Olive oil against dementia? Study shows reduced risk of death

This was the result of a large US study with more than 92,000 participants and an observation period of 28 years. According to the experts, other nutritional factors had no relevance to deaths from dementia.

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Anne-Julie Tessier from the Chan School of Public Health (Boston/Massachusetts) and her co-authors combined in their work, which has now been published in JAMA Network Open of the US Medical Association (AMA) (doi:10.1001/jamanetworkopen.2024.10021 ), the information from two epidemiological studies that have been ongoing for decades: the US Nurses’ Health Study and the Health Professionals Follow-Up Study.

The subjects are nurses and men working in the healthcare sector. Since they have a particularly great interest in such scientific investigations due to their work, the failure rate is particularly low in these groups of people. This makes the evaluation easier.

More than 90,000 participants

In total there were 92,283 participants with a mean age of 56.4 years, 65.6 percent were women. The observation period was 28 years (1990 to 2018). The test subjects initially had no diagnosed cardiovascular disease or cancer. Eating habits were recorded at the beginning and every four years thereafter. This included consumption of olive oil (zero to 4.5 grams per day, 4.5 to seven grams and more than seven grams).

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“In the 28 years (around 2.2 million person-years; note) there were 4,751 deaths that were associated with dementia. (…) Consuming at least seven grams of olive oil per day was associated with a 28 percent lower risk of Death due to dementia compared to low consumption of olive oil (…),” the scientists wrote in the summary of their study. Certain genetic conditions (the body’s own production of apolipoprotein E4) caused an up to nine-fold increased risk of dementia. But the apparently protective effect of olive oil was also evident in this group of people.

The scientists wrote: “There was no interaction with the other quality of the diet.” If the test subjects consumed the corresponding amount of olive oil instead of five grams of margarine or mayonnaise per day, the dementia death rate fell by eight to 14 percent.