August 23, 2023
Opting for olive oil rather than processed fats or oils may be good for your brain, according to a new report. The study found that people who consumed more than half a tablespoon of olive oil per day had a 28 percent lower risk of dying from dementia compared to their peers who never or rarely consumed olive oil. In addition, replacing just one teaspoon of margarine and mayonnaise with the equivalent amount of olive oil per day was associated with an 8 to 14 percent lower risk of dying from dementia.
“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 study author Anne-Julie Tessier, a postdoctoral fellow at the Harvard T.H. Chan School of Public Health. “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.” Dr. Tessler presented the findings at Nutrition 2023, the annual meeting of the American Society of Nutrition.
For the study, scientists reviewed data from more than 90,000 Americans over the course of nearly three decades. During that time, 4,749 of them had died from Alzheimer’s disease or other forms of dementia.
The researchers found that those who included olive oil in their diets instead of butter or processed fats were less likely to die from dementia. And the benefits of olive oil where independent of a person’s overall diet. Many people who choose to include heart-healthy olive oil in their diets, for example, also tend to eat lots of fruits and vegetables, which are also tied to a lower dementia risk. But olive oil’s beneficial effects seemed to be independent of overall diet quality, suggesting olive oil has unique benefits for brain health.
“Some antioxidant compounds in olive oil can cross the blood-brain barrier, potentially having a direct effect on the brain,” said Dr. Tessier. “It is also possible that olive oil has an indirect effect on brain health by benefiting cardiovascular health.”
Olive oil is a key component of the Mediterranean diet, which is associated with a lower risk of heart disease and stroke as well as Alzheimer’s disease. In addition to olive oil, the Mediterranean diet puts a priority on foods like fruits, vegetables, whole grains and fish, while avoiding foods like butter and red meat.
The study showed only an association between eating olive oil and a lower risk of dementia but could not prove cause and effect. But numerous other studies have pointed to olive oil as a beneficial component of a brain-healthy diet. For example, researchers at Rush University Medical Center in Chicago used a rigorous randomized, controlled trial to look at the effects of diet on brain health and found that incorporating healthy fats like olive oil may be good for the brain.
They examined 604 men and women who were overweight and had a family history of Alzheimer’s disease. While the participants tended to eat an unhealthy diet, none had Alzheimer’s disease or serious memory impairments at the start of the study.
All of those in the study were given dietary counseling and provided with strategies, such as portion control, to reduce their daily calorie count by 250 calories. But half were put on the MIND diet, which mixes components of the Mediterranean diet along with the DASH diet, a low-salt diet designed to lower blood pressure. The MIND diet included brain-healthy foods like fish and chicken, leafy green vegetables like arugula and kale, and berries and nuts, while avoiding unhealthy foods like red meat, butter and margarine, full-fat cheese, pastries and sweets, and fried foods.
After three years, participants in both groups had lost an average of more than 5 percent of their body weight. And both groups showed signs of improvements in thinking and memory skills. The findings were published in the New England Journal of Medicine.
“What we saw was improvement in cognition in both groups, but the MIND diet intervention group had a slightly better improvement in cognition,” although the difference between the two groups was not statistically significant, said Lisa Barnes, the study’s lead author and associate director of the Alzheimer’s Disease Research Center at RUSH. Average weight loss in both groups was about 11 pounds, which may have accounted for the cognitive boost seen in both groups, she said.
“The benefits within the new study’s three-year clinical trial weren’t as impressive as we’ve seen with the MIND diet observational studies in the past, but there were improvements in cognition in the short-term, consistent with the longer-term observational data,” Dr. Barnes said. “These individuals were healthy at the start of the trial and had no cognitive impairment, and their cognition got slightly better over time. Why there was no difference between the two diet groups at the end of the trial could be a result of many factors, including that the control group had a relatively healthy diet.”
In addition, the study only lasted three years. Alzheimer’s disease is a multi-year process which may begin 10 to 20 years before memory loss and other symptoms become apparent. It may be that the benefits of eating a heart-healthy, brain-healthy diet is cumulative, and that the more years you eat healthfully, the better your brain health will be in the long-run.
The findings add to mounting evidence that what we eat can affect our cognitive health, and that what’s good the heart is good for the brain. And the sooner you begin to eat healthier, the greater your chances of living a longer life with your memory intact.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, Ph.D. Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Sources: Anne-Julie Tessier, R.D., Ph.D.: Presented at NUTRITION 2023, the flagship annual meeting of the American Society for Nutrition, July 24, Boston
Lisa L. Barnes, Ph.D.; Klodian Dhana, M.D.; Ph.D.; Xiaoran Liu, Ph.D.; et al: Trial of the MIND Diet for Prevention of Cognitive Decline in Older Persons. New England Journal of Medicine, July 18, 2023
