Can probiotics reduce bad breath?

Halitosis (bad breath) is a very unpleasant odor in the mouth, which seriously affects people's social interactions and mental health . According to the survey, the prevalence of halitosis in China is about 27. 5% . It can be caused by many reasons, such as poor oral hygiene, tooth decay, periodontal disease (such as periodontitis and gingivitis), food spoilage between teeth, tongue coating, and other unknown oral problems . Bad breath can be divided into three categories: true bad breath, false bad breath, and bad breath phobia (or psychological bad breath) . True bad breath is considered a pathological condition because it is caused by a bacterial infection of the oral cavity, which can lead to periodontal diseases such as dental plaque, periodontitis and gingivitis . In this case, it is necessary to treat the infection, and it can promote improvement and reduce odor . False halitosis is a person who feels bad breath but cannot detect an odor . After treatment for true or false halitosis, patients insist that they have bad breath or are afraid of bad breath, which is halitosis phobia . People with halitosis phobia always have an illusion of other people's disgust . Bad breath phobia may gradually transform into social anxiety disorder or social phobia, and may even commit suicide . 　　Gas compounds such as volatile sulfides are the main cause of oral odor, and their sources are divided into oral and non-oral sources . Volatile sulfides are considered to be metabolites produced by bacterial spoilage, including hydrogen sulfide and methyl mercaptan . In fact, most of the volatile sulfur compounds are produced by oral bacteria that degrade food and saliva proteins or use amino acids by bacteria that produce volatile sulfur compounds . Most of the bacteria associated with periodontitis can produce volatile sulfides, such as Porphyromonas gingivalis, Treponema, Prevotella intermedius, and Fusobacterium nucleatum . 　　Due to the relationship between bad breath and oral infections, more and more studies have begun to pay attention to the positive effects of probiotics in the prevention and even treatment of bad breath, and satisfactory results have been achieved. . 　　Oral halitosis and non-oral halitosis 　　Oral halitosis 　　According to the source of volatile sulfide, halitosis is divided into oral halitosis and non-oral halitosis . There are more than 700 kinds of oral resident bacterial flora, and the physical and chemical properties of saliva play an important role in the balance of oral flora . In addition, one milliliter of saliva contains about 100 million microorganisms . Poor oral hygiene and poor restoration of dental tissue defects cause food residue and dental plaque to accumulate on the teeth and tongue. These residual residues are degraded by bacteria and can cause bad breath . 　　Ninety percent of bad breath is related to oral bad breath, and only about 10% are related to non-oral bad breath . However, there is no obvious connection between bad breath and any specific bacterial infection. Therefore, bad breath reflects the complex interaction between certain oral bacteria . It is generally believed that gram-negative anaerobic bacteria digest proteins in food residues, oral mucosal exfoliated cells, and salivary proteins, convert them into amino acids, and accumulate in the oral cavity, resulting in bad breath . 　　These bacteria can be isolated from the subgingival plaque of patients with gingivitis or periodontitis and the saliva and back of the tongue of healthy subjects . Some microorganisms collected from periodontal lesions of gingivitis and periodontitis can produce a large amount of volatile sulfur compounds . Oral odor is significantly related to the total number of bacteria and the diversity of each type of bacteria . 　　Because bacteria can use the shed epithelial cells and food residues, spoilage occurs . In the process of bacterial spoilage, other compounds other than sulfide will also be formed . The lysis of certain amino acids leads to the production of bacterial metabolites, mainly volatile sulfides (hydrogen sulfide, methyl mercaptan and dimethyl sulfide), organic acids (butyric acid), aromatic compounds (indole, skatole) and amines class (putrescine, cadaverine) and the like . 　　Oral bad breath is caused by resident bacteria in the mouth . Oral bacteria, especially those in the tongue coating area, produce volatile sulfur compounds such as hydrogen sulfide and methyl mercaptan . Most cases of halitosis are related to oral halitosis, which is caused by different oral bacteria . Tongue coating, especially the back of the tongue, is considered to be the main part of bad breath . This area is the best place for the accumulation of various bacteria . Studies have shown that the back of the tongue has a special ability to bind various bacteria . In this area, each epithelial cell can bind more than 100 bacteria, in contrast, other types of oral epithelial cells have a binding capacity of about 25 bacteria . In addition, the presence of cracks on the back of the tongue provides an anoxic environment for the growth of anaerobic bacteria that produce volatile sulfides . Generally, volatile sulfur compounds and other odorous compounds are derived from the interaction of bacteria with specific amino acids . Generally speaking, anaerobic bacteria interact with cysteine, methionine, tryptophan, arginine and lysine to convert into hydrogen sulfide, methyl mercaptan, indole, putrescine, and cadaverine, respectively . 　　Non-oral halitosis 　　About 10% of cases of halitosis are related to non-oral halitosis . Non-oral halitosis is usually caused by diseases of adjacent tissues of the oral cavity, such as purulent tonsillitis, chronic sinusitis, atrophic rhinitis, lung disease and gastrointestinal diseases, etc. , which can produce purulent secretions and emit foul smell. In addition, There is also blood-borne bad breath . 　　In blood-borne bad breath, malodorous compounds in the blood are carried to the lungs, where they volatilize and enter the breath . The basis of blood-borne bad breath is certain systemic diseases (including liver pathology, endocrine diseases and metabolic diseases) and the intake of certain drugs and foods . Some respiratory diseases, such as lung abscesses or necrotic lung tumors, can also produce unpleasant odors; and some digestive diseases, such as gastroesophageal reflux or Helicobacter pylori infection, may also be related to bad breath . Several other recognized causes of non-oral odor include kidney failure, liver cirrhosis, and diabetes . 　　The beneficial effects of probiotics in preventing and improving bad breath 　　Probiotics can play a beneficial role in a variety of ways, such as: through antibacterial activity (production of organic acids, hydrogen peroxide and bacteriocins) to increase resistance to infections and form biofilm protection The oral tissue is protected from the invasion of infectious bacteria and the competitive adhesion of pathogenic bacteria to the tooth surface, adjusts the pH value and redox potential, and enhances the host's cellular and humoral immune system . In addition, the fermentation of probiotics can produce vitamins B6 and B12, riboflavin, folic acid, niacin, short-chain fatty acids and other substances, which can help improve gastrointestinal function and even halitosis . 　　Streptococcus salivarius K12 and bad breath 　　Although many factors, such as food residues, metabolic diseases and respiratory infections, may cause bad breath, the main cause of bad breath is the imbalance of oral symbiotic flora . 　　Streptococcus salivarius is a non-pathogenic dominant species in the oral cavity and is often isolated from human oral cavity without bad breath . According to research, Streptococcus salivarius K12 can produce two kinds of antibiotics: Sialin A2 and Sialin B. They have antibacterial activity that inhibits the growth of a variety of pathogens. They can competitively bind to pathogens and inhibit the binding of pathogens to the host and participate in regulating the body's immune function . 　　The results of clinical trials show that the antibacterial mouthwash containing Streptococcus salivarius K12 can significantly reduce the level of volatile sulfide-producing bacteria . Therefore, the use of Streptococcus salivarius K12 as a probiotic derived from the oral cavity can play a key role in the treatment of bad breath . 　　Probiotics and prevention of dental 　　caries　　 dental caries is one of the pathogenic factors of oral halitosis . Dental caries is one of the most common oral diseases in the world. It is a multifactorial disease caused by the acid demineralization of tooth enamel caused by oral pathogens . 　　Studies have shown that taking certain probiotics by mouth can help prevent dental caries . For example: Ingestion of milk containing Lactobacillus rhamnosus GG and Lactobacillus reuteri can significantly reduce the number of S. mutans and S. sobrinus, which are two causes of caries. The main pathogenic bacteria . In recent years, in vitro and in vivo experiments have proved that Weissella cibaria, as a new probiotic strain, can also prevent dental caries and significantly inhibit the formation of Streptococcus mutans biofilm . The bacterium produces a large amount of hydrogen peroxide, and can also accumulate with Fusobacterium nucleatum to inhibit these pathogens from producing volatile sulfur compounds in the oral cavity . 　　It is worth noting that certain lactobacilli, such as Lactobacillus salivarius LS1952R, can closely adhere to the hydroxyapatite present on the surface of teeth, and may have cariogenic activity in animal rat models . 　　The immunomodulatory effect of probiotics in periodontal disease Periodontal 　　disease (or gum disease) is caused by bacteria in dental plaque, especially Gram-negative bacteria, including destructive inflammation in the support structure of the gums and teeth. They are gingivitis and periodontitis . If periodontal disease is not treated, persistent infection may cause bad breath . 　　Many probiotic strains can inhibit the growth of periodontal pathogens, such as Porphyromonas gingivalis, Prevotella intermedius, Agglomerata with actinomycetes, and Forsysteinella . The probiotic Lactobacillus paracasei LPc-G110 and Lactobacillus plantarum GOS42 can significantly reduce a variety of inflammatory mediators released by monocytes, and have a positive effect on reducing gum inflammation . For people with moderate gingivitis and dental plaque, ingesting chewing gum containing Lactobacillus reuteri can significantly reduce the levels of pro-inflammatory cytokines TNF-α and IL-8 in gingival crevicular fluid . 　　The protective effect of Lactobacillus reuteri on periodontal disease may be in three ways: First, Lactobacillus reuteri can produce two powerful bacteriocins reuterin and reutericyclin, which can inhibit the growth of a variety of pathogenic bacteria; Lactobacillus reuteri has strong adhesion to host tissues and strong ability to compete with pathogens; third, Lactobacillus reuteri has been shown to have anti-inflammatory effects on gastrointestinal infections as an immunomodulator, which also May be beneficial to periodontal disease . 　　Summary 　　Bad breath is an unpleasant odor emitted from the mouth, which seriously affects people's social interactions and mental health . 90% of bad breath is of oral origin. With the occurrence of oral flora imbalance, oral pathogens dominate, which can lead to the occurrence of periodontal disease, dental plaque, dental caries and other pathological conditions, and ultimately lead to bad breath. It is very useful to treat infections. Necessary . 　　In recent years, the emergence of antibiotic-resistant bacteria has become one of the main problems for humans in the fight against infectious diseases . It is imminent to adopt some alternative programs to prevent and treat infectious diseases . Many studies have shown that probiotics can better replace antibiotics and relieve gastrointestinal diseases. Therefore, the role of probiotics in the prevention and treatment of oral diseases is also receiving increasing attention . 　　Indeed, probiotics have many advantages, such as antibacterial activity, strong binding ability, formation of protective biofilm, adjustment of pH and redox potential, enhancement of the immune system, reduction of the production of pro-inflammatory cytokines, etc. , which can help improve the oral cavity Disease, thereby preventing or improving oral halitosis . Probiotics have the potential to help us keep our breath fresh . 　　Of course, further research is needed before probiotics are used for the prevention and treatment of bad breath and oral diseases. In addition, some probiotic strains that may cause caries, such as the Lactobacillus salivarius LS1952R we mentioned earlier . 　　references: 　　Karbalaei, M. , et al. (2021). "Alleviation of halitosis by use of probiotics and their protective mechanisms in the oral cavity. " New Microbes and New Infections 42: 100887.   Disclaimer: This article only represents the author's personal views and has nothing to do with China Probiotics. com . The originality and the text and content stated in the article have not been verified by this site. This site does not make any guarantee or commitment to the authenticity, completeness, and timeliness of this article, all or part of the content, and the text. Please readers for reference only, and please Verify the relevant content yourself .   Copyright Notice 1. Some of the reprinted articles on this site are not original, and the copyright and liability belong to the original author . 2. All reprinted articles, links and pictures on this website are for the purpose of conveying more information, and clearly indicate the source and author. 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Halitosis (bad breath) is a very unpleasant odor in the mouth, which seriously affects people's social interactions and mental health
.
According to the survey, the prevalence of halitosis in China is about 27.
5%
.
It can be caused by many reasons, such as poor oral hygiene, tooth decay, periodontal disease (such as periodontitis and gingivitis), food spoilage between teeth, tongue coating, and other unknown oral problems
.


　　Bad breath can be divided into three categories: true bad breath, false bad breath, and bad breath phobia (or psychological bad breath)
.
True bad breath is considered a pathological condition because it is caused by a bacterial infection of the oral cavity, which can lead to periodontal diseases such as dental plaque, periodontitis and gingivitis
.
In this case, it is necessary to treat the infection, and it can promote improvement and reduce odor
.
False halitosis is a person who feels bad breath but cannot detect an odor
.
After treatment for true or false halitosis, patients insist that they have bad breath or are afraid of bad breath, which is halitosis phobia
.
People with halitosis phobia always have an illusion of other people's disgust
.
Bad breath phobia may gradually transform into social anxiety disorder or social phobia, and may even commit suicide
.


　　Gas compounds such as volatile sulfides are the main cause of oral odor, and their sources are divided into oral and non-oral sources
.
Volatile sulfides are considered to be metabolites produced by bacterial spoilage, including hydrogen sulfide and methyl mercaptan
.
In fact, most of the volatile sulfur compounds are produced by oral bacteria that degrade food and saliva proteins or use amino acids by bacteria that produce volatile sulfur compounds
.
Most of the bacteria associated with periodontitis can produce volatile sulfides, such as Porphyromonas gingivalis, Treponema, Prevotella intermedius, and Fusobacterium nucleatum
.


　　Due to the relationship between bad breath and oral infections, more and more studies have begun to pay attention to the positive effects of probiotics in the prevention and even treatment of bad breath, and satisfactory results have been achieved.

.


　　Oral halitosis and non-oral halitosis

　　Oral halitosis

　　According to the source of volatile sulfide, halitosis is divided into oral halitosis and non-oral halitosis
.
There are more than 700 kinds of oral resident bacterial flora, and the physical and chemical properties of saliva play an important role in the balance of oral flora
.
In addition, one milliliter of saliva contains about 100 million microorganisms
.
Poor oral hygiene and poor restoration of dental tissue defects cause food residue and dental plaque to accumulate on the teeth and tongue.
These residual residues are degraded by bacteria and can cause bad breath
.


　　Ninety percent of bad breath is related to oral bad breath, and only about 10% are related to non-oral bad breath
.
However, there is no obvious connection between bad breath and any specific bacterial infection.
Therefore, bad breath reflects the complex interaction between certain oral bacteria
.
It is generally believed that gram-negative anaerobic bacteria digest proteins in food residues, oral mucosal exfoliated cells, and salivary proteins, convert them into amino acids, and accumulate in the oral cavity, resulting in bad breath
.


　　These bacteria can be isolated from the subgingival plaque of patients with gingivitis or periodontitis and the saliva and back of the tongue of healthy subjects
.
Some microorganisms collected from periodontal lesions of gingivitis and periodontitis can produce a large amount of volatile sulfur compounds
.
Oral odor is significantly related to the total number of bacteria and the diversity of each type of bacteria
.


　　Because bacteria can use the shed epithelial cells and food residues, spoilage occurs
.
In the process of bacterial spoilage, other compounds other than sulfide will also be formed
.
The lysis of certain amino acids leads to the production of bacterial metabolites, mainly volatile sulfides (hydrogen sulfide, methyl mercaptan and dimethyl sulfide), organic acids (butyric acid), aromatic compounds (indole, skatole) and amines class (putrescine, cadaverine) and the like
.


　　Oral bad breath is caused by resident bacteria in the mouth
.
Oral bacteria, especially those in the tongue coating area, produce volatile sulfur compounds such as hydrogen sulfide and methyl mercaptan
.
Most cases of halitosis are related to oral halitosis, which is caused by different oral bacteria
.
Tongue coating, especially the back of the tongue, is considered to be the main part of bad breath
.
This area is the best place for the accumulation of various bacteria
.
Studies have shown that the back of the tongue has a special ability to bind various bacteria
.
In this area, each epithelial cell can bind more than 100 bacteria, in contrast, other types of oral epithelial cells have a binding capacity of about 25 bacteria
.
In addition, the presence of cracks on the back of the tongue provides an anoxic environment for the growth of anaerobic bacteria that produce volatile sulfides
.
Generally, volatile sulfur compounds and other odorous compounds are derived from the interaction of bacteria with specific amino acids
.
Generally speaking, anaerobic bacteria interact with cysteine, methionine, tryptophan, arginine and lysine to convert into hydrogen sulfide, methyl mercaptan, indole, putrescine, and cadaverine, respectively
.


　　Non-oral halitosis

　　About 10% of cases of halitosis are related to non-oral halitosis
.
Non-oral halitosis is usually caused by diseases of adjacent tissues of the oral cavity, such as purulent tonsillitis, chronic sinusitis, atrophic rhinitis, lung disease and gastrointestinal diseases, etc.
, which can produce purulent secretions and emit foul smell.
In addition, There is also blood-borne bad breath
.


　　In blood-borne bad breath, malodorous compounds in the blood are carried to the lungs, where they volatilize and enter the breath
.
The basis of blood-borne bad breath is certain systemic diseases (including liver pathology, endocrine diseases and metabolic diseases) and the intake of certain drugs and foods
.
Some respiratory diseases, such as lung abscesses or necrotic lung tumors, can also produce unpleasant odors; and some digestive diseases, such as gastroesophageal reflux or Helicobacter pylori infection, may also be related to bad breath
.
Several other recognized causes of non-oral odor include kidney failure, liver cirrhosis, and diabetes
.


　　The beneficial effects of probiotics in preventing and improving bad breath

　　Probiotics can play a beneficial role in a variety of ways, such as: through antibacterial activity (production of organic acids, hydrogen peroxide and bacteriocins) to increase resistance to infections and form biofilm protection The oral tissue is protected from the invasion of infectious bacteria and the competitive adhesion of pathogenic bacteria to the tooth surface, adjusts the pH value and redox potential, and enhances the host's cellular and humoral immune system
.
In addition, the fermentation of probiotics can produce vitamins B6 and B12, riboflavin, folic acid, niacin, short-chain fatty acids and other substances, which can help improve gastrointestinal function and even halitosis
.


　　Streptococcus salivarius K12 and bad breath

　　Although many factors, such as food residues, metabolic diseases and respiratory infections, may cause bad breath, the main cause of bad breath is the imbalance of oral symbiotic flora
.


　　Streptococcus salivarius is a non-pathogenic dominant species in the oral cavity and is often isolated from human oral cavity without bad breath
.
According to research, Streptococcus salivarius K12 can produce two kinds of antibiotics: Sialin A2 and Sialin B.
They have antibacterial activity that inhibits the growth of a variety of pathogens.
They can competitively bind to pathogens and inhibit the binding of pathogens to the host and participate in regulating the body's immune function
.


　　The results of clinical trials show that the antibacterial mouthwash containing Streptococcus salivarius K12 can significantly reduce the level of volatile sulfide-producing bacteria
.
Therefore, the use of Streptococcus salivarius K12 as a probiotic derived from the oral cavity can play a key role in the treatment of bad breath
.


　　Probiotics and prevention of dental

　　caries　　 dental caries is one of the pathogenic factors of oral halitosis
.
Dental caries is one of the most common oral diseases in the world.
It is a multifactorial disease caused by the acid demineralization of tooth enamel caused by oral pathogens
.


　　Studies have shown that taking certain probiotics by mouth can help prevent dental caries
.
For example: Ingestion of milk containing Lactobacillus rhamnosus GG and Lactobacillus reuteri can significantly reduce the number of S.
mutans and S.
sobrinus, which are two causes of caries.
The main pathogenic bacteria
.
In recent years, in vitro and in vivo experiments have proved that Weissella cibaria, as a new probiotic strain, can also prevent dental caries and significantly inhibit the formation of Streptococcus mutans biofilm
.
The bacterium produces a large amount of hydrogen peroxide, and can also accumulate with Fusobacterium nucleatum to inhibit these pathogens from producing volatile sulfur compounds in the oral cavity
.


　　It is worth noting that certain lactobacilli, such as Lactobacillus salivarius LS1952R, can closely adhere to the hydroxyapatite present on the surface of teeth, and may have cariogenic activity in animal rat models
.


　　The immunomodulatory effect of probiotics in periodontal disease Periodontal

　　disease (or gum disease) is caused by bacteria in dental plaque, especially Gram-negative bacteria, including destructive inflammation in the support structure of the gums and teeth.
They are gingivitis and periodontitis
.
If periodontal disease is not treated, persistent infection may cause bad breath
.


　　Many probiotic strains can inhibit the growth of periodontal pathogens, such as Porphyromonas gingivalis, Prevotella intermedius, Agglomerata with actinomycetes, and Forsysteinella
.
The probiotic Lactobacillus paracasei LPc-G110 and Lactobacillus plantarum GOS42 can significantly reduce a variety of inflammatory mediators released by monocytes, and have a positive effect on reducing gum inflammation
.
For people with moderate gingivitis and dental plaque, ingesting chewing gum containing Lactobacillus reuteri can significantly reduce the levels of pro-inflammatory cytokines TNF-α and IL-8 in gingival crevicular fluid
.


　　The protective effect of Lactobacillus reuteri on periodontal disease may be in three ways: First, Lactobacillus reuteri can produce two powerful bacteriocins reuterin and reutericyclin, which can inhibit the growth of a variety of pathogenic bacteria; Lactobacillus reuteri has strong adhesion to host tissues and strong ability to compete with pathogens; third, Lactobacillus reuteri has been shown to have anti-inflammatory effects on gastrointestinal infections as an immunomodulator, which also May be beneficial to periodontal disease
.


　　Summary

　　Bad breath is an unpleasant odor emitted from the mouth, which seriously affects people's social interactions and mental health
.
90% of bad breath is of oral origin.
With the occurrence of oral flora imbalance, oral pathogens dominate, which can lead to the occurrence of periodontal disease, dental plaque, dental caries and other pathological conditions, and ultimately lead to bad breath.
It is very useful to treat infections.
Necessary
.


　　In recent years, the emergence of antibiotic-resistant bacteria has become one of the main problems for humans in the fight against infectious diseases
.
It is imminent to adopt some alternative programs to prevent and treat infectious diseases .
Many studies have shown that probiotics can better replace antibiotics and relieve gastrointestinal diseases.
Therefore, the role of probiotics in the prevention and treatment of oral diseases is also receiving increasing attention
.


　　Indeed, probiotics have many advantages, such as antibacterial activity, strong binding ability, formation of protective biofilm, adjustment of pH and redox potential, enhancement of the immune system, reduction of the production of pro-inflammatory cytokines, etc.
, which can help improve the oral cavity Disease, thereby preventing or improving oral halitosis
.
Probiotics have the potential to help us keep our breath fresh
.


　　Of course, further research is needed before probiotics are used for the prevention and treatment of bad breath and oral diseases.
In addition, some probiotic strains that may cause caries, such as the Lactobacillus salivarius LS1952R we mentioned earlier
.


　　references:

　　Karbalaei, M.
, et al.
(2021).
"Alleviation of halitosis by use of probiotics and their protective mechanisms in the oral cavity.
" New Microbes and New Infections 42: 100887.

---

Halitosis (bad breath) is a very unpleasant odor in the mouth, which seriously affects people's social interactions and mental health
.
According to the survey, the prevalence of halitosis in China is about 27.
5%
.
It can be caused by many reasons, such as poor oral hygiene, tooth decay, periodontal disease (such as periodontitis and gingivitis), food spoilage between teeth, tongue coating, and other unknown oral problems
.


　　Bad breath can be divided into three categories: true bad breath, false bad breath, and bad breath phobia (or psychological bad breath)
.
True bad breath is considered a pathological condition because it is caused by a bacterial infection of the oral cavity, which can lead to periodontal diseases such as dental plaque, periodontitis and gingivitis
.
In this case, it is necessary to treat the infection, and it can promote improvement and reduce odor
.
False halitosis is a person who feels bad breath but cannot detect an odor
.
After treatment for true or false halitosis, patients insist that they have bad breath or are afraid of bad breath, which is halitosis phobia
.
People with bad breath phobia always have an illusion of other people's disgust
.
Bad breath phobia may gradually transform into social anxiety disorder or social phobia, and may even commit suicide
.


　　Gas compounds such as volatile sulfides are the main cause of oral odor, and their sources are divided into oral and non-oral sources
.
Volatile sulfides are considered to be metabolites produced by bacterial spoilage, including hydrogen sulfide and methyl mercaptan
.
In fact, most of the volatile sulfur compounds are produced by oral bacteria that degrade food and saliva proteins or use amino acids by bacteria that produce volatile sulfur compounds
.
Most of the bacteria associated with periodontitis can produce volatile sulfides, such as Porphyromonas gingivalis, Treponema, Prevotella intermedius, and Fusobacterium nucleatum
.


　　Due to the relationship between bad breath and oral infections, more and more studies have begun to pay attention to the positive effects of probiotics in the prevention and even treatment of bad breath, and satisfactory results have been achieved.

.


　　Oral halitosis and non-oral halitosis

　　Oral halitosis

　　According to the source of volatile sulfide, halitosis is divided into oral halitosis and non-oral halitosis
.
There are more than 700 kinds of oral resident bacterial flora, and the physical and chemical properties of saliva play an important role in the balance of oral flora
.
In addition, one milliliter of saliva contains about 100 million microorganisms
.
Poor oral hygiene and poor restoration of dental tissue defects cause food residue and dental plaque to accumulate on the teeth and tongue.
These residual residues are degraded by bacteria and can cause bad breath
.


　　Ninety percent of bad breath is related to oral bad breath, and only about 10% are related to non-oral bad breath
.
However, there is no obvious connection between bad breath and any specific bacterial infection.
Therefore, bad breath reflects the complex interaction between certain oral bacteria
.
It is generally believed that gram-negative anaerobic bacteria digest proteins in food residues, oral mucosal exfoliated cells, and salivary proteins, convert them into amino acids, and accumulate in the oral cavity, resulting in bad breath
.


　　These bacteria can be isolated from the subgingival plaque of patients with gingivitis or periodontitis and the saliva and back of the tongue of healthy subjects
.
Some microorganisms collected from periodontal lesions of gingivitis and periodontitis can produce a large amount of volatile sulfur compounds
.
Oral odor is significantly related to the total number of bacteria and the diversity of each type of bacteria
.


　　Because bacteria can use the shed epithelial cells and food residues, spoilage occurs
.
In the process of bacterial spoilage, other compounds other than sulfide will also be formed
.
The lysis of certain amino acids leads to the production of bacterial metabolites, mainly volatile sulfides (hydrogen sulfide, methyl mercaptan and dimethyl sulfide), organic acids (butyric acid), aromatic compounds (indole, skatole) and amines class (putrescine, cadaverine) and the like
.


　　Oral bad breath is caused by resident bacteria in the mouth
.
Oral bacteria, especially those in the tongue coating area, produce volatile sulfur compounds such as hydrogen sulfide and methyl mercaptan
.
Most cases of halitosis are related to oral halitosis, which is caused by different oral bacteria
.
Tongue coating, especially the back of the tongue, is considered to be the main part of bad breath
.
This area is the best place for the accumulation of various bacteria
.
Studies have shown that the back of the tongue has a special ability to bind various bacteria
.
In this area, each epithelial cell can bind more than 100 bacteria, in contrast, other types of oral epithelial cells have a binding capacity of about 25 bacteria
.
In addition, the presence of cracks on the back of the tongue provides an anoxic environment for the growth of anaerobic bacteria that produce volatile sulfides
.
Generally, volatile sulfur compounds and other odorous compounds are derived from the interaction of bacteria with specific amino acids
.
Generally speaking, anaerobic bacteria interact with cysteine, methionine, tryptophan, arginine and lysine to convert into hydrogen sulfide, methyl mercaptan, indole, putrescine, and cadaverine, respectively
.


　　Non-oral halitosis

　　About 10% of cases of halitosis are related to non-oral halitosis
.
Non-oral halitosis is usually caused by diseases of adjacent tissues of the oral cavity, such as purulent tonsillitis, chronic sinusitis, atrophic rhinitis, lung disease and gastrointestinal diseases, etc.
, which can produce purulent secretions and emit foul smell.
In addition, There is also blood-borne bad breath
.


　　In blood-borne bad breath, malodorous compounds in the blood are carried to the lungs, where they volatilize and enter the breath
.
The basis of blood-borne bad breath is certain systemic diseases (including liver pathology, endocrine diseases and metabolic diseases) and the intake of certain drugs and foods
.
Some respiratory diseases, such as lung abscesses or necrotic lung tumors, can also produce unpleasant odors; and some digestive diseases, such as gastroesophageal reflux or Helicobacter pylori infection, may also be related to bad breath
.
Several other recognized causes of non-oral odor include kidney failure, liver cirrhosis, and diabetes
.


　　The beneficial effects of probiotics in preventing and improving bad breath

　　Probiotics can play a beneficial role in a variety of ways, such as: through antibacterial activity (production of organic acids, hydrogen peroxide and bacteriocins) to increase resistance to infections and form biofilm protection The oral tissue is protected from the invasion of infectious bacteria and the competitive adhesion of pathogenic bacteria to the tooth surface, adjusts the pH value and redox potential, and enhances the host's cellular and humoral immune system
.
In addition, the fermentation of probiotics can produce vitamins B6 and B12, riboflavin, folic acid, niacin, short-chain fatty acids and other substances, which can help improve gastrointestinal function and even halitosis
.


　　Streptococcus salivarius K12 and bad breath

　　Although many factors, such as food residues, metabolic diseases and respiratory infections, may cause bad breath, the main cause of bad breath is the imbalance of oral symbiotic flora
.


　　Streptococcus salivarius is a non-pathogenic dominant species in the oral cavity and is often isolated from human oral cavity without bad breath
.
According to research, Streptococcus salivarius K12 can produce two kinds of antibiotics: Sialin A2 and Sialin B.
They have antibacterial activity that inhibits the growth of a variety of pathogens.
They can competitively bind to pathogens and inhibit the binding of pathogens to the host and participate in regulating the body's immune function
.


　　The results of clinical trials show that the antibacterial mouthwash containing Streptococcus salivarius K12 can significantly reduce the level of volatile sulfide-producing bacteria
.
Therefore, the use of Streptococcus salivarius K12 as a probiotic derived from the oral cavity can play a key role in the treatment of bad breath
.


　　Probiotics and prevention of dental

　　caries　　 dental caries is one of the pathogenic factors of oral halitosis
.
Dental caries is one of the most common oral diseases in the world.
It is a multifactorial disease caused by the acid demineralization of tooth enamel caused by oral pathogens
.


　　Studies have shown that taking certain probiotics by mouth can help prevent dental caries
.
For example: Ingestion of milk containing Lactobacillus rhamnosus GG and Lactobacillus reuteri can significantly reduce the number of S.
mutans and S.
sobrinus, which are two causes of caries.
The main pathogenic bacteria
.
In recent years, in vitro and in vivo experiments have proved that Weissella cibaria, as a new probiotic strain, can also prevent dental caries and significantly inhibit the formation of Streptococcus mutans biofilm
.
The bacterium produces a large amount of hydrogen peroxide, and can also accumulate with Fusobacterium nucleatum to inhibit these pathogens from producing volatile sulfur compounds in the oral cavity
.


　　It is worth noting that certain lactobacilli, such as Lactobacillus salivarius LS1952R, can closely adhere to the hydroxyapatite present on the surface of teeth, and may have cariogenic activity in animal rat models
.


　　The immunomodulatory effect of probiotics in periodontal disease Periodontal

　　disease (or gum disease) is caused by bacteria in dental plaque, especially Gram-negative bacteria, including destructive inflammation in the support structure of the gums and teeth.
They are gingivitis and periodontitis
.
If periodontal disease is not treated, persistent infection may cause bad breath
.


　　Many probiotic strains can inhibit the growth of periodontal pathogens, such as Porphyromonas gingivalis, Prevotella intermedius, Agglomerata with actinomycetes, and Forsysteinella
.
The probiotic Lactobacillus paracasei LPc-G110 and Lactobacillus plantarum GOS42 can significantly reduce a variety of inflammatory mediators released by monocytes, and have a positive effect on reducing gum inflammation
.
For people with moderate gingivitis and dental plaque, ingesting chewing gum containing Lactobacillus reuteri can significantly reduce the levels of pro-inflammatory cytokines TNF-α and IL-8 in gingival crevicular fluid
.


　　The protective effect of Lactobacillus reuteri on periodontal disease may be in three ways: First, Lactobacillus reuteri can produce two powerful bacteriocins reuterin and reutericyclin, which can inhibit the growth of a variety of pathogenic bacteria; Lactobacillus reuteri has strong adhesion to host tissues and strong ability to compete with pathogens; third, Lactobacillus reuteri has been shown to have anti-inflammatory effects on gastrointestinal infections as an immunomodulator, which also May be beneficial to periodontal disease
.


　　Summary

　　Bad breath is an unpleasant odor emitted from the mouth, which seriously affects people's social interactions and mental health
.
90% of bad breath is of oral origin.
With the occurrence of oral flora imbalance, oral pathogens dominate, which can lead to the occurrence of periodontal disease, dental plaque, dental caries and other pathological conditions, and ultimately lead to bad breath.
It is very useful to treat infections.
Necessary
.


　　In recent years, the emergence of antibiotic-resistant bacteria has become one of the main problems for humans in the fight against infectious diseases
.
It is imminent to adopt some alternative programs to prevent and treat infectious diseases .
Many studies have shown that probiotics can better replace antibiotics and relieve gastrointestinal diseases.
Therefore, the role of probiotics in the prevention and treatment of oral diseases is also receiving increasing attention
.


　　Indeed, probiotics have many advantages, such as antibacterial activity, strong binding ability, formation of protective biofilm, adjustment of pH and redox potential, enhancement of the immune system, reduction of the production of pro-inflammatory cytokines, etc.
, which can help improve the oral cavity Disease, thereby preventing or improving oral halitosis
.
Probiotics have the potential to help us keep our breath fresh
.


　　Of course, further research is needed before probiotics are used for the prevention and treatment of bad breath and oral diseases.
In addition, some probiotic strains that may cause caries, such as the Lactobacillus salivarius LS1952R we mentioned earlier
.


　　references:

　　Karbalaei, M.
, et al.
(2021).
"Alleviation of halitosis by use of probiotics and their protective mechanisms in the oral cavity.
" New Microbes and New Infections 42: 100887.

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