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 Table of Contents  
Year : 2018  |  Volume : 7  |  Issue : 2  |  Page : 75-80

Probiotics for life – Part I general health perspectives

1 Department of Pedodontics and Preventive Dentistry, STES Sinhgad Dental College and Hospital, Pune, Maharashtra, India
2 Department of Orthodontics and Dentofacial Orthopedics, STES Sinhgad Dental College and Hospital, Pune, Maharashtra, India

Date of Web Publication1-Nov-2018

Correspondence Address:
Dr. Raju Umaji Patil
Department of Pedodontics and Preventive Dentistry, STES Sinhgad Dental College and Hospital, S. No. 44/1, Vadgaon Budruk, Off Sinhgad Road, Pune - 411 041, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jdas.jdas_4_18

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Scientific evidence is expanding continuously during the past few decades, pointing to the beneficial effects of probiotic bacteria on human health. Food industry has been very active in studying and promoting various probiotic products. The WHO has advocated the reduced use of antibiotics and microbial interference therapy (use of nonpathogens to eliminate pathogens), observing the increasing development of antimicrobial resistance. Initially, probiotics were traditional used for the treatment of gastrointestinal disorders and allergies; later, there has been an expansion in therapeutic uses of these agents in urogenital infections, carcinomas, etc. Due to the increasing mountain of literature on this topic, brief user-friendly information is provided in lucid language for busy clinicians. This Part I article gives an overview of the history and properties of probiotics, mechanisms of action, and uses to promote general health. The Part II article, coming in next issue of this journal, highlights on oral health. To understand oral effects of probiotics, their medical background knowledge is essential.

Keywords: Gastrointestinal diseases, health, microorganisms, probiotics

How to cite this article:
Dastoor PP, Patil RU, Unde MP, Patil SS. Probiotics for life – Part I general health perspectives. J Dent Allied Sci 2018;7:75-80

How to cite this URL:
Dastoor PP, Patil RU, Unde MP, Patil SS. Probiotics for life – Part I general health perspectives. J Dent Allied Sci [serial online] 2018 [cited 2023 Mar 26];7:75-80. Available from: https://www.jdas.in/text.asp?2018/7/2/75/244760

  Introduction Top

The human body lives in heavily contaminated bacterial environment, and symbiosis with these microorganisms seems to be an important requisite for survival. A human individual has more prokaryotic organisms associated with skin, lung, and gut surfaces than human eukaryotic cells.[1]

Chemotherapeutics are widely used to prevent and treat infection caused by indigenous and exogenous microbes.[2] There was a marked reduction in death rate seen in the developed countries in the latter half of the 20th century as a result of availability of cheap and effective antibiotics for the treatment of infectious diseases. However, the development of resistance to a range of antibiotics by some important pathogens has raised a possibility of a return to the preantibiotic dark ages. The developments have encouraged researchers in various fields of health care to develop alternative antimicrobial approaches such as the application of health-promoting bacteria for therapeutic purposes.[2]

The term “probiotics” was derived from the Greek word meaning “for life,” popularized by R. Fuller in 1989, was defined recently by an Expert Committee as “ Living micro-organisms which upon ingestion in certain numbers exert health benefits beyond inherent general nutrition.”[3],[4]

There are increasing experimental and clinical data to support their use in the prevention and treatment of many gastrointestinal disorders including inflammatory bowel disease (IBD), infectious and antibiotic-related diarrheas, and postresection disorders such as pouchitis.[4],[5],[6] The ecological balance of the intestinal flora may be altered favorably by ingestion of probiotics.[7],[8]

The various definitions of probiotics as given by different authors are given in [Table 1].[9]
Table 1: Definitions of probiotics

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  History Top

Since centuries, kefir, yogurt, and other fermentable products have been consumed due to their extensive health benefits on various parts of the body without actually understanding the mechanism as to what active component of these products causes the desired effects. The history of probiotics has been briefly described in [Table 2].[10],[11],[12],[13] The first probiotic product (Yakult) was introduced in Asia in 1935. Collins et al. described three distinct phylogenetic clusters in genus Lactobacillus using 16S rRNA sequence analysis: Lactobacillus delbrueckii group, Lactobacillus casei group, and Leuconostoc group, which was later modified by Shleifer and Ludwig in 1995 using polyphasic taxonomy to define five groups, namely, Lactobacillus acidophilus (previously L. delbrueckii group), Lactobacillus salivarius, Lactobacillus reuteri, Lactobacillus bucheri, and Lactobacillus plantarum (All previously L. casei groups). Hammes and Hertel in 2003 expanded the number of groups to seven: adding Lactobacillus sakei group and restoring L. casei group. Later, a number of new groups were added with the advent of the genomic era resulting in almost 12 groups and 109 species of lactobacilli that we know of as of today.[14]
Table 2: History of probiotics

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  Mechanism of Action Top

Probiotics exert their action through a variety of somewhat discrete, somewhat overlapping mechanisms. These include the regulation of intestinal microbial homeostasis, the interference with the ability of pathogens to colonize and infect the mucosa, the modulation of local and systemic immune responses, stabilization or maintenance of the gastrointestinal barrier function, inhibition of procarcinogenic enzymatic activity, and the induction of enzymatic activity that favors good nutrition. Each of these mechanisms may be further subdivided depending on the function involved.[15] [Table 3][15] and [Figure 1][16] show the major mechanisms of action of probiotics.
Table 3: Mechanisms of action of different probiotic bacteria

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Figure 1: Mechanism of action of probiotics

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An ideal probiotic preparation should have the following properties:[17]

  • High cell viability and resistant to low pH/acids and processing
  • Ability to persist in intestine even if the strain cannot colonize gut
  • Adhesion to the gut epithelium to cancel the flushing effects of peristalsis
  • Should be able to interact or to send signal to immune cells associated with gut
  • They should be of human origin and nonpathogenic
  • Must have capacity to influence local metabolic activity.[17]

“For adequate amount of health benefits, a dose of 5 billion colony-forming units a day (5 × 109 CFU/day) has been recommended, for at least 5 days.”[18] The microorganisms used in probiotic preparations should be Generally Recognized as Safe, they should be resistant to bile, hydrochloric acid, and pancreatic juice, have anticarcinogenic activity and stimulate immune system, have reduced intestinal permeability, produce lactic acid, and able to survive both in acidic conditions of the stomach and alkaline conditions of the duodenum.[19]

  Commonly Used Probiotics Top

Bacteria, before being selected as a probiotic, should be nonpathogenic, nontoxigenic, should retain viability during storage and use, should have the capacity to survive and metabolize in the gut, and finally should have documented health effects. Some of the microorganisms most commonly used to promote health and nutrition are given in [Table 4][20] and [Figure 2].[21]
Table 4: Commonly used probiotic organisms

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Figure 2: Probiotic microorganisms

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  Role of Probiotics in General Medical Health Top

Probiotics exert a wide spectrum of different effects such as direct antagonism against pathogens and influence on intestinal epithelium and immune system of host.[22] Thus, conceptually, the use of probiotics constitutes a purposeful attempt to modify the relationship with immediate microbial environment in ways that may benefit general health [Table 5] and [Table 6].[22],[23],[24]
Table 5: Potential and established effects of probiotic bacteria

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Table 6: Various studies on the effect of probiotics on general health

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Probiotics have been shown to be effective in varied clinical conditions:

  • Gastrointestinal: Several gastrointestinal health claims have been made for probiotics, such as the relief of enzymatic maldigestion, diarrhea, acute inflammatory disease ulcerative colitis, Crohn's disease, and pouchitis[24]
  • Elimination of lactose intolerance: Lactose intolerance is caused by reduced production of β-galactosidase leading to increased osmotic load in the small intestine with subsequent secretion of fluids characterized by loose stools and abdominal pain[25],[26] Fermented milk products have been observed to be tolerated well by lactose maldigesters as compared to milk due to the presence of β-galactosidase in the bacteria fermenting the milk and the more viscous properties of fermented milks, gives them a longer gastrocecal transit time, thus further aiding digestion of lactose[1],[27]
  • Antidiarrheal: The potential mechanisms by which probiotics fight infectious diarrhea include the exclusion of pathogens by means of competition for binding sites and available substrates, lowering of luminal pH and production of bacteriocins, and promotion of the production of mucus, enhancement of intestinal motility, and p-regulation of genes.[28],[29]Lactobacilli and Bifidobacteria produce short chain fatty acids which regulate cell growth and differentiation and have trophic effects on the intestinal epithelium and additionally stimulate Bifidobacteria and counteract urease producing strains, thus maintaining gut barrier function[30]
  • Helicobacter pylori infections: The mechanisms involved are unclear, but there is a presumption that the lactobacilli either induced a host response to negatively affect helicobacter survival or inhibited their spread through competitive adhesion to glycolipid receptors[31],[32]
  • Necrotizing enterocolitis (NE): The normal process by which organisms such as Lactobacillus species are ingested through vaginal birth and propagated by mother's milk does not occur in preterm infants[33] exposing them to a plethora of pathogenic microbes such as Clostridium,  Escherichia More Details, and  Salmonella More Details which colonize the intestine and increase the risk of NE. Further, preterm infants are given formula feeding, have less Lactobacillus and Bifidobacterium species in their stool compared to controls. This supports the concept of early intestinal colonization with organisms such as Lactobacillus rhamnosus and Bifidobacterium infantis and subsequent protection against NE[34]
  • Anti-inflammatory diseases: Inflammatory bowel disease, ulcerative colitis, Crohn's disease, pouchitis, and postoperative complications: Lactobacillus strains including L. casei downregulate the spontaneous release of tumor necrosis factor-a by inflamed tissue and also the inflammatory response induced by E. coli. The anti-inflammatory effect of L. casei is transduced to the underlying tissue and results in reduced expression of activation markers by lamina propria T-lymphocytes, suggests that signals generated at the mucosal surface can promote changes in the phenotype of lamina propria lymphocytes.[35] The currently available data demonstrate that probiotics are more effective in preventing relapse of IBDs than in suppressing active disease[36]
  • Anticarcinogenic (colorectal cancer): Potential mechanisms for probiotic-induced anticarcinogenic activity are as follows:

    1. Antigenotoxicity
    2. Inhibition of colonic enzyme activity
    3. Control of growth of potentially harmful bacteria
    4. Interaction with colonocytes
    5. Immune system stimulation
    6. Production of physiologically active metabolites
    7. Suppressing the carcinogen/procarcinogen by binding, blocking, or removing it
    8. Curbing the growth of bacteria with enzyme activities that directly or indirectly convert procarcinogens to carcinogens
    9. Reducing the intestinal pH, thereby altering microflora activity and bile acid solubility
    10. Altering colonic transit time to remove fecal mutagens more rapidly.[37]

  • Urogenital infection:The concept of restoring the Lactobacillus content of the vaginal microbiota as a barrier to prevent infection was first conceived by Canadian urologist Andrew Bruce in the early 1970s and since then research has shown that certain Lactobacillus strains are able to colonize the vagina following vaginal suppository use and reduce the risk of urinary tract infection, yeast vaginitis, and bacterial vaginosis[38],[39],[40],[41]
  • Hypocholesterolemic: The ability of probiotics to reduce serum cholesterol levels is still a matter for debate.[42] The range of mechanisms of action include assimilation of cholesterol by bacterial cells, deconjugation of bile acids by bacterial acid hydrolases (reduces cholesterol reabsorption, increases cholesterol excretion of deconjugated bile salts, and increases cholesterol uptake by low-density lipoprotein receptor pathway in the liver as a compensatory response), cholesterol binding to bacterial cell walls, and inhibition of hepatic cholesterol synthesis and/or redistribution of cholesterol from plasma to the liver (through the action of short-chain fatty acids, the end products of carbohydrate fermentation in the gut)[43],[44]
  • Antiallergic: Gut microflora appears to be a key factor in regulating both the intestinal and systemic immune system and inducing tolerance. To date, clinical effects have been seen as a significant improvement in the course of atopic eczema in infants given L. rhamnosus GG or Bifidobacterium laciis BB.[45],[46] The precise mechanisms are based on the ability of lactobacilli to reverse increased intestinal permeability, enhance gut-specific IgA responses, promote gut barrier function through the restoration of normal levels of microbes, and enhance transforming growth factor-b and interleukin-IO production as well as cytokines that promote the production of IgE antibodies[47]
  • Surgical infections: Rather than use antibiotics in an attempt to “decontaminate” the intestine before surgery, it is indicated that there is merit to administering probiotic organisms to reduce the risk of infections and complications and hasten wound healing. Further studies are needed to determine whether some patients should not be given this therapy because of elevated risk of Lactobacillus-associated bacteremia.[48]
  • Antihypertensive
  • Immunomodulatory
  • Clostridium difficile colitis.

Benefits for healthy subjects

The health effects of probiotics on healthy subjects are likely to be limited to risk reduction. As mentioned above, consumption of fermented dairy products may be related to a reduced risk for colorectal cancer. In children, long-term consumption of probiotics in nonfermented milk may reduce the risk for infections, absence from daycare due to illness and the use of antibiotics.[3] Probiotics are often marketed as “boosting the immune system.” However, for healthy individuals, this may not be the case, since the immune system is likely to be working optimally.[49] However, in combination with oral vaccination, improved antibody titers have been observed with probiotics.

  Conclusion Top

Today, modern experimental approaches to eradicate the infections are inevitable and compulsory requisite. Apart from probiotics, lot of other innovative microbiological modalities such as specifically targeted antimicrobial peptide molecules (stamps)[50] and bacterial replacement therapy are being researched. There is enough scientific evidence supporting the incorporation of probiotics in nutrition, as a mean to derive health benefits. This evidence seems adequate concerning the prevention and treatment of certain conditions while simply promising or even controversial when it comes to others. Further research, in the form of controlled human studies, is needed to determine which probiotics and what dosages are associated with the greatest efficacy for which patients, as well as, also to demonstrate their safety and limitations. In addition, the regulatory status of probiotics as food components need to be established on an international level with emphasis on safety, efficacy, and validation of health claims on commercial food labels.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Figure 1], [Figure 2]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]


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