MONDAY, May 21, 2018 (HealthDay News) -- The Mediterranean diet has long been lauded as a heart-healthy eating plan that can add years to your life.
Now, a new study suggests the diet could help protect against the harmful effects of air pollution and reduce the risk of death due to heart attack, stroke and other causes.
The Mediterranean diet emphasizes fruits, vegetables, whole grains, legumes, olive oil and lean protein, and limits red meat and processed foods. It's rich in antioxidants that neutralize free radicals that damage tissues and cells, the researchers explained.
"Previous studies have shown that dietary changes -- particularly the addition of antioxidants -- can blunt the adverse effects of exposure to high levels of air pollution over short time periods," said Chris Lim, a doctoral student at the NYU School of Medicine in New York City.
"What we did not know was whether diet can influence the association between long-term air pollution exposure and health effects," Lim added in a news release from the American Thoracic Society.
For the study, the researchers analyzed data from the NIH-AARP (U.S. National Institutes of Health/American Association of Retired Persons) Diet and Health Study, which followed nearly 549,000 older people from six states for a period of 17 years. During this time, about 127,000 of the study participants died.
The researchers divided the people into five groups based on how closely they followed the Mediterranean diet. Using Census data, the investigators also estimated the participants' exposure to certain air pollutants, including fine-particulate matter, nitrogen dioxide and ozone.
The study found that deaths due to heart disease rose by 17 percent for every 10 micrograms per cubic meter increase in long-term average fine-particulate matter exposure in those least compliant with the Mediterranean diet. By comparison, heart disease deaths only increased 5 percent among those who most closely followed this eating plan.
Deaths from all causes rose by 5 percent for every 10 parts per billion increase in long-term average nitrogen dioxide exposure among those who strayed the farthest from the Mediterranean diet. This compared to just 2 percent among those who most closely adhered to the eating regimen.
The one thing the diet didn't protect against was ozone, the researchers said.
"Given the benefits we found of a diet high in antioxidants, 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," said the study's senior author, George Thurston. He directs the NYU School of Medicine's Program in Exposure Assessment and Human Health Effects.
"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," he said.
It should be noted that the study didn't prove that the Mediterranean diet protects against air pollution, just that there was an association.
Still, the researchers said adhering to the diet could protect a significant number of Americans from the harmful effects of these air pollutants.
The study findings are scheduled for presentation Monday at the annual meeting of the American Thoracic Society, in San Diego. Research presented at meetings should be viewed as preliminary until published in a peer-reviewed journal.
The University of Minnesota has more on the Mediterranean diet.