Study: Adding More Olive Oil to Your Diet May Help Reduce the Risk of Dying From Dementia

Replacing some fats like margarine or mayonnaise with olive oil in your diet could help reduce the risk of dying from dementia—a particularly important finding as many countries face rising rates of Alzheimer’s disease and related dementias.

The claim comes from a new study presented Monday at NUTRITION 2023, the annual meeting of the American Society of Nutrition. It’s the first study to investigate the relationship between diet and dementia-related death.

“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,” presenting study author Anne-Julie Tessier, RD, PhD, a postdoctoral fellow at the Harvard T.H. Chan School of Public Health, said in a news release. “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.”

Dementia is not a specific condition but an umbrella term for a range of conditions that involve losing the ability to think and remember enough to interfere with daily life and activities. Alzheimer’s disease, which affects more than 6 million Americans, is the most common form of dementia. It’s also considered fatal because it has no cure.

Olive Oil May Be Beneficial for Brain Health

For the study, which has not yet been peer-reviewed or published in a scientific journal, scientists analyzed data from more than 90,000 Americans over the course of three decades—60,582 participants were women; 31,801 were men. Over the course of the study, 4,749 participants died from dementia.

Researchers found that participants who consumed more than half a tablespoon of olive oil each day had a 28% lower risk of dying from dementia, compared to those who never or rarely consumed olive oil.

Further, replacing 5 grams or about one teaspoon of margarine or mayonnaise a day with olive oil was associated with an 8–14% lower risk of fatal dementia. This was independent of overall diet quality, researchers said.

It’s also important to note that the individuals who died of dementia were more likely to be APOe4 carriers, a gene that increases the risk of Alzheimer’s disease and causes their bodies to make more cholesterol. Results were still consistent after adjusting for APOe4.

Though the research is observational and doesn’t prove that olive oil causes a reduced risk of fatal dementia, it does suggest that olive oil may have properties that are beneficial for brain health in addition to its heart health benefits.

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

Other Health Benefits of Olive Oil

The Dietary Guidelines for Americans already recommend limiting saturated fats and replacing them with unsaturated fats like olive oil to help lower “bad” LDL cholesterol in the blood and reduce the risk of cardiovascular disease.

A 2021 study published in the Journal of the American College of Cardiology found that the same olive oil measurement used in the new study—more than half a tablespoon of olive oil a day—was associated with a 14% lower risk of heart disease, compared to no olive oil consumption.

Olive oil has also been shown to help reduce inflammation and lessen the risk of type 2 diabetes. Replacing other fats like mayonnaise, butter, and margarine with olive oil has been associated with an 8–34% lower risk of death from all causes—including cancer-related mortality, neurodegenerative disease-related mortality, and respiratory disease-related mortality—as well.

While the new study has promising results and supports current research for the addition of olive oil as part of a healthy diet, more research needs to be done on olive oil’s impact on brain health and dementia-related death, and potentially determine optimal olive oil measurements.

Overall, the new research is in line with current dietary recommendations and adds even more evidence for using olive oil in place of other less-healthy fats like mayonnaise and margarine. It also offers hope that adopting healthy eating patterns that incorporate olive oil can help to prevent or slow down the progression of dementia.