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A Daily Drizzle of Olive Oil May Lower Your Dementia Risk

A wooden spoon filled with olives and olive oil.
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A daily dash of olive oil could help ward off dementia, according to a new study.

After analyzing the health data of 92,383 healthcare professionals, researchers from Harvard University found that participants who regularly consumed olive oil were, on average, 28% less likely to die from dementia than their animal-fat-frying counterparts.

The results were published in JAMA Network Open.

A well-oiled brain

To assess how beneficial the Mediterranean diet could be for the aging brain, the research team first accessed data from two ongoing health studies: the Nurses’ Health Study (a UK cohort of female nurses; data taken between 1990 and 2018) and the Health Professionals Follow-Up Study (a US study of male healthcare professionals; data taken between 1990 and 2018).

As part of a dietary questionnaire, all participants stated their level of olive oil intake every four years. The number of dementia deaths (4,751) was ascertained from death certificates.

Participants who consumed at least 7 grams of olive oil a day had, on average, a 28% lower risk of dementia-related death than participants who rarely or didn’t consume olive oil.

This association remained significant after the data were adjusted to account for other dietary factors, including adherence to the Mediterranean diet.

Participants with the ε4 allele of the apolipoprotein E (APOE) gene – a genetic risk factor for dementia – were 59 times more likely than non-carriers to die from dementia, yet the apparent benefits of olive oil still remained after the researchers accounted for the factor.

The research group estimated that substituting 5 grams of margarine a day with olive oil would be associated with significantly lower dementia-related death risk. However, this benefit would not be expected if substituting butter and other vegetable oils.

Although the relationship between olive oil and fewer dementia deaths was only observed – not proven to be causational – the researchers say their findings provide evidence to support dietary advice for the use of olive oil and other vegetable oils as a potential strategy to maintain overall health and prevent dementia.

“Our study reinforces dietary guidelines recommending vegetable oils such as olive oil and suggests that these recommendations not only support heart health but potentially brain health, as well,” said Anne-Julie Tessier, a postdoctoral fellow at the Harvard T.H. Chan School of Public Health.

“Opting for olive oil, a natural product, instead of fats such as margarine and commercial mayonnaise is a safe choice and may reduce the risk of fatal dementia.”

Several previous studies, including randomized controlled trials, have concluded that a diet rich in olive oil can enhance cognitive functioning and reduce cognitive decline. While it can be difficult to parse out the benefits of olive oil from the benefits of a healthy diet, it’s widely accepted that the oil is at least a healthier alternative to animal-based fats.

“Some antioxidant compounds in olive oil can cross the blood-brain barrier, potentially having a direct effect on the brain,” added Tessier. “It is also possible that olive oil has an indirect effect on brain health by benefiting cardiovascular health.”

This article is a rework of a press release issued by the American Society for Nutrition. Material has been edited for length and content.

Reference: Tessier A, Cortese M, Yuan C, et al. Consumption of olive oil and diet quality and risk of dementia-related death. JAMA Netw Open. 2024;7(5):e2410021. doi: 10.1001/jamanetworkopen.2024.10021