Effect of Garlic on Gut microbiota, Inflammation & Cognition in hypertensives: The GarGIC trial

INTERVENTION: Our study will comprise a double‐blind parallel randomised placebo‐controlled trial of 12 weeks duration investigating the effect of Kyolic aged garlic extract on gut microbiota, inflammatory markers, and cognitive function in patients with high blood pressure. The active treatment group will be allocated to two daily capsules of aged garlic extract (1.2 g Kyolic Reserve, 1.2 mg S‐allylcysteine). Compliance will be assessed by return of trial capsules, as well as diary entries. CONDITION: hypertension PRIMARY OUTCOME: Central hemodynamic measures ; Pulse Wave velocity (PWV)is a strong predictor of cardiovascular morbidity, and is most reliably measured by a comparison of carotid to femoral pulse wave. The SphygmoCor Xcel device (Atcor Medical) provides the gold standard validated instrument. Clinical blood pressure ; A trained research assistant will use a validated and calibrated digital sphygmomanometer with appropriate sized cuffs. The display of the sphygmomanometer is to be positioned away from the patient to assure blinding to the BP readings. BP measurement to be taken with patient in seated position with arm supported at heart level, after 5 min rest, after abstinence from food, nutritional supplements, caffeinated beverages, and smoking for a minimum of 2 hours prior to BP measurement at approximately the same time/day of the week. BP will be recorded as three serial measurements at intervals of 30 seconds. The mean of the three BP measurements will be used in the analysis. Stool test ; Enrolled patients will be provided with a test kit from Genova (www.gtx.com, USA) via Nutripath, Melbourne, Australia at their first appointment for baseline testing, and will be instructed to collect a stool sample as close as possible to their baseline appointment and sent the kit to Genova for a Microbial Ecological Profile (GI Effects Stool Profile), providing a comprehensive profile of commensal bacterial species in colony‐forming‐units (CFU)/g stool by PCR‐DNA analysis. PCR‐DNA analysis offers a more accurate result than standard culturing technologies. The report will be used to calculate Chaos diversity, Shannon diversity index, and Firmicute/Bacteroides ratio and relevant correlations. SECONDARY OUTCOME: Cognitive function testing ; Patients will undergo the Swinburne University Computerised Cognitive Assessment Battery (SUCCAB) test in the NIIM cognitive function labs. The SUCCAB test consists of eight computer‐based tasks assessing speed and accuracy, shown to correlate to cognitive decline through ageing, with a difference in 60 milliseconds in speed correlating to about 10 years of ageing. ; Our research team has been collaborating closely with the ‘inventor’ of the computerised test in a number of projects, and NIIM has recently built the laboratory facilities to undertake the testing in a controlled environment. ; Testing takes about 30 minutes including a practice session of about 10 minutes for the participant to familiarise themselves with the equipment and the task battery. Inflammatory markers ; The research assistant, trained in phlebotomy, will take a fasted blood sample for testing of inflammatory markers TNF‐alpha and interleukin‐6 or interleukin‐10. ; INCLUSION CRITERIA: Inclusion criteria ‐ Either not on blood pressure medication, or on established plan of blood pressure medication (one or more classes) for at least 2 months ‐ The patient’s doctor is not planning to change current treatment during the 3 month trial ‐ Able to give informed consent ‐ Essential hypertension: Mean systolic SBP >=140 mm Hg or diastolic blood pressure >=90 mm Hg to be confirmed under trial conditions at the screening appointment (at screening mean DBP of >=88 / SBP >=135 mm Hg will be included)