Olive Oil – 7 grams per day can prevent dementia!

In a recent study published in JAMA Network Open, researchers used a large prospective cohort study to examine long-term associations between olive oil consumption and risk of dementia mortality. Their cohort of 92,383 American adults found that consuming seven or more grams of olive oil per day was associated with a 28% reduction in dementia-related deaths compared with participants who did not consume olive oil. This study highlights the importance of diet in age-related cognitive decline and mortality. It suggests that consuming olive oil may be an effective strategy for reducing the risk of mortality from dementia.

Food may influence age-related cognitive decline

Dementia is an umbrella term for a spectrum of conditions that affect a person's ability to remember details and events, process data, or make rational decisions, affecting more than 55 million people and accounting for more 33% of all adult deaths worldwide. Despite recent advances in medicine that have led to an overall decline in mortality from cardiovascular disease (stroke and heart disease), trends in the prevalence of dementia and dementia-related mortality are alarmingly increasing, with more than 10 million new cases reported each year.

Extensive research, particularly during and immediately following the coronavirus disease 2019 (COVID-19) pandemic, has revealed a complex but compelling link between good health habits (especially sleep, physical activity and diet) and chronic disease outcomes, with all Nutrition interventions are being studied more for their beneficial effects on age-related cardiovascular and cognitive outcomes. The Mediterranean dietary pattern and its derivatives (eg, DASH - Dietary Approaches to Stop Hypertension), inspired by the traditional eating habits of southern Spain, southern Italy and Crete, are gaining global popularity due to observed anti-inflammatory and neuroprotective benefits.

Olive oil is a fundamental part of the Mediterranean diet and the main source of oils and fats in this diet. This oil is known for its rich content of monounsaturated fatty acids, vitamin E and polyphenols, antioxidant-rich compounds that have been observed to delay the onset of dementia and reduce the risk of Alzheimer's disease. Previous studies of olive oil consumption have shown that its regular consumption, combined with a healthy diet rich in fresh fruits and vegetables and low in processed fats and meats, can effectively improve cognitive outcomes compared with occasional or occasional consumption. Unfortunately, most studies examining the potential benefits of olive oil have been conducted in Mediterranean countries, with a lack of data from other countries.

In this study, researchers examined the long-term effects of olive oil consumption in a large American cohort to investigate possible improvements in dementia-related mortality outcomes in this population. They also examined how these results varied depending on the quality of the diet (eating a healthy diet) combined with regular olive oil consumption. Their prospective study included participants (N = 92,383) from two existing longitudinal studies—the Nurses' Health Study I (NHS; cohort of female participants) and the Health Professionals Follow-Up Study (HPFS; cohort of male participants).

Data for the study was collected over a 33-year period from 1990 to 2023 and included two-year assessments of participants' lifestyle habits and medical histories. NHS and HPFS participants with a clinical history of CVD, cancer, implausible daily calorie intake, or incomplete olive oil consumption data were excluded from subsequent analyses. The questionnaire (Food Frequency Questionnaire [FFQ]) was peer-validated in a smaller pilot cohort and included more than 130 items. A modified version of the Alternative Mediterranean Diet (AMED) index was used to assess diet quality.

“Participants were asked how often they consumed certain foods, including the types of fats and oils used in cooking or added to meals, over the past 12 months. Total olive oil consumption was determined by summing responses to three questions related to olive oil consumption (i.e., olive oil used for salad dressing, added to food or bread, and olive oil used for baking and frying at home).

Because the apolipoprotein E ε4 (APOE ε4) allele is almost always associated with an increased risk of dementia, particularly for homozygous carriers, blood (or mucosal swab) samples from a subset of participants (N = 27,296) were collected for APOE genotyping. Information on deaths and covariates (smoking status, body weight, physical activity level, menopausal status, medication and dietary supplement use) were obtained from the National Death Index and biennial questionnaires, respectively. For statistical validation, age-stratified Cox proportional hazards models were used to calculate the association between olive oil consumption and dementia-related mortality.

Study results and conclusions

Of the 92,383 participants (65.6% women) included in the study, 4,751 dementia-related deaths were reported during the 33-year follow-up period. The mean olive oil consumption in the cohorts was 1.3 g/day, with adherence to the Mediterranean diet estimated at 4.5 and 4.2 points for the NHS and HPFS cohorts, respectively.

"Olive oil consumption was inversely associated with dementia-related mortality in age-stratified and multivariable-adjusted models. Compared with participants with the lowest olive oil intake, the pooled HR for dementia-related death among participants with the highest olive oil intake (>7 g/day) was 0.72 (95% CI, 0.64-0.81), after adjusting for sociodemographic and lifestyle factors."

This study highlights that consistent olive oil intake, when consumed as part of a healthy balanced diet (here, the Mediterranean diet), can significantly reduce the risk of age-related dementia-related mortality, particularly among women. Surprisingly, consuming more than 7.0 g/day of olive oil was able to reduce the risk of dementia even in the absence of a Mediterranean diet, suggesting that it may independently slow the progression of cognitive decline.