Every year, the common cold and the flu incapacitate people for a few days to a few weeks at a time, making them miserable and causing them to miss work, among other things. Turns out that one virus linked to the common cold may also be making people fat.
The adenovirus-36 belongs to a family of viruses that are linked to colds and stomach ailments. There are 52 recognized adenoviruses, and adenovirus-36 is linked to respiratory and eye infections. Several studies have shown that this adenovirus has also been linked to obesity in animal and people.
The link between the adenovirus-36 and weight gain was first discovered by Dr. Nikhil Dhurandhar in 2000 in the study “Increased Adiposity in Animals Due to a Human Virus” in the International Journal of Obesity. The study found that chickens who had been inoculated with adenovirus-36 had increased fat tissue, and the virus was found in the fat tissue for as long as four months afterward. The study concluded that a link between the virus and fat gain in humans needed to be studied.
In September of last year, a study published in Pediatrics found that children who were exposed to adenovirus-36 were more likely to be obese than those who were not exposed. Antibodies to the virus were found in 19 of the 124 children studied, and 15 of those children were considered to be obese. The other 4 were considered to be of normal weight.
Of all the children in the study who were considered obese, 22 percent had antibodies to the adenovirus-36. Only 7 percent of children studied who were considered to be of normal weight had the antibodies. The obese children who had the antibodies were 35 pounds heavier than the obese children who did not have the virus.
The CDC has reported that the adenovirus-36 has been shown to cause a large accumulation of fat in chickens, mice, rats and monkeys, and it said that several studies have shown a link between the virus and obesity in humans. In one study cited, 30 percent of obese people had antibodies to adenovirus-36 present, and the overall body weight of all people who had been infected was about 55 pounds heavier than those who were not infected.
One noteworthy paradox in these studies was that triglycerides and cholesterol were reduced in these people, even with their obesity. However, no reason was found for this reduction.
It has been suggested that the reason adenovirus-36 may cause obesity is that the regulatory element binding proteins is increased, so there is increased binding of protein 1 and fatty acid synthase. Other processes increase the production of fatty acids and the transportation of lipids into the cells.
Studies also indicate that the virus may alter gene expression, as it was found in cells for many, many months after initial infection and was found in multiple tissues throughout the body.
There has been less conclusive evidence about how the adenovirus-36 may affect adults who become affected. Some studies suggest that there is a link, while others show that there is none. Adults studied in the United States, Korea and Italy were shown to be affected by the virus, while adults studied in Belgium and the Netherlands were shown to be unaffected. Studies have also shown that women are much more likely to show a connection between adenovirus-36 infection and obesity than are men.
With the rising rates of obesity in this country among both children and adults, it is worth looking more closely at the role the adenovirus-36 may play in it. Since some who are infected become obese and some don’t, it is still not clear what all the factors are in play. It is not known whether or not vaccination for this virus may help reduce the risk of later obesity, or whether any other treatments may have an impact on reducing the risk.
However, it is estimated that 30 percent of obese adults carry antibodies for adenovirus-36 infection, while only 10 percent of those considered to be of normal weight do. It is clear that there is some connection, and there needs to be more study to understand what kinds of changes can be made to reduce risks.