This study investigated whether high olive oil consumption and high plasma levels of oleic acid were associated with a lower occurrence of stroke in elderly people. The study included participants aged 65 years and older, with no history of stroke at baseline, from the multicenter prospective Three-City Study. These participants were followed-up for an average of 5.25 years with the focus being incidence of a first fatal or nonfatal ischemic or hemorrhagic stroke. The results suggested that high olive oil consumption and high plasma levels of oleic acid lowered the risk of stroke in the elderly people.
The incidence of cerebrovascular events or strokes in elderly people is on the rise. Studies have shown that olive oil has cardioprotective properties. Greater consumption of olive oil is associated with low risk of myocardial infarction. Mediterranean diet (with its high olive oil intake) is also associated with less risk of cardiovascular diseases and low blood pressure. It is also known that other factors like a well-balanced diet with good intake of fruits and vegetables, and low salt intake with regular exercise, reduce the risk of stroke. This study determines the association of high olive oil consumption with risk of stroke, independent of other dietary habits and risk factors.
- The study was conducted with two samples. The main sample had 7,625 participants, from whom data on olive oil intake were collected through face-to-face interview or through self-questionnaire. The use of olive oil use was classified into three categories – no use, moderate use (when the oil was used for cooking or dressing alone) and intensive use (used for cooking and dressing).
- The secondary sample had 1,245 participants. Fasting blood sample analyses for plasma fatty acids were performed on them and the percentage of oleic acid content among other fatty acids was determined in three tertiles (tertile is any of the two points that divide an ordered distribution into three parts, each containing a third of the population).
- Adjustments were done for sociodemographic and dietary variables, and other risk factors like alcohol use, smoking, antihypertensive therapy, diabetes and physical activity.
- Cox proportional hazard models were used to find out the hazard ratio (HR) and confidence intervals (CI) for stroke in the three types of olive oil users and in the three tertiles of oleic acid proportion.
- In the main sample, 148 strokes (115 ischemic, 28 hemorrhagic and 5 of undetermined cause) occurred. When compared with nonusers of olive oil, intensive users of olive oil had a 41 percent lower risk of experiencing stroke with a HR of 0.59 (95 percent CI: 0.37-0.94).
- In the secondary sample, 27 strokes (20 ischemic and 7 hemorrhagic) occurred. Participants with higher levels of oleic acid had a 73-75 percent reduction of stroke risk.
- In both the samples, the observed trend of low incidence of strokes was statistically significant for ischemic stroke.
Although this study was well designed with a large sample size and low attrition, it had some limitations. Plasma oleic acid could be derived from other dietary sources like butter and geese or duck fat; hence, its use as an indirect marker of olive oil intake is questionable. The diagnosis of stroke was based on self-reporting; there is a possibility of having missed out some strokes. The low number of cases for hemorrhagic stroke as compared to ischemic stroke limits the study power.
People who used olive oil intensively had less chance of having a stroke, as compared to those who never used olive oil. These results, therefore, suggest that olive oil plays a protective role and helps prevent stroke in elderly people. The ingredients of olive oil, including oleic acid and polyphenols, help in blood pressure reduction, lipid profile improvement, and improvement of oxidative vascular damage and endothelial function, thus helping stroke prevention. Along with the other important factors, high olive oil intake can also be suggested for elderly people, to prevent the occurrence of stroke.
For More Information:
Olive Oil Consumption, Plasma Oleic Acid, and Stroke Incidence: The Three-City Study
Publication Journal: Neurology, June 2011
By C. Samieri, PhD; C. Féart, PhD
From the Research Center INSERM, Bordeaux, France
*FYI Living Lab Reports Are Summaries of the Original Research.