Study design, participants and intervention
The D-Health Trial is a randomised, double-blinded, placebo-controlled trial among Australian adults. Detailed methods have been described previouslyThis study was conducted according to the guidelines laid down in the Declaration of Helsinki and all procedures involving human participants were approved by the QIMR Berghofer Medical Research Institute Human Research Ethics Committee (P1519). Written or online informed consent was obtained from all participants. It is registered with the Australian New Zealand Clinical Trials Registry (The Australian commonwealth electoral roll was used as the sampling frame. It is compulsory for all Australians aged 18 years and over to enrol to vote and 95 % of eligible people are enrolledWe used automated computer-generated permuted block randomisation, stratified by age (60–64, 65–69, 70–74, 75+), sex and state of residence to assign participants to the vitamin D or placebo groups. Staff and investigators did not have access to the allocation list.Vitamin D gel capsules contained 60 000 IU vitamin D