Does a preload containing whey protein and guar (Omniblend) reduce the fall in blood pressure and affect the rate of stomach emptying after a sugary drink?

INTERVENTION: Subjects will participate in two separate occasions at least five days apart after fasting from solids for 14 h and liquids for 12 h. Subjects will receive a phone call the day before the study to remind them of the requirement to fast and this will also be queried on the morning of the study. After a rest‐period of 15‐30 minutes to allow baseline BP to settle, subjects will be given: in random order, either: (i) a test drink containing 50 g glucose labelled with 20 MBq 99mTc‐calcium phytate, made up to 300ml water (ii) a preload containing 20g whey protein and 5g guar (Omniblend) made up to 150ml with water 15 minutes before the ingestion of the test drink. Subjects will undergo concurrent measurements of gastrointestinal (GI) symptoms (questionnaire), gastric emptying (scintigraphy), blood pressure, heart rate (DINAMAP), superior mesenteric artery blood flow (Doppler ultrasound), blood glucose, serum insulin, plasma Glucagon‐like peptide‐1 (GLP‐1), gastric inhibitory polypeptide (GIP) and glucose absorption (utilising 3‐OMG). CONDITION: Cardiovascular ‐ Other cardiovascular diseases Diet and Nutrition ‐ Other diet and nutrition disorders Metabolic and Endocrine ‐ Diabetes Postprandial hypotension; ; Postprandial hypotension PRIMARY OUTCOME: Blood pressure (BP) using automated BP cuff (DINAMAP ProCare 100, GE Medical Systems, Milwaukee, WI, USA). [BP will be measured at 3 min intervals prior to administration of test drink, and then regularly at 5 min intervals from t = 5 ‐ 180 min ] Gastric emptying assessed by Scintigraphy[Dynamic scintigraphic images will be acquired at 1 minute per frame for the first hour and at 3 minutes per frame for another two hours] Heart rate (HR) using automated BP cuff (DINAMAP ProCare 100, GE Medical Systems, Milwaukee, WI, USA).[HR will be measured at 3 min intervals prior to administration of test drink, and then regularly at 5 min intervals from t = 5 ‐ 180 min ] SECONDARY OUTCOME: Blood glucose measured with a portable glucometer on blood samples collected from an IV cannula[Blood glucose will be measured prior to the ingestion of the preload (t = ‐18 minutes) and/or test drink (t= ‐2 minutes) and then at t = 15, 30, 45, 60, 90, 120, 150, 180 minutes] Gastric inhibitory polypeptide (GIP) using plasma samples[GIP will be measured prior to the ingestion of the preload (t = ‐18 minutes) and/or test drink (t= ‐2 minutes) and then at t = 15, 30, 45, 60, 90, 120, 150, 180 minutes] Glucagon‐like peptide 1 (GLP‐1) using plasma samples[GLP‐1 will be measured prior to the ingestion of the preload (t = ‐18 minutes) and/or test drink (t= ‐2 minutes) and then at t = 15, 30, 45, 60, 90, 120, 150, 180 minutes] Glucose absorption using 3‐OMG[Glucose absorption will be measured prior to the ingestion of the preload (t = ‐18 minutes) and/or test drink (t= ‐2 minutes) and then at t = 15, 30, 45, 60, 90, 120, 150, 180 minutes] Insulin using serum samples[Insulin will be measured prior to the ingestion of the preload (t = ‐18 minutes) and/or test drink (t= ‐2 minutes) and then at t = 15, 30, 45, 60, 90, 120, 150, 180 minutes] Sensations of appetite measured with a visual analogue scale[A visual analogue scale (VAS) will be given immediately prior to the ingestion of the preload (t = ‐18 minutes) and/or test drink (t= ‐2 minutes) then at t = 15, 30, 45, 60, 90, 120, 150 and 180 minutes ] Superior mesenteric artery (SMA) blood flow assessed by Doppler ultrasonography using a Logiq 9 ultrasound system (GE Medical Systems)[SMA blood flow will be measured immediately prior to administration of the preload (t = ‐18 min) and/or test drink (t= ‐2 minutes) and then at t = 15, 30, 45, 60, 90, 120, 150, 180 minutes.] INCLUSION CRITERIA: • Healthy subjects • Body Mass Index 19‐30 kg/m²