There were a combined 92,383 participants in the study. The participant pool was comprised of 65% women with a mean age of 56 years. The researchers conducted a 28-year follow-up.

During the study period, there were 37,649 total deaths and 4,751 dementia-related deaths.

At the start of the study, the mean olive oil consumption was 1.3 grams/day.

Compared to those who never consumed olive oil or did so less than once a month, participants with higher olive oil consumption (greater than 7 grams/day) at the start of the study:

• Had higher caloric intake but not a higher BMI
• Had better quality diet
• Had higher alcohol consumption
• Were more physically active
• Were less likely to smoke

Overall, the researchers found that having at least 7 grams of olive oil every day was associated with a 28% lower risk of dementia-related death.

“This study is interesting and makes sense to me because we have a lot of research on monounsaturated fats and brain and cognitive health,” Caroline Thomason, RD, CDCES, a dietitian based in Washington, D.C. who was not involved in the study, told Medical News Today. “There seems to be a positive correlation between eating heart-healthy fats like olive oil and improved brain health.”

The scientists looked at substitutions for olive oil and found that:

• Substituting 5 grams/day of margarine and mayonnaise with the equivalent amount of olive oil was associated with an 8% to 14% lower risk of dementia-related deaths.
• Substitutions of other vegetable oils or for butter did not provide a significant reduction in risk.

The researchers also reported that diet quality did not influence the effectiveness of olive oil consumption.

The researchers concluded that, in US adults, higher olive oil intake was associated with a lower risk of dementia-related mortality, irrespective of diet quality.

Beyond heart health, the findings extend the current dietary recommendations of choosing olive and other vegetable oils for cognitive-related health.

“This is an observational study, so it doesn’t show a direct cause and effect,” said Anne Danahy, RDN, a registered dietitian nutritionist with a master’s in Food and Nutrition Science who was not involved in the study.

“Still, I’m not surprised to see that olive oil is associated with a lower risk of fatal dementia,” Danahy told Medical News Today. “Olive oil is rich in vitamin E and polyphenols — antioxidants that protect cells and blood vessels, including those in the brain. It also has anti-inflammatory properties. Inflammation can accelerate aging in the brain (and body) and it’s thought to be an underlying cause of dementia and cognitive decline.”

“Whether you prefer butter or olive oil, I would recommend a variety of cooking oils for your health,” Thomason said. “Both butter and olive oil can slow down your blood sugar response after your meal and each has its own unique health benefits. You don’t necessarily have to pick one over the other. In general, I recommend choosing unsaturated fats like olive oil most of the time and reaching for butter and saturated oils sometimes.”

“You can increase your daily olive oil consumption by swapping other types of cooking oils, like vegetable oil, for olive oil instead,” she added. “Make a salad dressing at home with olive oil, vinegar, spices, salt and pepper. Or drizzle olive oil over your protein source as part of your marinade before cooking or grilling.”

In addition to dementia, olive oil offers other benefits.

“A studyTrusted Source published in 2022 looked like it used the same cohort data, shows higher olive oil intake was associated with a lower risk of cardiovascular disease, cancer, neurodegenerative disease, and respiratory disease mortality,” Danahy said. “Other studies like this meta-analysis, also published in 2022, show a lower risk of diabetes, [cardiovascular disease], and all-cause mortality from higher olive oil intake.”

“There are so many studies that show a wide range of health benefits for olive oil, so I think everyone can benefit from eating it daily,” she added. “I always recommend using olive oil for most of your cooking. Butter has its place in certain recipes and applications, so it’s fine to use as needed. But try to make olive oil your go-to oil for everything else.”

“Taking olive oil supplements is not recommended as you can likely get all of the benefits from the food itself,” Thomason said. “The serving size and minimum effectiveness in a supplement are likely hard to find when you could cook more often with olive oil and reap the same benefits.”

Danahy agrees but notes that if you add supplements to an already unhealthy diet, there probably won’t be a benefit.

“They are safe, but it’s important to note that you won’t get any benefit if you add a supplement to an unhealthy diet. I’d prefer to see someone using olive oil as part of a healthy diet,” she said. “In fact, in this study, the lowest risk was from eating olive oil along with a healthy diet. If a person wants an extra boost, they can consider adding a supplement.”