Scientific Study

BACKGROUND AND AIMS: High dietary polyphenol intake is associated with reduced all-cause mortality and lower incidence of cardiovascular events. However, the mechanisms involved are not fully understood. The aim of this sub-study of the PREDIMED (Prevention with Mediterranean diet) trial was to analyze the relationship of polyphenol intake measured by total urinary polyphenol excretion (TPE), with circulating inflammatory biomarkers and cardiovascular risk factors in elderly individuals. MATERIALS AND METHODS: A sub-study of 1139 high-risk participants was carried out within the PREDIMED trial. The subjects were randomly assigned to a low-fat control diet or to two Mediterranean diets, supplemented with either extra-virgin olive oil or nuts. Dietary intake, anthropometrics, clinical and laboratory assessments including inflammatory biomarkers, and urinary TPE were measured at baseline and after one-year intervention. RESULTS: Participants in the highest tertile of changes in urinary TPE (T3) showed significant lower plasma inflammatory biomarkers [VCAM-1 (-9.47 np/mL), ICAM-1 (-14.71 np/mL), IL-6 (-1.21 pg/mL), TNF-α (-7.05 pg/mL), and MCP-1 (-3.36 pg/mL)] than those in the lowest tertile (T1, P < 0.02; all). A significant inverse correlation existed between urinary TPE and plasma concentration of VCAM-1(r = -0.301; P < 0.001). In addition, systolic and diastolic blood pressure (BP) decreased and plasma HDL-cholesterol increased in parallel with increasing urinary TPE (T3 vs T1)(P < 0.005 and P = 0.004, respectively). CONCLUSIONS: Increases in polyphenol intake measured as urinary TPE are associated with decreased inflammatory biomarkers, suggesting a dose-dependent anti-inflammatory effect of polyphenols. In addition, high polyphenol intake improves cardiovascular risk factors, mainly BP and the lipid profile.