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Obesity is a growing problem in the United States. More than a third of all adults in the United States and seventeen percent of children from the ages of two to nineteen are obese according to the Center for Disease Control. A study published in the journal Pediatrics and conducted by two pediatric gastroenterologists from California, led by Dr. Schwimmer, suggests a link between the adenovirus 36 virus(AD-36) and obesity in humans. It is important to note that the study does not negate lack of exercise or overeating as causes of obesity. Rather, researchers are looking into the possibility of AD-36 as a contributing "environmental factor" in the increasing obesity rates.
In lab studies involving animals, such as mice, chickens, rats, and monkeys, those infected with the virus became overweight despite maintaining a constant diet and exercise routine. These animals were found to have an increased amount of body fat and visceral fat, the kind that encircles inner organs.
Prior to Dr. Schwimmer's research, studies on the correspondence between AD-36 and obesity in humans were limited to adult subjects. Dr. Schwimmer focused his research on the virus's impact on childhood obesity. His study looked at children ranging from eight to eighteen years of age. Of those kids, sixty-seven were considered obese while fifty-seven were considered to be of normal weight based on their body mass index. Those with a body mass index in the 95th percentile or above were classified as obese. Each child's blood was taken to screen for the presence of antibodies to the AD-36 virus. Blood samples that tested positive for antibodies signified that that child had previously been exposed to AD-36. Out of the one-hundred and twenty-four children, nineteen were found to carry AD-36 antibodies. Moreover, fifteen of the antibody positive kids were obese while four of them were of normal weight.
The results showed that twenty-two percent of the overweight children showed signs of AD-36 antibodies as opposed to the seven percent of normal weight kids who tested positive for antibodies. On average the antibody positive children were fifty pounds heavier than those who tested negative for antibodies. In addition, obese children with prior exposure to AD-36 were about thirty five pounds heavier than obese children without prior exposure and had greater waist circumferences on average. Previous studies showed that approximately thirty percent of obese adults and ten percent of normal weight adults carry the AD-36 antibodies.
Opponents to this theory have also emerged. In a recent study three-hundred United States military members were screened for AD-36 antibodies. Roughly equal numbers of obese and lean subjects, thirty-four percent and thirty-nine percent respectively, tested positive for antibodies. However, Dr. Richard Atkinson, an endocrinologist at the Virginia Commonwealth University and founder of the company Obetech which screens for antibodies against AD-36, dismisses the research involving military personnel. Dr. Atkinson counters that military personnel have "incentives" to monitor their weight in contrast to the average person.
Scientists say more studies are needed to further explore the role AD-36 plays in obesity. It is unclear whether the virus directly causes obesity or if overweight people are more susceptible to contracting it. I think there are definitely some interesting factors that link AD-36 to obesity. At about the same time the virus was discovered in the 1970s obesity rates were beginning their rapid ascent. Dr. Atkinson also suggests that AD-36 helps to explain the growing problem of obesity in developing nations. Consumption of junk food and lack of exercise are not as prevalent in developing nations as they are in the United States. Nevertheless, obesity rates in developing nations are increasing at the same rate as obesity rates in the United States. In the meantime, there's no need to panic over catching the virus from others. In the time it takes for someone to become obese the virus is already "long gone and the person is no longer infectious."
References:
Discovery News. "Obesity in Children Linked to Common Cold Virus." Discovery. Feb 11, 2013.
Dooren, J. "Virus is linked to obesity."The Wall Street Journal. September 21, 2010.
Mayo Clinic. "Viral Infections May Be Linked To Obesity." Science Daily. October 24, 2007.
Dr. G. William Gary, Jr. (via CDC).
