Since the coining of the term “French Paradox” in 1992, researchers have been examining various aspects of the so-called “Mediterranean diet” to discover why the people of southern Europe live longer, with fewer cases of heart disease, than Americans and Northern Europeans. A new study from Yale University School of Medicine has identified oleuropein, a component in olive oil, as a possible factor.
During the study, recently published in the journal European Society for Vascular Surgery, Yale researchers tested the effects of oleuropein, a polyphenol in olive oil, on smooth muscle cells (SMC), which make up the muscles in blood vessels that regulate blood pressure. The scientists harvested SMC from cows and allowed the cells to grow in the lab, regulating their development and adding doses of oleuropein.
Normally, vascular SMC controls blood flow by increasing blood pressure as the muscle contracts and decreasing it as the muscle relaxes. When SMC is damaged by high LDL cholesterols (the “bad” kind of cholesterol found in gooey brie, for example) the body sends a team of white blood cells to fight off the inflammation. But white blood cells end up causing even more damage by mixing with oxidized LDL and forming "foam cells." SMC proliferates to try to heal itself. The new SMC cells combine with the foam cells to form plaques on artery walls. Over time, that process leads to atherosclerosis, high blood pressure and heart disease.
The scientists found that the more oleuropein they added, the less SMC developed. Growth decreased by as much as 92 percent when the team administered a high dose of oleuropein. The team concluded that oleuropein in olive oil restricts SMC from proliferating and therefore could be protective against heart failure.
On a practical level, that means if you're relaxing on the coast of France with a piece of fish drowning in olive oil followed by a cheese plate, you are jumpstarting the plaque-making process. But at the point where SMC is supposed to grow and mix with the foam cells, the oleuropein is restricting growth, leading to reduced plaques and a healthier, more Mediterranean heart.
Research on the benefits of olive oil is gathering steam. Earlier studies also found that extra-virgin olive oil limited LDL oxidization in rabbits, decreasing plaque formation. And in a study recently published in Neurology, researchers noted a 41 percent reduced risk of stroke for older French adults who consumed olive oil regularly. Researchers followed more than 7,500 French subjects and found the top third of heaviest olive oil consumers enjoyed a 73 percent decreased risk compared to those in the bottom tier.
The oleuropein study was not on human cells, and one would need to drink an extraordinary amount of extra-virgin oil to reach the high levels used in the study—oil containing 2 kilograms of oleuropein as opposed to the standard .50 milligrams currently ingested daily by most Mediterraneans.
Despite the study's limitations, the Yale scientists hypothesize that olive oil consumption could have cumulative effects throughout one’s lifetime. "These in vitro studies are important because there are so many polyphenols [in olive oil]," Dr. Bauer Sumpio, chief of vascular surgery at Yale School of Medicine and the lead author on the study, told Wine Spectator. "If we can screen these polyphenols based on their distinct biologic properties we may be able to have focused human trials.” Could this eventually mean olive oil polyphenols in a pill? Perhaps, but for now, just consider replacing that butter dish with a dipping bowl. That is, if anyone is still eating bread.