Can you fight dementia with olive oil?

The more olive oil Americans swallow, the fewer people die with a dementia diagnosis. Even when they eat poorly, move little, smoke, suffer from high blood pressure, etc. A Quebecer made these astonishing discoveries at Harvard University, thanks to the observation of more than 92,000 health workers over nearly 30 years.

More than seven grams per day

A gap separates Americans who ingest more olive oil – more than a tablespoon and a half per day – from those who consume little or no olive oil. The former are in fact 28% less likely to die with a diagnosis of dementia. “The association is linear. For each additional teaspoon [5 grammes], the risk was 9% lower,” explains Anne-Julie Tessier, professional dietitian-nutritionist and postdoctoral researcher in the department of nutrition at Harvard University, in an interview. A third of older people are already dying from Alzheimer’s disease and other forms of dementia, and their numbers are increasing, she points out: “Consuming more olive oil could therefore be a potential strategy to improve the longevity without dementia. »

Separate role

The results of the study – published May 6, in the Journal of the American Medical Association (JAMA Network Open) – give us hope that olive oil preserves our brain in a specific way. Thanks to the wealth of information collected and the impressive size of their sample, the researchers were able to create subgroups and measure the influence of more than 25 potential confounding factors.¹. Against all expectations, olive oil seems to play a separate role and offer protection that does not depend on other lifestyle habits, illnesses, family history, etc. “Olive oil contains fatty acids, vitamins and polyphenols which could exert anti-inflammatory and neuroprotective effects,” explains M.^me Tessier, who holds a doctorate in nutrition.

Advantaged women

Swallowing more olive oil appears to be even more beneficial for women. “Among those who consume the most, the risk of dying from dementia is consistently lower by around 33%, regardless of the variables considered, including body mass index [IMC] », Indicates Anne-Julie Tessier. Among male fans of olive oil, this probability decreases by 25%. Considering the BMI also seems to cause them to lose any significant benefit. “Men and women do not have exactly the same brain structures or the same hormone levels and they do not face the same social influences,” explains Anne-Julie Tessier. Further research will be required to fully understand the implications of these differences. »

Genetic variant

Even people who have inherited a genetic variant that predisposes them to death from dementia appear to benefit from high olive oil consumption. This variant (called APOE ε4) interferes with lipid and glucose metabolism, and the brain can suffer in many ways. “In people carrying the gene, using olive oil seems even more strongly linked to lower mortality and could therefore represent a slightly greater advantage,” observes Anne-Julie Tessier. Among all study participants, those who carried two copies of this gene died five to nine times more often with a diagnosis of dementia.

Mayonnaise and margarine

Poor nutrition does not prevent heavy consumers of olive oil from dying less often from dementia. But when they adhere to dietary recommendations, their risk decreases even more. In the study, margarine and mayonnaise still contained trans fats, which are very harmful. Which could explain why substituting an equivalent amount of olive oil (five grams per day) appears to have reduced the likelihood of dying with a dementia diagnosis by 8% or 14%. Substituting other vegetable oils or butter is not associated with this change. The researchers do not know which olive oils the participants consumed. Since they vary in their content of polyphenols and other compounds, future studies may reveal that some types are more beneficial than others.

Not a miracle product

Despite its benefits, olive oil does not cancel out the ravages of cigarettes, a sedentary lifestyle, etc. “I don’t believe in superfoods,” says Anne-Julie Tessier. But since it possibly reduces the risk of fatal dementia, using it for cooking or in salad dressings, instead of more processed fats, is a reasonable recommendation. » There is no point, however, in stuffing yourself with it: “We have not observed a quantity above which the risk is seen to be reversed. On the other hand, its consumption remains very low in North America, while in Mediterranean regions, people can consume up to 3 to 4 tablespoons per day. But you shouldn’t consume a lot of it to the detriment of other healthy foods. »

Consult the study

1. Factors considered: sex, age, socioeconomic status, diet, energy intake, weight, body mass index, physical activity, smoking, alcohol consumption, vitamin intake, personal history of type 2 diabetes, hypertension and high cholesterol, family history of dementia and depression, Southern European ancestry, marital status, hormonal status, hormone intake, genes, consumption of red meat, fruits and vegetables, nuts, soda, whole grains, trans fats.