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February 20, 2016

Air pollution can cause you to gain weight, new study finds

Researchers have long known that air pollution can lead to asthma and other respiratory issues, but a new study suggests clean air might be important for a different and unexpected health related reason.

In research published in the March issue of the Journal of the Federation of American Societies for Experimental Biology (FASEB), an international team of researchers found that rodents breathing the highly-polluted air of Beijing, China for three to eight weeks began to experience weight gain, cardio-respiratory issues, and metabolic dysfunctions.

As part of the study, senior author Junfeng "Jim" Zhang, a professor of global and environmental health at Duke University, and his colleagues placed pregnant rats and their offspring in two chambers: one which was exposed to the outdoor air in Beijing, and one which contained an air filter that removed the majority of the atmospheric pollution particles.

‘Clear evidence’ that air pollution increases obesity risk

After just 19 days, the lungs and livers of pregnant rats exposed to the polluted air were heavier and showed increases levels of tissue inflammation, the study authors said in a statement. Also, these rats were found to have 50 percent higher LDL levels and 97 percent higher total levels of cholesterol, as well as 46 percent higher triglyceride levels.

Furthermore, the insulin resistance level (which is a precursor of Type 2 diabetes) of the rodents in the polluted air was found to be higher than their healthy-air counterparts, and at the end of the experiment, the first group weighed 10 to 18 percent more than the second, even though both groups had eaten the same diet. The findings seem to suggest that exposure to air pollution may lead to metabolic dysfunction, which itself is known to be a precursor to obesity.

Similar results were also observed in the offspring, which were kept in the same chambers as their mothers. However, Zhang’s team noted that the negative effects were less pronounced at three weeks than they were after eight weeks, which would appear to indicate that longer-term exposure to unclean air is necessary for the negative health effects to completely set in.

“Since chronic inflammation is recognized as a factor contributing to obesity and since metabolic diseases such as diabetes and obesity are closely related, our findings provide clear evidence that chronic exposure to air pollution increases the risk for developing obesity,” Zhang explained. “If translated and verified in humans, these findings will support the urgent need to reduce air pollution, given the growing burden of obesity in today's highly polluted world.”


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