Consuming more olive oil is associated with less risk of death related to dementia, according to a new study in the journal JAMA Open Network.
In a Harvard-led international study that included a team of researchers from the U.S., China and Denmark, researchers wanted to see if olive oil intake had any effect on the risk of dementia-related death. The study used data on women from the Nurses’ Health Study (1990-2018) and men in the Health Professionals Follow-up Study (also 1990-2018) who had no heart disease or cancer when the study started. In all, 92,383 people participated in the study. The average age was 56 at the beginning of the project.
The researchers concluded that “In U.S. adults, higher olive oil intake was associated with a lower risk of dementia-related mortality, irrespective of diet quality. Beyond heart health, the findings extend the current dietary recommendations of choice olive oil and other vegetable oils for cognitive-related health.”
The study reported that one-third of older adults die with Alzheimer’s disease or another dementia. “While deaths from disease such as stroke and heart disease have been decreasing over the past 20 yeras, age-standardized dementia mortality rates have been on the rise.”
Study design
They looked at olive oil consumption every four years based on a food frequency questionnaire, grouping the participants into four categories based on how much olive oil consumed per day, ranging from almost none to more than half a tablespoon. They also looked at overall diet quality. And they controlled for potential confounders including genetic, sociodemographic and lifestyle.
To determine the rate of dementia deaths, they looked at death records. During the 28-year study, 4,751 participants died of dementia out of 37,649 deaths. They found those with two APOE4 genes were five to nine times more apt to die with dementia than others.
But the researchers also found that consuming at least 7 g/d of olive oil was associated with a 28% lower risk of dementia-related death compared to the group that rarely or never ate olive oil. That’s about 1.5 tablespoons.
They didn’t find any impact based on diet quality.
How does diet impact brain health?
Olive oil is believed beneficial for the brain because of anti-inflammatory impacts from its monounsaturated fatty acids, and “other compounds with antioxidant properties such as vitamin E and polyphenols.” The introduction to the study said that a substudy that was randomized showed evidence that higher intake of olive oil for 6.5 years combined with adherence to a Mediterranean helped preserve cognition, compared with a low-fat control diet.
The Mediterranean diet embraces lots of fresh fruit, vegetables, whole grains, nuts and some fish and poultry. There are similar versions with the same benefits but using more local foods, including the Atlantic diet, as Deseret News reported in February. Per the article, “A study in JAMA Network Open said those who followed the diet for six months lowered their cholesterol, lost belly fat and otherwise countered metabolic syndrome symptoms, including high blood pressure, high cholesterol and high triglycerides. Those factors all raise the risk of heart disease.”
That diet, too, emphasizes fruits, vegetables, fish, grains, beans and olive oil, but includes more dairy, fish, potatoes, fruits and vegetables, than the better-known Mediterranean diet.
Of the new research, Caroline Thomason, a Washington, D.C.-based dietitian who was not involved in the study, told Medical News Today, “This study is interesting and makes sense to me because we have a lot of research on monounsaturated fats and brain and cognitive health. There seems to be a positive correlation between eating heart-healthy fats like olive oil and improved brain health.”
The researchers also considered common substitutions, like replacing margarine and mayonnaise with the same amount of olive oil. A bit over a teaspoon resulted in 8% to 14% less risk of dementia-related death. As Medical News Today wrote, “Substitutions of other vegetable oils or for butter did not provide a significant reduction in risk.”
The study found association, not causation.