Statistical analysis Data analysis will proceed according to guidelines for randomised controlled trials. The first stage of analysis will be to use descriptive statistics to describe recruited individuals in relation to those eligible, and to investigate comparability of the trial arms at baseline. The primary analysis will be an intention-to-treat comparison between the two groups for both primary and secondary outcomes. The primary outcome will be presented as Effective Dose with confidence intervals. Categorical data will be presented as number and % of events.