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Can Obesity Be Caused by Oral Bacteria?

Posted Nov 25 2011 5:43am

Image by mike-burns

This is a guest post by Phyllis Schaub of

In the last few years, scientists investigating the relationship between inflammation and cardiac health have discovered an unexpected and potentially significant connection between oral bacteria and obesity.

Researchers at the Forsyth Institute, a Harvard Medical School-affiliated scientific research organization whose mission it is to study the links between oral and systemic health, announced their findings in The Journal of Dental Research.

The team of scientists at the Forsyth Institute analyzed saliva samples from 313 middle-aged women who had a body mass index between 27 and 32, and compared the results of that analysis with the bacterial populations measured in the saliva of 232 individuals whose body mass index was below 27.

The human mouth is home to about 700 species of bacteria. According to the researchers, there were “significant differences” between the two groups with respect to 7 of the 40 species of bacteria that were identified and studied.

Nearly all of those bacteria were present in greater numbers in overweight individuals (those whose body mass index was above 27), and one species in particular, Selenomonas noxia, was present in significantly higher numbers in 98% of those who were classified as overweight.

The results of the study indicate that certain types of bacteria are more likely to be found in greater numbers in the saliva of overweight individuals as compared to healthy individuals. Whether the bacteria themselves are the cause of weight gain or are a symptom of it will require more analysis.

Previous research in animals has also suggested a link between bacteria and obesity. In one study, mice infected with a particular germ had 60% more fat than their germ-free counterparts. Germ-free mice who were later infected subsequently gained weight as well. Interestingly, the germ that appeared to predispose infected mice to weight gain belonged to the same phylum (Firmicutes) as Selenomonas noxia, the bacteria most closely associated with obesity in the Forsyth Institute study.

Other human studies also suggest some connection between bacteria and obesity. For example, it has been shown that spouses and siblings are more likely to gain weight at the same time than individuals in other relationships, such as friends or neighbors. That may suggest weight gain is “infectious” and more likely to be “spread” by individuals who interact and come into close contact with one another more frequently than with others.

Moreover, periodontal disease, which is believed to be caused by three different bacteria, causes increased levels of inflammatory mediators, and the impact of inflammation on cardiac health is currently being studied by the National Institutes of Health. Studies and surveys have also suggested a correlation between periodontal disease and overweight conditions.

For example, one survey showed that overweight or obese individuals are significantly more likely to have periodontal disease than non-overweight individuals, and those overweight or obese individuals who have the disease are more likely to have a severe form of it.

Of course, none of this is to say that there is a conclusive link between oral bacteria and obesity, only intriguing circumstantial evidence. As the Forsyth Institute noted, the presence of certain bacteria in overweight individuals suggests a connection between the two, but not necessarily causation.

The bacteria identified by the study may directly contribute to weight gain, multiply as the individual gains weight, or both. And since obesity is a major cause of cardiovascular disease, the role of bacteria in obesity could have important implications for reducing the adverse effects of weight gain on overall health.

A dentist can tell you more about this study, the role of bacteria in oral and systemic health, and the importance of maintaining healthy teeth and gums. Your dentist will advise you of the most effective ways of avoiding the harmful effects of bacteria. Depending on the scientific knowledge that develops in the coming years, your dentist may be able to help you manage your weight, as well.

Phyllis Schaub DDS is a Mission Viejo cosmetic dentist who performs general preventative dentistry in addition to providing cosmetic dentistry services

Post from: Weight Loss Blog (Lose That Tyre)

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