Recent Journal Reviews Nature Reviews Microbiology We investigated the interactions between oral and gut microbiota and their overall impact on human health.
Study authors Jack A. Gilbert of the University of California, San Diego and Erica M. Hartman of Northwestern University found that oral microbes can enter the digestive tract and cause gut dysbiosis, but the mechanisms and broader effects of these interactions require further study.
Review article: The indoor microbiome and human health. Image credit: Lightspring / Shutterstock
The Importance of Gut Microbiota
The human body harbors a diverse range of microbes that play an important role in health by supporting the immune system and protecting against pathogens, but can also contribute to chronic diseases.
Disturbances in the gut microbiome, or dysbiosis, are associated with metabolic disorders, autoimmune diseases and gastrointestinal problems. The intestine and oral cavity are two important areas densely populated by microorganisms.
The oral microbiome is influenced by diet and the environment, is associated with oral diseases such as gingivitis and periodontitis, and impacts systemic health by influencing the microbial communities of the digestive and respiratory systems.
The gut microbiome is shaped by genetics, diet, and lifestyle and is crucial for immune response and infection prevention. Understanding the interplay between the gut microbiome and the oral microbiome is essential to understand their impact on diseases such as colorectal cancer (CRC) and inflammatory bowel disease (IBD).
The mouth is the entrance
The digestive tract begins at the mouth and continues to the anus, containing organs such as the liver, pancreas, and gallbladder. The oral cavity is highly vascularized and home to a diverse microbial community, and is the main portal of entry for microorganisms into the body.
More than 770 species of bacteria inhabit different microenvironments, such as the oral mucosa, tongue, and dental plaque. The main genera include: Streptococcus, veillonellaand PrevotellaThe intestinal flora is composed mainly of anaerobic bacteria, Bacteroides and RuminococcusAlthough it shares some taxa with the oral cavity, distinct physical and chemical barriers usually prevent oral microbes from colonizing the gut.
However, oral bacteria can migrate to the gut and cause disease, for example when there is low stomach acid or when antibiotics are used. Understanding this microbial movement from the mouth to the gut is crucial for exploring its role in disease and health.
The connection between the mouth and the intestine
The oral cavity plays an important role in overall health, predisposing it to conditions such as tooth decay, oral cancer and periodontal disease (gingivitis and periodontitis), a condition in which the tissues surrounding the teeth are destroyed by an inflammatory response to plaque and microorganisms.
Gingivitis is a reversible inflammation of the gums that, if untreated, can progress to periodontitis, which can cause deeper tissue damage and bone loss. Research suggests a strong link between oral health and gut disease.
Periodontal pathogens, e.g. P. gingivalis and F. nucleatumcan travel from the mouth to the intestine and cause conditions like IBD. These bacteria promote inflammation and upset the microbial balance in the gut.
Studies have found elevated levels of oral bacteria in the gut of patients with inflammatory bowel disease, suggesting that the oral-gut system plays a role in these diseases. Additionally, the oral microbiome has been associated with CRC. F. nucleatum It may affect tumor growth and treatment resistance in CRC.
This association highlights the importance of oral hygiene in preventing and managing systemic disease. Understanding these associations could lead to better prevention and treatment strategies for intestinal diseases and cancer.
Oral Health and General Health
Poor oral hygiene, especially periodontitis, can have serious consequences for the entire body. Bacteria in the mouth can travel through the digestive tract and bloodstream and cause a variety of diseases.
Periodontitis induces low-grade systemic inflammation that can impair overall health and promote diseases such as inflammatory bowel disease and cardiovascular disease. Increased levels of pro-inflammatory cytokines in the blood indicate an ongoing inflammatory response.
One of the mechanisms by which oral health affects the body is via bone marrow, where inflammation from periodontitis promotes immune cell production, leading to enhanced inflammatory responses in other sites.
Another mechanism is that periodontal bacteria release toxins that promote inflammation and diseases such as rheumatoid arthritis and atherosclerosis, and directly affect distal organs. Furthermore, oral health has a direct impact on the gut: oral bacteria can colonize the gut and exacerbate conditions such as inflammatory bowel disease.
Treating periodontal disease reduces systemic inflammation and improves symptoms of chronic disease, demonstrating the bidirectional relationship between oral health and systemic disease. Addressing oral health is therefore critical to overall health and the management of systemic disease.
Conclusion
Alterations in oral bacteria can affect gut health and lead to systemic inflammation and a variety of diseases. The relationship between the oral cavity and the gut is bidirectional, but the exact mechanisms are unclear.
Further studies are needed to understand the impact of oral bacteria on chronic diseases and develop better models to study these interactions. Future studies should elucidate the oral-gut microbiota axis at the strain level, confirm the role of oral bacteria in chronic diseases, and investigate the role of translocated strains in gut microbiota-associated diseases through in vivo and in vitro models.
