People who consume at least seven grams per day of olive oil, equivalent to half a tablespoon, have a 28% lower risk of developing dementia than those who do not include olive oil in their diet, according to research from Harvard University based on data from over 150,000 individuals in the United States.
The results, presented in the journal JAMA Network Open, add to those of previous studies conducted in Mediterranean countries, which had already observed a correlation between higher olive oil consumption and a lower risk of Alzheimer’s.
“We know that olive oil improves mental function thanks to the polyphenols it contains,” says Ramon Estruch, a researcher at the Clínic Hospital in Barcelona and scientific director of the Mediterranean Diet Foundation, who did not participate in the US study. “In our environment, we have clearly observed how olive oil, especially extra virgin olive oil, improves cognitive functions and reduces the risk of stroke.”
The Harvard study, co-led by Catalan researcher Marta Guasch-Ferré, analyzed data from about 90,000 female nurses and 60,000 male health professionals between 1990 and 2018. They had an average age of 56 in 1990 and every four years they answered questionnaires about their health status and lifestyle, including detailed questions about their diet.
The researchers divided the respondents into four groups based on their olive oil consumption levels: high (more than 7 grams per day, which would be low in Spain); medium (between 4.5 and 7 g/day); low (between 0 and 4.5 g/day); and none.
During the 28 years of follow-up in the study, 4,751 dementia-related deaths were recorded among the participants.
The results show that the higher the consumption of olive oil, the lower the risk of dementia. Compared to those who never consumed olive oil, the risk decreased by 12% in those with low consumption, 16% in those with moderate consumption, and 28% in those with high consumption.
This benefit was independent of whether participants had a healthier or less healthy diet, except for the type of fats they consumed. In fact, those who consumed more olive oil also had a higher alcohol intake, a higher total calorie consumption, and higher cholesterol levels.
“It has been shown, in both our study and others, that higher olive oil consumption is associated with a lower risk of cardiovascular diseases and dementia-related mortality, regardless of the consumption of other foods and lifestyle factors,” declares Marta Guasch-Ferré, who trained in nutrition and metabolism at the Universitat Rovira i Virgili before conducting research at the Harvard T.H. Chan School of Public Health.”
The polyphenols in olive oil “can reduce inflammation [in the brain], oxidative stress and restore the blood-brain barrier, thus reducing brain pathologies associated with tau and beta-amyloid proteins,” such as Alzheimer’s disease, researchers write in JAMA Network Open. Additionally, they add, olive oil improves cardiovascular health, which also contributes to preventing cognitive decline.
In Spain, the Predimed study (acronym for “prevention with Mediterranean diet”) recommended between four and five tablespoons of extra virgin olive oil per day, mainly as a dressing and to a lesser extent for cooking. This amount is equivalent to almost ten times more than the 7 grams daily considered as high consumption in the US. This study certified improved cognitive performance in both verbal fluency and memory tests in individuals with a diet rich in olive oil.
