High olive-oil consumption linked to lower stroke risk
Bordeaux, France - A diet rich in olive oil may reduce the risk of stroke in older adults, new research suggests [1].
In roughly 7600 elderly adults, higher olive-oil consumption at baseline was associated with a lower incidence of stroke over roughly the next five years, after researchers controlled for numerous confounding factors, including lifestyle and nutritional factors, stroke risk factors, and blood lipids.
Dr Cecilia Samieri (University of Bordeaux, France) and colleagues report their findings online June 15, 2011 inNeurology.
"The high prevalence of stroke in older subjects emphasizes the need for primary and secondary prevention in this age group," they conclude. "Showing a strong association between intensive olive-oil use and lower stroke incidence, our study suggests a novel approach of dietary recommendations to prevent stroke occurrence in elderly populations."
But the authors of a commentary caution against jumping to any conclusions, noting that the putative health benefits of olive oil and a Mediterranean-style diet are complex.
The Three-City Study
Samieri and colleagues examined the association between olive-oil intake and stroke incidence in 7625 people aged 65 and older from Bordeaux, Dijon, and Montpellier, France. They are enrolled in the ongoing, population-based FrenchThree-City Study, which is looking at vascular risk factors for dementia.
At baseline, 1738 (22.8%) subjects reported no olive-oil use, 3052 (40.0%) reported moderate olive-oil use, and 2835 (37.2%) reported intensive olive-oil use.
The authors note that moderate and intensive olive-oil users (relative to nonusers) were younger than nonusers and had lower values or frequencies for several stroke risk factors, weighed less, and had lower triglycerides and a lower total/HDL cholesterol ratio. They were also more apt to be regular exercisers and ate fish, fruits, and vegetables and omega-3 rich oils more often than nonusers.
Over a median of 5.25 years, 148 incident strokes were recorded (115 ischemic, 28 hemorrhagic, five undetermined).
After adjusting for sociodemographic and dietary variables, physical activity, body-mass index, and risk factors for stroke, the researchers observed a lower incidence of stroke with higher olive-oil use (p for trend=0.02). Compared with those who did not use olive oil, those with intensive use had a 41% lower risk of stroke. No other dietary variable was significantly associated with stroke incidence.
Multivariate association between olive-oil use and six-year incident stroke | Olive-oil use | Hazard ratio (95% CI)* | p |
| None | Ref | — |
| Moderate (with cooking or dressing) | 0.80 (0.53-1.20) | .28 |
| Intensive (both cooking and dressing) | 0.59 (0.37-0.94) | .03 |
*Fully-adjusted model
The researchers also examined the association between plasma oleic acid and stroke incidence in a subgroup of 1245 subjects. In this group, there were 27 incident strokes during a median follow-up of five years, including 20 ischemic and seven hemorrhagic strokes.
After adjustment for a wide variety of potentially confounding factors, compared with those in the first tertile of plasma oleic acid, those in the third tertile had a 73% reduction in stroke risk (HR 0.27, 95% CI 0.08-0.90, p=0.03).
However, in the fully-adjusted model utilizing "component analysis" of total saturated fatty acids, total omega-3 fatty acids, and other dietary factors, the intensity of the association between plasma oleic acid and stroke was reduced (HR 0.25, 95% CI 0.08-0.86; p=0.03).
One limitation of the study, Samieri and colleagues say, is not being able to distinguish between the different types of oil olive consumed. They also say the validity of plasma oleic acid as an indirect marker of olive-oil consumption remains to be evaluated.
Olive oil pertinent to neurologic disease, too?
In their commentary, Dr Nikolaos Scarmeas (Columbia University Medical Center, New York, NY) and Dr Luc Dauchet (Institut Pasteur de Lille, France) make the point that exploration of the relation of the Mediterranean-type diet with neurologic diseases has started "only very recently and has suggested potentially beneficial associations for Alzheimer's disease, mild cognitive impairment, cognitive decline, essential tremor, Parkinson disease, and stroke."
While the current study suggests a protective effect of olive oil in stroke, the authors caution against drawing any firm conclusions from this study until the observations "withstand the trial of randomized intervention."
They point out that covariate adjustment "can never be complete." In addition, other potentially beneficial effects of olive oil, not considered in the analyses, may be mediating the association.
They also note that olive oil is not consumed in isolation, but with a whole host of potentially healthy foods. "To add further to the complexity, the potentially beneficial biological elements of olive oil are not clear."
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