SAN DIEGO — Olive oil supplements produce cardiovascular effects that could protect healthy people from vascular endothelial dysfunction related to exposure to particulate matter in the air, a new study shows.
Endothelial dysfunction is a risk factor for cardiovascular events and progression of atherosclerosis.
"For people living in areas with pollution levels above the EPA standard, something very easy, like a dietary supplement, could offer some protection," said Haiyan Tong, MD, PhD, research biologist at the US Environmental Protection Agency (EPA).
She presented the research here at the American Thoracic Society 2014 International Conference.
Dr. Tong and her colleagues evaluated how protective olive oil and fish oil are against the reduction in flow-mediated dilation of the brachial artery that results from exposure to concentrated ambient particulate matter.
The researchers recruited 42 healthy men and women 50 to 72 years of age (mean, 58 years) with no evidence of cardiovascular disease.
After the subjects underwent 2 weeks of dietary restriction, they were randomized to receive supplemental olive oil 3 g/day or fish oil 3 g/day or no supplement (control group) for 4 weeks.
Subjects were then challenged with a 2-hour exposure to filtered air to get baseline measurements. The next day, they were challenged with fine to ultrafine concentrated ambient particulate (mean concentration, 253 µg/m³) in a condition-controlled exposure chamber.
Sonographic measurement of flow-mediated dilation before, immediately after, and 20 hours after the exposures was used to evaluate endothelial function. Blood markers of vasoconstriction and fibrinolysis were analyzed at the same time points.
Immediately after exposure to the particulate matter, reductions in flow-mediated dilation were significant in the control and fish oil groups, but not in the olive oil group.
In the olive oil group, tissue plasminogen activator levels increased 11.6% immediately after particulate exposure; this effect persisted for at least 20 hours.
In addition, there was a decrease of 11.6% in D-dimer at 20 hours in the olive oil group. In the control group, there was an increase of 20.5% in endothelin-1 at 20 hours.
"If this study can be replicated in a large group of people, I think the outcome might apply to the general public, Dr. Tong said. She acknowledged that the current results do not support a general recommendation for olive oil supplementation.
The fact that this study focused on people 50 to 72 years of age is both a strength and a weakness, said session moderator Christopher Carlsten, MD, associate professor of medicine at the University of British Columbia in Vancouver, Canada.
"It's an important caveat. It's good in that these might be the most vulnerable individuals, and they are often not studied; most studies focus on younger populations. I credit the researchers for doing that," Dr. Carlsten told Medscape Medical News. "But it does limit the generalizability to that older age group."
The inclusion of multiple end points is a strength of the study. Results were fairly consistent across the different measures. "They had similar results where olive oil tended to have a protective effect. That's attractive," he said.
It remains to be seen whether the protective effects seen in healthy subjects will be reproduced in subjects with cardiovascular disease, who could most stand to benefit from a supplement. It is often assumed that people who are ill are likely to get stronger benefits from an intervention, but that might not always be the case, said Dr. Carlsten.
Dr. Tong and Dr. Carlsten have disclosed no relevant financial relationships.
American Thoracic Society (ATS) 2014 International Conference: Abstract 55100. Presented May 19, 2014.
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Cite this: Olive Oil Might Have Protective Effect Against Air Pollution - Medscape - May 22, 2014.