The gut microbiota
Human microbiota is the aggregate of the symbiotic microorganisms living in the human body, without damaging it; the gut microbiota is the portion that colonize the intestine.
The microbiota shapes itself with birth and since then it modifies itself with external factors, as the environment, diet, the use of drugs, etc. So, each person has a unique microbiota, with a specific composition, which keeps evolving from birth through all life, based on genetic and environmental factors.
The gut microbiota has a fundamental role in the health of the intestinal tract and of the whole body. The functions exert by the gut microbiota are numerous: it contributes to the intestinal mucosa integrity; it counteracts pathogens, blocking their adhesion to intestinal epithelium; it supports the intestinal immune system; it produces some nutrients, as amino acids and vitamins; it is involved in digestion and nutrient absorption; it is involved in bile acids metabolism.
Since the gut microbiota is so important, it is clear that we have to take care of it. So, it is fundamental to have a healthy life style, with a varied, balanced diet and regular sport activity.
However, in some circumstances and in some moments of the life, the gut microbiota could transit from a healthy condition to dysbiosis, meaning that it happens an imbalance between the healthy commensal species and pathogen species. This leads to intestinal pathologies. Often, dysbiosis happens after an antibiotic therapy. In these cases, we can support the gut microbiota to restore its balance and treat the intestinal pathologies through the administration of probiotics.
According to FAO and OMS definitions, probiotics are “Live microorganisms which when administered in adequate amounts confer a health benefit on the host”. So, probiotics promote health starting from the gut, favoring microbiota balance and supporting the beneficial species at the expanses of pathogens. They also support the immune system. Probiotics can be administered with diet or as dietary supplement.
Probiotics, to be defined as it, have to follow some characteristics:
- Stability and survival to the gastro-intestinal tract: probiotics need to be alive and active when we eat them, reach the gut and here exert their probiotic function.
- Functionality: each probiotic strain has specific characteristics and functions; different strains have different effects on the host.
- Dosage: it is important to get specific doses of probiotics, so that they can exert their activities; doses depend on the strains/mixture of strains.
- Efficacy: the probiotic effects have to be documented in scientific publications.
- Safety: probiotics should not represent a danger for people health, they should not be pathogens or virulent, these aspects have to be checked in laboratories.
In general, among the beneficial effects of probiotics we have: regularization of defecation frequency, protection during antibiotic treatment, analgesic effect, reduction of bloating and flatus associated to intestinal inflammatory diseases, support to lactose digestion, protection toward microbial infections, decreasing of intestinal permeability, modulation of the immune response.
Typical probiotics strains belong to the species: L. acidophilus, L. rhamnosus, L. casei, L. paracasei, B. animalis subps. lactis, B. longum subsp. longum, B. breve.