● Effect of extra-virgin olive oil to protect from dementia

Extra-virgin olive oil (EVOO) contains various phenolic compounds and is known to contain considerable amounts of tyrosol and hydroxytyrosol. There is a suggestion that people who regularly take EVOO as food have lower risk of dementia. Is this true?

Here we introduce a study conducted in Spain, which verifies this view. In this study, 295 participants (mean age: 67 years old) were randomly allocated to 3 groups. They were told to take 1) Mediterranean diet (MedDiet) + EVOO (1L/week), 2) MedDiet + nuts (30g/day), or 3) low-fat control diet, and were observed for six and half years. Participants in group 1 had better cognitive performance across memory and fluency tasks in various cognitive tests in comparison to those in group 3. However, participants in group 2 did not differ from group 3. Further, participants in group 1 showed better cognitive performance than those in group 2.

Interestingly, at the end of follow-up, participants in group 1 had significantly less MCI (7%), compared with those in group 3 (19%), but there was no difference in the percentage of MCI between participants in group 2 (12%) and controls.

This study indicates that adherence to EVOO-rich MedDiet can inhibit the occurrence of MCI. On the other hand, nuts-rich MedDiet does not appear to have such effect. Thus, MedDiet itself is not sufficient to prevent MCI, and EVOO seems to contain important protective factors. One litter of EVOO contains approximately 40 mg of tyrosol plus hydroxytyrosol, and such small amounts may have a protective effect.

This study implies that tyrosol is beneficial for the prevention of dementia. It is hoped that clinical studies will be conducted to test such effect of tyrosol instead of EVOO.