Effect of the Intake of Corbella Extra Virgin Olive Oil on the Microbiota-gut-brain Axis in Healthy Adults (HEVOOC)

Serum samples will be analysed for mature BDNF using a Mature BDNF Rapid ELISA kit.

Fecal samples will be collected by the volunteers using a system for easy self-collection and stabilization of microbial DNA for gut microbiome profiling (OMNIgene - GUT). The extraction of genomic DNA from fecal samples will be carried out utilizing the DNeasy Power Kit. Subsequently, microbial profiling will employ 16 S ribosomal RNA (rRNA) sequencing to investigate microbial communities, with a specific focus on bacterial phylogeny and taxonomy.

Polyphenols and their metabolites derived from intestinal gut microbiota will be identified and quantified in human plasma, urine, feces, and saliva samples using high performance liquid chromatography (HPLC) - Linear Trap Quadrupole (LTQ) Orbitrap-MS/MS and HPLC-MS/MS techniques.

Carotenoids and their metabolites derived from intestinal gut microbiota will be identified and quantified in human plasma, urine, feces, and saliva samples using high performance liquid chromatography (HPLC) - Linear Trap Quadrupole (LTQ) Orbitrap-MS/MS and HPLC-MS/MS techniques.

After acidifying the fecal samples with formic acid, a quantification of short-chain fatty acids will be performed using gas chromatography by direct injection according to previously described methodology (Zhao et al., 2006).

Bile acids will be assayed using a validated liquid chromatography-mass spectrometry (LC-MS) method

Cerebrovascular function will be measured using functional magnetic resonance imaging (FMRI), a non-invasive method for assessing brain activity. FMRI maps blood oxygenation levels in the brain and estimates changes in the blood flow that depends on metabolic function and is correlated with specific brain region activities

Body weight in kilograms (kg)

BMI will be calculated as body weight (kg) divided by height (m). Weight and height will be combined to report BMI in kg/m^2

It will be measured with a tape-measure in triplicate, in centimeters (cm)

It will be measured with a tape-measure in triplicate, in centimeters (cm)

Body fat percentage will be measured using a bioelectrical impedance analysis monitor.

Diastolic and systolic blood pressure will be measured by a blood pressure monitor in triplicate.

Heart rate (bpm) will be measured with an automatic monitor in triplicate.

Total cholesterol, HDL-cholesterol, LDL-cholesterol and triglycerides (mg/dL) will be measured by molecular absorption spectrometry.

Alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) and albumin will be assayed by immunoenzymatic methods.

Glucose (mg/dL) will be measured by molecular absorption spectrometry.

Cytokines (pg/mL) will be assayed by immunoenzymatic methods.

Tumor necrosis factor α (TNF-α) (pg/mL) will be assayed by immunoenzymatic methods.

C-reactive protein (CRP) (mg/dL) will be assayed by immunoenzymatic methods.

A 7-day food recall will be used. The data will be analyzed using a software called Professional Nutritional Calculation Program (PCN Pro)

Participants will fill the validated Mediterranean Diet Adherence Screener (MEDAS) questionnaire used in the PREDIMED study. This questionnaire has been validated for the Spanish population and assesses adherence to the Mediterranean diet.The MEDAS score can range from 0 to 17 and higher scores mean better outcome.

Physical activity will be assessed with the ActiGraph® wGT3X-BT accelerometer

Sleep quality will be assessed with the ActiGraph® wGT3X-BT accelerometer.