Poor Oral Hygiene Increases Colorectal Cancer Risk

Here are a few practices to maintain good oral health and reduce the prevalence of a type of bacteria linked to colorectal cancer.

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Oral hygiene is not just about keeping your teeth healthy; oral bacteria have also been linked to colorectal cancer. How do oral bacteria enter the gut? Can mouthwash help? Shao-Hung Wang, a Taiwanese microbiology expert, discussed the relationship between oral bacteria, gut health, and cardiovascular diseases on The Epoch Times’ “Health 1+1” program and outlined methods for maintaining good oral hygiene.

A study published in the prestigious international journal Nature revealed that Fusobacterium nucleatum, an oral bacterium associated with gum disease, was found in the tumors of some colorectal cancer patients. This bacterium may promote the growth of colorectal tumors and increase the risk of cancer recurrence, leading to a poorer prognosis.

Mr. Wang said that the Fusobacterium nucleatum subspecies Fna C2 can withstand acidic conditions, allowing it to pass through the digestive tract and enter the colon and rectum. Once there, it produces adhesion factors to attach to cells and releases toxic molecules that induce inflammation, promoting tumor development.

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Mr. Wang believes antibiotics may not be suitable for combating these oral bacteria that can cause colorectal cancer, as they indiscriminately kill all bacteria, including beneficial ones. Instead, some microbiologists utilize bacteriophages or antibacterial molecules in green tea to reduce Fusobacterium nucleatum. In addition to green tea extract, consuming vegetables high in polyphenols, as well as black tea extracts and catechin derivatives found in tea, can also help cleanse the mouth and inhibit Fusobacterium nucleatum in the gut.

Mr. Wang mentioned that in ancient times, people did not have toothbrushes and tended to use tea leaves to rinse their mouths after meals to remove dental plaque, in which Fusobacterium nucleatum persists as one of the most common bacteria. However, due to tea leaves’ tendency to leave stains, most people eventually discontinued this practice.

How Do Oral Bacteria Enter the Gut?

Mr. Wang stated that some oral bacteria are present in undercooked food, while others form biofilm plaques through bacterial aggregation, which may be swallowed with saliva or food. If oral bacteria form clusters, they may survive exposure to stomach acid and gastric motility.

Interestingly, certain microorganisms develop acid resistance as they pass through the esophagus into the stomach, enabling them to adhere to the stomach lining. Some bacteria, such as Lactobacillus reuteri, even possess a specialized outer coating for protection. Additionally, while a person eats, stomach acid can dilute from pH 1 or 2 to around pH 5, allowing bacteria to potentially evade the acidic environment.

Mr. Wang emphasized the importance of eating slowly and chewing food thoroughly to prevent microorganisms from hiding in food chunks and escaping stomach acid. Moreover, maintaining proper oral hygiene is crucial for reducing the formation of bacterial biofilm plaques.

Oral Bacteria Increase Cardiovascular Risk

Mr. Wang pointed out that Fusobacterium nucleatum can enter the bloodstream through bleeding gums caused by brushing, mouth wounds, or periodontal diseases. Butyrate, produced in the mouth by Fusobacterium nucleatum, increases the risk of periodontal disease by enhancing the production of porphyrin, which promotes bacterial growth. Additionally, butyrate serves as a nutrient for some bacteria and activates pathogenic viruses, leading to inflammation and even the death of gum cells.

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Mr. Wang noted that oral bacteria can contribute to periodontitis. Inflammatory substances and bacteria can enter the bloodstream through gum wounds or gastrointestinal mucosal lesions. When these substances reach the liver, they trigger the release of more acute phase response proteins, including zymogens such as prothrombin, which are involved in blood clotting. As prothrombin travels through the bloodstream, it can cause blood clots if it encounters areas with cholesterol buildup or inflammation in the blood vessels, thus resulting in symptoms associated with coronary heart disease.

Therefore, Mr. Wang advises everyone to manage their cholesterol levels and to take measures to prevent oral microorganisms from entering the body, as this can lead to inflammation.

Best Practices for Oral Hygiene

Mr. Wang recounted his personal experience from about 20 years ago when he suffered from a stomach ulcer. At that time, there was no standard treatment for Helicobacter pylori, so he took antibiotics for four weeks. By the third week, his tongue had developed a thick coating because the antibiotics killed the bacteria but allowed fungi, including Candida albicans, to flourish, causing an imbalance in the oral microbiome.

He emphasized that the key to oral hygiene is not necessarily killing bacteria but physically brushing off the surfaces of teeth and areas where tongue coating tends to form.

Therefore, Mr. Wang outlined the following recommendations for maintaining oral health:

• Brush your teeth twice a day.
• Use dental floss or floss picks after meals to help remove plaque or food debris.
• Regularly visit the dentist for check-ups and cleanings to remove calcified plaque.
• Avoid frequent use of mouthwash.

Mr. Wang explained that fluoride-containing mouthwashes could affect the gut microbiome significantly, so it is best not to use them more than twice a week. Mouthwashes containing the antiseptic chlorhexidine are toxic to bacteria but can disrupt the balance of the oral microbiome if used frequently.

The oral microbiome plays a crucial role in the cycle of nitrates and nitric oxide. Nitrogenous compounds found in vegetables, such as nitrates, are initially converted by oral bacteria into nitrites. These nitrites then enter the bloodstream through the mucosa and blood vessels. Furthermore, stomach acid can further process nitrites to form nitric oxide.

Nitric oxide has been found to regulate blood pressure and vascular permeability, thereby reducing the risk of hypertension and other cardiovascular diseases. It also inhibits platelet aggregation and leukocyte adhesion. However, excessive nitric oxide can inhibit nerve transmission and mitochondrial respiration. Frequent use of mouthwash can lower nitric oxide levels in the body, potentially leading to increased blood pressure and a higher risk of death from ischemic heart disease.