A prospective, randomized, double-blind, placebo-controlled trial of polyphenols on the outcomes of inflammatory factors and oxidative stress in patients with type 2 diabetes mellitus

Background: Type 2 diabetes mellitus (T2DM) is commonly associated with hyperglycemia, dyslipidemia, oxidative stress and inflammation which are well known cardiovascular risk factors. Pomegranate peel polyphenols have a proven hypolipemic, antioxidant and anti-inflammatory activity. However, there is a lack of clinical studies that would confirm its antioxidant and anti-inflammatory effects in diabetic patients. The potential of pomegranate peel extract (PoPEx) to counteract inflammation and oxidative stress in T2DM patients was investigated. For this purpose, a randomized, double-blind placebo-controlled study involving adult T2DM patients treated with PoPEx or placebo for eight-weeks was conducted. Methods: Patients were randomly divided into two groups: the first group (n = 30) received capsules containing PoPEx 250 mg twice daily, while the placebo group (n = 30) received placebo capsules twice daily. Plasma concentration of inflammatory factors (interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha) and high sensitivity C reactive protein (hsCRP)), oxidative stress biomarkers (thiobarbituric acid reactive substances (TBARS), nitrites (NO2-), superoxide anion radical (O2-), hydrogen peroxide (H2O2), total antioxidant capacity (TAC)), homocysteine and lipid profile were analyzed. Results: The PoPEx treatment showed a significant reduction of inflammatory factors (IL-6, TNF-alpha, hsCRP), oxidative stress biomarkers (TBARS, NO2-, O2-) and homocysteine, while the TAC was increased. Moreover, a significant improvement in lipid profile was observed in the PoPEx group. Additional analysis showed a significant inverse correlation between the decrements of all measured inflammatory markers and TAC in the PoPEx group. Conclusions: The study demonstrated that eight-week-long PoPEx administration had favorable effects on inflammatory status and oxidative stress biomarkers in diabetic patients.