mouth Picture1The gastrointestinal microbiome is getting so much attention these days, but what about the mouth and pharynx? Doesn’t it all start there? In fact a number of conditions have to be just right to prevent dysbiosis of the mouth: saliva flow, pH, low-sugar diet, brushing, flossing, and dental cleanings.[1] This isn’t just to prevent cavities and periodontal disease. It’s because the microbes in the mouth are a significant contributor to the gut microbiome. You are swallowing one trillion bacteria each day, seeding your gastrointestinal tract with the microbes from your mouth.[2] Data from the Human Microbiome Project showed that there was a 45% overlap in the microbes found in the mouth and in the colon.[2]
The oral microbiome impacts the body in countless ways, which we are only now uncovering. Oral microbes have been implicated in cardiovascular disease,[3] rheumatoid arthritis,[4] inflammatory bowel disease,[5] and recurrent Helicobacter pylori infections.[6] Oral microbes contribute up to 25% of the nitric oxide levels in your blood, making it possible for blood vessels to relax and to lower blood pressure.[7] Perhaps with this in mind, the Surgeon General described “the mouth as a mirror of health or disease” and an early indicator of disease in other tissues and organs in the body.[8]
My dental hygienist agrees. So many diseases are evident in the oral mucosa, she believes the mouth will be a site for early diagnosis and prevention of disease in the future. She was once able to tell a patient that she was pregnant- before she had the pregnancy test! Apparently a woman’s gums are puffy and inflamed with higher levels of estrogen.
There are 700 aerobic and anaerobic species of bacteria in the mouth, living in biofilm communities. The oral microbiome establishes itself early and is healthier and more diverse in babies born vaginally, compared to those born by C-section.[9] This is similar to what we know about gut microbial biodiversity- it’s greater when a baby is born vaginally. There are so many overlaps in the research regarding the oral microbiome and the gastrointestinal microbiome. Perhaps it shouldn’t be a surprise. For instance, most healthy people carry around oral pathogens in low numbers with no ill effects. These “pathogens” might better be classified as commensal organisms because they only cause disease when there is dysbiosis.[2]
Problems in the mouth are mirrored in distant organs and in systemic disease. Inflammatory bowel disease and periodontal disease often present as co-morbidities and have been investigated in the literature for similar immune-pathogenesis. It is hard to know where precisely the pathology begins, but disruption of microflora, mucosal health, and immune responses are evident in both sites along the alimentary canal.[10] For this reason, authors suggest treating the local inflammation in the mouth and systemic inflammation as a way to treat inflammatory bowel disease and periodontitis.[5]
So as you go along in your daily life, remember the downstream effects of having a healthy oral microbiome. And think twice before you use mouthwash, as this has been shown to dramatically reduce the bacteria in the mouth and even eliminate their health benefits![7]
We explore all of these topics and more in the podcast I recorded with Dr. Kara Fitzgerald July 9, 2015. Special thanks to Dr. Stephen Olmstead and ProThera, who jumpstarted this conversation. Their fully referenced newsletter on the oral microbiome can be found with the podcast.

oral microbes cartoon Picture1References

1. Struzycka I. The oral microbiome in dental caries. Polish journal of microbiology / Polskie Towarzystwo Mikrobiologow = The Polish Society of Microbiologists. 2014;63(2):127-135.
2. Segata N, Haake SK, Mannon P, et al. Composition of the adult digestive tract bacterial microbiome based on seven mouth surfaces, tonsils, throat and stool samples. Genome Biol. 2012;13(6):R42.
3. Reichert S, Schlitt A, Beschow V, et al. Use of floss/interdental brushes is associated with lower risk for new cardiovascular events among patients with coronary heart disease. Journal of periodontal research. Apr 2015;50(2):180-188.
4. Ogrendik M. Rheumatoid arthritis is an autoimmune disease caused by periodontal pathogens. Int J Gen Med. 2013;6:383-386.
5. Vavricka SR, Manser CN, Hediger S, et al. Periodontitis and gingivitis in inflammatory bowel disease: a case-control study. Inflammatory bowel diseases. Dec 2013;19(13):2768-2777.
6. Jia CL, Jiang GS, Li CH, Li CR. Effect of dental plaque control on infection of Helicobacter pylori in gastric mucosa. Texas dental journal. Oct 2012;129(10):1069-1073.
7. Hyde ER, Andrade F, Vaksman Z, et al. Metagenomic analysis of nitrate-reducing bacteria in the oral cavity: implications for nitric oxide homeostasis. PLoS ONE. 2014;9(3):e88645.
8. HHS. Oral Health in America: A Report of the Surgeon General- Executive Summary. National Institute of Dental and Craniofacial Research;2000.
9. Lif Holgerson P, Harnevik L, Hernell O, Tanner AC, Johansson I. Mode of birth delivery affects oral microbiota in infants. Journal of dental research. Oct 2011;90(10):1183-1188.
10. Singhal S, Dian D, Keshavarzian A, Fogg L, Fields JZ, Farhadi A. The role of oral hygiene in inflammatory bowel disease. Digestive diseases and sciences. Jan 2011;56(1):170-175.

Cass Nelson-Dooley, M.S.
Cass Nelson-Dooley, M.S.

Cass Nelson-Dooley, MS, is a researcher, author, educator, and laboratory consultant. She studied medicinal plants in the rain forests of Panama as a Fulbright Scholar and then launched a career in science and natural medicine. Early on, she studied ethnobotany, ethnopharmacology, and drug discovery at the University of Georgia and AptoTec, Inc. She joined innovators at Metametrix Clinical Laboratory as a medical education consultant helping clinicians use integrative and functional laboratory results in clinical practice. She owns Health First Consulting, LLC, a medical communications company with the mission to improve human health using the written word. Ms. Nelson-Dooley is an oral microbiome expert and author of Heal Your Oral Microbiome. She was a contributing author in Laboratory Evaluations for Integrative and Functional Medicine and Case Studies in Integrative and Functional Medicine. She has published case studies, book chapters, and journal articles about the oral microbiome, natural medicine, nutrition, laboratory testing, obesity, and osteoporosis.