A daily dose of one vegetable oil may lower risk of dying from dementia, research finds

By Kristen Rogers, CNN

(CNN) — Including olive oil in your regular diet offers several benefits — such as protecting heart health or cognitive function.

The Mediterranean staple might also reduce your risk of dying from dementia by 28% if you eat just a spoonful every day.

This new finding is according to research presented Monday in Boston at Nutrition 2023, the annual meeting of the American Society for Nutrition.

Whether olive oil is linked with risk of dementia-related death had never been studied until now, according to the authors.

“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,” said Anne-Julie Tessier, a coauthor of the research and postdoctoral fellow at the Harvard T.H. Chan School of Public Health, 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.”

Research participants included nearly 60,600 women who had participated in the Nurses’ Health Study from 1990 to 2018, and nearly 32,000 men who had been in the Health Professionals’ Follow-Up Study during the same time period. The former study investigated risk factors for major chronic diseases among women in North America, whereas the latter is looking into the same topics but for men.

The authors of the latest research assessed the diet of the participants — who were age 56 on average at the start of the study — every four years via a questionnaire. The team also reviewed diet quality using the Alternative Healthy Eating Index, which assigns ratings to foods and nutrients predictive of chronic disease. The higher people score on this index, the better.

Over a follow-up period of 28 years, regardless of diet quality, eating more than half a tablespoon of olive oil per day was associated with a 28% lower risk of dying from dementia, compared with participants who never or rarely consumed olive oil.

Additionally, replacing a daily teaspoon of mayonnaise or margarine with the same amount of olive oil was correlated with an 8% to 14% lower risk of dementia-related death, the authors found.

However, this research is early, so some experts uninvolved with it urge caution.

“These findings are simply being reported at a conference and have not undergone peer-review so there has been no examination of the study by independent experts,” said David Curtis, honorary professor at the UCL Genetics Institute at University College London, in a statement. “We do not know whether the results will end up being published in a journal. If the study does eventually result in a published paper, we do not know whether the published results will be the same as those now being presented.”

The 4,749 participants who died from dementia were more likely to have APOE e4 — the strongest known genetic risk factor for Alzheimer’s disease — according to analysis of DNA from participants’ blood or mouth cells. But having the gene doesn’t mean a person will certainly develop the disease, and the authors’ findings were still consistent after taking this factor into account, they said.

Regardless, “it is important to note that this is not causal, as the authors point out, only an association,” said registered dietitian Duane Mellor, a senior teaching fellow at Aston Medical School of Aston University in England. “More research is needed.”

Olive oil and dementia risk

The potential benefits of olive oil for brain health could be due to antioxidant compounds that can cross the blood-brain barrier, directly affecting the brain, Tessier said.

“It is also possible that olive oil has an indirect effect on brain health by benefiting cardiovascular health,” she added.

Though participants’ overall diet quality didn’t make a difference in the findings, those who consume olive oil may have overall healthier lifestyles.

“There are many, many differences between people who consume olive oil and those who do not, and it is never possible to fully account for all possible confounding factors,” Curtis said.

Another important point to keep in mind is that about half of dementia cases are caused by vascular disease, Curtis added.

“Anything which improved cardiovascular health, such as not smoking, would be expected to reduce dementia risk,” he said. “It has been shown that olive oil consumption is associated with better cardiovascular health, so one would expect that it would also be associated with lower dementia risk.”

Olive oil is a staple of the Mediterranean diet, which has been found helpful for health of the brain, heart, bones and more. Besides cooking with olive oil, you can also use it to make salad dressings or vinaigrettes, mayonnaise, pesto or bread dip. And people should also remember that when it comes to food and brain function, it’s not just about what we eat, but how we eat, Mellor said.

“Remaining sociable around mealtimes and eating with others can benefit our mental health in the short term and cognitive function as we age,” he added.

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