With increasing life expectancy, neurodegenerative diseases have become one of the leading causes of ill-health in the elderly. Preventive strategies include following healthy diets, such as the Mediterranean diet, which is particularly rich in polyphenols, bioactive compounds with neuroprotective properties. The aim of this study was to assess the association of microbial phenolic metabolites (MPM) with cognition. This cross-sectional analysis was performed with 200 participants of the PREDIMED trial (Barcelona-Clinic recruitment center). A novel method based on liquid chromatography coupled to mass spectrometry was used to identify urinary MPM (protocatechuic acid, enterodiol glucuronide, enterolactone glucuronide, urolithin B glucuronide, and vanillic acid glucuronide), and cognitive function was evaluated with neuropsychological tests. Multivariable-adjusted ordinary least squares regression was used to assess the associations between cognitive function and MPM, and a score was calculated as the weighted sum of MPM. A higher MPM score was associated with better frontal lobe function. Among individual metabolites, vanillic acid glucuronide was correlated with frontal cognitive performance. Participants with higher concentrations of vanillic acid glucuronide and urolithin B glucuronide obtained better scores in the Color Trail Test part 2. A higher score for urinary multi-MPM was associated with better frontal cognitive performance in an older Mediterranean population.

Background: The protective role of (poly)phenols against metabolic disorders has been extensively studied in adults but not in adolescents.

Objective: To assess associations of dietary (poly)phenols and their subclasses with cardiometabolic health parameters in adolescents.

Methods: A cross-sectional study was conducted in 944 individuals aged 11 to 14 years enrolled in the SI! Program for Secondary Schools trial (NCT03504059).  (Poly)phenol intake was assessed using semi-quantitative food frequency questionnaires and the Phenol-Explorer database. The measured cardiometabolic parameters were waist circumference (WC) age-sex z-score, blood pressure (BP) age-sex z-score, blood glucose (BG), triglycerides (TG), and high-density lipoprotein cholesterol (HDL-c). Multilevel mixed-effect linear regression models were applied to examine the association between (poly)phenol quintiles and cardiometabolic health parameters.

Results: Compared to the lowest quintile, adolescents in the highest quintile of total (poly)phenol intake had lower WC z-scores (β=-0.09, 95%CI=-0.09;-0.08, P-for trend=0.002), mean arterial pressure z-scores (β =-0.11, 95%CI=-0.12;-0.09, P-for trend=0.206), and HDL-c (β=-1.52, 95%CI=-2.90;-0.14, P-for trend=0.108), after multivariable adjustment. The WC z-scores (β=-0.11, 95%CI=-0.19;-0.03, P-for trend=0.013) and HDL-c (β=-2.16, 95%CI=-3.78;-0.53, P-for trend=0.046) were lower in the highest quintile of flavonoid intake compared to the lowest quintile. The highest quintile of phenolic acid intake was associated with a lower WC z-score (β=-0.14, 95%CI=-0.26;-0.02, P-for trend=0.011) and TG levels (β=-8.83, 95%CI=-12.37;-5.30, P-for trend <0.001), and the highest quintile of stilbene intake with lower BG (β=-1.83, 95%CI= -3.103;-0.64, P-for trend <0.001) and TG (β=-3.22, 95%CI= -4.95;-1.49, P-for trend=0.034), and with higher HDL-c (β=2.328, 95%CI= 1.40;3.17, P-for trend=0.466) compared to the lowest quintile.

Conclusion: A higher intake of (poly)phenols, especially flavonoids, phenolic acids, and stilbenes, was associated with better cardiometabolic parameters in adolescents.