Part 2: Build the Microscopic Army in Your Mouth to Fight Oral Cancer and Improve Dental Health

Last week in part 1, oral cancer was defined with a potential cause being oral dysbiosis identified. This week, I will give supporting evidence of this connection along with strategies to avoid this dysbiosis.

When we talk about an unhealthy microbiome, we often use the word, “dysbiosis.” Oral dysbiosis is a mouth that is unhealthy because the microorganisms are out of balance. An imbalanced microbiome may lead to symptoms or disease.

Symptoms of Oral Dysbiosis:

  • Bad breath
  • Bleeding, puffy, swollen gums
  • Cavities
  • Gingivitis
  • A history of “bad teeth” or lots of dental work
  • Periodontal disease
  • Root canal infections
  • Teeth that are loose or fall out

One of the most common ways we keep a balanced oral microbiome is with oral hygiene. Brushing, flossing, water flossing, dental health check-ups, and oil pulling promote a healthier oral microbiome. When oral care habits fall to the wayside, that’s when oral cancers rear their ugly heads.1 And that’s not all. Poor dental health habits increase the risk for other cancers, too.

Oral Health Habits Can Make or Break Cancer

  • Good dental hygiene reduces the risk of oral cancer by 62%.
  • People who have lost teeth (a sign of gum disease and oral dysbiosis) have an increased risk of gastric cancer and pancreatic cancer.
  • People with gum disease have four times higher risk of head and neck cancer and five times higher risk of tongue cancer!
  • People who don’t brush have two times higher risk of esophageal cancer.

Why? It’s because a healthy oral microbiome protects you from infections. If you have gum disease, then you have imbalanced bacteria in your mouth causing destruction and inflammation. This harmful environment gives more chances for cells to become damaged and turn into cancer. Fewer infections and less inflammation in your mouth means you are safer from developing cancer.

Beyond Mouth and Throat Cancers

It’s clear that certain oral pathogens are involved in mouth and throat tumors.2,3 But the oral microbiome may influence cancers elsewhere too, not just oral cancers! Oral pathogens increase the risk of colorectal cancer and may help to predict gastrointestinal cancer.4 Also, there is more oral dysbiosis in people who have esophageal, gastric, pancreatic, and colorectal cancers.

How Does Oral Dysbiosis Lead to Cancers?

It’s well accepted that oral dysbiosis and infections can set someone up for cancer.2,4-10 But just how do imbalanced bacteria cause mouth cancers? Here are the different ways an imbalanced oral microbiome could lead to cancer.6,9

Inflammation– if someone has oral dysbiosis such as cavities or gum disease, they have inflammation in the mouth. These immune products can harm healthy cells and cause them to mutate into unhealthy cancer cells.

Harmful bacterial byproducts– microorganisms can produce cancer-causing toxic byproducts, including free radicals that can damage your cells and turn them rogue.

Antiapoptotic activity– some microbes may suppress the body’s self-defense mechanism of programmed cell death, known as apoptosis. This means harmful mutated cells can live forever and cause cancer when they shouldn’t be allowed to.

Immune suppression– some microbes lower your immune defenses so that your immune system can’t fight dysbiosis or cancer cells.

Damage to the oral lining (leaky mouth)– having oral dysbiosis and inflammation in the mouth can produce chemicals that damage the lining of the mouth. That means harmful chemicals, proteins, and microorganisms can enter the bloodstream, where they don’t belong.

Epigenetic changes to host cells– some evidence suggests that microbes can influence our DNA, possibly producing tumors. Epigenetics describes the changes to how our DNA acts that often come from environmental causes and can be passed down. These changes are overlaid on our genes; they are not changes to our actual raw DNA code.

Decreased production of anticancer metabolites by friendly bacteria2– one reason bad bacteria may cause cancer is because they push out all of the good bacteria that actually fight cancer with their healthy byproducts.

Boost Your Oral Microbiome with These Natural Oral Health Solutions

  • Get all of the information you need in my book, Heal Your Oral Microbiome.
  • Brush, floss, and stay on top of your dental health visits.
  • Get screened; some dental offices do free screening in April for Oral Cancer Awareness.
  • Eat whole foods, especially colorful veggies.
  • Just say no to sugar and refined carbohydrates.
  • Take chewable probiotics containing Streptococcus salivarius. I also recommend oral probiotics, which have good evidence to support prevention of colorectal cancer. However, evidence for anticancer effects in the mouth are limited.
  • Test your mouth and your gut microbiomes to look for dysbiosis.
  • Stop smoking.
  • Stop drinking (too much) alcohol.
  • Choose organic foods and non-toxic dental products to reduce cancer-promoting chemicals in the mouth

Your oral health is now more important than ever. From diabetes to heart disease to Alzheimer’s, the list of diseases linked to your oral health grows longer and longer. Imbalanced microorganisms in the mouth can cause cancers of the mouth, throat, esophagus, stomach, pancreas, and even the colon. A healthy and strong oral microbiome may be your best weapon against oral cancer and other cancers.


  1. Meurman JH. Oral microbiota and cancer. Journal of oral microbiology. 2010;2.
  2. Su SC, Chang LC, Huang HD, et al. Oral microbial dysbiosis and its performance in predicting oral cancer. Carcinogenesis. 2021;42(1):127-135.
  3. Mäkinen A, Nawaz A, Mäkitie A, Meurman JH. Role of Non-Albicans Candida and Candida Albicans in Oral Squamous Cell Cancer Patients. Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 2018;76(12):2564-2571.
  4. Zhang S, Kong C, Yang Y, et al. Human oral microbiome dysbiosis as a novel non-invasive biomarker in detection of colorectal cancer. Theranostics. 2020;10(25):11595-11606.
  5. Mascitti M, Togni L, Troiano G, et al. Beyond Head and Neck Cancer: The Relationship Between Oral Microbiota and Tumour Development in Distant Organs. Frontiers in cellular and infection microbiology. 2019;9:232.
  6. Sun J, Tang Q, Yu S, et al. Role of the oral microbiota in cancer evolution and progression. Cancer medicine. 2020;9(17):6306-6321.
  7. Hong BY, Sobue T, Choquette L, et al. Chemotherapy-induced oral mucositis is associated with detrimental bacterial dysbiosis. Microbiome. 2019;7(1):66.
  8. Koliarakis I, Messaritakis I, Nikolouzakis TK, Hamilos G, Souglakos J, Tsiaoussis J. Oral Bacteria and Intestinal Dysbiosis in Colorectal Cancer. International journal of molecular sciences. 2019;20(17).
  9. La Rosa GRM, Gattuso G, Pedullà E, Rapisarda E, Nicolosi D, Salmeri M. Association of oral dysbiosis with oral cancer development. Oncology letters. 2020;19(4):3045-3058.
  10. Mohammed H, Varoni EM, Cochis A, et al. Oral Dysbiosis in Pancreatic Cancer and Liver Cirrhosis: A Review of the Literature. Biomedicines. 2018;6(4).

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Cass Nelson-Dooley MS