Pollution, excess weight and microbiota: conections have been identified

Recent studies seem to indicate that an increased exposure to traffic-related air pollution plays an important role in type 2 diabetes. A team of American researchers showed that it also affected the intestinal microbiota of overweight or obese teenagers, and was thus detrimental to the proper metabolic functioning.

 

Unhealthy diet, sedentary lifestyle and low socioeconomic level are the risk factors generally associated to type  2 diabetes. Exposure to traffic-related air pollution could soon be added to this list. The team of researchers tried to assess the capacity of this environmental factor to increase the risk of developing this chronic disease. To this end, they wanted to ascertain if air pollutants reached the intestine and the bloodstream and if they modified the composition and/or the function of the intestinal microbiota since we know that these parameters are also impaired in obese subjects or type 2 diabetics.

Impact of the intestinal microbiota

The authors first determined if there was a correlation between the exposure to air pollutants and the composition of the intestinal microbiota of the 43 volunteers. They then investigated if specific bacteria could be associated with type 2 diabetes risk factors (fasting blood sugar and insulin levels, insulin resistance...). By analyzing the intestinal flora of teenagers, the authors showed that an increased exposure to air pollution was associated to the same microbiota imbalance (dysbiosis) than that observed in cases of obesity, metabolic disorders, gut inflammation and type 2 diabetes. The study also demonstrated that the link between exposure to traffic-related air pollution and fasting blood sugar level could partly be explained by the proportion of these bacteria in the microbiota, independently of the body mass index (BMI).

Adverse health effects

This study still requires further investigation, but it already definitely confirms that, in humans, exposure to specific environmental factors impacts the proportion of certain intestinal bacteria. It also proves that the impact of air pollution on the intestinal bacterial ecosystem might have detrimental effects on the proper metabolic functioning such as altered immune system and contribution to obesity, insulin resistance and onset of chronic inflammatory bowel diseases (CIBD) like Crohn’s disease.

 

Sources:

Alderete T., Jones R., Chen Z. et al., Exposure to traffic-related air pollution and the composition of the gut microbiota in overweight and obese adolescents. Environmental Research 161 (2018) 472–478