Olive oil consumption may curb dementia-related death risk: Harvard study

Between May 2022 and July 2023, researchers from the Harvard T.H.Chan School of Public Health analyzed data from 92,383 women and men who participated in the Nurses’ Health Study (NHS) and Health Professionals Follow-Up Study (HPFS), both conducted from 1990 to 2018. Subjects (65.6% women) had a mean age of 56 years and were cancer- and cardiovascular disease-free at enrollment.

Over the 28-year period, there were 4,751 dementia-related deaths as established by death records. Olive oil intake was assessed every four years using a food frequency questionnaire, and diet quality was based on the Alternative Healthy Eating Index and Mediterranean Diet score.

“In two large U.S. prospective cohorts of men and women, we found that participants who consumed more than 7 g/d of olive oil had 28% lower risk of dying from dementia compared with participants who never or rarely consumed olive oil,” the researchers wrote in the journal Jama Open Network.​ “This association remained significant after adjustment for diet quality scores including adherence to the Mediterranean diet.”

The study also estimated the difference in risk when other dietary fats like mayonnaise and butter were substituted with an equivalent amount of olive oil.

Olive oil and U.S. dementia mortality rates 

Most studies to date have explored the association between olive oil consumption and cognition in Mediterranean countries. Studying populations in the U.S.—where olive oil consumption has traditionally been lower and where age-standardized dementia mortality rates are on the rise—could offer unique insights, according to the Harvard researchers.