People who eat 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 research. from Harvard University 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 carried out in Mediterranean countries, which had already observed a correlation between greater 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,” says Ramon Estruch, a researcher at the Hospital Clínic in Barcelona and scientific director of the Mediterranean Diet Foundation, who was not involved in the US study. “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, has analyzed data from some 90,000 nurses and 60,000 male health professionals between 1990 and 2018. They had an average age of 56 years in 1990 and every four years they answered questionnaires about their health status and lifestyle, which included detailed questions about their diet.
The researchers divided respondents into four groups based on their level of olive oil consumption: high (more than 7 grams a day, which would be low in Spain); medium (between 4.5 and 7 g/day); low (between 0 and 4.5 g/day) and zero.
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 greater 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% in those with low consumption; 16% in those who had average consumption; and 28% in those who had a high consumption.
This benefit was independent of whether participants had a more or less healthy diet, except for the type of fats 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 greater the consumption of olive oil, the lower the risk of cardiovascular diseases and death from dementia, independently of the consumption of other foods and lifestyle factors,” declares Marta. Guasch-Ferré, who trained in nutrition and metabolism at the Rovira i Virgili University before going to do 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, thereby reducing brain pathologies associated with tau and beta-amyloid proteins,” such as Alzheimer's, the researchers write in JAMA Network Open. In addition, they add, olive oil improves cardiovascular health, which also helps prevent cognitive decline.
In Spain, the Predimed study (acronym for “prevention with a 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 per day considered high consumption in the United States. This study certified better cognitive performance, both in verbal fluency and memory tests, in people who have a diet rich in coconut oil. olive.
