It was towards the end of the 19th century that a link was established for the first time between intestinal disorders and changes in intestinal flora*. Following certain observations, discoveries were gradually made: demonstrating and then cultivating certain lactic ferments, which were then used as foods to restore intestinal health*.
In the 20th and 21st centuries, discoveries of various microbiota in our body followed; their roles and compositions were "refined", showing the importance of lactic bacteria and their stability on the health of the host, pointing to links between the various microbiota. Knowledge which highlights just how important it is to maintain these various flora, firstly through diet and through hygiene practices.
A little history…
In the early 20th century Elie Metchnikoff, a Russian microbiologist and winner of the Nobel prize in medicine, is intrigued by the longevity of the Bulgarians, great consumers of fermented products with a high content of lactic ferments, so called because they produce lactic acid.
He concludes that these bacteria have a positive effect on the intestines and on health. At the time yoghurt was sold exclusively by pharmacies.
Also at this time, Henry Tissier, a French paediatrician, isolated a bacteria Bifidobacterium breve in the flora of healthy, breastfed babies. This bacteria was not present in infants suffering from diarrhoea. He therefore recommended giving them this strain.
Probiotics through the ages: discoveries and milestones
The term probiotic (from the Greek biotikos, "promoting life") only appeared in 1953, used by Kollath. Research thus focussed thoroughly on the effects of intestinal bacteria. In 2001 the FAO/WHO experts committee gave the following definition: "Live microorganisms which, when administered in adequate amounts, confer a health benefit on the host". Nowadays, probiotics are still being intensively researched.
Lactic bacteria are among the main probiotics; they notably include the lactobacilli (from the genus Lactobacillus) and bifidobacteria (from the genus Bifidobacterium).
Probiotics in your meals
Dairy: Yoghurts and fermented milk. Cheese. Fruit and vegetables: Pickled cabbage (raw if possible), fruit juice. Sea food: Smoked fish. Olives, sourdough bread, soy sauce
Lactic ferments and microbiota
Our body: 10% human cells and 90% microbes!
The human body in effect hosts bacterial ecosystems known as microbiota. The most well-known being intestinal microbiota. Less well-publicised are respiratory, urinary, vaginal, cutaneous, oral and even ocular microbiota. This collection of microorganisms, each one living in a specific environment, is not there purely by chance and plays multiple roles, including the protection of the body against "intruders".
• Intestinal microbiota Our intestine is an immense bacteria tank (1014 microorganisms belonging to more than 1000 different species), including numerous lactic bacteria. This microbiota is specific to each of us, just like our finger prints, and lives in balance. It plays 3 major roles in our health:
A nutritional role via the digestion of fibres, amino acids, lactose; synthesis and absorption of vitamins (B2, B5, B6, B8, B12, K), etc.
A barrier role against the entry and/or embedding of pathogens in the body through a variety of mechanisms;
These benefits depend on bacteria: some have a more digestive purpose (Lactobacillus paracasei, acidophilus, plantarum, Bifidobacterium longum, etc.), others an immune purpose, notably Lactobacillus rhamnosus LGG, which has been the subject of numerous publications.
• Vaginal and urinal microbiota Vaginal microbiota is largely dominated (95%) by lactobacilli type living organisms. A second group, bifidobacteria, is also part of this vaginal ecology. Evolving in communities, these lactic bacteria cover the vaginal walls, creating a protective biofilm and stimulating local immune processes.
Note: contrary to popular belief, urine is not sterile! The bladder also hosts specific microbiota where lactobacilli predominate.
• Microbiota of the respiratory / pulmonary tree With specific purification phenomena, the respiratory tree has long been considered as a sterile place in healthy individuals. We now know that this is not the case: the respiratory pathways also host diverse microbiota, again composed of lactic bacteria.
• The balance of each of the microbiota is fragile. Thus an unbalanced diet, the prolonged use of antibiotics or certain antifungal medications, etc. but also stress, an impaired immune system, etc. will imbalance these microbiota constituting an area of vulnerability exposing either to contamination by a pathogen (hence urinary or vaginal disorders disrupting daily life) or digestive disorders, a weakened immune system...
• Certain microbiota are also inter-dependent: With a profile specific to each woman, a strong degree of homology (quantitative and qualitative) is found between the bacteria present in the vaginal microbiota and the intestinal microbiota. This may be considered as a bacterial reservoir for vaginal microbiota. When lactic ferments are taken by mouth, we observe that the strains colonise the gastro-intestinal microbiota before migrating to the genital mucosa, where they establish themselves and act: increase in the total quantity of vaginal lactobacilli from the 7th day after taking them with restoration of vaginal pH and purification of the vaginal flora. Likewise, the presence of imbalanced vaginal bacteria may reactivate in the bladder, thus causing urinary disorders . We also now know that intestinal microbiota play a key role in the initiation and adaptation of the immune response, not only in the digestive tract, but also remotely in the lungs . Indeed, an alteration in the intestinal microbiota may impact the respiratory system leading to the onset of allergies for example.
 EL AILA, N. A. et al. Strong correspondence in bacterial loads between the vagina and rectum of pregnant women. Res. Microbiol. 162, 506–513 (2011).  STRUS, M. et al. Studies on the effects of probiotic Lactobacillus mixture given orally on vaginal and rectal colonization and on parameters of vaginal health in women with intermediate vaginal fl ora. Eur. J. Obstet. Gynecol. Reprod. Biol. 163, 210–215 (2012).  https://blog.santelog.com/2017/04/02/microbiote-vaginal-pourquoi-linfection-urinaire-suit-souvent-les-rapports-sexuels-plos-pathogens/  Samuelson DR et al. Regulation of lung immunity and host defense by the intestinal microbiota. Front Microbiol. 2015; 6: 1085.
Lactic ferments, an essential addition for vitality
To preserve the balance of each of these microbiota, healthy practices are of course essential, from eating the most "healthy" and "living" food as possible (without forgetting probiotics "for life"), to looking after our mental health... However, in certain circumstances, taking a lactic ferment or probiotic supplement is an essential addition for vitality.