People who take at least seven grams of olive oil a day, which is 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 a Harvard University study based on data from more than 150,000 people in the US.
The results, presented yesterday in the journal JAMA Network Open, add to those of previous studies done in Mediterranean countries, which had already observed a correlation between a higher consumption of olive oil and a lower risk of Alzheimer's .
"We know that olive oil improves mental function thanks to the polyphenols it contains," declares Ramon Estruch, researcher at the Clínic hospital in Barcelona and scientific director of the Mediterranean Diet Foundation, who did not participate in the study of USA "In our environment we have clearly observed how olive oil, especially if it is extra virgin olive oil, improves cognitive functions and reduces the risk of stroke."
The Harvard study, co-directed by Catalan researcher Marta Guasch-Ferré, analyzed data from around 90,000 nurses and 60,000 male health professionals between 1990 and 2018. They had an average age of 56 in 1990 and one in four years answered questionnaires about their health and lifestyle, which included detailed questions about their diet.
The researchers divided the respondents into four groups based on their level of olive oil consumption: high (more than 7 grams per day, which would be a low level in Spain); medium (between 4.5 g and 7 g/day); low (between 0 and 4.5 g/day) and nil.
During the 28 years of follow-up of the study, 4,751 deaths from dementia 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 took olive oil, the risk was reduced by 12% among those with low consumption; 16% among those who had an average consumption, and 28% among those who had a high consumption.
This benefit was independent of whether the participants had a more or less healthy diet, except for the type of fat they consumed. In fact, those who consumed more olive oil also had higher alcohol consumption, higher total calorie consumption and higher cholesterol levels.
"It has been shown, both in our study and in others, that the more olive oil you consume, the lower your risk of cardiovascular disease and death from dementia, regardless of the consumption of other foods and environmental factors. lifestyle", declares Marta Guasch-Ferré, who trained in nutrition and metabolism at Rovira i Virgili University before going to research at the School of Public Health T.H. Chan from Harvard.
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 now Alzheimer's, the researchers write in JAMA Network Open.
In addition, they add that olive oil improves cardiovascular health, which also contributes to preventing cognitive impairment.
In Spain, the Predimed study (acronym for prevention with a Mediterranean diet), recommended between four and five tablespoons of extra virgin olive oil a day, mainly for dressing and to a lesser extent for cooking. This amount is almost ten times more than the 7 grams per day considered high consumption in the US. This study certified better cognitive performance, both in verbal fluency and in memory tests, in people who have a diet rich in olive oil.
