Author Chris Lim, who presented the findings at the American Thoracic Society’s 2018 International Conference earlier last month, examined data from a cohort of nearly 550,000 people across the United States for a period of 17 years.
Given the benefits we found of a diet high in anti-oxidants, our results are consistent with the hypothesis that particle air pollution caused by fossil fuel combustion adversely affects health by inducing oxidative stress and inflammation.
Lim and his colleagues wanted to determine whether an antioxidant-rich MedDiet that eschews red meat and processed foods in favor of fruits, vegetables, legumes, whole grains, fish and olive oil impacts the correlation between prolonged exposure to ambient air pollution and cause-specific mortality.
“Air pollution is hypothesized to cause bad health effects through oxidative stress and inflammation,” explained Lim, “and the Mediterranean diet is really rich in foods that are anti-inflammatory and have antioxidants that might intervene through those avenues.”
The researchers first grouped participants based on how closely their eating habits aligned with the MedDiet at the outset of the trial before referencing census tract information to estimate participants’ long-term exposure to three specific types of air pollution: particulate matter (PM2.5), nitrous oxide (NO2) and ozone (O3).
The subsequent analysis focused on the statistically significant impact of the MedDiet on deaths from all causes, in addition to cardiovascular disease-related deaths and heart attacks.
When it came to deaths from all causes, the results revealed a 5‑percent increase for every 10 parts per billion (ppb) increase in NO2 exposure for those least adherent to the MedDiet, compared to 2 percent for the most adherent.
Results for cardiovascular disease were similar, with a 17-percent increase in deaths for every 10 micrograms per cubic meter increase in PM2.5 exposure for those least adherent to the diet, compared to 5 percent for the most adherent.
The trends for heart attack deaths were also aligned, with a 20-percent increase compared to 5 percent in terms of exposure to PM2.5 exposure and 12 percent compared to 4 percent for NO2. In fact, the only measurable outlier was O3 exposure, which results revealed was not correlated with a MedDiet.
“Given the benefits we found of a diet high in anti-oxidants, our results are consistent with the hypothesis that particle air pollution caused by fossil fuel combustion adversely affects health by inducing oxidative stress and inflammation,” explained George Thurston, senior study author and director of the Program in Exposure Assessment and Human Health Effects at the Department of Environmental Medicine. “On the other hand, the ozone effect was not significantly blunted by a Mediterranean diet, so ozone apparently affects cardiac health through a different mechanism.”
Two key caveats, however, were that the eating patterns of participants may have shifted over the course of the study, as well as the fact that the demographics (majority white, higher income) were not an accurate representation of the population at large.
However, as Lim noted to Olive Oil Times, the results are nonetheless interesting. “Our study draws on a very detailed and large cohort, uses latest air pollution prediction models and provides very novel results.”