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A diet that regularly includes olive oil could benefit brain health regardless of what else a person eats, according to a study that tracked the health and diets of more than 92,000 adults for 28 years. “Those who consumed more than half a tablespoon of olive oil per day had a 28 percent lower risk of dying from dementia compared to those who never or rarely consumed olive oil,” says Marta Guasch-Ferré, PhD, author of the study, which was published in JAMA Network Open in May 2024.
While previous research has shown that olive oil supports cardiovascular and brain health when consumed as part of a so-called Mediterranean diet, this new study suggests that olive oil can have such benefits even in the absence of a healthy diet. The study subjects ate the same amounts of red meat, soda, and margarine, and those who consumed the most olive oil ate only a bit more fruit, vegetables, and whole grains than subjects who consumed those foods the least.
“Typically, people who use olive oil for cooking or as a dressing have an overall better quality of diet,” says Dr. Guasch-Ferré, an adjunct associate professor of nutrition at the Harvard T.H. Chan School of Public Health. “But interestingly, we found the association [for lower risk of dementia-related death] regardless of this factor.”
The Mediterranean diet and a variation known as MIND (Mediterranean-DASH Intervention for Neurodegenerative Delay) both call for using olive oil instead of butter or vegetable oil. Adhering more closely to the MIND diet was associated with a lower risk of dementia, according to a meta-analysis of studies involving more than 8,000 people, published in JAMA Psychiatry in May 2023.
Olive oil contains compounds called polyphenols as well as monounsaturated fats, which are considered “healthy” fats. “Polyphenols clean up free radicals, molecules produced naturally that can damage cells and cause illness and aging,” says neurologist Domenico Praticò, MD, director of the Alzheimer’s Center at Temple University, who has studied olive oil and cognition. “Nerve cells communicate with each other at their synapses. When there are lots of free radicals around, they don’t communicate as effectively. With polyphenols, the connection is better.”
Despite the findings of the newer study, people who expect that adding a little olive oil to a diet of unhealthy foods will generate big results may be disappointed, says David Knopman, MD, FAAN, a clinical neurologist and Alzheimer’s researcher at Mayo Clinic in Rochester, MN. “The research was well done by a reputable group that looked at a long-running, observational study of nurses and doctors,” he says. “But it can’t be taken at face value for several reasons.”
Those reasons include that the study was observational (it followed people over time as they lived their lives), not a randomized, controlled trial, says Dr. Knopman. Furthermore, although the study authors adjusted the results to account for many differences between the groups—including smoking, alcohol use, marital status, high blood pressure, diabetes, high cholesterol, calorie intake, family history of dementia, and diet—the olive oil users may still have had healthy advantages that explain the results.
“Diet is strongly related to socioeconomic status, probably lifelong,” Dr. Knopman says, “and socioeconomic status has a huge impact on incidence of dementia.” Eating healthfully is also linked to preventing or treating diabetes, high blood pressure, and sleep problems—all of which may increase the risk for dementia, he says. In addition, the study began tracking diet when margarine and other foods contained more trans-fatty acids—processed fats associated with higher risk for dementia, cardiovascular disease, diabetes, and death. In 2018, the U.S. Food and Drug Administration ruled that trans fats could no longer be added to food. Small amounts still show up in some foods, notably in ultra-processed foods, says Laurel Cherian, MD, FAAN, associate professor of neurology at Rush University and a MIND diet researcher.
“Generally, we look for beneficial patterns. I would caution people against focusing on one component,” Dr. Cherian says. In fact, Dr. Guasch-Ferré and her colleagues noticed a bonus for the healthiest eaters in the study: Those who scored highest on a healthy-eating scale and consumed the most olive oil had a 32 percent lower risk for dementia-related death than those who scored lowest and consumed the smallest amount of olive oil. “Combining a higher-quality diet with higher olive oil intake may confer enhanced benefits,” the authors wrote.
The MIND and Mediterranean diets emphasize whole grains, leafy greens, nuts, berries, beans, and lean protein such as fish and poultry (instead of red meat). They also recommend avoiding or minimizing processed foods and using olive oil rather than butter or margarine in cooking. You also can use it on your morning toast and on bread at lunch and dinner, says Dr. Praticò.
Read More: Affordable Ways to Follow a Mediterranean-Style Diet
Another way to consume olive oil is in salad dressing or marinade: Whisk it with balsamic vinegar or lemon juice, minced garlic, fresh or dried herbs (such as parsley, oregano, or thyme), and salt and pepper to taste. Use on salad or when grilling chicken and fish.
Olive oil has 120 calories per tablespoon, which may be a concern for some people. “Just because the data suggest it’s healthy doesn’t mean you should go overboard,” says Dr. Cherian. Two tablespoons of olive oil is the recommended maximum per day.
In the supermarket, look for cold-pressed, extra-virgin olive oil, says Dr. Praticò. “Olive oil producers press olives several times and can use heat in processing. Extra-virgin olive oil is the first press, so it contains more polyphenols,” he explains. Read the fine print on the label since some olive oils are blends with other oils.
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