Poor dental health is linked to the heart disease and dementia. So why do we neglect it?

A new study published in The Journals of Gerontology Series A finds that if you don't take care of your teeth, you are more likely to suffer inflammation, reduced brain size and damage to your heart. At first glance, this may seem like a reach — what do teeth have to do with the brain and heart? But as one of the researchers, Dr. Benjamin Trumble, told Salon, our culture errs when "the way we think about health is that we split the body into two parts," with the mouth in one category and everything else in the other.

In fact, the health of your mouth profoundly impacts other areas of your body. The scientists behind the recent paper learned this by examining more than 700 sets of teeth — all among members of a little-known South American tribe.

The Tsimané, an Indigenous people of lowland Bolivia, lead much simpler lives than the vast majority of humans. While the rest of us flourish/wallow in our world of post-industrial technology, this community leads a traditional lifestyle of foraging and growing their own food. They are not as exposed to the problems of pollution, low physical activity and poor diet that cause epidemic levels of heart and brain disease in industrialized societies. As a result, when researchers drew links between each individual's oral health and their cardiovascular and brain health, they could feel more comfortable that the findings were not confused by unrelated variables.

The study found that though this community has generally poor oral hygiene, it also had low rates of dementia and cardiovascular disease. Nevertheless, individuals who had large amounts of damaged teeth possessed higher rates of inflammation, brain tissue loss and aortic valve calcification. By contrast, damaged and lost teeth were not associated with coronary artery calcium or thoracic aortic calcium.

"I think that this really highlights the importance of oral health in overall health," Trumble, a professor at Arizona State University's Center for Evolution and Medicine, told Salon by email. Trumble pointed to the famous expression "don't look a gift horse in the mouth" as proof that people have always suspected a connection between health and examining an animal's teeth. Yet humans often culturally fail to apply the same logic to themselves that they do to horses.

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"Somewhere along the line we lost this understanding when it comes to overall health and dental health," Trumble said. "Now we differentiate health insurance from dental insurance, but really they both impact our health and aging."

So why do we arbitrarily divide dental into its own separate form of health care, one that isn't covered equally by insurance? Indeed, teeth are often treated as a "cosmetic" problem, despite clear evidence to the contrary. In fact, the website for Covered California, the largest state-based health insurance marketplaces in the U.S., spells it out plainly: "Dental coverage for adults is not considered an essential health benefit, so dental coverage for adults is offered separately from health insurance plans. No financial assistance is available to purchase these dental plans."

Yet even before this study, scientists had established strong links between oral health and inflammatory, cardiovascular and brain health. The new paper adds more clarity to that connection, however, by showing that it exists in a population that is free not only from the environmental scourges of industrialism and factory farming, but also its social injustices — particularly those that negatively impact oral health.

The Tsimané "have far less of a socioeconomic gradient, and very little access to modern dentistry at all," Trumble said. "This makes it possible to actually examine associations between oral health and chronic disease without confounding social factors" — namely, the fact that industrialized societies like the United States tend to provide inferior dental care to people in lower socioeconomic conditions.

"That is what really sets this paper apart — we can assess the association between dental health and cardiovascular and brain health independent of any confounding from socioeconomic status," Trumble said.

The new paper also provides useful context to research done into how oral health is connected to other forms of health. A January paper in the journal BMC Oral Health found that dental cavities decrease the cerebral cortical thickness of the BANKSSTS, a region of the brain crucial for language-related functions and the most affected area in Alzheimer's disease.

Similarly, a January paper in the European Journal of Preventive Cardiology determined that people who use dentures are more likely to have coronary artery disease, strokes, myocardial infarctions, heart failures and type 2 diabetes. And a 2022 paper in the International Journal of Dentistry also determined that people with significant tooth loss and diabetes mellitus, as well as those with just significant tooth loss, were more likely to have elevated levels of serum C-reactive protein (CRP), a liver enzyme that indicates inflammation. It also found that people who regularly floss are more likely to have lower CRP levels.

There is plenty we just don't understand about how our mouth and the rest of our health are intertwined. Just last week, researchers at the Fred Hutchinson Cancer Center in Seattle reported in Nature that a bacterium that lives in our mouths, known as Fusobacterium nucleatum, is linked to an increase in colorectal tumors.

However, much of this previous research exists with the possibility of some outside factor, such as diet or environment, that could explain the link between the mouth and these conditions. Because of Trumble and the extensive research team that joined him — including anthropologists, cardiologists, neurologists, radiologists and dentists — researchers can now look at a study with a large cohort in which post-industrial society simply does not exist.

The experience wasn't just educational — Trumble found it inspirational.

"It has been one of the great honors of my life to get to work with the Tsimané for the last decade and half," Trumble said. "Modern urban life is evolutionarily novel — we were hunter gatherers for 99% of human history. The sedentary lifestyle we live today is very different from the rest of the human past."

Because post-industrial city life is so unusual compared to what our physiology was designed to do, "we are essentially living outside of the manufacturer's recommended warranty for our bodies," Trumble said. "Most of human evolution occurred in traditional subsistence populations, but nearly all health research is done in urban centers, so we really don’t have a great idea of what health was like before electricity, cars and grocery stores."

Trumble added, "Getting to work with a population like the Tsimané is an amazing experience, and gives a better idea of the health issues that people had prior to city life."