The best kind of olive oil for brain health

We all got the message: olive oil is good for us. It reduces “bad cholesterol”, fights inflammation and protects against various chronic diseases, including certain cancers. More recently, however, there is growing evidence to suggest that its benefits extend beyond the body to the brain.

I wanted to know what that really meant. What aspects of my cognition might this influence? How did it go? I also had practical questions: did it really have to be extra-virgin (and therefore extremely expensive)? And how much should I consume to make a difference?

The answers are more promising – and less restrictive – than I expected. It turns out that olive oil may not be the only oil that has beneficial effects on brain health.

But first, the usual caveats. It is common knowledge that any nutritional research is difficult to carry out. Studies often require participants to keep a food diary, and I probably don’t need to tell you how easy it is to “remember” what we ate, or to discreetly eliminate the less virtuous bits. For this and other reasons, truly robust dietary studies are relatively rare.

However, trends may emerge. Observational studies can offer clues, especially when supported by experiments that probe the underlying biology. Put them together and we can paint a reasonably convincing picture of which foods do what for our health.

Olive oil has been a hot target lately. Much of the noise comes from its main role in the Mediterranean diet – the most attractive of all diets, in my opinion. Who can object to advice that encourages eating more tomatoes, bread, fresh fish and olive oil with a little red wine from time to time? Numerous studies have linked this way of eating to decreased rates of heart disease, type 2 diabetes, and, more recently, dementia.

At first glance, this seems to go against common dietary theories, because the Mediterranean diet is actually quite high in fat. But a closer look showed that the main source of fat comes from olive oil. This prompted scientists to wonder whether olive oil itself was doing the heavy lifting. “The Mediterranean diet is much more effective if it includes extra virgin olive oil,” said nutritionist Richard Hoffman of the University of Hertfordshire in the United Kingdom. New scientist in 2024.

One influential trial involved more than 7,000 people in Spain aged 55 to 80. One group was given a one-liter bottle of extra virgin olive oil each week and encouraged to consume about 4 to 5 tablespoons per day while following the Mediterranean diet. The second group ate the same way, but instead of adding olive oil, they supplemented their diet with nuts, while people in the third group were asked to reduce their intake of dietary fat.

Over five years, people in the olive oil group had significantly lower rates of heart disease and stroke. For every 10 grams of oil consumed per day – or just under a tablespoon – the risk of cardiovascular disease and mortality was reduced by 10 and 7 percent, respectively.

Most scientists are now reasonably confident that olive oil helps reduce inflammation and improves cardiovascular health. But what does this do for the brain?

To find out, a large study published in 2024 examined data from more than 92,000 adults whose olive oil consumption was assessed every four years over nearly three decades. The result was clear: those who consumed more olive oil were less likely to die from dementia.

While it’s reasonable to assume that people who consume larger amounts of olive oil may also lead generally healthier lives, researchers did their best to account for this, adjusting for factors such as body mass index, physical activity, smoking, socioeconomic status, and overall diet. The association between olive oil and a lower risk of dementia-related death persisted.

They also modeled what might happen if participants replaced other fats with olive oil. “Additional benefits are seen if butter and other animal fats are replaced with olive oil,” explains Marta Guasch-Ferré of Harvard University. Their substitution analysis showed that replacing one teaspoon of margarine or mayonnaise with the equivalent amount of olive oil was associated with an 8 to 14 percent lower risk of dying from dementia.

Olive oil appears to have a protective effect on the brain, but why? Polyphenols seem to play a major role. Olive oil contains the highest number of these bioactive compounds of any oil. In plants, polyphenols help protect against stress, pests and other trauma. In humans, they appear to do something similar: eliminate harmful molecules called free radicals, reduce inflammation, and prevent “bad” fats from oxidizing in the body, which can otherwise cause the formation of plaque that contributes to strokes.

Polyphenols are also beneficial to gut microbes, which feed on them, giving them the energy to grow and interact with our immune system, calming inflammation.

Inflammation drives many of our leading causes of death, such as heart disease, but it also contributes to dementia, with growing evidence suggesting that Alzheimer’s disease may be initially triggered by inflammation in distant organs like the skin, lungs or gut.

“Mechanistic evidence is accumulating to support the hypothesis that olive oil…reduces the underlying pathology of Alzheimer’s disease and other neurodegenerative diseases,” says Guasch-Ferré.

Which oil is best?

Not all olive oils are equal. Extra virgin olive oil is the “purest” or least processed. It is made by crushing the olive with the pit or pit, then extracting the oil using a centrifuge, preserving its polyphenols. Virgin olive oil is similar but has undergone a little more extensive processing, sometimes using chemicals or high temperatures. Then you have “common” or “standard” olive oil, which is further processed, removing many of its beneficial compounds.

So, does it really matter which one you buy? “We found that consumption of olive oil, regardless of type, is associated with a lower risk of death,” says Guasch-Ferré. “The combination of healthy unsaturated fats coupled with other bioactive compounds is what makes olive oil one of the healthiest vegetable oils.”

However, a recent study published in January explored this distinction in more detail, examining the effect of different olive oils on the microbiome and cognitive function of older adults. The results were striking.

The study evaluated 656 people aged 55 to 75 who were overweight and suffering from metabolic syndromes. Participants who consumed more virgin olive oil showed improvements in several cognitive domains, while those who consumed standard olive oil experienced more rapid cognitive decline, although both types of oil contained similar amounts of fat.

The differences were associated with changes in the microbiome. Consumption of virgin olive oil was associated with greater microbial diversity, whereas standard olive oil was associated with less diversity. The researchers also identified a particular group of bacteria, Adlercreutziawhich appears to mediate approximately 20 percent of the effect of virgin olive oil on cognition.

This is very early evidence and a small trial with only two years of follow-up, so we need to take it with a grain of salt. Nonetheless, it offers compelling insight into how diet, bacteria, and brain health may be linked.

So where does this leave us? Although it appears that standard olive oil may confer health benefits for cardiovascular disease thanks to its favorable fat profile, extra virgin olive oil adds something extra: a layer of helpful compounds such as polyphenols that may help protect the brain.

The good news (at least for your bank balance) is that olive oil may not be alone. Other vegetable oils, including canola, corn, and safflower, also contain beneficial fats and moderate levels of polyphenols. When Guasch-Ferré and colleagues replaced olive oil with these other vegetable oils in their hypothetical substitution model, they saw no increased benefits for brain health, suggesting that they also appeared to offer health benefits.

“Consuming other vegetable oils could also be a healthy alternative to animal fats, especially because they tend to be more affordable than olive oil,” she says, while cautioning that more evidence is needed to confirm these findings.

For now, the simplest advice is to opt for the highest quality extra virgin olive oil you can afford. Otherwise, replacing animal fats with other vegetable oils would likely be a step in the right direction for brain health. And if you want to be particularly thorough, you can even pay attention to the bottle it’s stored in: light reduces the amount of polyphenols over time, thus affecting subsequent health benefits, which is why darker bottles may be preferable.

I’m convinced enough to spend a few extra pounds on a bottle of quality extra virgin olive oil, not only for its superior taste, but also for its superior brain-stimulating abilities.