Air pollution can have devastating effects on a person’s health. According to the World Health Organization, being exposed to air pollution increases a person’s risk of heart disease, lung cancer, and respiratory diseases. Now, Duke University researchers have found that breathing in the polluted air could also increase one’s risk of obesity.
Laboratory rats that were exposed to Beijing’s highly polluted air gained weight and developed cardiorespiratory and metabolic dysfunction. The rats developed the symptoms between three to eight weeks. The symptoms were more pronounced the longer the rats breathed in the polluted air.
To study the effect of the polluted air on the animal models, the researchers placed pregnant rats and their offspring in two chambers. One of the chambers was exposed to outdoor Beijing air. The other chamber contained an air filter that removed most of the air pollutants.
After 19 days, the lungs and livers of the pregnant rats living in Beijing air had become heavier and their tissue was inflamed. Compared to the rats living in filtered air, these rats had 50 percent higher LDL cholesterol, 46 percent higher triglycerides, and 97 percent higher total cholesterol. In addition, they had a higher insulin resistance level than the clean-air rat group and were therefore at a higher risk of developing type-2 diabetes.
The two rat groups ate the same diet, but the pregnant pollution exposed rats were significantly heavier at the end of their pregnancy than the clean-air rats. The results suggest that breathing in air pollution results in metabolic dysfunction, which is a precursor to obesity.
The offspring of the mice displayed similar results. At eight weeks old, the polluted air male rats were 18 percent heavier than their clean air counterparts. The polluted air female rats were 10 percent heavier.
"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 [of] developing obesity," said Junfeng "Jim" Zhang, a professor of global and environmental health at Duke University and a senior author of the paper.
"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," Zhang said.
The study was published on February 18, 2016, in the FASEB journal.