Effects of black tea with and without a fat load on vascular function in mildly hypertensive volunteers

INTERVENTION: After a 7‐day run‐in period, participants were randomly assigned to consume a hot beverage containing 150 mg tea polyphenols (equivalent to 129 mg flavonoids) or placebo twice a day for 8 days in a double‐blind cross‐over design. Wash‐out between the two treatments was 13 days. During these periods subjects were asked to maintain their normal diet and lifestyle avoiding consumption of tea, red wine, chocolate‐based products, dietary supplements or aspirin. Vascular function and blood pressure were assessed prior to (baseline) and after consumption of the test beverage on day 7 and day 8 of each of the two intervention phases. On day 7 all measurements were performed in a fasted state before (t=0) and 1, 2, 3 and 4 h after consumption of the tea in a supine position in a quiet, temperature‐controlled (22° to 24°C) room by trained, certified staff, who were blind about the study protocol. This procedure was repeated on day 8, but volunteers also consumed a fat load (ultra‐heat‐treated whipping cream: 1 g fat per kg bodyweight; for 100 ml of product: fats 27 g, carbohydrates 12.6 g, proteins 2.1 g; energy value 302 kcal) approximately 30 minutes after consuming the test product. Patients did not present any pain during the measures. Composition of the test products (black tea) (mg per dose): Polyphenols: Placebo: 0, Active: 150 Total caffeine: Placebo: 37.3, Active: 37.3 Tea solids: Placebo: ‐, Active: 497.5 Caffeine added: Placebo: 37.3, Active: ‐ Caramel colour: Placebo: 90, Active: ‐ Tea flavour: Placebo: 10, Active: ‐ Sugar (sucrose): Placebo: 1362.7, Active: 1402.5 CONDITION: Hypertension and arterial stiffness ; Circulatory System ; Essential (primary) hypertension PRIMARY OUTCOME: 1. Flow‐mediated dilatation of the brachial artery of the dominant arm was measured by ultrasonography with a non‐invasive probe at approximately 5‐10 cm above the elbow. After a 1‐minute baseline measurement a cuff placed at the forearm just below the elbow will be inflated at 250 mmHg for 5 minutes and then deflated and the maximal dilation of the brachial artery will be measured.; 2. Digital volume pulse measurements were evaluated by a validated finger photoplethysmographic device (a little clip on the finger). Three consecutive recordings were obtained in the index finger of the non‐dominant hand with participants resting 15 min in supine position. ; 3. Office blood pressure measurements were recorded by a validated oscillometric device with appropriately sized cuffs (Omron 705 CP; Omron Matsusaka Co. Ltd., Matsusaka‐City, Japan) on the dominant upper arm. For this purpose, patients rested 15 min in supine position. Then, the first blood pressure measurement was discarded and the subsequent three consecutive BP readings, taken at 5‐min intervals, were recorded. The average of these latter measures was considered for statistical analysis.; ; All outcomes were measured on day 7 and day 8 of each of the two intervention phases. INCLUSION CRITERIA: 1. Never‐treated essential hypertensive (EH) patients referred to the outpatient unit Centre of Hypertension and Cardiovascular Prevention of L?Aquila 2. = 18 and = 75 years of age 3. Non‐diabetic 4. SBP between 140 and 159 mmHg or DBP between 90 and 99 mmHg 5. Body mass index between 19 and 31 kg/m2 SECONDARY OUTCOME: 1. In all individuals, a routine hematochemical check was performed by standard methods after each active treatment phase. Plasma glucose and insulin, serum total cholesterol, high‐density lipoprotein (HDL) cholesterol, low‐density lipoprotein (LDL) cholesterol, and triglyceride levels were assessed in the clinical chemistry laboratory using routine procedures. Plasma glucose and insulin values were used to calculate the index of insulin resistance, homeostasis model assessment of insulin resistance (HOMA‐IR). ; 2. Further, blood samples were collected for clinical chemical analyses of vascular function and inflammation (endothelial activation): C‐reactive protein, E‐selectin, ICAM‐1, Endothelin‐1 and VCAM‐1 levels (immuno‐enzymatic methods ‐ ELISA kits), including assessment of the number of circulating endothelial progenitor cells (counted manually in 10 randomly selected microscopic fields by two independent investigators with an inverted fluorescence microscope, after some laboratory phases).; ; All outcomes were measured on day 7 and day 8 of each of the two intervention phases.