Chios mastic improves night-time diastolic pressure in well-controlled patients with hypertension; preliminary results of the hyper-mastic clinical trial

Objective: Chios mastic is a natural nutritional supplement consisting of several bioactive compounds and it possesses antioxidant and anti-inflammatory activities. Preliminary recent evidence suggests an anti-hypertensive effect of mastic. HYPER-MASTIC is a double-blind, randomized and controlled clinical trial, with the aim of investigating the additional effect of a three-month supplementation with Chios mastic on arterial hypertension of Greek patients with well-managed cardiovascular risk factors. Design and method: Patients with well controlled hypertension are being consecutively recruited and randomly allocated into three groups of supplements: 1500mg of mastic, 2800 mg of mastic and placebo in this ongoing study. For the current analyses, the two mastic groups were merged. Blood pressure measurements, using both office and 24h blood pressure measurement, and blood tests were performed at baseline and at 3 months. Flow-mediated dilatation (FMD) at the level of the brachial artery was measured in all patients as a measure of endothelial function. Patients reported no recent history of acute myocardial infarction or stroke and no history of heart failure. Herein, the preliminary results of the study are presented. Results: At the time of analysis, twenty one patients [48% females, age: 62 (14)] were consecutively recruited and randomized, with available data at 3 months. Thirteen volunteers were allocated to mastic and eight to placebo. No difference was found regarding age, sex distribution, BMI levels, personal or family history of hyperlipidemia and hypertension, diabetes mellitus type 2 and coronary artery disease between the two groups. Patients in the mastic group reduced their night-time diastolic blood pressure compared to placebo [-5 (10) vs -2.5 (16.3) mmHg | p = 0.025, respectively]. No other differences from placebo were observed on the effect of mastic on BP parameters. FMD dropped with time in the placebo group, whereas in the mastic group it was preserved [-1.2 (2.7) vs -0.2 (0.8) | pinteraction = 0.010]. Conclusions: Chios mastic supplementation leads to improved night-time diastolic blood pressure and preserved endothelial function in patients with well-controlled hypertension, suggesting that it may incrementally exert anti-hypertensive and vasculoprotective properties over anti-hypertensive medication.