[Autochthonous microbiota, probiotics and prebiotics]

The autochthonous microbiota is the community of microorganisms that colonizes the skin and mucosal surfaces. The symbiosis is, generally, mutualistic but it can become parasitic due to immune response alterations. The skin microbiota includes bacteria (95%), lipophilic fungi and mites. In the digestive apparatus, each cavity presents its own microbiota, which reaches its target organ during the perinatal period, originating complex and stable communities (homeostasis). The vaginal microbiota varies with the endocrine activity, significantly increasing during the fertile and pregnancy periods, when lactobacilli are the most abundant organisms. Four are the main benefits of the autochthonous microbiota: i) delivery of essential nutrients, such as vitamins and some amino acids; ii) utilization of undigestible diet components, the colonic microbiota degrades complex glycans and fulfils almost 20% of the calories present in a normal diet; iii) development of the immune system: the continuous contact with the immune system maintains it alert and in good shape to repel pathogens efficaciously and iv) microbial antagonism, hinders colonization of our mucosal surfaces by alochthonous, potentially pathogenic, organisms. This works through three mechanisms: colonization interference, production of antimicrobials and co-aggregation with the potential pathogens. The microbiota can, sporadically, produce damages: opportunistic endogenous infections and generation of carcinogenic compounds. Probiotics are "live microorganisms that when administered in adequate amounts, confer a health benefit to the consumer". Prebiotics are undigestible glycans that enhance the growth or activity of the intestinal microbiota, thus generating a health benefit. Synbiotics are mixes of probiotics and prebiotics that exert a synergistic health effect.