Fig 3 Fall prevention by dose and achieved 25(OH)D concentrations. Circles represent relative risks and error bars represent 95% confidence intervals. Trendline is based on series of effect sizes (circles). There were three trials with 800 IU D₃,^{w5 w6 w7} so the effect size for 800 IU D₃ is the pooled result from these three trials. Likewise, the effect size for 1000 IU D₂ is the pooled result from the two trials with 1000 IU D₂.^{w3 w4} We have listed the same dose D₂ and D₃ separately in the graph to account for their potential different impact on fall reduction. As there were two data points from the Broe et al trial that reached 48 nmol/l,^w1 two trials that reached 60 nmol/l,^{w1 w3} and two trials that reached 66 nmol/l,^{w6 w7} we pooled each of the sets. On the basis of visual inspection of figure 3, the benefits of vitamin D for fall risk started at a dose of 700 IU a day