Beneficial effects of polyphenol-rich olive oil in patients with early atherosclerosis

Abstract

Purpose: Diets rich in plant-derived polyphenols such as olive oil (OO) and/or catechins such as epigallocatechin 3-gallate (EGCG) have been shown to reduce the incidence of cardiovascular diseases, potentially by improving endothelial function, an important surrogate for atherosclerosis. The possible augmentation of endothelial function with the combined efforts of OO and EGCG is intriguing, yet unknown.

Methods: Eighty-two patients with early atherosclerosis (presence of endothelial dysfunction) were enrolled in this double-blind, randomized trial with 52 completing the study. The aim of the study was to compare the effect of a daily intake of 30 ml simple OO, with 30 ml of EGCG-supplemented OO, on endothelial function as well as on inflammation and oxidative stress after a period of 4 months. Endothelial function was assessed noninvasively via peripheral arterial tonometry (Endo-PAT®).

Results: After 4 months, when OO and EGCG-supplemented OO groups were combined, OO significantly improved endothelial function (RHI, 1.59 ± 0.25-1.75 ± 0.45; p < 0.05). However, there were no significant differences in results between the two olive oil groups. Interestingly, with OO supplementation there was a significant reduction in inflammatory parameters: sICAM (196 to 183 ng/mL, p = < 0.001); white blood cells (WBCs) (6.0 × 10⁹/L-5.8 × 10⁹/L, p < 0.05); monocytes (0.48 × 10⁹/L to 0.44 × 10⁹/L, p = 0.05); lymphocytes (1.85 × 10⁹/L to 1.6 × 10⁹/L, p = 0.01); and platelets (242-229 × 10⁹/L, p = 0.047).

Conclusions: Improvement in endothelial dysfunction in patients with early atherosclerosis in association with significant reduction in leukocytes may suggest an important role of early cellular inflammatory mediators on endothelial function. The current study supports one potential mechanism for the role of olive oil, independent of EGCG, modestly supplemented to a healthy cardiovascular diet.

Trial registration: ClinicalTrials.gov NCT00865787.

Figure 1. Protocol

Schematic representation of the patient selection and trial execution.

Figure 2

Comparing Reactive Hyperemia Indices (RHI, ratio) for patients at baseline and after 4 months of treatment. No statistical differences exist when treatment arms of the OO groups are separated. There is a significant difference between baseline and four month endothelial function when the groups are combined (A+B) suggesting that OO alone can improve endothelial function (* p<0.05).

Figure 3

Graphical representation demonstrating that those with reduced endothelial function (baseline Endo-PAT® reactive hyperemia index (RHI) < 1.6) show significant improvements in endothelial function after 4 months of OO treatment (p=0.004).