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Prebiotics and probiotics for the skin. An update.

It used to be that we only discussed bacteria when speaking about infections. In skin care, it was all about acne and how to kill the recently renamed acne bacterium, Cutibacterium acnes (a.k.a. Propionibacterium acnes). Now, you can see bacteria and the “microbiome” everywhere in magazines that advertise skin care products.

Bacteria are essential to the human body’s function, and many species live in us, and on us. We are familiar with the negative effect of taking oral antibiotics on our gastrointestinal tract and the flora that resides there. For example, the probiotic supplement market is booming, and even major yogurt brands now carry probiotic formulas.
Our skin includes an ecosystem known as the skin microbiome—trillions of microbes that live on our skin and in our pores. Most of these microbes are not dangerous; they’re more like an outer layer of skin that no one knew we had, and they influence everything from acne, eczema, and dry skin, to how we smell. The aim of skincare should be to keep a healthy microbiome, not “overcleaning” to kill every single bacterium!

Human skin functions as a physical barricade to stop the entry of pathogens and hosts innumerable commensal organisms. Commensal means living in a relationship where one organism derives food or other benefits from another organism without hurting it. The skin cells and the immune system regularly interact with microbes maintaining equilibrium, despite continuous changes in the environment. Many factors influence the species composition of the microbiome, like diet, gender, ultraviolet radiation, family.

Just like it is possible to manipulate soil bacteria to prevent the infection and dissemination of viral and bacterial disease in crops, it should be possible to control the bacteria that live in and on our bodies to prevent infection by “bad” bacteria, but this is a huge task. Why? Sometimes we don’t even know which bacteria are growing in the environment we are studying. In the skin, many bacterial species will not grow well in culture, so a complete identification of bacteria requires DNA technology. Proteobacteria, Actinobacteria, Bacteriodetes, and Firmicutes dominate dry skin. Moist areas are rich in Staphylococcus and Corynebacterium spp. A lower bacterial diversity is seen in oilier sites, suggesting that only a few bacterial communities, like Propionibacterium, can flourish under those conditions.

Scientists are getting to know more about the skin microbiome but it will take a lot of research and a long time before we know enough to effect a positive change (as usual, changes for the worse are easy to get).

Also, just in case you are still using them, stop using antibacterial soaps. Frequent use of some antibacterials will promote the development of bacteria resistant to antibiotics, promoting the proliferation of drug-resistant infections, a scourge of medicine. The skin microbiome is best left alone unless its disruption becomes apparent, like with acne.


A probiotic is a mix of live bacteria and/or yeast that are ingested to improve the health of the digestive system. A common use of probiotics is when we use them during or after taking an antibiotic, to compensate for the disruption of the natural digestive flora.

Why can’t you buy probiotics for the skin? The FDA (Food and Drug Administration in the USA) sets strict limits for the number of live bacteria present in cosmetics. This rule makes sense: we must avoid excess or dangerous bacteria from entering our bodies. Our digestive system, with a stomach maintained at a very low pH, is well equipped to kill bacteria. Conversely, our skin is not well equipped to kill dangerous bacteria. In the old times (as I always say, the old times were not better) without preservatives, contaminating bacteria present in cosmetics caused terrible damage, including blindness.


What is a prebiotic? Prebiotics are chemicals in food that induce the growth or activity of beneficial microorganisms such as bacteria and fungi. The most common example is in the gastrointestinal tract, where prebiotics like natural food fibers can alter the composition of organisms in the gut microbiome.

What would be the equivalent of prebiotics in relation to our skin? Some strains of S Staphylococcus epidermidis can ferment carbohydrates to produce succinic acid, a chemical that has potent anti-S. aureus and anti-C. acnes activity. This is relevant to acne treatment because, in theory, we could improve skin health and control acne by using prebiotics like succinic acid and glycerol that will discourage C. acnes from spreading.

As I said above, we can’t use probiotics (live bacteria) on our skin for very good reasons, but we can use prebiotics, and we already do! The Skin Actives Scientific acne control products contain prebiotics that modify the skin environment to make it less hospitable to the acne bacteria. We can do even more and we will continue to improve our products as we learn more about the skin microbiome.

Our main probiotic ingredient is “sea kelp bioferment” (this is the INCI name) we use as a base for many of our products starts with the sea kelp, a plant material that is rich in biochemical components that are already beneficial to our skin. But then we cultivate yogurt bacteria in this broth, and the microorganisms will make their own beneficial biochemicals and enrich the mix with prebiotics that will benefit the skin in other ways: supplying yet more vitamins and building blocks that our skin will use to make its own proteins (collagen, elastin and more), polysaccharides and DNA. We are already experimenting with the use of a bacteria and yeast mix to provide a different probiotic base serum.

Take home lesson: don’t attack what you don’t know: if you start using strong oxidants or anti-bacterial products, or remove the external layers of the epidermis that constitute the natural skin barrier, or change the pH of your skin with “natural” antiperspirants, you may get into trouble because you will be disrupting the natural equilibrium achieved by the skin and its microbiome.


DISCLAIMER: These claims have not been evaluated by the FDA and are not intended to diagnose, cure, treat or prevent any disease.