Obesity risk linked to history of chronic ear infections

August 14, 2008

GAINESVILLE, Fla. — More than 5 million children cope with the agonizing ache of ear infection annually, but a new discovery suggests damage to taste nerves caused by the common childhood ailment might increase the risk of obesity later in life, say University of Florida College of Dentistry researchers.

Chronic ear infections appear to trigger a preference for high-calorie food, leading to increased consumption and excessive weight gain in adulthood, said Linda Bartoshuk, a UF expert on the sense of taste and genetic variations in taste perception. She reported study findings from health surveys establishing the link at today’s (Aug. 14) annual meeting of the American Psychological Association in Boston.

Bartoshuk’s preliminary study findings suggested a link between the infections and obesity. Researchers from other academic institutions confirmed the discovery with data from three independent studies.

“We have known for a long time that ear infections can damage taste because the major taste nerve, the chorda tympani nerve, passes through the middle ear on its way to the brain,” said Bartoshuk, a presidential endowed professor of community dentistry and behavioral science affiliated with the McKnight Brain Institute’s Center for Smell and Taste. “When we learned that taste damage can intensify non-taste sensations from foods, all of the pieces of the puzzle fell into place.”

When ear infection pathogens damage the main sensory taste nerve it can intensify sensations produced by fatty foods. This heightens the preference for those foods and can lead to weight gain, Bartoshuk said.

In 1993, Bartoshuk and her students began collecting general health information from written questionnaires distributed during taste lectures she gave across the country. Since 1993, she has surveyed more than 6,500 people ages 16 to 92. With age, those individuals who had moderate to severe histories of ear infections gained weight at a faster rate than those who had never had an ear infection. Of respondents over 30 years old, 39 percent of those with no history of chronic ear infections were overweight or obese, whereas 51 percent of those with ear infections were overweight or obese.

In addition, UF researchers found that those with ear infections liked sweet foods such as cookies and milk chocolate 14 percent more than those without ear infections. And they liked high-fat foods such as mayonnaise and butter 18 percent more than those without ear infections.

In a supporting study examining the predictors of obesity in Puerto Rican children, obese children were more likely to have experienced ear infections.

“One public health consequence of these observations may well be to alert parents and pediatricians to the long-term consequences of childhood earaches,” said Jim Weiffenbach, a retired researcher from the National Institute of Dental and Craniofacial Research. “Knowledge of a sensory basis for this class of over-nutrition might allow for the development of new obesity prevention strategies.”

UF researchers and National Institutes of Health researchers are now examining whether tonsillectomies also influence weight gain. They suspect the procedure can damage other taste nerves, which might affect weight in a similar manner.

“Obesity is heavily inherited,” Bartoshuk said. “But (ear infections) are not genetic. This is environmental and this is something you can stop.”