Study Findings: Olive Oil, Cognitive Health, and the Gut Microbiota

A recent cohort study published in the journal Microbiome suggests a significant link between olive oil consumption, cognitive aging, and gut microbiota profiles in older adults.

A recent cohort study suggests that virgin olive oil (VOO) may be associated with favorable cognitive aging and gut microbiota profiles over two years in older adults. Conversely, common olive oil (COO) showed less favorable associations.

The study investigated the intricate relationships between olive oil intake, changes in gut microbiota, and cognitive function.

Background

Cognitive decline is a growing public health concern, prompting researchers to explore dietary patterns as potential preventive strategies for age-associated neurodegeneration. Virgin olive oil (VOO), a cornerstone of the Mediterranean diet, is prized for its rich phenolic compounds and beneficial monounsaturated fats.

In contrast, common olive oil (COO) often contains more refined olive oil or olive-pomace oil, leading to significantly lower levels of these crucial bioactive compounds. While previous evidence has hinted at olive oil's benefits for intestinal health and gut microbiota, human research specifically connecting VOO, gut microbiota, and cognitive function has been limited until now.

Study Design and Participants

Researchers analyzed data from 656 adults aged 55 to 75 years, all of whom had overweight or obesity and metabolic syndrome. These participants were drawn from the larger PREDIMED-Plus randomized controlled trial.

Food frequency questionnaires were completed at baseline and during follow-up to assess dietary habits. Neuropsychological tests were administered at both baseline and after two years to evaluate cognitive changes.

Olive oil intake was categorized into three types:

• Virgin Olive Oil (VOO)
• Common Olive Oil (COO): This combined intake of refined olive oil and olive-pomace oil.
• Total Olive Oil (TOO): The overall consumption of all three types of olive oil.

Cognitive function was comprehensively assessed using a battery of tests, including the clock drawing test, mini-mental state examination, and verbal fluency tests. Results were aggregated into composite z-scores for domains such as executive function, attention, and general cognitive function. Stool samples were collected at baseline for detailed gut microbiota profiling.

Key Findings: Olive Oil and Cognitive Changes

The study revealed distinct associations between different types of olive oil and cognitive trajectories over two years:

Total Olive Oil (TOO)

Participants in the highest tertile of Total Olive Oil (TOO) intake displayed modest but statistically significant improvements in general cognitive function, attention, and global cognitive function when compared to those in the lowest tertile. Furthermore, each 10g per day increase in TOO intake was positively associated with improvements in executive function, attention, and global and general cognitive function.

Virgin Olive Oil (VOO)

Similar positive associations were observed for Virgin Olive Oil (VOO) intake. This suggests that VOO was the primary driver of the beneficial relationships seen with total olive oil consumption.

Common Olive Oil (COO)

Conversely, the findings for Common Olive Oil (COO) were less favorable. Each 10g per day increase in COO intake was associated with worse changes in executive function, language, and global and general cognitive function.

Gut Microbiota and Olive Oil

The study also shed light on how olive oil intake relates to the gut microbiota:

Alpha Diversity

Higher VOO intake was linked to higher inverse Simpson and Chao1 diversity indices, indicating greater gut microbiota diversity. In contrast, higher COO intake was associated with lower alpha diversity. No significant differences were observed for total olive oil intake.

Taxonomic Associations

Nineteen specific bacterial genera were found to be associated with olive oil intake. Among these, Streptococcus, Adlercreutzia, and Eubacterium hallii group were linked to all three olive oil types.

Microbial Taxa and Cognition

Six microbial taxa were directly associated with changes in cognitive function. Notably, higher intakes of VOO and TOO were associated with a reduced abundance of Adlercreutzia, which itself was negatively linked to changes in general cognitive function. Akkermansia was negatively associated with changes in attention.

Gut Microbiota as a Mediator

Mediation analyses offered a compelling insight: the gut microbiota might partially mediate the relationship between olive oil intake and cognitive changes.

Mediation analyses suggested that the gut microbiota might partially mediate the relationship between olive oil intake and cognitive changes.

Specifically, Adlercreutzia was identified as a significant, albeit modest, mediator for the association between VOO intake and improvements in general cognitive function.

Implications

This study indicates that greater total and virgin olive oil intake correlated with more favorable cognitive changes over two years, while common olive oil intake was linked to less favorable cognitive trajectories. These findings suggest that the gut microbiota, particularly Adlercreutzia, may contribute to the association between olive oil intake and cognitive function. This is in addition to other potential mechanisms such as metabolic, vascular, and anti-inflammatory effects.

Further clinical studies are crucial to confirm the efficacy of dietary strategies that specifically target the microbiota for promoting healthy aging and optimal brain health.