Olive oil has been a staple of Mediterranean kitchens for thousands of years, and it's long had a reputation as one of the healthier fats. In recent years, researchers have started asking a more specific question: could it also be good for the brain?
In 2024, a large study from Harvard added to that conversation. It found that people who used a small amount of olive oil every day were less likely to die from dementia-related causes.
This article explains what the study found, what it can and can't tell us, how olive oil fits into a brain-healthy diet, and simple ways to use more of it.
What the Harvard study found
The study, published in JAMA Network Open in May 2024, followed 92,383 American adults for 28 years. The participants were part of two long-running studies of nurses and other health professionals. Every four years, they filled in detailed questionnaires about what they ate, including how much olive oil they used.
The researchers found that people who consumed more than 7 grams of olive oil a day had a 28 percent lower risk of dementia-related death, compared with people who never or rarely used it. According to the Harvard T.H. Chan School of Public Health, the link held regardless of genetic risk and overall diet quality.
Seven grams is a small amount, about half a tablespoon. That's roughly the amount you might drizzle over a salad or use to cook vegetables.
The team also looked at swaps. Replacing about a teaspoon a day of margarine or mayonnaise with olive oil was linked to an 8 to 14 percent lower risk of dementia-related death, according to Medscape's report on the study. Swapping olive oil for butter or other vegetable oils didn't show a significant difference.
What the study can't tell us
These results are encouraging, but it's important to read them carefully.
It shows a link, not proof. This was an observational study. It found that people who used more olive oil tended to have a lower risk of dementia-related death. It can't prove that olive oil caused that lower risk. The lead researcher, Anne-Julie Tessier, has said that intervention studies are needed to confirm cause and effect and the best amount to eat.
It measured death, not diagnosis. The study looked at deaths linked to dementia, not whether people developed dementia in the first place.
The participants weren't typical. They were nurses and other health professionals, who may eat and live differently from the wider population, so the results may not apply equally to everyone.
The results differed by sex. The link was clear in women but not statistically significant in men.
So olive oil isn't a proven way to prevent dementia. But as a simple, low-risk swap within a healthy diet, it's a reasonable choice for most people.
Why olive oil might help the brain
Researchers have a few ideas about why olive oil might be linked to better brain health.
Extra virgin olive oil is rich in monounsaturated fats and contains natural compounds called polyphenols, which have antioxidant and anti-inflammatory effects. Tessier has said these compounds may play a protective role for the brain.
Olive oil also supports heart and blood vessel health. Because the brain depends on a healthy blood supply, what's good for the heart is often good for the brain too. High blood pressure, high LDL cholesterol and diabetes are all risk factors for dementia, as our guide to preventing or delaying dementia explains.
Olive oil and the bigger picture of diet
Olive oil is a central part of the Mediterranean diet and the MIND diet, which combines Mediterranean and DASH eating patterns. Both are rich in vegetables, fruit, whole grains, beans, nuts and fish, with olive oil as the main fat.
Observational studies have linked these eating patterns to better brain health. But trials have produced more mixed results. A three-year trial of the MIND diet, published in the New England Journal of Medicine in 2023, found that cognition improved in both the MIND diet group and a comparison group eating a healthier diet with fewer calories. The difference between the two groups wasn't statistically significant.
The researchers suggested that the trial may have been too short, or that both groups benefited from eating better and losing weight. That's a useful reminder: no single food or diet is a magic answer, but overall healthy eating seems to matter. Our article on whether diet can prevent dementia looks at this in more detail.
Easy ways to use more olive oil
You don't need to change everything to include a little more olive oil. A few simple ideas:
Dress salads and vegetables. Mix olive oil with lemon juice or vinegar for a quick dressing.
Cook with it. Use olive oil for roasting vegetables, sautéing, or cooking eggs.
Swap spreads. Dip bread in olive oil instead of spreading margarine.
Replace mayonnaise. Use olive oil and lemon instead of mayonnaise in potato or tuna salad.
Finish a dish. Drizzle a little over soup, beans or grilled fish.
Extra virgin olive oil contains the most polyphenols. Store it in a cool, dark place and use it within a few months of opening.
Olive oil is high in calories, so the goal is to use it instead of other fats rather than adding lots extra. If you have health conditions or follow a special diet, check with a doctor or dietitian.
For more meal ideas, see our guide to food that feeds your brain.
Other ways to look after your brain
Diet is one part of brain health. The strongest evidence points to a combination of healthy habits:
Keep moving. Even a little activity every day helps. Our article on why moving a little every day helps your body and brain explains why.
Stay socially connected. Regular contact with others supports mental health and brain health.
Keep learning. Our article on why it's never too late to learn something new has ideas.
Look after your heart. Keep blood pressure, cholesterol and blood sugar in check.
Protect your hearing and eyesight. Get them checked and treated if needed.
Healthy habits are easier to keep when they're part of the daily routine. Elli Cares helps older adults with gentle reminders for meals, drinks, medications and activities, plus a simple daily wellbeing check-in. Family members in the care circle can see how the day is going and offer encouragement from anywhere. See how Elli supports seniors and families.
If you're worried about memory
Eating well is worth doing, but it isn't a substitute for checking out changes in memory or thinking. If you've noticed changes in yourself or someone you love, talk to a doctor. Our guide to what a memory assessment is like explains what to expect.
A simple, sensible swap
The evidence on olive oil and dementia is promising but not proven. What we can say is that swapping processed fats like margarine and mayonnaise for olive oil is an easy, low-risk change that fits well with a healthy, Mediterranean-style diet. Half a tablespoon a day is a small step, and it might just be a step in the right direction.
