ABSTRACT
Here we present new and original data on the endogenous conversion of tyrosol (Tyr) into hydroxytyrosol (OHTyr) in humans and its effects on the cardiovascular system. A randomized, crossover, controlled clinical trial was performed with individuals at cardiovascular risk (n = 33). They received white wine (WW) (females 1, males 2 standard drinks/day), WW plus Tyr capsules (WW + Tyr) (25mg Tyr capsule, one per WW drink), and water (control) ad libitum. Intervention periods were of 4 weeks preceded by three-week wash-out periods. We assessed the conversion of Tyr to OHTyr, its interaction with a polygenic activity score (PAS) from CYP2A6 and CYP2D6 genotypes, and the effects on cardiovascular risk markers. For further details and experimental findings please refer to the article "Cardiovascular benefits of tyrosol and its endogenous conversion into hydroxytyrosol in humans. A randomized, controlled trial" [1].
ABSTRACT
INTRODUCTION: The simple phenol hydroxytyrosol (OHTyr) has been associated with the beneficial health effects of extra virgin olive oil. Pre-clinical studies have identified Tyr hydroxylation, mediated by cytochrome P450 isoforms CYP2A6 and CYP2D6, as an additional source of OHTyr. AIM: We aimed to (i) confirm Tyr to OHTyr bioconversion in vivo in humans, (ii) assess the cardiovascular benefits of this bioconversion, and (iii) determine their interaction with a polygenic activity score (PAS) from CYP2A6 and CYP2D6 genotypes. METHODS: Randomized, crossover, controlled study. Individuals at cardiovascular risk (n = 33) received: white wine (WW) (females 1, males 2 standard drinks/day), WW plus Tyr capsules (WW + Tyr) (25 mg Tyr capsule, one per WW drink), and water (control) ad libitum. Participants were classified by a PAS as low versus normal activity metabolizers. RESULTS: OHTyr recovery following WW + Tyr was higher than after other interventions (P < 0.05). Low PAS individuals had lower OHTyr/Tyr ratios compared to individuals with normal PAS. WW + Tyr improved endothelial function, increased plasma HDL-cholesterol and antithrombin IIII, and decreased plasma homocysteine, endothelin 1, and CD40L, P65/RELA, and CFH gene expression in peripheral blood mononuclear cells (pâ¯<â¯0.05). Combining Tyr capsule(s) with WW abolished the increase in iNOS, eNOS, VEGFA, and CHF expressions promoted by WW (pâ¯<â¯0.05). CONCLUSIONS: Tyr, and its partial biotransformation into OHTyr, promoted cardiovascular health-related benefits in humans after dietary doses of Tyr. The study design allowed the health effects of individual phenols to be singled out from the dietary matrix in which they are naturally found.
