Frequent exposure to diesel engine exhaust increased indicators of metabolic diseases in mice.
Non-caloric influences such as diesel exhaust pollution can impact body fat.
Fatty tissue significantly changes upon exposure to diesel exhaust pollution, leading to growth of fat cells.
Amid a much-of-the-world weight crisis and the health problems that it brings, a new study is shining light on a perhaps unexpected factor that can contribute to diabetes, obesity and heart disease: Diesel exhaust and the small particulate pollution it creates.
A poor diet and lack of exercise are known factors in metabolic diseases. But a study by researchers at Brigham Young University showed that frequent exposure to the exhaust from diesel engines boosted the amount of fat, fat cell size, insulin resistance and inflammation in mice. In humans, those factors are linked to various bad health outcomes, including diabetes, obesity and heart disease.
“Two items have become increasingly clear to us: There are non-caloric influences on body fat and inhaled pollution is one of them,” study senior author Benjamin Bikman, professor of cell biology, said in a written statement on the study, which was published in the International Journal of Molecular Sciences.
The team of researchers, which included three professors and eight BYU students, set out to determine what happens to fat cells due to diesel exhaust — a quest driven by the observation that in much of the world, both pollution and obesity are on the rise. They used a nose-only tool to deliver diesel exhaust to the mice for a half-hour daily for 30 days, Juan Arroyo, a professor of cell biology and physiology, told Deseret News. The “nose-only” part was important for measuring pollution exposure, as levels go up and down as animals groom. It allowed for a controlled dose similar to human exposure in high-pollution areas.
Breathing consistent bad air
In the study, one group of mice breathed room air, while the others also breathed the diesel-laden air. Then the rodents’ adipose or fatty tissue was analyzed, said Paul Reynolds, a professor who also specializes in cell biology and physiology.
Fatty tissue is changed significantly by diesel exhaust pollution, the researchers found. For one thing, fat cells grow, which is associated with insulin resistance and inflammation. Per the release, “While most people focus on fat mass, it’s actually the excessive enlargement of fat cells that lead to metabolic issues.” And other fat increased, including visceral fat and subcutaneous fat. The former surrounds organs, while the latter is just under the skin.
The systemic inflammation created by regular exposure to exhaust pollution has been tied to heart disease, Type 2 diabetes and autoimmune disorders, the researchers said.
Just controlling diet is likely not enough to improve metabolic health completely. Arroyo said that reducing exposure to small particulate pollution is also very important and that exercise and calorie counting alone won’t take care of the issue.
“Basically, what we’re trying to show is there’s potential influences that affect metabolic status and adipose tissue,” he said. “There’s tons of ways that focus on dietary adjustment for metabolic outcomes, but this gave us another avenue to help in getting a better metabolic outcome outside of diet.”
He noted that the lungs are important for more than just breathing and what happens to them can have far-reaching health implications.