People who consume higher amounts of olive oil are less likely to die with dementia compared with those whose intake is minimal, as shown in a study.
In two large prospective cohorts of men and women in the US, consumption of at least 7 g/d of olive oil was associated with a 28-percent lower risk of dementia-related mortality compared with nonconsumption or consumption frequency of less than once a month (adjusted pooled hazard ratio [HR], 0.72, 95 percent confidence interval [CI], 0.64–0.81; p<0.001). [JAMA Netw Open 2024;7:e2410021]
The association remained significant after further adjustment for APOE ε4 allele and diet quality scores including adherence to the Mediterranean diet, the investigators noted.
Each 5-g increase in olive oil intake corresponded to a 9-percent reduction in the risk (adjusted pooled HR, 0.91, 95 percent CI, 0.87–0.94; p<0.001). This held true for women (HR, 0.88, 95 percent CI, 0.84–0.93) but not men (HR, 0.96, 95 percent CI, 0.88–1.04).
In modeled substitution analyses, replacing 5 g/d of margarine and mayonnaise with the equivalent amount of olive oil reduced the risk of dementia-related mortality by between 8 percent (95 percent CI, 4–12) and 14 percent (95 percent CI, 7–20). This was not seen for butter and other vegetable oils.
“Substituting olive oil intake for margarine and mayonnaise … may [then] be a potential strategy to improve longevity free of dementia,” the investigators said. “These findings extend the current dietary recommendations of choosing olive oil and other vegetable oils in the context of cognitive health and related mortality.”
How olive oil consumption may lower dementia-related mortality may be attributed to its positive effect on vascular health. Phenolic compounds in olive oil, particularly extra-virgin olive oil, have been shown to attenuate inflammation and oxidative stress, as well as restore blood–brain barrier function, “thereby reducing brain amyloid-β and tau-related pathologies and improving cognitive function,” the investigators pointed out. [Lancet 2020;396:413-446; Aging Cell 2020;19:e13076; J Alzheimers Dis 2020;78:801-817; Nutrients 2022;14:5102]
A total of 92,383 adults (mean age 56.4 years, 65.6 percent women) participated in the study, with 4,751 dementia-related deaths documented over 28 years of follow-up. Individuals who were homozygous for the APOE ε4 allele were 5.5 to 9.4 times more likely to die with dementia compared with noncarriers.
The mean olive oil intake was 1.3 g/d. Participants with the highest versus lowest olive oil intake at baseline had an overall higher caloric intake but not a higher body mass index, had better diet quality, had higher alcohol intake, were more physically active, and were less likely to smoke.
The study had several limitations, including the inclusion of mostly non-Hispanic White participants and the inability to differentiate among various types of olive oil that differ in their polyphenols and other nonlipid bioactive compounds content.