A large cohort study suggests that not all olive oils are equal, with virgin olive oil showing a positive association with cognitive aging and gut microbiome profile over 2 years.
study: Changes in total and different types of olive oil intake, gut microbiota, and cognitive function in older adults. Image credit: Mehes Daniel / Shutterstock
In a recent study published in the journal microbiomeresearchers examined the association between: olive oil intake, intestinal floraand cognitive function in older adults.
Cognitive decline is a major public health concern that has a significant impact on healthcare costs. Dietary patterns have emerged as a preventive strategy to reduce age-related neurodegeneration and cognitive decline. virgin olive oil (VOO) is a major component of the Mediterranean diet and is well known for its high content of phenolic compounds and monounsaturated fats.
In contrast, common olive oil (COO) Contains more olive pomace oil or refined olive oil and has minimal VOO, resulting in lower levels of trace bioactive compounds despite a similar fatty acid profile. Emerging evidence suggests that consuming olive oil may benefit gut health and the gut microbiome. Despite preclinical insights into the relationship between VOO intake, gut microbiota, and cognitive function, human studies remain limited.
Population and design studies
Researchers evaluated the association between olive oil intake, gut microbiota, and cognitive function in older adults. PREDIMED-Plus, an ongoing randomized controlled trial, included individuals aged 55 to 75 with overweight or obesity and metabolic syndrome.
Participants completed a validated food frequency questionnaire that was administered repeatedly during follow-up, and baseline energy-adjusted intakes were used for primary analyses. A series of neuropsychological tests were performed at baseline and 2-year follow-up.
Classification of olive oil intake
Three questionnaire items focused on the consumption of different types of olive oil: virgin olive oil, refined olive oil, and olive pomace oil.
General olive oil intake is defined as the sum of olive pomace and refined olive oil intake;too much) Intake was defined as the intake of all three types.
Cognitive function assessment and scoring
Cognitive function was assessed using the Clock Drawing Test, Mini-Mental Status Examination (MMSE), Verbal Fluency Test, Digit Span Test, and Trail Making Test.
Z-scores were calculated for each cognitive test at baseline and follow-up. These scores were aggregated to generate composite scores for neurocognitive domains such as executive function and attention.
A general cognitive function score was calculated by combining the clock drawing test and MMSE scores. An overall cognitive function score was calculated by adding or subtracting individual Z scores based on whether a higher score indicated better or worse performance.
The primary outcome was change in composite cognitive score from baseline to follow-up.
Gut microbiota profiling and analytical approaches
Stool samples collected at baseline were used for taxonomic profiling of the gut microbiota.
Analyzes assessed the association between olive oil intake and changes in cognitive function over the follow-up period, the composition and diversity of olive oil intake and gut microbiota at baseline, and the association between olive oil-associated microbial signatures and changes in cognitive function.
Olive oil type intake was not randomized, so these analyzes were observations within a randomized lifestyle trial cohort.
Participant characteristics and olive oil intake
The study involved 656 adults with an average age of 65 years.
Mean total olive oil intake was 30 g, 50 g, and 58 g per day in the lowest, middle, and highest tertiles, respectively.
Those in the middle tertile showed higher baseline cognitive performance and lower prevalence of depression, hypercholesterolemia, and type 2 diabetes. Participants in the highest tertile had higher rates of smoking and lower levels of education.
Olive oil intake and cognitive changes
Participants in the highest tertile of total olive oil intake showed modest but statistically significant improvements in general cognitive function, attention, and overall cognitive function compared to participants in the lowest tertile.
Each 10 g/day increase in total olive oil intake was positively associated with changes in executive function, attention, and global and general cognitive function. A similar association was observed for virgin olive oil intake, which appears to drive most of the beneficial association.
In contrast, every 10 g/day increase in general olive oil intake was associated with worse executive function, language, and global and general cognitive function.
Diversity of intestinal flora and types of olive oil
Significant differences in alpha diversity index were observed between tertiles of general and virgin olive oil intake.
Higher virgin olive oil intake was associated with higher Simpson and Chao1 inverse diversity indices, and higher general olive oil intake was associated with lower alpha diversity.
No significant differences in alpha diversity were observed between total olive oil intake tertiles.
Olive oil intake and taxonomic associations
After correcting for false discovery rate, 19 bacterial genera were associated with olive oil intake.
Nine taxa were associated with total olive oil intake, 16 with virgin olive oil intake, 5 with general olive oil intake, and the Streptococcus, Adler’s cloutia, and Eubacterium harii groups were associated with all three exposures.
No significant association was observed between alpha diversity index and changes in cognitive function.
Microbial taxa associated with cognitive changes
Six microbial taxa were associated with changes in cognitive function, and only two remained significant after adjustment.
High intakes of virgin and total olive oil were associated with decreased abundance of Adler’s kreutza, which was negatively associated with changes in general cognitive function. Akkermansia was negatively correlated with changes in attention.
Mediated by intestinal microbiota
Mediation analysis suggested that the gut microbiota may partially mediate the relationship between olive oil intake and changes in cognitive function.
Adler’s kreuzia has been identified as an important mediator of the association between virgin olive oil consumption and improvements in general cognitive function, accounting for a small proportion of the overall effect.
The indirect effects were small and should be interpreted with caution.
Impact of cognitive function on health and aging
Overall, higher total olive oil intake was associated with more favorable cognitive changes over 2 years, whereas higher general olive oil intake was associated with less favorable cognitive trajectories.
The results of this study suggest that the gut microbiota, particularly Adler’s Kreutia, together with metabolic, vascular, and anti-inflammatory mechanisms, may contribute to the association between olive oil intake and cognitive function.
Further high-quality clinical research is needed to clarify this. efficacy of Dietary strategies that target the microbiome to promote healthy aging and brain health.