Revolutionizing the Potential of Probiotics an Evidence-Based Review

Pranjal Sachan ^1*, Prachi Shrivastava ², Meenakshi Goswami ³

¹ Assistant Professor, Department of Pharmaceutics, Sanskriti College of Higher Education and Studies, Kanpur Dehat, Uttar Pradesh (UP)

² Assistant Professor, Anjali College Of Pharmacy And Science Etmadpur, Agra.

³ Assistant Professor, School of Pharmacy, Babu Banarasi Das University Lucknow, Uttar Pradesh (UP)

Abstract

Background Probiotics, which are live microorganisms beneficial to human health, have garnered significant attention in recent years due to their potential therapeutic and preventive effects on various health conditions. The human gut microbiota, comprising trillions of microorganisms, plays a crucial role in digestion, metabolism, immune function, and overall health. Disruptions in the gut microbiota have been associated with various diseases, including gastrointestinal disorders, metabolic syndrome, immune-related conditions, and even mental health disorders.

Objective The objective of conducting an evidence-based review on the potential of probiotics is to assess their efficacy, safety, and mechanisms of action in various health conditions.

Methods A literature search was conducted in PubMed, Scopus, along EBSCO databases. The topics include " Probiotics", " History", " Composition", " Clinical significance, Prevention ", or " Recent advancements,".

Results This involves gathering and analyzing scientific research, clinical trials, and meta-analyses to evaluate the effects of probiotics on specific health outcomes. The review aims to provide an unbiased synthesis of available evidence to inform healthcare professionals, researchers, and policymakers about the role of probiotics in disease prevention, treatment, and maintenance of overall health. Key objectives may include:

Conclusion In conclusion, an evidence-based review on probiotics aims to assess their efficacy, safety, and mechanisms of action across various health conditions. By synthesizing scientific research and clinical trials, such reviews provide valuable insights into the role of probiotics in disease management, overall health promotion, and potential adverse effects. Through rigorous analysis, these reviews inform healthcare professionals, researchers, and policymakers about the appropriate use of probiotics to optimize health outcomes.

Keywords:  Probiotics, History, Composition, Clinical Significance, Prevention, Recent Advancements.

 

Introduction

Probiotics were described in 2001 by an FAO/WHO Expert Consultation group as living microorganisms that provide a health benefit to the host when provided in suitable doses. Lactobacillus along with bifidobacterium constitute the most popular bacteria used as probiotics, along with yeast and bacilli [1]. They are ingested as fermented foods containing active living cultures, such as yoghurt as well as dietary supplements. Probiotic has become a relatively recent term that means 'for life' and refers to bacteria that have beneficial effects on people and animals. These microbes help to maintain gut microbial balance and overall health.

 

Probiotic bacteria are mostly composed of Lactobacillus and Bifidobacterium strains, but Bacillus, Pediococcus, and certain yeasts have also been identified as acceptable options. Together, they serve a crucial function in protecting the organism from hazardous microorganisms while also strengthening the host's immune system. Probiotics can be found in both dairy and nondairy products [2]. They are typically ingested following antibiotic therapy (for certain disorders), which eliminates the digestive tract's microbial flora (both beneficial and dangerous microorganisms). Regular ingestion of foods containing probiotic bacteria is suggested to maintain a healthy balance of helpful or beneficial germs in the gut flora.

The bacteria that comprise the microbiota are dispersed irregularly throughout the digestive system. These organisms play a major part in the usage of nutrients absorbed through food due to their metabolic activities; they also have a substantial impact on the development and functioning of the body's immune system along with other functions. The immune system's cells, which are responsible for defensive reactions against infections, are mostly concentrated in lymphatic structures found in the gastrointestinal tract's basement membrane, termed lamina propria [3].

The GALT includes several follicular structures and Peyer's patches, as well as T lymphocyte aggregates, antigen presentation cells (APC), including B lymphocytes, all of which produce IgA. IgA antibodies are resistant towards proteolysis and cannot stimulate the complement, therefore they provide protection without causing inflammation.

T lymphocytes are classified as CD4+ Helper T lymphocytes (TH1, TH2, TH17, and TH9), CD8+ T cytotoxic cells, or Regulatory T (Treg) gd cells. The relationship between bacteria and host organisms provides various benefits to both parties. The primary functions of the microbiota that have a favourable impact on the host organism include the following: participation in the formation of the intestinal wall resistance to colonisation: in 1916, Nissle demonstrated for the first time the role of human microbiota in conferring resistance to typhoid Salmonella infection and identified in the microbiota, as later confirmed, the first line of defence against pathogenic bacteria invasion production of short chain fatty acids, metabolites that play important physiological functions in fermentation  (acetic acid for muscle, heart, and brain; propionic acid essential gluconeogenesis; butyric aci for enterocyte function) Vitamin production, particularly of the B group, and interactions that involve the mucosalimmune system breakdown of xenobiotics, including genes capable of synthesising enzymes with catabolic activity against these chemicals [4].

Following early snags, probiotic research has advanced significantly over the last two decades, with major breakthroughs in the selection as well as characterisation of individual probiotic cultures, as well as notable health advantages upon ingestion.

Understanding the gut flora's role in human health, in addition to the probiotic food idea, requires an ecological perspective. Each person has a distinct profile of about 100-1000 microbial species in the gastrointestinal tract (GIT). Bacterial cells account for half of the moist weight of colonic waste and outnumber tissue cells tenfold [5].

Normally, the stomach has 103 distinct bacterial species, and the colon's total microbial population is around 1011e1012 cfu/g. Bacterial colonisation of the stomach starts at birth, when neonates are first exposed to a nonsterile environment. It will now change and transform throughout the course of a lifetime, based on a complex and dynamic interaction between the host's nutrition, DNA, and lifestyle, as well as antibiotic usage.

 

Notable age-related compositional variations in gut microbiota composition include a fall in the Bacteroidetes/Firmicutes ratio including a significant decrease in bifidobacteria in adults over 60 years old, which coincides with the onset of immune system deterioration. In general, the core gut microbiota is thought to remain rather consistent throughout adulthood [6].

Probiotics are active bacteria that benefit the host. Furthermore, bacteria that match the fundamental requirements for probiotics may develop into probiotics. Probiotics encompass a wide range of bacteria, including Bifidobacterium, Lactobacillus, Saccharomycetes, Bacillus, among others. Concurrently, the health benefits of probiotics have become a study hotspot. Probiotics have been shown to preserve normal intestinal flora structure, resist pathogen infection, ease constipation and diarrhoea, alleviate lactose intolerance, lower blood cholesterol levels, and boost immune system development [7].

Probiotics' mode of action consists essentially of three aspects: (1) increasing host defence capability, (2) directly battling bacteria, and (3) metabolites playing a vital role. Probiotics are beneficial in treating functional gastrointestinal diseases including irritable bowel syndrome. Several intestinal flora colonise the gastrointestinal system, which is implicated in the development of FD owing to mucosal injury and inflammation. As a result, controlling the gut flora may help alleviate FD symptoms. In this post, we will review and analyse several vital probiotics that can benefit human health, how they impact an individual's nutritional condition, and how probiotics work to prevent illnesses.

Additionally, the health-promoting function of probiotics and their action mechanisms in some of the most common disorders are discussed.

 

What Are Probiotics?

The term probiotic is derived by the Greek 'pro bios', which means 'for life'. Probiotics have been around since the beginning of time; the Greeks and Romans were well aware of cheese along with fermented milk and encouraged their intake, particularly for youngsters and convalescents.

Probiotics are described as live microorganisms supplied in sufficient quantities to thrive in the gut environment. Someone must have a good impact on the hosts. Lilly and Stillwell coined the word 'probiotic' in 1965 to refer to'substances released by one microbe that encourage the development of another' [8].

A strong evolution claimed that probiotics are "organisms and substances that help maintain intestinal microbial balance." In more modern definitions, the concept of an action on the gut microflora, and even that of live microorganisms, has disappeared. Probiotics are now defined as'microbial cell preparations or components of microbial cells that have a beneficial effect on the health and well-being'.

Some contemporary definitions specifically incorporate probiotics' preventative or therapeutic actions. Despite these multiple theoretical classifications, the practical challenge is whether a specific bacterium is a probiotic [9].

Several strict criteria were recently proposed for selecting a probiotic, such as total host safety, durability against gastric acidity along with pancreatic secretions, adhesion to epithelial cells, antimicrobial activity, inhibition of pathogenic bacteria adhesion, antibiotic resistance evaluation, tolerance towards food additives, along with stability in the matrix of food.

 

The probiotics that are used today were not chosen based on all of these criteria, but the most common probiotics are lactic acid bacteria strains such as Lactobacillus, Bifidobacterium, and Streptococcus (S. thermophilus); both of these strains have been shown to resist gastric acid, bile salts, along with pancreatic enzymes, adhere to colonic mucosa, and colonise the intestinal tract easily [10].

History

In the early twentieth century, Nobel laureate Élie Metchnikoff, a professor at the Pasteur Institute in Paris, hypothesised that the seeming life of Bulgarian peasants was due to their consumption of enormous quantities about fermented milk products such as curd and buttermilk. He felt that the lactic acid bacteria in these items replaced harmful organisms present in the intestines, reducing the creation of toxins that cause sickness and infection [11].

Composition

Probiotics can include bacteria, moulds, including yeast. However, most probiotics are bacteria. Lactic acid bacteria are the most commonly employed bacteria in probiotic production among the organisms listed. Lactobacillus bulgaricus (L. bulgaricus), Lactobacillus plantarum, Streptococcus thermophillus (S. thermophillus), Enterococcus faecium, Enterococcus faecalis, Bifidobacterium species, and Escherichia coli were identified.

Optimal probiotic characteristics

In 1989, Fuller identified the following characteristics of something probiotic. It should be a strain that can benefit the host animal, such as increasing growth or resistance to illness. It ought to be nonpathogenic and nontoxic. It should exist as live cells, ideally in huge numbers.

It should be able to survive and metabolise in the gut environment, including tolerance to low pH, organic acids, and bile. It should be stable in storage and in the field, and the microorganisms must be microbiologically characterised and tested in randomised clinical trials. It must, first and foremost, be of human origin, with scientific evidence indicating favourable physiological effects and safety for human usage. Furthermore, it must be efficient in adhering to the target organ [12].

Microorganisms with probiotic properties

The probiotic potential of various bacterial strains varies, even within the same species. Individual strains of a single species are always diverse, with varying regions of adherence (site-specific), distinctive immunological responses, and activities on a healthy vs. inflamed mucosal environment.

Current probiotic research tries to characterise each individual's natural, healthy gut microbiota, including species composition and bacterial concentrations in each section of the intestine.
The goal is to learn about host-microbe interactions in the gut, microbe-microbe interactions in the microbiota, and the overall health impacts of these interactions. The objective is to describe and characterise the microbiota as a tool for nutritional treatment of certain gut-related disorders, as well as to find novel bacteria for future probiotic bacteriotherapy applications [13].

This might potentially include microbes selectively isolated to give site-specific effects in illnesses like irritable bowel syndrome. In accordance with Shah and Chow, the most common strains can be identified by each of the following genera: Probiotics include Lactobacillus, Streptococcus, and Bifidobacterium, as well as enterococci and yeasts.

These strains were chosen based on critical selection criteria for effectiveness, including origin, in vitro adhesion to intestinal cells, and survival throughout transit through the GI system.

Clinical importance of probiotics and their prospective applications

The utilisation of probiotics towards clinical health advantages is an intriguing field of study that the current generation has yet to investigate. Some of the outstanding qualities of probiotics, such as antipathogenicity, anti-diabetes, anti-obesity, anti-inflammatory, anti-cancer, anti-allergic, and angiogenic activities, as well as their influence on the nervous system of the brain (CNS), are briefly reviewed here and illustrated in Fig. 1 [14].

Anti-pathogenic action of probiotics

Anti-pathogenic action is recognised as one about the most beneficial benefits of probiotics since, unlike traditional antibiotics, disruption or modification in the makeup of the complex gut microbiota community is prevented. There has been much study into the anti-pathogenic properties of probiotics or probiotic mixtures. Probiotics affect the survival microorganisms Salmonella enterica, Serovar typhimurium, and Clostridium difficile in an in vitro model, and it is proposed that probiotics suppress pathogens by producing short-chain fatty acids (SCFAs) such as acetic, propionic, butyric, and lactic acids [15].

SCFAs contribute to the maintenance of an optimum pH in the intestinal lumen, which is required for the production of several bacterial enzymes as well as the metabolism of foreign chemicals and carcinogens in the gut. According to Islam, many probiotics create a wide range of anti-pathogenic substances such as bacteriocins, ethanol, organic acids, diacetyl, acetaldehydes, hydrogen peroxide (H2O2), and peptides.

Peptides and bacteriocins, for particular, play an important role in enhancing the membrane permeability about target cells, which leads to membrane potential depolarization and, eventually, cell death. Similarly, these bacteria produce H2O2 [16].

Groups promotes the oxidation of sulfhydryl groups, leading in the denaturation of numerous enzymes, which causes the peroxidation of membrane lipids, increasing the pathogenic microorganism's membrane permeability and, as a consequence, cell death. Some of these chemicals may work by reducing pH with organic acids such as lactic and acetic acids.

Probiotics not only produce anti-pathogenic bioactive compounds that directly affect pathogens, but they also stimulate host antipathogenic defence pathways, such as the pathway involved in the production of defensins, which are cationic anti-microbial peptides produced in several cell types, including Paneth cells in the small intestine crypts and intestinal epithelial cells.

Probiotics can also exhibit anti-pathogenic effect by competing both pathogen binding promoting receptor sites, along with available nutrition and growth [17].

 

Fig. 1 Probiotic applications and mechanisms of action

 

Care for the urinary tract

According to the Centres for Disease Control and Prevention (CDCP), over one billion women worldwide suffer from non-sexually transmitted urogenital infections such bacterial vaginosis (BV), urinary tract infection (UTI), and a variety of other yeast infections. Gardnerella vaginalis, Ureaplasma urealyticum, and Mycoplasma hominis are typical BV species.
Sexually transmitted infections (STDs) are a major source of illness and mortality across the globe. In certain affluent nations, the most often described bacterial STDs are gonorrhoea and Chlamydia, caused by Neisseria gonorrhoeae and Chlamydia trachomatis, respectively. The primary challenge facing the present decade is that while having advanced drugs to treat numerous medical illnesses, these harmful [18].

Microbes, among others, are growing resistant to conventional medications. Therefore, instead of producing new drugs, our current focus should be on generating new life supplements, such as non-pathogenic microorganisms that work against infections. It is widely understood that aberrant vaginal microbial flora is associated with an increased risk of urinary tract infection (UTI).

The vagina contains approximately 50 different species, including Lactobacillus species, Lactobacillus brevis, Lactobacillus casei, Lactobacillus vaginalis, Lactobacillus delbrueckii, Lactobacillus salivarius, Lactobacillus reuteri, and Lactobacillus rhamnosus, which are considered the primary regulators of the vaginal micro-environment [19].

Imbalances in microbial composition have a significant impact on the health of the vaginal milieu, possibly leading to impaired bacterial vaginosis (BV) and UTI. These impaired conditions can be comforted by balancing the quantity of Lactobacillus sp. with probiotics.

 

Anti-diabetic properties of probiotics

According to the International Diabetes Federation (IDF) of Southeast Asia, 425 million people worldwide suffer from diabetes, with 78 million living in Southeast Asia. Furthermore, if nothing is done, this figure would climb to 629 million by 2045. Although there is no cure for diabetes, it is managed with a variety of drugs. Nonetheless, bimolecular and pharmacological researchers have made progress in understanding the role of synbiotics in the disorder's treatment [20].

The relationship between the makeup of the gut microbiota and metabolic illnesses such as obesity and diabetes is being investigated using large-scale 16 S rRNA gene sequencing, quantitative real-time PCR, and fluorescent in situ hybridization.

As a result, using probiotics to boost the beneficial microbiota is predicted to play an important role in neutralising the illness.

Gram-negative bacteroidetes and Gram-positive firmicutes are two distinct bacterial phyla that dominate the gut microbiota. Recent study has shown that obesity is connected with a rise in bacteroidetes with time, whereas firmicutes decrease. More precisely, individuals with type 2 diabetes have considerably less firmicutes species, resulting in an increase in the bacteroidetes/firmicutes ratio, which correlates favourably with plasma glucose levels. A similar trend has been linked to the development of auto-immune disorders, including type 1 diabetes [21].

Changes in the microbiome also promote the invasion of opportunistic infections, which are resistant to oxidative stress and can reduce sulphates while suppressing the growth of butyrate-producing bacteria. Another effective technique for managing type 2 diabetes is to modulate gut hormones such as gastric inhibitory polypeptide and glucagonlike peptide-1 by probiotic and prebiotic therapies.

In this context, hormones play an important role in glucose homeostasis, which neutralises the problem produced by peripheral insulin resistance or b-cell failure to generate insulin. Currently, research is focusing on developing novel prebiotics, such as arabinoxylan and arabinoxylan oligosaccharides, which have shown promising effects in combating associated metabolic problems, since both carbs have been connected to weight loss [22].

 

Probiotics' ability to reduce obesity

Abnormal or excessive fat (obesity) buildup, which directly harms health, is associated with increased energy availability, sedentariness, and improved control over ambient temperature, resulting in an imbalance in energy intake and expenditure. Transplanting obese mice's intestinal microflora into germ-free mice has been shown to duplicate the obesity phenotype and improve energy extraction and lipogenesis [23].

Probiotics have physiological effects that help to maintain the health of the host environment by controlling microorganisms. In most cases, weight reduction is aided by thermogenic and lipolytic reactions that stimulate the sympathetic nervous system. Lactobacillus gasseri BNR17, a probiotic strain, has been demonstrated to suppress the rise of adipocyte tissue, which is the primary source of leptin and adiponectin, restricting leptin release. Other probiotic microorganisms, including L. casei, Lactobacillus acidophilus, and Bifidobacterium longum, have been shown to lower cholesterol levels [24].

 

Probiotics have anti-cancer properties

According to the WHO cancer information sheet, cancer is a devastating illness that affects people all over the world, with roughly 14 million new cases and 8.2 million cancer-related deaths reported till 2012. Asia, Africa, and the Americas account for more than 70% of worldwide cancer mortality. Intensive cancer research integrating genomes, proteomics, and molecular pathology has increased cancer knowledge and public awareness during the last decade. Concurrently, several novel medications employing biotechnology and nanotechnology (nanocapsule) with exciting luminous features have been found, but tolerance to their load and side effects remains a significant constraint [25].

Probiotics, for example, have received a lot of attention in recent years as natural sources with anti-carcinogenic properties. Clinical nutritionists, scientists, as well as industrialists have shown a strong desire to collaborate in order to combat the condition and find an effective medicine with few, if any, adverse effects [26].

In vitro investigations have shown that the probiotic strains Lactobacillus fermentum NCIMB-5221 and -8829 are particularly effective at inhibiting colorectal cancer cells and encouraging normal epithelial colon cell development by producing SCFAs (ferulic acid). This capacity was also compared to other probiotics, including L. acidophilus ATCC 314 along with L. rhamnosus ATCC 51303, both of which have previously been identified as having tumorigenic activity [27].

Again, two separate probiotic strains, L. acidophilus LA102 and L. casei LC232, were found to exhibit strong cytotoxic properties, including anti-proliferative activity against 2 colorectal cancer cell lines (Caco-2 and HRT-18). Though probiotics may have an important role in cancer treatment, research is now restricted to in vitro experiments. As a result, probiotics' anti-cancer potential must be demonstrated in vivo before moving further with animal and human trials [28].

Probiotics possess anti-allergic properties

The growing frequency of allergy illnesses caused by immunological disorders imposes a significant economic and social cost over the world. Understanding the core molecular process that leads to the aetiology of allergy disorders, as well as innovative therapeutic methods, is critical for monitoring and preventing these conditions. In recent years, the beneficial effect of probiotics in the protection and management of allergic illnesses has enhanced our understanding of their causes and prevention [29].

Certain probiotics, including Lactobacillus plantarum L67, have been proven in vitro to prevent allergy-related diseases by increasing interleukin-12 and interferon-g production in their host. Another study found that L. plantarum 06CC2 substantially decreased allergy symptoms and levels of total immunoglobulin E, ovalbumin-specific immunoglobulin E, and histamine in the sera of ovalbumin-sensitised mice [30].

L. plantarum 06CC2 has been shown in mouse spleen cells to greatly increase interferon-g and interleukin-4 secretions, which are important for the relief of allergy symptoms. Further research may be useful in determining probiotics' anti-allergic efficacy and method of action [31].

 

Probiotics' angiogenic action

Angiogenesis has been a significant phenomena that is required for wound healing through defined cellular responses to rebuild damaged tissues. The angiogenic programme is a well organised set of biological events that promotes inflammatory cell recruitment and the production of cytokines, matrix-degrading enzymes, and chemokines, resulting in the formation of new capillaries from existent ones [32].

Deregulated angiogenesis has a significant influence on important human illnesses such as cancer, diabetic retinopathy, and IBD, which includes CD and UC. Nonpathogenic probiotic yeast, S. boulardii, has been shown to protect against intestinal damage and inflammation [33].

However, the molecular processes by which probiotics exert their therapeutic benefits are unknown. Probiotics may alter inflammatory cytokine profiles, downregulate pro-inflammatory cascades or induce strain-specific regulatory mechanisms, improve epithelial barrier function, reduce visceral hypersensitivity, spinal afferent traffic, and modulate stress response [34].

 

Probiotics' effects on the brain and the central nervous system

Microbiota colonisation in the GIT is strongly linked to both GIT and gastrointestinal disorders. Furthermore, in recent years, several research have been conducted to better understand the impact of gut microbiota on the CNS. The "microbiota-gut-brain axis" is a two-way communication system formed by the exchange of regulatory signals between both GIT and the CNS [35].

The effect of probiotics on the CNS has mostly been explored in clinical studies, which have shown that gut microbes influence human brain development function. In a randomised trial involving healthy volunteers treated with oral administration of Lactobacillus helveticus R0052 and B. longum R0175, a daily dose of L. plantarum WCFS1 (4.5 _ 1010 CFU/day) resulted in an improvement in their school records and attitude towards food, as well as reduced psychological distress [36].

Another clinical experiment found that administering L. casei strain Shirota to individuals suffering from chronic fatigue syndrome reduced their anxiety symptoms. Despite a rise in Lactobacillus as well as Bifidobacteria levels, bowel function was not investigated. As a result, it is possible that the decreased anxiety was attributable to better gastrointestinal function [37].

According to Szajewska, administering L. rhamnosus to the mother four weeks before expected birth can prevent autism spectrum and attention-deficit/hyperactivity problems in children. It has been shown that many gut bacteria create neuroactive chemicals that are comparable to those generated by the host brain [38].

Human intestinally generated strains of L. brevis DPC6108 and Bifidobacterium dentium have been shown to generate substantial levels of g-aminobutyric acid, a neurotransmitter that aids in the suppression of anxiety and sadness. Doses of a multispecies probiotic including L. brevis W, B. lactis W, L. acidophilus W37, Bifidobacterium bifidum W2, L. salivarius W2, L. casei W5, and Lactococcus lactis (W19 and W58) to healthy individuals resulted in a substantial overall decrease in cognitive reactivity to sadness.

However, probiotic studies including individuals suffering from anxiety and severe depression are scarce, necessitating further time and effort to confirm this benefit. Oral L. acidophilus supplementation has been found to help people modulate their mood towards rewards and addictive behaviour [39].

Nutritional and Health Benefits of Probiotics

Humans have an inherent urge for good health. Humans prioritised using natural resources to achieve optimal health results. In the twentieth century, it was discovered that healthy children given breast milk have Bifidobacteria in their gut microbiome. It established a positive relationship between health and gut microbiota, and several research have been undertaken to study the appropriate mechanism of this link, with some discovering that some bacteria have a good correlation with health [40].

The word probiotics were originally introduced in 1965 by Stillwell and Lilley to describe these helpful microorganisms. Élie Metchnikoff, a Nobel laureate and professor, discovered the health-promoting characteristics of fermented dairy products around the turn of the century in Paris.  He went on to say that the abundance of lactic acid bacteria for fermented dairy products keeps the immune system active, resulting in longer consumer lifetime.

Some important characteristics of probiotics were introduced in the 1980s, including: (a) beneficial strains, (b) non-toxic, non-allergic, and nonpathogenic, (c) available in large quantities as viable cells, (d) suitable for the gut environment, and (e) storable and stable. Although bacteria, particularly lactic acid, are the most popular probiotics, moulds and yeasts may serve as probiotics [41].

The previously Food and Agriculture Organisation and the World Health Organisation council defined probiotics in 2001, which was later refined in 2014 by Hill et al. as "live micro-organisms that, when administered in adequate amounts, confer a health benefit on the host," which can be understood to mean that probiotic strains must be (i) sufficiently characterised; (ii) safe for the intended use; and (iii) supported by at least one positive human clinical trial conducted according to Live bacteria such as Lactobacillus, Bifidobacterium, and others are examples [42].

Probiotics and their advantages

Probiotics across the form of live microorganisms are increasingly being used to promote health in both animals and humans. Today, a large variety of fermented foods and drinks are accessible, accounting for around one-third of the global human diet. Probiotic levels in meals range from 2 to 20 g/day, depending on the component and intended impact, and they may be added to a variety of food products such as cereals, biscuits, bread, sauces, yoghurts, and beverages.

Curd is regarded as the most preferable source of both probiotics and prebiotics, with greater knowledge of its health-promoting characteristics. They improve intestinal health and reduce the risk of illness, which is why they are utilised in treatment [43].

All probiotic products have unique nutritional and therapeutic properties due to a variety of factors such as the strain's genetic makeup, the number of probiotics utilised in the product, the reason for which it is used, and its shelf life.

The production, effect, and health advantages of a probiotic strain are all considered before choosing one. To provide health benefits, a probiotic food must contain 106 CFU/g of probiotic microorganism. The suggested human dose is 107-109 CFU/mg/day. It is known because the effect of probiotic food intake is dependent on the strain utilised in the product [44].

The following genera are essential for obtaining effective probiotic strains: Lactobacillus, Bifidobacterium, Enterococcus, Saccharomyces, Pediococcus, Streptococcus, and Leuconostoc. Lactic acid bacteria (LAB) and Bifidobacteria are the most often employed microorganisms in probiotics.

Lactobacillus species strains often detected in saliva samples include L. paracasei, L. plantarum, and L. rhamnosus. Bifidobacterial species are anaerobes that are also prevalent in the oral cavity. Both species are detected in breast milk and are generally considered harmless. Nutrition, age, environmental factors, incompatibilities, diseases, and treatment approaches all have a significant influence on gut microbiota development, maintenance, and functionality [45].

When picking the strain, keep in mind that it should be derived from target and natural microflora, as this is critical for its survival within an acidic environment when travelling to the colon. Probiotics improve the host's immune system and have been shown to alter the good bacteria found in the gut or intestine. Probiotics boost the immune system by influencing the humoral along with cellular immunological responses. Figure 2 summarises the health advantages of several probiotics [46].

Fig 2. Probiotics provide therapeutic advantages.

The strains chosen must also meet biosafety standards, implying they should not be poisonous or pathogenic. They should be evaluated for safety characteristics such as antibiotic susceptibility, resistance gene, and hemolytic activity [47]. Antimicrobial synthesis is a crucial property of probiotics against infections, however suboptimal antimicrobial activity disrupts the healthy microbiota in the intestines and has negative consequences. Higher amounts of bile resulted in reduced strain development. Probiotics can affect the pH of the surrounding environment, and consequently they can compete with the pathogens existing there [48].

 

Probiotics' Role in Disease Prevention

Probiotics can avoid chronic illnesses by moderating their effects. They have a favourable impact on gut health and can aid with skin problems including burns, scars, infections and wounds. They boost the skin's natural immunity and help renew healthy skin. The effect of Saccharomyces cerevisiae dressing dramatically enhanced burn skin healing, as proven by, whereas a fictitious representation of intestinal microbiota regulating wound healing via gut-brain-skin axis explains injured tissue recovery. The difference in gut microbiota composition, as well as lower amounts of Bifidobacteria as well as lactobacillus in newborns' intestines, causes allergy symptoms to develop [49].

Both the studies on specific probiotic strains as well as the outcomes show that they can be utilised to prevent eczema. Dysbiosis, also known as dysbacteriosis, is a word used to describe an imbalance of bacteria within the body, such as a defective microbiota, which is frequently linked to inflammatory bowel disease, colonic cancer, metabolic syndrome, and allergic responses. Improving gut microbiota balance by various dietary principles or by swallowing particular microorganisms resulted in considerable health improvements, reduced illness risk, and changed treatment modality [50].

 

Irritable bowel syndrome is related with a disruption in intestinal homeostasis, which leads in an unregulated immunological response to gut microbiota by intestinal immune cells and epithelial cells, leading to consequences such as ulcers and fibrosis.

A prebiotic is a helpful dietary ingredient that can aid in the growth of beneficial bacteria that alter the gut microbiota. Both probiotics and prebiotics can assist with irritable bowel syndrome. Probiotics have been shown to help cure intestinal ulcers and infected cutaneous lesions.

Skin microbiota serves as a defence barrier, regulating the skin's inflammatory response to mild epidermal damage by reducing and increasing cytokine production to keep the skin healthy [51].

Probiotics provide favourable benefits via directly eliminating the pathogen, strengthening the epithelial barrier, competitive displacement of harmful bacteria, and inducing fibroblasts. Probiotics are also extremely useful to burn sufferers since they lower the bacterial burden in the ulcer region. Skin injuries disrupt microbiota levels, increasing the frequency of microorganisms that have negative effects on wounds. Furthermore, having a wound produces stress, which disrupts neuro-endocrine responses and inhibits wound healing [52].

Chronic wounds are ones that are difficult to heal and can place a strain not only on the patient but also on the healthcare system, such as diabetic foot ulcers (DFU), venous leg ulcers (VLU), and decubitus ulcers (DU). Polymicrobial biofilms are common in chronic wounds and play a significant role in the development of impaired wounds by promoting pathogenic microbial growth and interfering with wound healing. Probiotics play a crucial role in autism therapy by influencing the gut microbiota, which is responsible for unbalanced neurodevelopmental diseases such as autism [53].

Gut microorganisms can disrupt gene Shank3, affecting a person's behaviour and perhaps leading to autism. There are many medications that can be used for treatment, but they all have negative effects; to prevent these adverse effects, probiotics are employed as an alternative therapy. To cure this disorder, probiotics modify the gene responsible for neurodevelopment while also maintaining the intestinal environment. This bacterial illness promotes several pathophysiological gastrointestinal disorders, including bowel syndrome, obesity, diarrhoea, and food allergies.

Dietary biotics are used to maintain the gastrointestinal flora while also relieving pain, vomiting, nausea, in addition to bowel syndrome. The most effective probiotic strains for treating GIT disorders are L. rhamnosus GG, L. reuteri 17938, VSL 3, and Bifidobacteria species [54].

Stool PCR testing on autistic children revealed a rise in the colony count of Bifidobacteria and lactobacilli, as well as a significant reduction in the severity of autism and gastrointestinal issues. During pregnancy, Interleukin-6 and 17a cytokines cause autism spectrum disorder. Probiotics reduce cytokine generation and prevent autism spectrum disease caused by maternal immunological stimulation.

Osteoporosis is a disease of the skeletal system that causes low bone mass density, skeletal system degradation, increased bone brittleness, and fracture sensitivity. The majority of cracks appear in the distal forearm, femur, as well as back [55].

These fissures are more prevalent in postmenopausal women. The reason of bone loss is a low amount of the hormone oestrogen, which plays an important role in bone development and maintenance. Many people in America suffer from osteoporosis, and the majority of the population is at high risk of having poor bone mass [56].

 

Osteoporosis can affect both men and women at any age, although it is more common in elderly women. Probiotics work as a medicinal agent to treat a variety of bone ailments, including osteoporosis along with rheumatoid arthritis. Probiotics affect bones by a variety of methods; the most hidden action of probiotics affecting bone occurs through vitamin integration.  Calcium metabolism involves vitamin D, C, K, as well as folate, all of which are required for bone growth [57].

Commercial relevance of probiotics, recent advances, and the usefulness of prebiotics

Although probiotics continue to be in the pipeline and require additional research and development to overcome challenges to effective administration and minimum adverse effects, numerous types of probiotics are commercially accessible and widely used. Some of the most popular commercial microbial strains offered as probiotics, along with their origins. The species described below are based on manufacturer standards and features, and may not reflect the latest recent taxonomy [58].

Prebiotics, like probiotics, are being extensively researched for their potential use in a variety of fields of applied science, notably as nutritional supplements. However, unlike the new, research on the utility of prebiotics is limited.

The following are some of the cutting-edge studies that have advanced our understanding of prebiotics. According to Wikipedia, "prebiotics comprise a collection of nutritional enriched compounds grouped according to the efficiency to enhance and support the establishment and sustenance of specific beneficial gut microflora" . Prebiotics are defined as non-digestible substances that can particularly modify the nutrition of health-promoting gut microorganisms [59].

The advent of numerous 'omic' methods like as proteomics, genomics, metabolomics, transcriptomics, and so on has greatly expanded our understanding of the complexity and utility of these non-digestible substances.

As a result, the current emphasis of study is on diverse modes of synthesis. The food businesses of the current decade demand simple, long-term, cost-effective, and highly efficient techniques of large-scale manufacturing and application. Prebiotic oligosaccharides can be derived naturally from food; however, they can also be synthesised chemically or enzymatically using disaccharides or other substrates, as well as by polysaccharide hydrolysis.
The majority of natural prebiotics have previously been investigated for their beneficial effect; so, the present hunt is for further new prebiotic oligosaccharides using different enzyme-based technologies. Enzymes (bgalactosidase, fructosyltransferase, etc.) from a variety of sources, including microorganisms and plants, are used for synthesis [60].

Furthermore, enzymes are modified to better control regioselectivity and increase reaction yield, hence improving glycodiversification and product quality. Again, the introduction of genetically modified microbes has led in increased synthesis of oligosaccharides (20fucosyllactose) via fermentation for large-scale industrial manufacturing.

Because of the tangible association of prebiotic oligosaccharides with the gut microbiome, as well as their role in the maintenance and restoration of microbial homeostasis, which is again closely linked to the host's positive health outcome, prebiotic research is receiving a lot of attention in the present day.

 

Prebiotic chemicals are food-grade molecules that can be converted into beneficial short-chain fatty acids by microorganisms such as bifidobacteria as well as lactobacilli in the host, making them ideal for use as nutritional supplements. Their biological benefits extend beyond the gastrointestinal system and include other systems. Recent research on rat models have shown that consuming galactooligosaccharides (GOS) particularly improves calcium absorption, retention, bone density, and strength [61].

Gut microbes influence the expression of gamma-aminobutyric acid receptors in the brain; prebiotics such as FOS and GOS are likely to use this connection to modulate brain-derived neurotrophic factors, D-serine, along with other synaptic proteins such as synaptophysin and N-methyl-D-aspartate receptor subunit. Prebiotics such as oligofructose, b-fructan, and oligofructose/inulin mix have been shown to have immunomodulatory advantages in the cases of pathogenic attack, atopic dermatitis, allergy prevention, chronic inflammation, and up-regulated responses to immunisations [62].

This non-digestible chemical has also shown benefits for a range of skin diseases. GOS supplementation improved water retention and prevented erythema in hairless mice's skin. Studies have also shown that enhanced dermal expression of cell adhesion along with matrix formation markers CD44 and type 1 collagen following GOS therapy improves skin barrier characteristics [63]. Again, GOS, either alone or in combination with B. breve, has been shown to inhibit phenolic compound-induced water and keratin depletion. Similarly, prebiotics are now being extensively researched for their potential use in the treatment of a variety of disorders and illnesses [64].

 Future developing topics of research

1.     Concerted investigations are underway to determine the impact of probiotics on cardiovascular illnesses such as myocardial infarction and atherosclerosis.

2.     Dr. Gershon, a neuro-gastroenterologist, proposes the presence of an enteric neural system, as well as its role and participation in gut physiology and related gut illnesses. Understanding the involvement of BMicrobial endocrinology can help address the idea outlined above. Probiotics synthesise and react to neuroactive substances [65].

 

Probiotic compositions pose a challenge

Inappropriate usage of the name Bprobiotic, as well as a failure to recognise the relevance of strain and dosage specificity, are current concerns. Probiotics manufactured as nutritional supplements rather than pharmaceuticals face less regulatory scrutiny since manufacturers are not required to justify effectiveness or safety claims for foods as well as nutraceutical supplements. This is a major reason why most commercial goods have little to no effectiveness and safety information [66].  

The task at hand for experts engaged with the medical aspect of nutritional foods and probiotics, prebiotics, synbiotics, along with novel foods is to apply new knowledge generated by basic researchers in the field regarding intestinal flora has suggested the fact that probiotic research today stands at the intersection of gastroenterology, immunology, and microbiology, and is highly dynamic in both the basic and clinical fields. Further knowledge of the complicated molecular pathways that contribute to probiotic efficiency will also aid in the creation of more successful probiotic compositions [67].

 

The hazards and inherent flaws of commercial probiotic products and corrective measures include insufficient transport of probiotics through the lower gastrointestinal system, particularly the acidic environment inside the stomach. As a result, a more targeted delivery method with suitable dose must be developed. Additional advancements are necessary.

1) The beneficial bacteria formulation should have an extended shelf life and deliver live, active probiotic cells even after lengthy storage.

2). Evaluation procedures must be created to ensure that the formulation contains clinically confirmed live probiotic microorganisms [68].

Probiotic research has limitations

Our understanding of the processes involved in the positive benefits of probiotics, including synbiotics, is limited. Incomplete knowledge on probiotic doses necessary for certain clinical outcomes emphasises the importance of molecular characterization of probiotics for establishing health claims.

Direct data is currently inadequate for understanding the immunological processes that allow probiotics to exert their therapeutic benefits. Probiotic interactions between strains in formulations such as VSL-3 have not been examined. This remains a murky area that has to be investigated [69].

Understanding the interplay between the microbiota, the host, and the prebiotic component is critical in planned clinical trials as well as validation studies with higher sample sizes [70]. There is very little published literature on the production process and subsequent formulation, and more work still needs to be done to increase strain survivability during formulation and storage. There is a need for more.

The functions of probiotics and prebiotics are under debate. Probiotic(s) causing damage are uncommon, although the most usually reported adverse effect is gastrointestinal distress, such as bloating. S. boulardii along with Lactobacillus GG have been observed to accelerate problems in select patient populations, particularly immune-compromised people [71].

Pregnant women, neonates, and the elderly are more vulnerable to probiotic infections due to their compromised immune systems [72]. Several Lactobacillus strains are inherently resistant to vancomycin, raising worries about the potential spread of such resistance to more dangerous organisms in the gut environment [73]. The fermentation of FOS in the colon produces hydrogen and carbon dioxide, which might be uncomfortable for some. Excessive use of prebiotics, particularly oligosaccharides such as FOS and GOS, produces gastrointestinal discomfort such as bloating along with distension, as well as substantial amounts of flatulence [74].

Conclusion

To summarise, the data supporting the potential of probiotics is encouraging but requires additional investigation and refining. This evidence-based research revealed that probiotics are effective in a variety of health diseases, including gastrointestinal illnesses, immunological regulation, and even mental health difficulties. However, the efficacy of probiotics varies depending on strain specificity, dose, period of administration, and the individual's baseline health state.

While many studies show favourable results, several discrepancies and limits in research methodology underscore the importance of more rigorous clinical trials and standardised procedures. Furthermore, knowing the mechanisms of action that underpin probiotic effects is critical for optimising their usage and identifying target populations that might benefit the most from supplementation.

Furthermore, it is critical to understand that probiotics are not a cure-all and should not be used instead of traditional medical therapies. They should be considered as a complimentary approach to general health and wellbeing, to be combined with a healthy lifestyle and diet. Given the increased interest and developing body of data, further inquiry into probiotics' potential is necessary.

This involves investigating novel strains, evaluating their effects on various health outcomes, identifying their mechanisms of action, and determining appropriate doses and delivery regimens. Overall, while the subject of probiotics offers great promise, more scientific research is needed to fully realise their potential and properly incorporate them into clinical practice for the enhancement of public health.

 

References

1.     Aureli P, Capurso L, Castellazzi AM, Clerici M, Giovannini M, Morelli L, Poli A, Pregliasco F, Salvini F, Zuccotti GV. Probiotics and health: an evidence-based review. Pharmacological research. 2011 May 1;63(5):366-76.

2.     Harish K, Varghese T. Probiotics in humans–evidence based review. Calicut Med J. 2006;4(4):e3.

3.     Hungin AP, Mulligan C, Pot B, Whorwell P, Agréus L, Fracasso P, Lionis C, Mendive J, Philippart de Foy JM, Rubin G, Winchester C. Systematic review: probiotics in the management of lower gastrointestinal symptoms in clinical practice–an evidence‐based international guide. Alimentary pharmacology & therapeutics. 2013 Oct;38(8):864-86.

4.     Peivasteh-Roudsari L, Pirhadi M, Karami H, Tajdar-Oranj B, Molaee-Aghaee E, Sadighara P. Probiotics and food safety: an evidence-based review. Journal of Food Safety and Hygiene. 2019 Dec 31;5(1):1-9.

5.     McFarland LV. Evidence-based review of probiotics for antibiotic-associated diarrhea and Clostridium difficile infections. Anaerobe. 2009 Dec 1;15(6):274-80.

6.     Hungin AP, Mitchell CR, Whorwell P, Mulligan C, Cole O, Agréus L, Fracasso P, Lionis C, Mendive J, Philippart de Foy JM, Seifert B. Systematic review: probiotics in the management of lower gastrointestinal symptoms–an updated evidence‐based international consensus. Alimentary Pharmacology & Therapeutics. 2018 Apr;47(8):1054-70.

7.     Viswanathan S, Lau C, Akbari H, Hoyen C, Walsh MC. Survey and evidence based review of probiotics used in very low birth weight preterm infants within the United States. Journal of Perinatology. 2016 Dec;36(12):1106-11.

8.     Deshpande GC, Rao SC, Keil AD, Patole SK. Evidence-based guidelines for use of probiotics in preterm neonates. BMC medicine. 2011 Dec;9:1-3.

9.     Ma T, Shen X, Shi X, Sakandar HA, Quan K, Li Y, Jin H, Kwok LY, Zhang H, Sun Z. Targeting gut microbiota and metabolism as the major probiotic mechanism-An evidence-based review. Trends in Food Science & Technology. 2023 Jun 11.

10.  McKenzie YA, Thompson J, Gulia P, Lomer MC, (IBS Dietetic Guideline Review Group on behalf of Gastroenterology Specialist Group of the British Dietetic Association). British Dietetic Association systematic review of systematic reviews and evidence‐based practice guidelines for the use of probiotics in the management of irritable bowel syndrome in adults (2016 update). Journal of Human Nutrition and Dietetics. 2016 Oct;29(5):576-92.

11.  Rondanelli M, Faliva MA, Perna S, Giacosa A, Peroni G, Castellazzi AM. Using probiotics in clinical practice: Where are we now? A review of existing meta-analyses. Gut microbes. 2017 Nov 2;8(6):521-43.

12.  Koretz RL. Probiotics in gastroenterology: how pro is the evidence in adults?. Official journal of the American College of Gastroenterology| ACG. 2018 Aug 1;113(8):1125-36.

13.  Levri KM, Ketvertis K, Deramo M, Merenstein JH, D'Amico F. Do probiotics reduce adult lactose intolerance? A systematic review.(APPLIED EVIDENCE: New research findings that are changing clinical practice. Journal of Family Practice. 2005 Jul 1;54(7):613-21.

14.  Depoorter L, Vandenplas Y. Probiotics in pediatrics. A review and practical guide. Nutrients. 2021 Jun 24;13(7):2176.

15.  Cheng L, Shi J, Peng H, Tong R, Hu Y, Yu D. Probiotics and liver fibrosis: An evidence-based review of the latest research. Journal of Functional Foods. 2023 Oct 1;109:105773.

16.  Szajewska H. What are the indications for using probiotics in children?. Archives of disease in childhood. 2016 Apr 1;101(4):398-403.

17.  Hojsak I. Probiotics in children: what is the evidence?. Pediatric gastroenterology, hepatology & nutrition. 2017 Sep;20(3):139.

18.  Niu HL, Xiao JY. The efficacy and safety of probiotics in patients with irritable bowel syndrome: Evidence based on 35 randomized controlled trials. International Journal of Surgery. 2020 Mar 1;75:116-27.

19.  Mihatsch WA, Braegger CP, Decsi T, Kolacek S, Lanzinger H, Mayer B, Moreno LA, Pohlandt F, Puntis J, Shamir R, Stadtmueller U. Critical systematic review of the level of evidence for routine use of probiotics for reduction of mortality and prevention of necrotizing enterocolitis and sepsis in preterm infants. Clinical nutrition. 2012 Feb 1;31(1):6-15.

20.  McFarland LV, Elmer GM. Properties of evidence-based probiotics for human health. Probiotics in food safety and human health: New York Marcel Dekker, Inc. 2005 Oct 10:109-37.

21.  Cruchet S, Furnes R, Maruy A, Hebel E, Palacios J, Medina F, Ramirez N, Orsi M, Rondon L, Sdepanian V, Xóchihua L. The use of probiotics in pediatric gastroenterology: a review of the literature and recommendations by Latin-American experts. Pediatric Drugs. 2015 Jun;17:199-216.

22.  Marteau PR. Probiotics in clinical conditions. Clinical Reviews in Allergy & Immunology. 2002 Jun;22:255-73.

23.  Shirvani-Rad S, Tabatabaei-Malazy O, Mohseni S, Hasani-Ranjbar S, Soroush AR, Hoseini-Tavassol Z, Ejtahed HS, Larijani B. Probiotics as a complementary therapy for management of obesity: a systematic review. Evidence-Based Complementary and Alternative Medicine. 2021 Jan 23;2021.

24.  Lahner E, Annibale B. Probiotics and diverticular disease: evidence-based?. Journal of Clinical Gastroenterology. 2016 Nov 1;50:S159-60.

25.  Zheng J, Feng Q, Zheng S, Xiao X. The effects of probiotics supplementation on metabolic health in pregnant women: An evidence based meta-analysis. PLoS One. 2018 May 21;13(5):e0197771.

26.  Parker EA, Roy T, D'Adamo CR, Wieland LS. Probiotics and gastrointestinal conditions: An overview of evidence from the Cochrane Collaboration. Nutrition. 2018 Jan 1;45:125-34.

27.  Guarino A, Guandalini S, Vecchio AL. Probiotics for prevention and treatment of diarrhea. Journal of clinical gastroenterology. 2015 Nov 1;49:S37-45.

28.  Hernell O, West CE. Clinical effects of probiotics: scientific evidence from a paediatric perspective. British journal of nutrition. 2013 Jan;109(S2):S70-5.

29.  Hill C. Probiotics and pharmabiotics: alternative medicine or an evidence-based alternative?. Bioengineered bugs. 2010 Mar 1;1(2):79-84.

30.  Amir LH, Griffin L, Cullinane M, Garland SM. Probiotics and mastitis: evidence-based marketing?. International breastfeeding journal. 2016 Dec;11:1-5.

31.  Stavropoulou E, Bezirtzoglou E. Probiotics in medicine: a long debate. Frontiers in immunology. 2020 Sep 25;11:554558.

32.  Scarpellini E, Cazzato A, Lauritano C, Gabrielli M, Lupascu A, Gerardino L, Abenavoli L, Petruzzellis C, Gasbarrini G, Gasbarrini A. Probiotics: which and when?. Digestive Diseases. 2008 Apr 21;26(2):175-82.

33.  Lokhande S, More S, Raje V. A systematic study of probiotics-an update review. Asian Journal of Pharmacy and Technology. 2018;8(3):149-57.

34.  Neunez M, Goldman M, Ghezzi P. Online information on probiotics: does it match scientific evidence?. Frontiers in medicine. 2020 Jan 15;6:296.

35.  Martinez RC, Bedani R, Saad SM. Scientific evidence for health effects attributed to the consumption of probiotics and prebiotics: an update for current perspectives and future challenges. British Journal of Nutrition. 2015 Dec;114(12):1993-2015.

36.  Doron S, Snydman DR. Risk and safety of probiotics. Clinical Infectious Diseases. 2015 May 15;60(suppl_2):S129-34.

37.  Shewale RN, Sawale PD, Khedkar CD, Singh A. Selection criteria for probiotics: A review. International Journal of Probiotics & Prebiotics. 2014 Feb 1;9(1/2):17.

38.  Tamboli CP, Caucheteux C, Cortot A, Colombel JF, Desreumaux P. Probiotics in inflammatory bowel disease: a critical review. Best Practice & Research Clinical Gastroenterology. 2003 Oct 1;17(5):805-20.

39.  Rozga M, Cheng FW, Handu D. Effects of probiotics in conditions or infections similar to covid-19 on health outcomes: An evidence analysis center scoping review. Journal of the Academy of Nutrition and Dietetics. 2021 Sep 1;121(9):1841-54.

40.  Mantegazza C, Molinari P, D’Auria E, Sonnino M, Morelli L, Zuccotti GV. Probiotics and antibiotic-associated diarrhea in children: A review and new evidence on Lactobacillus rhamnosus GG during and after antibiotic treatment. Pharmacological research. 2018 Feb 1;128:63-72.

41.  Szajewska H. Advances and limitations of evidence-based medicine–impact for probiotics. Annals of nutrition & metabolism. 2010 Jan 1;57:6-9.

42.  Ouwehand AC. A review of dose-responses of probiotics in human studies. Beneficial Microbes. 2017 Apr 26;8(2):143-51.

43.  Hempel S, Newberry SJ, Maher AR, Wang Z, Miles JN, Shanman R, Johnsen B, Shekelle PG. Probiotics for the prevention and treatment of antibiotic-associated diarrhea: a systematic review and meta-analysis. Jama. 2012 May 9;307(18):1959-69.

44.  Dale HF, Rasmussen SH, Asiller ÖÖ, Lied GA. Probiotics in irritable bowel syndrome: an up-to-date systematic review. Nutrients. 2019 Sep 2;11(9):2048.

45.  Sivamaruthi BS, Kesika P, Chaiyasut C. The role of probiotics in colorectal cancer management. Evidence-Based Complementary and Alternative Medicine. 2020 Oct;2020.

46.  Meurman JH, Stamatova I. Probiotics: contributions to oral health. Oral diseases. 2007 Sep;13(5):443-51.

47.  Amdekar S, Singh V. Probiotics: For Stomach Disorders-An Evidence Based Review. American Journal of Pharmatech and Research. 2012;3(4):34-45.

48.  Wallace TC, MacKay D. The safety of probiotics: considerations following the 2011 US Agency for Health Research and Quality report. The Journal of nutrition. 2011 Nov 1;141(11):1923-4.

49.  Hempel S, Newberry S, Ruelaz A, Wang Z, Miles JN, Suttorp MJ, Johnsen B, Shanman R, Slusser W, Fu N, Smith A. Safety of probiotics used to reduce risk and prevent or treat disease. Evidence report/technology assessment. 2011 Apr 1(200):1-645.

50.  Abe AM, Gregory PJ, Hein DJ, Cochrane ZR, Wilson AF. Survey and systematic literature review of probiotics stocked in academic medical centers within the United States. Hospital pharmacy. 2013 Oct;48(10):834-47.

51.  New FJ, Theivendrampillai S, Juliebø-Jones P, Somani B. Role of probiotics for recurrent UTIs in the twenty-first century: a systematic review of literature. Current urology reports. 2022 Feb;23(2):19-28.

52.  Merenstein D. Evidence-based Usage of Probiotics for Pediatric Acute Gastroenteritis. Journal of Pediatric Gastroenterology and Nutrition. 2020 Aug 1;71(2):146-7.

53.  Wojtyniak K, Szajewska H. Systematic review: probiotics for functional constipation in children. European journal of pediatrics. 2017 Sep;176:1155-62.

54.  AlFaleh K, Anabrees J. Probiotics for prevention of necrotizing enterocolitis in preterm infants. Evidence‐Based Child Health: A Cochrane Review Journal. 2014 Sep;9(3):584-671.

55.  Rafter J. Probiotics and colon cancer. Best Practice & Research Clinical Gastroenterology. 2003 Oct 1;17(5):849-59.

56.  Szajewska H, Setty M, Mrukowicz J, Guandalini S. Probiotics in gastrointestinal diseases in children: hard and not-so-hard evidence of efficacy. Journal of pediatric gastroenterology and nutrition. 2006 May 1;42(5):454-75.

57.  Di Cerbo A, Palmieri B. The market of probiotics. Pakistan journal of pharmaceutical sciences. 2015;28(6):2199-206.

58.  Dwivedi J, Sachan P, Wal P, Dwivedi S, Sharma MC, Rao SP. Detailed review on phytosomal formulation attenuating new pharmacological therapies. Advances in Traditional Medicine. 2023 Oct 6:1-26.

59.  Zhong DY, Li L, Ma RM, Deng YH. The effect of probiotics in stroke treatment. Evidence-based Complementary and Alternative Medicine. 2021 Oct 28;2021.

60.  Rijkers GT, Bengmark S, Enck P, Haller D, Herz U, Kalliomaki M, Kudo S, Lenoir-Wijnkoop I, Mercenier A, Myllyluoma E, Rabot S. Guidance for substantiating the evidence for beneficial effects of probiotics: current status and recommendations for future research. The Journal of nutrition. 2010 Mar 1;140(3):671S-6S.

61.  Salminen S, Ouwehand A, Benno Y, Lee YK. Probiotics: how should they be defined?. Trends in food science & technology. 1999 Mar 1;10(3):107-10.

62.  Rafter J. The effects of probiotics on colon cancer development. Nutrition research reviews. 2004 Dec;17(2):277-84.

63.  Disamantiaji AP, Izza EF, Soelaeman MF, Sembiring T, Louisa M. Probiotics in the management of atopic dermatitis for children: a case-based review. Dermatology research and practice. 2020 Dec 7;2020.

64.  Schwenger EM, Tejani AM, Loewen PS. Probiotics for preventing urinary tract infections in adults and children. Cochrane Database of Systematic Reviews. 2015(12).

65.  Shanahan F. Probiotics in perspective. Gastroenterology. 2010 Dec 1;139(6):1808-12.

66.  Viswanathan S, Lau C, Akbari H, Hoyen C, Walsh MC. Erratum: Survey and evidence based review of probiotics used in very low birth weight preterm infants within the United States. Journal of Perinatology. 2017 Jan 1;37(1):104-5.

67.  Dwivedi J, Kumar P, Sachan P, Singh C, Saxena B, Wal A, Wal P. Phyto-pharmacological Potential of Aegle marmelos (L.) for Neurological Disorders: Progress and Prospects. Recent Advances in Food, Nutrition & Agriculture. 2024 Mar 11.

68.  Martinelli M, Banderali G, Bobbio M, Civardi E, Chiara A, D’Elios S, Lo Vecchio A, Olivero M, Peroni D, Romano C, Stronati M. Probiotics’ efficacy in paediatric diseases: which is the evidence? A critical review on behalf of the Italian Society of Pediatrics. Italian journal of pediatrics. 2020 Dec;46:1-3.

69.  Shanahan F. Probiotics in inflammatory bowel disease—therapeutic rationale and role. Advanced drug delivery reviews. 2004 Apr 19;56(6):809-18.

70.  Sen M. Role of probiotics in health and disease–A review. International Journal of Advancement in Life Sciences Research. 2019 Apr 30:1-1.

71.  Gill HS, Guarner F. Probiotics and human health: a clinical perspective. Postgraduate Medical Journal. 2004 Sep;80(947):516-26.

72.  Shanahan F. A commentary on the safety of probiotics. Gastroenterology Clinics. 2012 Dec 1;41(4):869-76.

73.  Yadav M, Mandeep, Shukla P. Probiotics of diverse origin and their therapeutic applications: a review. Journal of the American College of Nutrition. 2020 Jul 3;39(5):469-79.

74.  Barclay AR, Stenson B, Simpson JH, Weaver LT, Wilson DC. Probiotics for necrotizing enterocolitis: a systematic review. Journal of pediatric gastroenterology and nutrition. 2007 Nov 1;45(5):569-76.