Wood 2012.

Methods	Randomised, double‐blind, placebo‐controlled trial using parallel group design (3 intervention groups)
Participants	Number of participants randomised: 305 healthy postmenopausal women aged 60 to 70 years, mean age 64 years. Inclusion criteria: white postmenopausal women. Exclusion criteria: pre‐existing cardiovascular disease, diabetes, asthma, malabsorption, hypertensive blood pressure measurements of at least 160 mm Hg systolic or 99 mm Hg diastolic, difficulty in swallowing tablets or capsules, or who were taking medications or supplements known to affect any dependent variable, current smokers or participants with abnormal blood biochemistry at screening
Interventions	Participants were randomly assigned to receive: Intervention group 1: 400 IU oral vitamin D₃ daily (n = 102) Intervention group 1: 1000 IU oral vitamin D₃ daily (n = 101) Comparator group: matched placebo capsule of vitamin D (n = 102), for a 1‐year period.
Outcomes	Outcomes reported in abstract of publication Primary outcomes: serum lipid profile, estimate of insulin resistance, inflammatory biomarkers, and blood pressure. Secondary outcomes: none defined.
Stated aim of study	Quote from the publication: "to test whether daily doses of vitamin D₃ at 400 or 1000 IU/d for one year affected conventional markers of cardiovascular disease risk."
Notes	"This work was funded by the UK Department of Health. The authors have nothing to disclose."
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote from the publication: "Randomization was computer generated. Research nurses assigned participants to one of three intervention groups using an automated telephone service (Health Services Research Unit, University of Aberdeen, UK)." Comment: sequence generation was achieved using computer random number generation.
Allocation concealment (selection bias)	Low risk	Quote from the publication: "Capsules containing vitaminD₃ (400 or 1000 IU) or identical placebo were purchased (Pure Encapsulations, Sudbury, MA), packaged into white plastic coded containers, and sealed in sequentially numbered study packs (Bilcare, Powys, UK)." Comment: the allocation was controlled by a central and independent randomisation unit.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote from the publication: "Both participants and study investigators were blinded to intervention groupings throughout the study." Comment: The allocation sequence was unknown to the investigators.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote from the publication: "Both participants and study investigators were blinded to intervention groupings throughout the study." Comment: the outcome assessors were masked to treatment allocation.
Incomplete outcome data (attrition bias)	Low risk	Quote from the publication: "A total of 305 women were randomly assigned to one of three study interventions. In total, 40 withdrew (six due to personal reasons, 34 due to clinical reasons)." Comment: the numbers and reasons for dropouts and withdrawals in all intervention groups were described.
Selective reporting (reporting bias)	Low risk	Comment: all clinically relevant and reasonably expected outcomes were reported.
For‐profit bias	Low risk	Quote from the publication: "Capsules containing vitamin D₃ (400 or 1000 IU) or identical placebo were purchased (Pure Encapsulations, Sudbury, MA)." Comment: the trial appears to be free of industry sponsorship or other kind of for‐profit support that may manipulate the trial design, conductance, or results of the trial.
Other bias	Low risk	Comment: the trial appears to be free of other components that could put it at risk of bias.