Gum disease isn’t just terrible for oral health, its impact on the human body may extend well beyond the mouth. Previously, researchers found a strong association between gum disease and Alzheimer’s. Now, a new study has found that gum disease is strongly linked to cancers that affect the gut.

Gum disease, which affects a third of all people, is caused by oral bacteria like P. gingivalis. In its mild form, known as gingivitis, only the gum line is affected. However, if left untreated, the bacteria can travel below the gum line and into the bone, causing a more serious form of gum disease known as periodontitis.

Besides swollen gums, smelly breath, and bad teeth, gum disease is also known to contribute to diabetes, heart disease, osteoporosis, and pneumonia.

Most recently, researchers at the Harvard T.H. Chan School of Public Health in Boston have also found an association between a history of periodontal disease and a heightened risk of esophageal (gullet) cancer and gastric (stomach) cancer.

The researchers examined datasets pertaining to 98,459 women from the Nurses’ Health Study (1992-2014) and 49,685 men from the Health Professionals Follow-up Study (1988-2016). The researchers gained access to dental measures, demographics, lifestyle, and diet for each participant, as well as follow-up reports of cancer diagnostics.

During the two decades of follow-up, there were 199 cases of esophageal cancer and 238 cases of gastric cancer recorded for the two cohorts.

When all other factors were accounted for, the researchers found that those with a history of periodontal disease had a 43% and 52% increased risk of esophageal cancer and gastric cancer, respectively.

The participants who lost two or more teeth had a 42% and 33% higher risk of developing oesophageal and gastric cancer, respectively, compared to those with no tooth loss.

Compared with those who had no history of periodontal disease and no tooth loss, the participants who had the gum disease and lost one or more teeth had a 59% increased risk of oesophageal cancer. The same group had a 68% greater risk of gastric cancer.

Since this is an observational study, the authors of the study could not draw any cause-effect conclusions. However, the researchers have some ideas about potential causal mechanisms that may explain the findings.

The presence of oral bacteria like Tannerella forsythia and Porphyromonas gingivalis was associated with a heightened risk of oesophageal cancer. Regarding gastric cancer, gum disease could promote the formation of endogenous nitrosamines through nitrate-reducing bacteria, which are known to cause this type of cancer.

In any event, these findings reinforce the importance of proper oral health — not just for the sake of your gums and teeth, but for your very own life, too.

“Together, these data support the importance of oral microbiome in oesophageal and gastric cancer. Further prospective studies that directly assess oral microbiome are warranted to identify specific oral bacteria responsible for this relationship. The additional findings may serve as readily accessible, non-invasive biomarkers and help identify individuals at high risk for these cancers,” the authors concluded in their study, which was published today in the journal Gut.