Exposure to air pollution may up obesity, diabetes risk

Exposure to polluted air may increase the risk of obesity and lead to high cholesterol and more insulin resistance, a precursor of Type 2 diabetes, a new study has warned.
Researchers from Duke University in US found that laboratory rats who breathed Beijing's highly polluted air gained weight and experienced cardio-respiratory and metabolic dysfunctions.
The pollution-breathing pregnant rats had heavier lungs and livers and increased tissue inflammation, researchers said.
For the study, they placed pregnant rats and their offspring in two chambers, one exposed to outdoor Beijing air and the other containing an air filter that removed most of the air pollution particles.

After only 19 days, the lungs and livers of pregnant rats exposed to the polluted air were heavier and showed increased tissue inflammation.
These rats had 50 per cent higher Low-density lipoprotein (LDL) cholesterol; 46 per cent higher triglycerides; and 97 per cent higher total cholesterol.

Their insulin resistance level, a precursor of Type 2 diabetes, was higher than their clean air-breathing counterparts.
The results show that air pollution exposure results in metabolic dysfunction, a precursor to obesity.
Pollution-exposed rats were significantly heavier at the end of their pregnancy even though the rats in both groups were fed the same diet.

Similar results were shown in the rat offspring, which were kept in the same chambers as their mothers.
The negative effects of air pollution were less pronounced after three weeks than they were at eight weeks, suggesting that long-term exposure may be needed to generate the continuous inflammatory and metabolic changes that ultimately increase body weight.
At eight weeks old, female and male rats exposed to the pollution were 10 per cent and 18 per cent heavier, respectively, than those exposed to clean air.
"Since chronic inflammation is recognised 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," said Junfeng Zhang from Duke University.

"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," said Zhang.
The findings were published in the Journal of the Federation of American Societies for Experimental Biology.