Vitamin D and cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of death worldwide. Vitamin D is important for bones and for other body functions. Whether insufficient vitamin D causes CVD is unclear. Previous trials of vitamin D were unable to evaluate effects on CVD. This thesis will (i) review the literature on vitamin D and CVD; (ii) evaluate the observational associations between plasma 25(OH)D levels and CVD; and (iii) describe the design and results of the BEST-D trial. (i) Associations between baseline 25(OH)D levels and cause-specific mortality were evaluated in the Whitehall Resurvey of survivors undertaken in 1995, and findings included in a meta-analysis of similar studies. (ii) The BEST-D study was a randomised trial in older healthy volunteers of the effects of two doses of vitamin D3 (4000 IU or 2000 IU daily) compared to placebo, on blood 25(OH)D concentrations and CVD risk factors including blood pressure and arterial stiffness. (i) The Whitehall Resurvey of 5409 men with mean age of 77 years, among whom there were 3215 deaths showed an approximately linear (log-log scale) inverse association of plasma 25(OH)D concentrations and both CVD and non-vascular causes of death between 30 to 90 nmol/L. The meta-analysis confirmed the associations of 25(OH)D with CVD mortality. (ii) The BEST-D trial showed marked increases in 25(OH)D blood concentrations but no effects of taking higher doses of vitamin D3 for 12 months on blood pressure or arterial stiffness, compared to placebo. Plasma 25(OH)D is inversely associated with both CVD and non-vascular mortality. No effects were found after oral intake of vitamin D3 on blood pressure or arterial stiffness after 1 year. Randomised trials using adequate doses of vitamin D3 are needed, to evaluate causal effects of taking vitamin D on CVD outcomes