Probiotics are living bacteria that provide health benefits when eaten in large enough quantities. They are similar to the beneficial microorganisms that naturally reside in and on our bodies. Many microorganisms feed our bodies, helping us to continue to develop and fight off harmful bacteria that may enter us. When their quantities are reduced, such as when taking antibiotics, the addition of probiotics to the diet can help to replace the microorganisms taking residence in the body to promote a balanced balance. To get a wide variety of probiotics, many foods and beverages are fermented, such as pasteurized whole milk, sauerkraut, and miso. In dietary supplements, probiotics are also available.
The probiotic “market” had no clear intent to consume them at the time. More time and research are required to demonstrate their effectiveness, and there is no most effective time or mandatory period needed to be eaten. Adding probiotics to your diet can have numerous benefits, from helping relieve bowel issues and inflammatory responses to reducing depression and anxiety. Scientists have begun to test the probiotics for their inherent health advantages in their fields of psychology and psychiatry as well as the normally discussed fields of good digestion and gene activity. The initial conclusions show that when managing problems such as depression and anxiety, “it’s not just the belly that matters.” According to the evidence so far, our gut influences how we feel mentally and how our brain processes the data emotionally we receive from both the good and the bad encounters.
Types of Probiotic Microorganisms
Belly bugs, good gut bugs, probiotics – the old definitions are giving way to a new appreciation of the role of this ecological community in human health. Every day, we are learning more about how an imbalance in our microflora can contribute to the development of chronic diseases. The scientific evidence supporting the use of probiotics for health is encouraging, but for many, it remains an area of confusion. In many ways, it appears that the health benefits of probiotic use are more a result of the probiotics modifying the function of the host than the direct activity of the microorganisms. A major shift and investment in our view of health and disease is the understanding that the cause of many chronic diseases is representative of a breakdown in the relationship between what microorganisms are in our gut and what our immune system needs to function properly. In this scenario, the native bugs in our gut contribute to the pro- rather than anti-inflammatory activities of the immune system, and also contribute to appropriate responses to harmful bugs that are introduced into the gut by food or the environment.
However, for the purposes of this presentation, we will keep to the classic definitions and lines of reasoning. There is a lot of microbial diversity in the world – over 1 trillion species – only a handful of which human beings study. In the human body, we have at least 90 trillion cells, only 1 in 10 of which is human by population. As we look at the microbial community in our bodies, most live in the lower part of the gut. They comprise more than 1,000 possible bacterial species, and we consume about 11,000 more per day. More than 400 different kinds of microorganisms have been isolated from the intestines of prosimians, monkeys, apes, and humans, and almost 80% of them have not yet been cultivated in the laboratory and characterized. For humans, it has become behavioral custom to classify them as either beneficial or harmful. Yeasts such as Saccharomyces boulardii and many strains of bacteria such as lactobacilli and Bifidobacterium have beneficial effects.
Mechanisms of Action of Probiotics
Probiotics are live microorganisms which, when administered in adequate amounts, confer a health benefit to the host. The most studied and commercialized probiotics are Gram-positive bacteria, with Lactobacillus, Bifidobacterium, and Streptococcus being the most well-known genera. However, evidence is accumulating of potential benefits of certain non-pathogenic Gram-negative bacteria, as well as yeast-like fungi. Evidence has shown that probiotics can work in several ways to exert beneficial effects in the host. This includes direct effects against pathogens, competitive exclusion of pathogens, promotion of beneficial commensals, strengthening of the epithelial barrier of the host, and immunomodulation. Therefore, by improving gut health, probiotics may have the potential to positively affect various health outcomes.
As to how probiotics work via immunomodulation, it depends on the strain and the specific mechanisms. The characteristics of probiotics’ immunomodulatory effects might include direct interaction with immune cells and the promotion of anti-inflammatory cytokines, such as IL-10, and reduction of pro-inflammatory cytokines, such as tumor necrosis factor, IFN-γ, or IL-17. This inhibition of pro-inflammatory cytokines is likely mediated through the interaction of microorganism-associated molecular patterns (MAMPs) with a range of pattern recognition receptors (PRRs) on host immune cells, such as toll-like receptors (TLRs) and nucleotide oligomerization domain receptors (NOD-like receptors, NLRs). Additionally, the strains may exert systemic immunomodulatory effects, such as signaling to distant organs, e.g., through the gut-brain or microbiome-skin axis.
Health Benefits of Probiotics
Probiotics have gained increasing interest in recent years due to their many health benefits. The best defined pro bono publico effect related to probiotics is the improvement in gut health, such as the prevention and treatment of acute infectious diarrhea, treatment of rotaviral diarrhea, shortening the symptoms of bacterial enteritis, preventing antibiotic-associated diarrhea, elevating the immune responses in the gut mucosa, and reducing inflammation response in regard to functional bowel disorder, irritable bowel syndrome in adults, and colitis. Besides the favorable effects on health in relation to the colon, some studies demonstrate that probiotics can also provide protection against a range of diseases that are linked to poor mucosal immunity, such as infections, allergies, and other immune-mediated and inflammatory diseases. The moral of the story is that probiotics have many health benefits, mainly based on the probiotic strain, the type of administration (food or pharmaceutical), and the dosage of the probiotic product. Most of the well-documented effects of probiotics are found from lactobacilli and bifidobacteria. It is likely that the health benefits are best documented for antibiotics, especially concerning the prevention and reduction of diarrhea and infections.
It should be kept in mind that the benefits of probiotics are strain specific. Consumers are becoming more and more informed, so it is likely worthwhile to emphasize the positive effects related to the specific strains used in one’s probiotic products. Moreover, the benefits of individual strains are based on detailed scientific documentation. In any regard, safety concerns related to the use of probiotics must be handled systematically. Probiotics are becoming more and more integrated into various foods, including baby nutrition in infant formula. In order to ensure standardized terminology when discussing probiotics, the FAO/WHO (2002) expert panel revised the definition of probiotics in the new guidelines for their use: probiotics are ‘live microorganisms, which when administered in adequate amounts confer a health benefit on the host.’ A daily intake of approximately 109 CFU (colony-forming units) of probiotic bacteria is often required, and this number is often attainable through food or pharmaceuticals.
Digestive Health
Probiotics have been studied for their potential in preventing and helping with digestive disorders such as diarrhea, irritable bowel syndrome, ulcers, and inflammation of the intestines. In healthy people, probiotics can also help in promoting a healthy gut by reducing the symptoms of bloating, flatulence, and stomach discomfort. There is good evidence to suggest that probiotics help prevent the development of conditions such as antibiotic-associated diarrhea for as long as they are taken. Studies have shown that continued use can help maintain the effectiveness of probiotics initially provided in the intestines.
Research is being undertaken to investigate the various mechanisms by which different probiotics help various digestive conditions. The wide number of probiotics and potential combinations of probiotics along with varying conditions and outcomes mean that there is a wide and diverse range of evidence for the use of probiotics. However, if you need evidence to support these potential applications, you can also refer to other reviews and meta-analysis on this site. Additionally, many reviews summarized studies involving probiotics for digestive health. Probiotics are thought to work by a range of mechanisms. For example, they can interfere with the production of toxic or damaging components made by infectious organisms. In the intestine, they can help fortify the intestinal barrier by stimulating the growth and development of cells that maintain the barrier, as well as stimulating the production of mucus. Producing more mucus can help reduce inflammation when infectious organisms try to invade the space linked to produce infection.
Immune System Support
Probiotics have a unique role in supporting overall immune function. A large number of studies are showing that the administration of these live microorganisms exerts immunomodulatory effects and hence may represent a very powerful tool to counteract infection or inflammation in the human host. It has been demonstrated that probiotics can interact with both the innate immune system and the acquired immune system. Benyacoub et al. fed two doses of probiotic strain L. paracasei to mice mixed in a commercial yogurt for 5 days, followed by a Salmonella infection carried out 3 days after administration of the second “treatment”. Analysis showed a dose-dependent protection in the mice administered probiotics against a Salmonella challenge, as survival significantly increased in this group compared to both control groups. The immune response mirrored this protection, as enteric antibodies (IgA, IgG, and IgM) against Salmonella (S. Typhi LPS) increased in a dose-dependent manner in the probiotic-treated mice. However, the top-dose mice (i.e. 9×109 cfu and Salmonella challenge) showed a large increase in IgG, associated with the peak of the response and a clear protection.
Several mechanisms are concerned with the modulation of host immunity. Different trials reported an up-regulation of cell-mediated immune responses, particularly in professional athletes. The up-regulation of the cellular immune response conducted to a greater extension of opportunistic infections, particularly when strenuous training regimens are expected. In fact, CD4, CD8 counts, and CD4/CD8 ratio increased after consumption of the probiotics. Most likely, these results could be related to a plausible role played by the modulating effect of the probiotic on the immunity of the host, as documented by the status of certain cytokines. More recently, different trials focusing also on the immune responses against pathogens were following marathoners, mountaineers, tourists, and farmers. It is reasonable to suppose that the changes occurring in the intestinal microbiota in the gut of the host by the consumption of specific probiotics could be concerned with modest beneficial influences on the host defense system. The bacteriocins produced by the two Lactobacilli strains may play a role in the antagonism. A potential explanation lies in the fact that NCC3001 9 L.AB SGL07.013 strain could induce local and systemic host immune responses by inducing T-cell activation and the reacted pro- and anti-inflammatory cytokine production.
Mental Health and Mood Regulation
The emerging view that the composition of gut microbiota is likely to modulate behaviors associated with mental health and mood is intriguing. Indeed, there is preliminary research to suggest daily probiotics, or at least increased consumption of foods that have a high concentration of probiotics, alter brain response to threatening stimuli. Moreover, researchers studying cognition in healthy human subjects have found that the administration of beneficial gut bacteria, such as Lactobacillus rhamnosus, modulated affect and corticosterone release compared to controls over the study period. While the results from these studies in healthy human subjects are promising, there are mixed results from clinical trials utilizing different probiotic strains with patients suffering from mood disorders and stress. Thus, experiments in animal models of disease or depression are still invaluable to unravel the potential interactions from the gut to the brain.
The mechanisms of how beneficial compounds or gut bacteria communicate with the brain are currently unclear. However, recent work has proposed several potential pathways and mechanisms. Firstly, it is already established that areas of the brain that are important for cognition and emotional regulation, such as the amygdala, show altered function during inflammation. It is hypothesized that signals of infection or ‘harm’ elsewhere in the body are transmitted to the brain where they affect mood and cognitive functions. Secondly, large molecules, such as lipopolysaccharides (LPS) that are common bacterial cell wall products, are able to pass the blood-brain barrier after an immune challenge and directly affect the hypothalamic-pituitary-adrenal (HPA) axis, which is the brain’s central stress response system. Thus, this mechanism alone could explain the detrimental effect of high-fat diets that change gut bacteria on the brain and cognitive functions.
Sources of Probiotics
Probiotics are living microorganisms that, when administered in adequate amounts, can have a beneficial effect on the host’s health. They are naturally found in fermented foods and ingredients of fermented food products and known as “friendly” or “good” bacteria. Several microorganisms that are of human origin, like those belonging to the genera Lactobacillus, Bifidobacterium, and Streptococcus, are utilized as food-grade microorganisms for the fermentation of meat and dairy products. Yogurt is a classic food product known to deliver probiotics. Kefir, a fermented dairy drink, kimchi, a spicy fermented cabbage, miso, a paste used in Japanese cuisine, pickles, a vegetable, tempeh made from fermented soybeans, etc., are some examples of food items offering benefits of different types of beneficial microorganisms capable of altering gut microbiota.
There are also some commercially available probiotic foods and supplements having sufficient scientific evidence. They also have the ability to ease problems of dysbiosis or only deficiency of a particular strain of microorganism, or fecal dryness, or even various therapeutic achievements including better absorption of nutritional elements, immunopotentiation in specific allergies, antimicrobial activity that also leads to decrease the load of various toxins and carcinogens. The risk factors include non-resistance against reduced pH, bile salts, antibiotics, bad taste, synthetic origin, and their degradation in the stomach and intestine. High cost for the production of probiotics is also a concern.
Fermented Foods
Fermented foods are probably the most familiar sources of naturally occurring probiotics, and many of these can be considered ‘functional foods’ in the light of the term’s more recent definition. have referred to them as part of culture-dependent health foods. What unites all these traditional foods is that the action of microorganisms during fermentation leads to an improvement in palatability and extended shelf life. It is now well understood that the microorganisms that drive this fermentation have numerous additional benefits, including food preservation and bioconservation, flavor formation, degradative actions, a reduction in toxicity, and, increasingly, the provision of bioactive compounds such as antimicrobials, antifungals, antioxidants, antihypertensives, and anti-inflammatories. Recent research initiatives aim to develop an extended catalogue of such new ‘fermented functional foods’, extending beyond probiotics to cover these beneficial aspects of fermentation.
This diversification of the probiotics concept applied to traditional fermented foods is an exciting prospect. Contrary to the general impression of probiotics as principally being bacteria, there are several examples of yeast-based probiotics that are used in mass-market applications. Yeast species that are used, either on their own or in combination with bacteria, in the production of fermented foods include Saccharomyces cerevisiae, Kluyveromyces lactis, Torulaspora delbrueckii, Pichia kudriazevii, Saccharomyces boulardii, and Debaryomyces hansenii. Moreover, the abundance and diversity of lactic acid bacteria and bifidobacteria species in the host gut, in dairy products, and in fermented food products, combined, represent sources of traditional natural probiotic microorganisms.
Probiotic Supplements
For some populations, specifically those with particular health conditions, it may be beneficial and/or necessary to improve health or modulate gut microbiota. It would be extremely challenging to change percentages and ratios of bacterial groups in the gut in the long term, or in some cases even the short or medium term, through consumption of microorganisms in a diet. By consuming supplements, a more concentrated source of beneficial microorganisms may be delivered to support existing, or indeed perhaps even seed, a probiotic population. A probiotic supplement is a formulation comprising viable, beneficial bacteria administered in a manner to reach the gut, in an amount which can have a beneficial effect on health. Consequently, the live organisms must survive exposure to bile and gastric juices, and must survive at least the length of the gut for which the effect is claimed.
Microencapsulation of probiotics has shown some promise for protecting bacteria from the acid in simulated physiological conditions. Options for population include delivery in foods in which conditions for probiotics in production approximately match their conditions in the gut—the key benefit being aimed to reduce this transition shock that may occur when live cells with clearly differing physiological environments may be suddenly exposed to each at a high level once consumed. The most popular probiotic supplements are presented as pills or capsules. The efficacy or otherwise of a probiotic supplement will depend on a number of factors—the type and numbers of microorganisms used, the formulation used to deliver them, the intended effect, overall diet and indeed healthy status of the host, and the ability of a consumer to make a good decision in relation to correct use. It is evident that the use of probiotics in the general food supply market will be less liable to misuse or abuse than the dedicated supplements market, especially if no advice is sought or taken. The market may explode in time—and diversify—as the tonic for realizing individual good health at a time when consumers are better informed about nutrition and the relation between an appropriate diet and health. However, increasingly the most convenient, and evidence-backed, way to take probiotics is through the use of dedicated individual products. Products within a certain category of probiotics, or food used in the past to support the growth of beneficial microorganisms, have been proven to have a larger probability of having health claims compliant with nutrient function.