Science has already established a link between periodontal (gum) disease and metabolic syndrome. A group of Japanese researchers went looking for a more specific linkage. They wanted to know what the specific connection was between gum disease and metabolic syndrome. They believe they have found it.
Metabolic syndrome is a combination of conditions including high blood pressure, elevated blood sugar and serum triglycerides and low serum high-density lipoproteins (HDL cholesterol.) These conditions are usually linked to excess abdominal fat and put those who have them at greater risk of type 2 Diabetes and cardiovascular disease.
Yet some overweight and obese people don’t suffer from metabolic syndrome, while some people with normal levels of body fat do. Several other risk factors have been identified over the years. One of those is periodontal disease.
In a new study from a research team at Tokyo Medical and Dental University (TMDU,) gum disease has been positively associated with the precursor to metabolic syndrome. The scientists have discovered that Porphyromonas gingivalis, which is the bacterium that causes gum disease, leads to metabolic dysfunction in skeletal muscle. This leads to metabolic syndrome by changing the composition of your gut microbiome.
The periodontal bacteria living in your sublingual microbiome can not only cause oral cavity inflammation, but can increase inflammatory mediators systemically as well. Long-term infection with periodontal bacteria, then, can spur an increase in your body weight and potentially lead to insulin resistance. Insulin resistance is linked to type 2 Diabetes.
Glucose in the blood is moved into muscle tissue with the help of insulin. It makes sense, then, that being insulin resistant would create problems for your metabolism. These problems begin in the skeletal muscle tissue. We know that skeletal muscle is involved in reducing blood glucose levels. So far, however, no specific link between bacterial infection of the gums and the metabolic function of skeletal muscle has been made.
“Metabolic syndrome has become a widespread health problem in the developed world,” says first author of the study Kazuki Watanabe. “The goal of our study was to investigate how periodontal bacterial infection might lead to metabolic alterations in skeletal muscle and thus to the development of metabolic syndrome.”
To prove their hypothesis, the scientists looked for antibodies to Porphyromonas gingivalis in the blood of people who had metabolic syndrome. They discovered a positive between the antibody levels, known as titers, and increased insulin resistance. The antibodies indicated that these people were almost certain to have been infected with Porphyromonas gingivalis. The resulting immune response to the bacterium would result in the production of those antibodies.
They had their positive clinical observation. Now, they needed to know the how and why behind the result. They decided to get a bunch of mice fat. The mice were fed a high-fat diet. High-fat diets are believed to be a cause of metabolic syndrome. They noticed that their fat mice had reduced glucose uptake in skeletal muscle, increased fat infiltration and of course, increased insulin resistance. Mice not fed a high-fat diet didn’t exhibit these symptoms.
But how did Porphyromonas gingivalis do it’s dirty work? What was the mechanism that caused the systemic inflammation and metabolic syndrome? I’ve previously written about your gut microbiome. This is the neighborhood of billions of bacteria (viruses and other critters, too) that live in your gut, co-existing with you and making many of your body functions operate efficiently and effectively. It turns out that the mice given Porphyromonas gingivalis had their gut microbiome changed. This might well be the cause of the reduction in insulin sensitivity.
“These are striking results that provide a mechanism underlying the relationship between infection with the periodontal bacterium Porphyromonas gingivalis and the development of metabolic syndrome and metabolic dysfunction in skeletal muscle,” says corresponding author of the study Professor Sayaka Katagiri.
What happens in the gut can change the health and proper function of your body and it’s systems. With this research, it seems we’ve discovered that what’s going on in your mouth, bacteria-wise, has an impact on your gut, too. Gum disease, then, has effects well beyond plain old bad breath.
Keep the faith and keep after it!
Journal Reference – Kazuki Watanabe, et al., Porphyromonas gingivalis impairs glucose uptake in skeletal muscle associated with altering gut microbiota. The FASEB Journal, 2020; DOI: 10.1096/fj.202001158R