There may soon be a simple way to identify children at risk for developing obesity later in life.

Researchers from Pennsylvania State University analyzed the bacteria in the mouths of 226 2-year-olds and found that a child's oral microbiota can be used as a tool to predict weight gain during the first two years of life.

The study is part of a project of 300 children at the Penn State Health Milton S. Hershey Medical Center that seeks to identify biological and social risks for obesity. The results were published Wednesday in the journal Scientific Reports.

"One in three children in the United States is overweight or obese," said Kateryna Makova, a biology professor at Penn State and senior author of the paper. "If we can find early indicators of obesity in young children, we can help parents and physicians take preventive measures."

The children, who were from central Pennsylvania, had experienced rapid weight gain as infants, which is a strong indicator for childhood obesity.

Researchers also found that the oral microbiota among these children contained fewer types of bacteria. A larger diversity of bacteria helps protect against inflammation and is important for the stability of digestion.

"A healthy person usually has a lot of different bacteria within their gut microbiota," said Sarah Craig, a postdoctoral scholar in biology at Penn State and first author of the paper.

While previous studies in adults and adolescents have linked obesity to gut microbes, this is the first time a relationship between the oral microbiota and weight gain in children has been explored, the researchers said.

"The oral microbiota is usually studied in relation to periodontal disease, and periodontal disease has in some cases been linked to obesity," said Craig.

The researchers did not investigate how diet or environmental changes over time could affect the link between oral bacteria and obesity. Makova said the fact that mothers now spend less time breast-feeding children than they did in the 1960s could be a factor.

Obesity is a complex issue and has many different causes, she said.

"Of course, as a parent you should be watching for the best diet and exercise," Makova said.