Thursday, March 10, 2016

Can Exposure to Air Pollution Make You Fat?

The air that makes you fat (David Robson, BBC Future, Feb. 1, 2016)

Also discussed here: Residential Proximity to Major Roadways and Prevalent Hypertension Among Postmenopausal Women: Results From the Women's Health Initiative San Diego Cohort (12 page pdf, J Am Heart Assoc., Oct 1, 2014)

Today we review research based on exposing mice to the various types of air pollution found in American cities. Results indicate their fat cells were 20% larger when exposed to high levels of air pollution after just 10 weeks because of less sensitivity to insulin which converts blood sugar into energy. This conclusion is similar to a study in Ontario where the risk of diabetes rose 11% for every 10 mico gram/m3 increase in particulate matter.

  pollution fat  

Key Quotes:

 “residential proximity to major roadways has been associated with increased prevalence of coronary heart disease, increased risk of acute myocardial infarction, increased risk of stroke mortality, increased risk of death following stroke and acute myocardial infarction, Increased evidence of coronary atherosclerosis, increased left ventricular mass index, narrower retinal arteriolar diameter, and reduced renal function” “living 100 m versus 1000 m from a major roadway was associated with a 9% (95% CI: 3, 16) higher prevalence of hypertension.”

 “After just 10 weeks, the effects were already visible. The mice exposed to the air pollution showed greater volumes of body fat, both around the belly and around the internal organs; at the microscopic level, the fat cells themselves were around 20% larger in the mice inhaling a fine mist of pollutants”

“they seemed to have become less sensitive to insulin, the hormone that signals to cells to convert blood sugar into energy: the first step towards diabetes.”

 “When we breathe in, the pollutants irritate the tiny, moist air sacs that normally allow the oxygen to pass into the blood stream. As a result, the lungs’ lining mounts a stress response, sending our nervous system into overdrive. This includes the release of hormones that reduce insulin’s potency and draws blood away from the insulin-sensitive muscle tissue, preventing the body from tightly controlling its blood sugar levels.”

“the medical records of 62,000 people in Ontario, Canada over a 14-year period… the risk of developing diabetes rose by about 11% for every 10 micrograms of fine particles in a cubic metre of air” “children born in the most polluted areas were 2.3 times more likely to be considered obese, compared to those living in cleaner neighbourhoods”  

babies of mothers living in polluted areas appear to put on weight more rapidly than those in cleaner areas

“whenever the city’s [Beijing’s] infamous smog descended, giveaway signs of developing problems like insulin resistance and hypertension peaked – providing more concrete evidence that the air quality was indeed driving changes to the metabolism.”

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