Probiotics can be our micro-allies
The human body can be described as a complex ecosystem containing trillions of bacteria and other microorganisms that inhabit the skin, the genitourinary tract, the mouth, and especially the digestive tract. The number of bacterial cells is much greater than the number of human cells, in a ratio of ten to one. This community of microorganisms is known as the microbiota, and although we are often unaware of its presence, it plays a vital role in health by supporting the host's biological processes, including digestion, growth, and immunity, and can even influence mood and behavior.
Until a few years ago it was considered that, immediately after birth, the colonization of the gastrointestinal tract began from the oral cavity and was dependent on exposure to the extrauterine environment, but recent studies have shown that the development of the newborn's intestinal microbiota is programmed from intrauterine life.
The theory that the gut is sterile during the fetal stage and that exposure to maternal microorganisms occurs after birth has been modified in light of recent research demonstrating that the fetus's first contact with the maternal gut microbiota occurs through the placenta and amniotic fluid. Massive colonization of the fetal gut then continues during birth through contact with maternal bacteria from the perianal region. Following birth, intestinal colonization of the newborn is initiated primarily by facultative anaerobic microorganisms, such as Enterobacteriaceae and Lactobacilli, followed by non-facultative anaerobes, such as Bifidobacterium, Bacteroides, and Clostridium. Once established, the microbiota is virtually permanent and generally remains stable throughout life, although certain circumstances can alter its balance.
The gut microbiota constitutes an ecosystem where many different species participate in interrelated or interdependent life cycles, within a context of great biodiversity. These bacteria are adapted to their habitat because they have been associated with human life for millennia and have evolved alongside it. The main function of this microbiota is the fermentation of indigestible dietary substrates and the mucus produced by the intestinal epithelium. As a result of this activity, metabolic energy and absorbable substrates are recovered, and the microbial population proliferates. Lactic acid and short-chain fatty acids (SCFAs) are also produced as a consequence of the fermentation of carbohydrates that reach the colon and constitute a good source of energy.
The microbiota is currently considered an organ integrated into the host's physiology; among its main functions are: the nutritive and metabolic function, which helps in the digestion, absorption and synthesis of many nutrients; the protective function creating a barrier that inhibits the development of some viruses and prevents the development of other types of bacteria that could produce infections; and the immunomodulatory function that has an essential role in the proper functioning of the immune system.
This gut flora feeds on what a person consumes, and this obviously has an impact on health. The healthier the microbiota, the healthier the individual, and the key to a healthy microbiota is nurturing a balance among the nearly 1,000 different species of bacteria in the gut. There are two ways to maintain this balance: the first is by helping the microbes already present to grow by giving them the foods they like (prebiotics), and the second is by adding live microbes directly to the system (probiotics). In this way, these microorganisms become our allies for better health.
There are circumstances that can disrupt the balance of the gut flora, such as stress, inadequate diets (low in fiber, high in protein and fat, or with excessive coffee, chocolate, or sugar), harmful habits like alcohol and tobacco use, certain illnesses like gastroenteritis, and some medications such as antibiotics or drugs that damage the gastric or intestinal mucosa. Food intolerances and even aging itself can lead to a decrease in microbial colonies.
Probiotics can be defined as live microorganisms that, when ingested in adequate amounts, beneficially affect the development of the gut microbiota, exerting health benefits beyond those inherent to basic nutrition. They are also known as biotherapeutics, bioprotectants, or bioprophylactics and are used to prevent enteric and gastrointestinal infections. For a microorganism to perform this protective function, it must meet Huchetson's postulates: be a normal inhabitant of the intestine, have a short reproduction time, be capable of producing antimicrobial compounds, and be stable during the production, marketing, and distribution processes so that it reaches the intestine alive. It is important that these microorganisms be able to cross the gastric barrier to multiply and colonize the intestine. The most common bacteria associated with probiotic activity are: Lactobacillus acidophilus , L. casei, L. reuteri , L. plantarum , and L. casei GG . Bifidobacterium brevis , B. longum , B. infantis , B. animalis ; Streptococcus salivaris subspecies thermophilus, and some varieties of yeast such as Saccharomyces boulardii.
The mechanisms of action involved include: induction to pH below 4, inhibition of the growth of pathogenic bacteria, production of lactic acid, decreased intestinal permeability, increased lactase activity, competitive effect on other pathogenic bacteria, reduction in rotavirus elimination time, increased production of T helper lymphocytes, and increased secretory immunoglobulin A.
Most probiotics are stable for limited periods when stored in a cool, dry place. Many are frozen powders containing dormant bacteria, and their availability depends on the form (tablets, capsules, or powder), the packaging (bulk), and the package size; as well as how they have been stored (refrigerated or in ordinary storage). When probiotics are exposed to moisture, oxygen, or heat, the microbial cells are irreversibly damaged. Liquid probiotic products have reduced stability; however, powdered probiotics, whether tablets or capsules, can be dissolved in food or liquids before ingestion, resulting in much greater stability and making them suitable for children and infants. Microencapsulation has represented a significant advancement, increasing survival rates even after passing through gastric and biliary secretions.
Some of the diseases we suffer from today originate in the gut and are caused by an imbalance of the gut flora. Probiotics offer various benefits: they aid in the digestion of certain foods, play a role in the synthesis of B vitamins, improve calcium absorption, help maintain the balance of gut and vaginal flora, improve and regulate bowel movements, and generally contribute to strengthening the immune system. The effects of probiotics have been demonstrated in vitro and in vivo in pathological conditions such as diarrhea, urinary tract infections, immune disorders, lactose intolerance, hypercholesterolemia, cell proliferation processes, and food allergies.
The most studied effects of probiotics relate to their effectiveness in treating certain digestive problems, especially diarrhea. Probiotics have been shown to help combat infectious diarrhea, acute diarrhea caused by rotavirus (gastroenteritis), and diarrhea associated with antibiotic use, among others. There is some evidence suggesting that probiotics may improve the symptoms of inflammatory bowel diseases, such as irritable bowel syndrome and Crohn's disease.
Numerous human studies have suggested that certain probiotics help strengthen and boost the immune system. Therefore, it may be beneficial to use probiotics when we have the flu, a cold, suspect we have a virus like SARS-CoV-2 (COVID-19), or suffer from infectious diseases such as cystitis or vaginitis, among others.
Generally, probiotic foods and probiotic supplements They are safe and tend to be well tolerated by most people who consume them; however, in people with a serious illness involving the immune system, the use of probiotics should be supervised by a doctor.
Ramona Ávila Núñez, Ph.D.
References
- Rondón L., Años M., Salvatierra A., Meneses R., Heredia M. Probiotics: generalities . Archivos Venezolanos de Puericultura y Pediatría . 2015; 78 (4), 123-128. Available from: http://ve.scielo.org/scielo.php?script=sci_arttext&pid=S0004-06492015000400006&lng=es&tlng=es.
- Fujimura K., Slusher N., Cabana M. , Lynch S. Role of the gut microbiota in defining human health. Expert Review Anti-Infective Therapy. 2010;8(4):435-54
- De las Cagigas A., Blanco J. Prebiotics and Probiotics, a Beneficial Relationship. Cuban Journal of Food and Nutrition. 2002; 16(1):63-8
- MAYO CLINIC. Prebiotics, probiotics, and health. Available at: https://www.mayoclinic.org/es-es/prebiotics-probiotics-and-your-health/art-20390058
- Tormo Carnicé , R. Probiotics . Concept and mechanisms of action. Annals of Pediatrics. 2006; 4: S1, 30-41