Emerging research is focusing on the study of the oral microbiome for predicting diseases, as it has been related not only with oral health but also as an indicator for screening and monitoring Crohn’s disease and ulcerative colitis patients. Even though the oral microbiome is not currently included in the GMFH list of topics, we need to keep up-to-date with this field of research—which emphasizes early life—by referring to data that shows how the oral and gut microbiota correlate during disease states.

In parallel with the study of the gut microbiome, emerging research is focusing on how the oral microbiome develops during early childhood and to what extent external factors influence its colonization and development.

A new study published in The ISME Journal studied the temporal maturation of the oral microbiome ecosystem and how it is affected by environmental factors in 90 children followed from birth to 7 years of age.

The study’s authors MSc. Majda Dzidic and Dr. Maria Carmen Collado, from the Institute of Agrochemistry and Food Technology at the Spanish National Research Council (IATA-CSIC), and Dr. Alex Mira, from the Department of Health and Genomics at the Centre for Advanced Research in Public Health at the FISABIO Foundation (Valencia, Spain), corresponded with GMFH editors about the significance of this work.


GMFH: How does oral microbiome development run in parallel with infant gut colonization patterns?

Microbial diversity and richness of the oral cavity increased with age, and other studies have shown that this also happens in the gut microbiota ecosystem. Bacterial colonization in the gut has also been shown to be affected by delivery mode, and in both the gut and the oral cavity, some bacteria colonize later if the baby is born by C-section. However, it would be of great interest to conduct a study where both oral and fecal samples from the same children were analyzed throughout infancy.


GMFH: Based on your findings, to what extent do you think saliva samples could be used in the coming years as a non-invasive method of predicting what goes on in children’s guts?

Saliva samples provide a good representation not only of overall oral health but also of systemic health, and there are many research teams around the world, including a start-up company in California, specializing in that. In general, saliva is considered a body probe where signals of our health are constantly secreted. For instance, diabetes and several types of cancer can be detected in saliva if you look at the right molecules. Further studies are needed to understand the association between oral and gut microbiota and the potential impact on infant health. We know, for example, that oral bacteria are needed for our systemic health but that they must stay in the mouth: in patients with a compromised immune system, oral bacteria can invade the gut or the lungs and contribute to inflammation and disease. We have to remember that we swallow almost a liter of saliva per day and that an oral bacterium (Fusobacterium nucleatum) has been found to be associated with colorectal cancer.


GMFH: What are you working on next?

We are investigating the importance of breastmilk bacterial content and composition in relation to allergy development during childhood. We believe that the bacteria to which babies are exposed during their first years of life are vital for future health, and the current way of life in Western societies is reducing the diversity of our microbial companions.




Xun Z, Zhang Q, Xu T, et al. Dysbiosis and ecotypes of the salivary microbiome associated with inflammatory bowel diseases and the assistance in diagnosis of diseases using oral bacterial profiles. Front Microbiol. 2018; 9:1136. doi: 10.3389/fmicb.2018.01136.

Dzidic M, Collado MC, Abrahamsson T, et al. Oral microbiome development during childhood: an ecological succession influenced by postnatal factors and associated with tooth decay. ISME J. 2018; doi: 10.1038/s41396-018-0204-z.