After baseline measurements are taken at the end of the 2-week run in period, participants will be randomised to either the low salt arm or the standard treatment arm using computer-generated randomisation. Patients will be asked to bring in a food diary from the weekend and two week days so that dietary advice can be tailored to the individual. Patients allocated to the low salt diet group will be advised by a doctor to achieve a dietary salt intake of less than 5g per day (80mmol/day). The control group will be instructed to continue with their usual diet, therefore no advice will be given about salt reduction, but otherwise the groups will follow an identical trial protocol.