Ozone pollution alters the gut microbiota
For the first time a study has shown that exposure to air pollution–and particularly ozone pollution–alters the composition and function of the intestinal flora in humans.
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The fine particles and pollutants in the air we breathe not only poison our lungs, but apparently disrupt the intestinal microbiota also. The mechanisms involved remain unknown but according to a recent study involving one hundred young Californians exposed to certain air pollutants, science is beginning to hone in on the culprits.
Ozone has been singled out
After measuring the air quality around the volunteers’ homes and analyzing their gut microbiota, the researchers found that nitrogen oxides (nitrogen monoxide and dioxide from road traffic or energy generation) disrupt the intestinal flora. However, it appears that the most significant damage is caused by ozone, a pollutant formed through reactions between various other pollutants. Ozone reduces diversity within the gut microbiota, thereby disrupting its functioning. The study found that almost 130 bacterial species are affected by ozone, with only 9 influenced by nitrogen oxides.
High ozone exposure is thought to impact important cellular mechanisms, such as cell growth, insulin secretion or fatty acid synthesis and degradation. Some of these processes may also affect the integrity of the intestinal barrier and the metabolism. The researchers suggest that, through their impact on the gut microbiota, air pollutants may lay the groundwork for metabolic disorders such as type 2 diabetes mellitus or obesity.
Fighting pollution to protect the microbiota
This hypothesis should be evaluated in future epidemiological studies and in studies on animals in order to identify the exact mechanisms whereby pollution impacts the intestinal flora and promotes the onset of diseases among humans. However, these preliminary results are a reminder that pollution is a major public health issue that urgently needs to be addressed.
Fouladi F, Bailey MJ, Patterson WB, et al. Air pollution exposure is associated with the gut microbiome as revealed by shotgun metagenomic sequencing. Environ Int. 2020 May;138:105604.