More Olive Oil May Ward Off Stroke

A French study, published in the journal Neurology, has renewed interest in the health properties of olive oil, one of the chief components of the Mediterranean diet.  Stroke-free participants in the Three-City Study who were over 65 provided information on their diets and other lifestyle factors; if they reported using olive oil for both cooking and as a dressing they were considered to be “intensive users”.  They were followed for 5¼ years, and cases of stroke were analyzed for an association with olive oil consumption or plasma oleic acid level.

There were more than 7,600 subjects in the main sample (oil consumption) and over 1,200 subjects in the oleic acid sample.  (In France, 98% of the olive oil sold is extra virgin olive oil.)  At baseline, 23% of subjects reported not using olive oil, 40% used it moderately (for cooking or as a dressing), and 38% were intensive users.  A total of 148 confirmed strokes occurred during the follow-up period.

Higher use of olive oil was associated with a lower stroke incidence; the stroke rate was 0.3% per year for intensive users, 0.4% per year for moderate users, and 0.3% per year for non-users.  After adjusting for differences in diet (fish, fruit, vegetables, and other types of oils and fats), physical activity, body mass index, and known stroke risk factors, the risk for stroke in intense users was 41% lower than that in non-users.

In the sample of those who had oleic acid levels measured as a marker for olive oil intake, higher plasma oleic acid was associated with a lower stroke incidence.  The one-third of participants (tertile) with the highest oleic acid levels were 73% less likely to have a stroke than the tertile with the lowest levels.  

The usual caveats to this type of study apply.  While the association shown is plausible – beneficial effects of olive oil have been reported in diabetes, high blood pressure, obesity, and coronary heart disease – it remains an observational study, and, as my readers know by now, cannot demonstrate a cause-and-effect.  For that, a prospective study is needed, that randomly allocates volunteers to high or low olive oil intake, counting the stroke rate in both groups over a number of years.  “Good luck with that”, as they say!  In the meantime, remember the healthy Mediterranean diet contains other good things – fruit, vegetables, whole grains, fish, and red wine.