May 7, 2024 – It’s rich and fruity, makes a mean salad dressing and, new research suggests, could possibly reduce your risk of dying from dementia-related causes.
The benefit of consuming a lot of olive oil comes regardless of the overall quality of your diet, the study of more than 92,000 people found. The results showed that consuming at least 7 grams of olive oil a day — about half a tablespoon — was linked to a 28% lower risk for dementia-related death.
Replacing one teaspoon of margarine and mayonnaise with the equivalent amount of olive oil was tied to an 8%-14% lower risk for dementia-related death.
"Opting for olive oil, a natural product, instead of more processed fats such as margarine and mayonnaise, is a safe choice and may reduce risk of fatal dementia," lead investigator Anne-Julie Tessier, PhD, a registered dietician and research associate in the Department of Nutrition, at Harvard’s T.H. Chan School of Public Health, said.
She added, however, that more studies are need to confirm the connection.
The study was published online Monday in JAMA Network Open.
A Spoonful of Olive Oil
A growing body of evidence has shown a link between the Mediterranean diet and better cognitive function and lower risk for cardiovascular disease). But its association with dementia mortality was unknown.
Investigators studied data on over 92,000 participants who were free of cardiovascular disease and cancer at the beginning of the study.
The researchers also evaluated the connection between diet quality and olive oil consumption with the risk for dementia-related death. And they estimated the difference in the risk for dementia-related death when other dietary fats were substituted with an equivalent amount of olive oil.
There were 4,751 dementia-related deaths during the 28-year follow-up period. People with two copies of a known risk factor for Alzheimer's disease had a fivefold to nine fold greater likelihood of dementia-related death.
No Link With Diet Quality
"Typically, people who use olive oil for cooking or as a dressing have an overall better quality of their diet, but interestingly, we found the association between more olive oil and reduced risk of dementia-related death to be regardless of this factor," Tessier said.
Replacing 5 grams per day of margarine and mayonnaise with the equivalent amount of olive oil was linked to an 8%-14% lower risk for dementia mortality. Substitutions for other vegetable oils or butter were not significant.
"Some antioxidant compounds in olive oil can cross the blood-brain barrier, potentially having a direct effect on the brain," Tessier said. "It is also possible that olive oil has an indirect effect on brain health by benefiting cardiovascular health."
The authors noted several potential limitations of their study, including that higher olive oil consumption could mean a person’s diet is already healthier and that they may be in a higher socioeconomic status, although the results remained consistent after accounting these factors, they said.
The study population included only health care professionals and was primarily non-Hispanic White people, which could limit how broadly the results apply.
Causality vs Connection
Commenting on the findings, Rebecca M. Edelmayer, PhD, senior director of scientific engagement for the Alzheimer's Association, cautioned that the study was designed to show a connection, not that olive oil causes directly a reduced risk of dementia-related death.
Moreover, people in the highest olive oil consumption group also had better diet quality, higher alcohol intake, were more physically active, and less likely to smoke, Edelmayer said.
"All of these factors may have an impact on risk of cognitive decline and dementia, separately from or in addition to olive oil consumption," said Edelmayer, who was not involved with the study.
