Effects of pomegranate peel extract and vitamin E on the inflammatory status and endothelial function in hemodialysis patients: a randomized controlled clinical trial

Abstract

Inflammation and endothelial dysfunction are major problems in hemodialysis (HD) patients. This study assessed the effects of an 8 week administration of pomegranate peel extract (PPE) and vitamin E (Vit E) alone or in combination on the biomarkers of inflammation, including C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α), and the biomarkers of endothelial function, including intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and P-selectin, in HD patients. In a randomized, double-blind, parallel, placebo-controlled trial, 100 HD patients were randomly divided into 4 equal groups: (a) PPE + Vit E, received 2 pomegranate tablets (each tablet contained 225 mg PPE, equal to 90 mg ellagic acid) + 1 Vit E soft gel (400 IU) daily, (b) PPE, received 2 pomegranate tablets + 1 Vit E placebo soft gel daily, (c) Vit E, received 1 Vit E soft gel + 2 pomegranate placebo tablets daily, and (d) placebo, received 2 pomegranate placebo tablets + 1 Vit E placebo soft gel daily. For group allocation, a stratified block randomization procedure based on sex, age, and HD duration was used. Each intervention product and its placebo had identical shape, color, size, and packaging. Consumption of PPE + Vit E significantly reduced the serum CRP level (mean change: −7.12 ± 4.59 mg l⁻¹, P < 0.001) compared to other groups, while reduced levels of IL-6 (mean change: −2.19 ± 2.33 pg ml⁻¹, P < 0.001), TNF-α (mean change: −2.41 ± 3.21 pg ml⁻¹, P = 0.008), ICAM-1 (mean change: −64.2 ± 111.0 ng ml⁻¹, P = 0.017), and VCAM-1 (mean change: −117.7 ± 177.1 ng ml⁻¹, P = 0.002) were observed compared to the control. There was no significant difference in the P-selectin level among the groups. Consumption of PPE or Vit E alone significantly reduced the CRP level (mean change for PPE: −3.58 ± 5.41 mg l⁻¹, P < 0.001; mean change for Vit E: −3.25 ± 8.29 mg l⁻¹, P = 0.002) compared to the control. As a result, consumption of PPE in combination with Vit E enhanced the inflammatory status and endothelial function in HD patients.