RIBOGENE: Optimisation of Riboflavin Status in Hypertensive Adults With a Genetic Predisposition to Elevated Blood Pressure

Recruitment - Potential participants will be identified and recruited via GP practices, hospital outpatient clinics, pharmacies and workplaces throughout Northern Ireland. A letter of invitation and a study package containing a participant information sheet to explain the study, a consent form and a buccal swab DNA collection kit will be included. Inclusion / Exclusion The main inclusion criteria are that individuals must have the TT genotype. Exclusion criteria includes a history of gastrointestinal, hepatic, renal or haematological disorders, B-vitamin supplements consumer (including multi-vitamins containing B-vitamins), anticonvulsant therapy or any other drugs known to interfere with folate/B-vitamin metabolism. Suitable individuals that participated in the screening process will be contacted and invited to participate in the intervention study. Participants will be given at least forty eight hours to consider the written information and decide if they wish to participate. Study Design Participants with the TT genotype who have given informed consent will be stratified by blood pressure and subsequently randomised to receive placebo, low dose (1.6mg/d) or low supplemental dose (10mg/d) riboflavin for the 16 week intervention period. It is important to be aware that no upper limit has been established for this water-soluble B-vitamin and there are no safety concerns regarding these doses of riboflavin or indeed higher doses (including 25mg/d) administered in previous studies (Madigan et al. 1998). Participants, depending on geographical location, will be asked to attend two appointments (Baseline and week 16) at the participants local GP Practice, The Clinical Translational Research and Innovation Centre (CTRIC) at Altnagelvin Area Hospital, The Welcome Trust-Wolfson Northern Ireland Clinical Research Facility (NICRF) Belfast City Hospital, the Northern Ireland Centre for Food \& Health (NICHE) (University of Ulster, Coleraine) or at another convenient location. At both sampling points blood pressure (SBP/DBP mmHg) will be measured, a 30ml blood sample will be taken by a trained phlebotomist and the patient's height (m), weight (kg), waist circumference (cm) and BMI (kg/m2) will be measured. A detailed health and lifestyle questionnaire will collect information on medical and family history, medication and supplement use and dietary intake. Statistical analysis Statisticalanalysis will be performed using SPSS (Statistical Package for Social Sciences, Version 17.0; SPSS UK Ltd, Chersey, United Kingdom). Data that is not normally distributed will be transformed to obtain normality before statistical analysis is performed. Data will then be analysed to investigate if any differences exist in the BP response between the two riboflavin treatment groups.