiotics:
1. Probiotic-infused skincare products are beneficial to people with chronic inflammation specially those with acne, rosacea or eczema.
2. They boost the skin’s functionality in dealing with external damaging factors including free radicals, sun, and pollution which helps preventing premature aging.
3. “Through the fermentation process, probiotic bacteria produce acidic compounds like lactic acid, reducing the pH of skin. Acidifying the skin discourages the growth of most pathogens favoring growth of resident bacteria.” Lactic acid acts as a natural moisturizing factor and antimicrobial, and acts on epidermal and dermal remodeling.
4. They produce potent antimicrobials such as bacteriocidins, organic acids and H2O2 that prevent bad bacteria adhesion.
5. “As the probiotics break down on skin’s surface, probiotic bacterial lysates create new ingredients for skin which leads to diminished signs of aging, better hydration, and less breakouts. Some other ingredients are:
+ Hyaluronic acid to improve moisturization and barrier function
+ Lipotechoic acid and peptidoglycan on the skin and stimulate the production of antimicrobial peptides (AMPs); including beta defensins, and stimulate innate immunity via induction of toll-like receptors (TLR)
+ Sphingomyelinase upregulates Ceramide production.
+ Diacetyl is antibacterial against gram negative pathogens including Pseudomonas and E. coli. Acetic acid also has antibacterial effects.
Pre-biotics & Post-biotics
Prebiotics are plant-based carbohydrates that serve as a food source to Probiotics. They also discourage the growth of pathogens while preserving beneficial bacteria. They can be readily incorporated into skincare products and are an excellent alternative to live bacteria (probiotics).
Postbiotics are enzymes, organic acids, polysaccharides, peptides that further reinforce your skin’s healthy barrier. Postbiotic skincare is the next trend in bio-skincare after prebiotics and probiotics! When we feed specific substances to the healthy bacteria living on the skin they transform into Postbiotics. Postbiotics are great alternatives to some active ingredients that we already use because unlike synthetic actives, these are natural habitants of the skin and the risk of causing irritation and inflammation by these is very low! Many of the microbial ferment lysates and extracts and antimicrobial peptides can therefore be thought of as Postbiotics.
Tips to determine which Probiotic is suitable for your skin
*”a probiotic product should contain a mix of probiotics, prebiotics (to fuel the probiotics), and lysate ingredients to help reinforce skin’s surface and improve its appearance”.
*Probiotics in skincare products are unstable, light and air cause them to break down faster so better avoid jar packaging and opt for well-known brands in this area.
*The dose of applied bacteria plays an important role in the balancing capacity.
Next chart shows a list of common pre-pro-postbiotics and their application.