Polyphenol intake from a Mediterranean diet decreases inflammatory biomarkers related to atherosclerosis: a substudy of the PREDIMED trial

Abstract

High dietary polyphenol intake is associated with reduced all-cause mortality and a lower incidence of cardiovascular events. However, the mechanisms involved are not fully understood. The aim of the present substudy of the PREvención con DIetaMEDiterránea (Prevention with Mediterranean diet; PREDIMED) trial was to analyse the relationship between polyphenol intake measured by total urinary polyphenol excretion (TPE), and circulating inflammatory biomarkers and cardiovascular risk factors in elderly individuals. A substudy 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, anthropometric data, clinical and laboratory assessments, including inflammatory biomarkers, and urinary TPE were measured at baseline and after the one-year intervention. Participants in the highest tertile of changes in urinary TPE (T3) showed significantly lower plasma levels of inflammatory biomarkers [vascular cell adhesion molecule 1 (VCAM-1) (-9.47 ng ml-1 ), intercellular adhesion molecule 1 (-14.71 ng ml-1 ), interleukin 6 (-1.21 pg ml-1 ), tumour necrosis factor alpha (-7.05 pg ml-1 ) and monocyte chemotactic protein 1 (-3.36 pg ml-1 )] than those inthe lowest tertile (T1, P < 0.02; all). A significant inverse correlation existed between urinary TPE and the plasma concentration of\VCAM-1 (r = -0.301; P < 0.001). In addition, systolic and diastolic blood pressure (BP) decreased and plasma high-density lipoprotein cholesterol increased in parallel with increasing urinary TPE (T3 vs. T1) (P < 0.005 and P = 0.004, respectively). 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.

Keywords: Folin-Ciocalteu; Mediterranean diet; blood pressure; hypertension; inflammatory biomarkers; urinary polyphenol biomarker.

© 2016 The British Pharmacological Society.

Figures

Figure 1

Changes from baseline in plasma concentrations of the inflammatory biomarkers (A) vascular cell adhesion molecule (VCAM), (B) soluble intercellular adhesion molecule (ICAM), (C) plasma interleukin 6 (IL‐6), (D) tumour necrosis factor alpha (TNF‐α) and (E) monocyte chemotactic protein 1 (MCP‐1) after 1 year, according to tertiles of changes in total urinary polyphenols excreted. *P < 0.05; **P < 0.01. indicates statistical significance between the baseline and 1 year of intervention period, with a confidence interval of 95%

Figure 2

Changes from baseline in plasma concentrations of the inflammatory biomarkers (A) vascular cell adhesion molecule (VCAM), (B) soluble intercellular adhesion molecule (ICAM), (C) plasma interleukin 6 (IL‐6), (D) tumour necrosis factor alpha (TNF‐α) and (E) monocyte chemotactic protein 1 (MCP‐1) after 1 year, according to intervention groups. EVOO, extra‐virgin olive oil; Med‐diet, Mediterranean diet. **P < 0.01, *P < 0.05 indicates statistical significance between the baseline and 1 year of intervention period, with a confidence interval of 95%