High olive oil consumption linked to reduced risk of dementia-related mortality

Recent research highlights a significant association between high olive oil consumption and a decreased risk of mortality due to dementia, regardless of overall diet quality. This insight comes from a prospective study involving over 92,000 participants, suggesting that an intake of at least 7 grams of olive oil daily — approximately half a tablespoon — is linked with a 28% reduction in the risk of dementia-related death.

The research also examined the health benefits of substituting olive oil for more commonly used fats like margarine and mayonnaise. “Replacing one teaspoon of margarine and mayonnaise with the equivalent amount of olive oil was associated with an 8%-14% lower risk for dementia-related mortality,” Anne-Julie Tessier, RD, PhD, from the Department of Nutrition at Harvard T.H. Chan School of Public Health, shared with Medscape Medical News. She emphasised the advantages of opting for natural products like olive oil over more processed fats, highlighting their potential in reducing the risk of fatal dementia. However, Tessier added, “intervention studies are needed to confirm causal effect and optimal quantity of olive oil intake.”

Published on the 6th of May, 2024, in JAMA Network Open, the study leveraged data from the Nurses’ Health Study and the Health Professionals Follow-Up Study, which tracked over 92,000 participants from 1990 to 2018. These individuals, who were free from cardiovascular disease and cancer at the start, were monitored for dietary habits every four years through a food frequency questionnaire and for dementia-related mortality via death records.

The findings showed no interaction by diet quality scores, meaning the reduced risk associated with olive oil consumption occurred independently of overall diet quality. Tessier pointed out that while typically, “people who use olive oil for cooking or as a dressing have an overall better quality of their diet, but interestingly, we found the association between more olive oil and reduced risk of dementia-related death to be regardless of this factor.”

The study acknowledges several limitations, including its observational nature, which makes it challenging to establish cause and effect. “It is also plausible that higher olive oil intake could be indicative of a healthier diet and higher socioeconomic status, although the results remained consistent after accounting for these factors,” the authors noted.

Commenting on the implications of the findings, Rebecca M. Edelmayer, PhD, senior director of scientific engagement for the Alzheimer’s Association, noted the correlation shown by the study but cautioned against drawing causal conclusions. “It would be wonderful if a particular food could delay or prevent Alzheimer’s disease, but we do not have scientific evidence that these claims are true,” Edelmayer commented. She highlighted the necessity for randomised controlled clinical trials to establish whether any foods, including olive oil, have a scientifically proven beneficial effect on cognitive decline and dementia.

This study underscores a promising link between olive oil intake and a reduced risk of dementia-related death, suggesting potential protective benefits. However, further research, particularly interventional studies, is crucial to confirm these observations and understand the underlying mechanisms more fully.