Our skin hosts more than 500 species of bacteria: Nutri-Dermatologist Doctor Bucci explains why the “good” ones are fundamental, even in cosmetics.

Credit to passion artist/Shutterstock
Credit to passion artist/Shutterstock

Would you ever suspect that our bodies are populated by bacteria that influence up to the 3% of our body weight? Yes! The human body hosts microorganisms that coexist with our organism without damaging it, and some of these are “good bacteria”. This set of microorganisms is called microbiota. Even our skin hosts various communities of bacteria, more than 500 species! These microorganisms represent the Skin Microbiota, a precious system of protection that contributes to our immune defenses. The new cosmetic frontier is the research of solutions that protect and reinforce the Skin Microbiota and its community of good bacteria, to keep the healthy skin in balance, in particular, sensitive and hyper-responsive skin.

The beauty of our skin is closely linked to the balance of the microorganisms that populate it, which are the first line of defense from external threats. When the bacterial ecosystem is balanced and differentiated, the skin remains healthy. A low diversification in the bacterial ecosystem, caused by external and internal factors, can erase cutaneous reactivity and sensitivity, and even provoke pathological conditions (dermatitis, acne, rosacea, etc.) The cutaneous microbiota stimulates the immune system, activating the natural physiological response and the regulation of our biofilm that stops the colonization of harmful agents. The ecosystem of our “good bacteria” is influenced by imbalances that are particularly linked to lifestyle, anxiety, and stress conditions that can alter the natural skin defenses.


  • Hereditary factors, age, gender.
  • Physical and chemical characteristics of specific cutaneous areas: the different “habitats” are determined, for example, by skin thickness, and the number of sweat and sebaceous glands.
  • pH, skin moisture, sebum content, barrier function and hydration.
  • Environmental factors: exposure to UV rays, nutrition, consumption or application of antibiotics. 
  • Climate, environment, and location in which you live.
  • Lifestyle, profession, sports activity, clothing.
  • The use of cleansers and cosmetics – especially if used in an excessive or inappropriate way.


The new frontier of cosmetics is the use of ingredients that protect the good bacteria community and our cutaneous microbiota. This type of approach paves the way for the use of new ingredients such as prebiotics.

Prebiotics are fundamental to feed the best-known probiotics (contained in several foods, such as yogurt):
living organisms that, used in adequate quantities, have a good effect on the organism. However, being living microorganisms, probiotics are difficult to integrate, in a stable manner, in topical formulations.   

Prebiotics instead, with adequate formulation techniques, can be inserted into lotions or emulsions, thereby increasing the good bacteria of each person and giving a great benefit to skin immunity and health.

Therefore, the use of prebiotics in cosmetics represents a new frontier: to take care of our cutaneous microbiota and preserve the health, beauty and youth of our skin. 

What are prebiotics and probiotics?

Probiotics: living bacteria present in some foods (the best known are the lactobacillus and
bifidobacteria present in fermented products such as yogurt, kefir, miso, tempeh, kombucha, fermented cheeses) or in food supplements. When applied locally, they influence the balance and the composition of skin microflora. Through the natural process of fermentation, probiotic bacteria produce acid compounds such as lactic acid that lowers the skin pH. The acid pH prevents the growth of the most harmful bacteria. Although the good effect for the skin of probiotic bacteria is documented, living ferments are generally unstable in cosmetic formulas.

Prebiotics: generally plant-derived (mostly fibers, such as beets and asparagus, beans, oats, garlic, dandelion and dried fruit, and especially nuts) that human beings are unable to digest. Good bacteria (or probiotics) eat these “prebiotic fibers” to grow, multiply, and improve the balance of bacterial microflora. Prebiotics, with adequate formulation techniques, can be used, with more stability, in cosmetics.