In a new study to be published in the Journal of Dental Research, investigators from The Forsyth Institute set out to measure the salivary bacterial populations in overweight women. They collected samples from 313 women with a body mass index between 27 and 32, which placed them into the overweight category. The investigators used DNA analysis to measure the bacterial populations of this group, then compared their findings to 232 non-overweight people. In 7 of the 40 species of bacteria studied, they found “significant differences” between the two subject groups. Even more dramatic was the presence of Selenomanas noxia, a single bacterial species, at levels greater than 1.05 percent of the total population of salivary bacteria.

"There has been a world-wide explosion of obesity, with many contributing factors," says Dr. J. Max Goodson, senior staff member at The Forsyth Institute and senior author of the study. "However, the inflammatory nature of the disease is also recognized. This led me to question potential unknown contributing causes of obesity. Could it be an epidemic involving an infectious agent? It is exciting to image the possibilities if oral bacteria are contributing to some types of obesity," adds Dr. Goodson, whose research data suggest that certain bacteria species found in higher populations in overweight people may serve as indicators of a developing weight problem.

Dr. Goodson plans to continue his research in order to better understand the relationship between obesity and oral bacteria that may exist, citing that “the observed relationship may be circumstantial as being related to diet or opportunistic due to metabolic changes.” Future work will include a controlled cohort study to see if he and his colleagues can replicate the results. They also plan to conduct longitudinal studies in children to determine if oral infection is related to weight gain. However, only by developing ways to eliminate specific oral bacteria will the researchers be able to gain definitive evidence of a link to obesity.

News Release: Is obesity an oral bacteria disease?   www.sciencedaily.com July 9, 2009