Children who tested positive for a virus strain that causes respiratory and gastrointestinal illness weigh more than those who didn’t, suggesting that infections may cause or contribute to obesity, a study showed.
Obese children who were found to have been exposed to a strain called adenovirus 36 weighed about 35 pounds more on average than obese children who tested negative, researchers said today in the journal Pediatrics. Children, whether obese or not, who tested positive were 52 pounds heavier on average than those showing no evidence of the virus, according to the study of 124 kids, including 67 who were obese.
While the number of obese children in the U.S. has tripled since 1980, the proportion of kids with the condition appears to have leveled off during the past decade, at about one in five, U.S.-sponsored researchers said in January. The latest study provides a possible link between obesity in children and a strain of adenovirus, author Jeffrey Schwimmer said.
“Our study is one example of the complexity of obesity,” said Schwimmer, an associate professor of pediatrics at the University of California, San Diego, in a telephone interview on Sept. 14. “It can’t simply be reduced to eating too much and moving too little. That’s not the whole story.”
Schwimmer said more studies are needed to determine what role adenovirus 36 infections play in causing people to gain weight.
“This work is really a starting point,” he said.
While the findings are “novel,” they aren’t likely to solve the puzzle of childhood obesity, said Evan Nadler, co- director of the Children’s National Obesity Institute at Children’s National Medical Center in Washington, who wasn’t involved in the research.
“Even in the event that this particular virus may predispose certain children to obesity, it’s not going to be the magic bullet to change the course of the obesity epidemic,” Nadler said in a telephone interview on Sept. 16. “There will be some patients who are obese for genetic reasons, some obese for environmental reasons and perhaps some that are obese because of infection. I don’t think we’ll ever likely find one cause of obesity.”
Almost 20 percent of 6- to 11-year-olds were considered obese in 2007-2008, while 18 percent of those ages 12 to 19 were deemed so, according to the Atlanta-based Centers for Disease Control and Prevention. Obesity is measured as a ratio between height and weight.
Seeking New Drugs
Two-thirds of American adults are overweight or obese, raising their risk of diabetes, heart disease, high blood pressure and cancer, according to the 2008 National Health & Nutrition Examination Survey. Orexigen Therapeutics Inc. and Arena Pharmaceuticals Inc., both of San Diego, and Mountain View, California-based Vivus Inc. are vying to sell obesity drugs that are under review by the Food and Drug Administration.
Adenovirus 36, one of more than 50 strains of the virus, appears to infect immature fat cells, making them develop more quickly and increasing the number of fat cells in the body, Schwimmer said. The strain also appears to make it harder to break down mature fat cells, causing more fat to be stored in the body, he said. The virus typically causes short-term illnesses.
Studies in animals and in adults showed an association between adenovirus 36 and obesity, the authors wrote.
Researchers in the study published today tested 124 children ages 8 to 18 for antibodies specific to adenovirus 36. Sixty-seven participants were obese.
The researchers found that 19 children, or 15 percent, tested positive for the antibodies. Of those, 15 were obese.
“The reality is that the development of obesity is much more complicated then what we used to think,” said Schwimmer, who has run an obesity program for children for eight years. “If people understand that something uncontrollable like a viral infection can be a cause or contributor to obesity, perhaps that will enable people to be more open minded to how they approach the issue or to people who have it.”