Conclusions Vitamin D supplementation did not improve EF .
The significant effect of vitamin D in diabetics and a tendency for an association with BMI may indicate a role of excess adiposity and insulin resistance in modulating the effects of vitamin D on vascular function .
Abstract Background In addition to regulating calcium homoeostasis and bone health , vitamin D influences vascular and metabolic processes including endothelial function ( EF ) and insulin signalling .
Effect of a single, oral, high-dose vitamin D supplementation on endothelial function in patients with peripheral arterial disease: a randomised controlled pilot study.
OBJECTIVE Apart from its role in bone metabolism , vitamin D may also influence cardiovascular disease . The objective of this study was : ( 1 ) to determine the effect of a single , oral , high-dose vitamin D supplementation on endothelial function and arterial stiffness in patients with peripheral arterial disease ( PAD ) and ( 2 ) to investigate the impact of this supplementation on coagulation and inflammation parameters . METHODS In this double-blind , placebo-controlled , interventional pilot study , we screened 76 Caucasian patients with PAD for vitamin D deficiency . Sixty-two were r and omised to receive a single , oral supplementation of 100,000 IU vitamin D3 or placebo . At baseline and after 1 month , we measured serum vitamin D and parathormone levels , and surrogate parameters for cardiovascular disease . RESULTS Sixty-five of 76 patients ( 86 % ) had low 25-hydroxyvitamin D levels ( < 30 ng ml(-1 ) ) ; of those , 62 agreed to participate in the study . At baseline , only parathormone was related to vitamin D. In supplemented patients , vitamin D levels increased from 16.3 ± 6.7 to 24.3 ± 6.2 ng ml(-1 ) ( P < 0.001 ) , with wide variations between single patients ; in the placebo group vitamin levels did not change . Seasonal factors accounted for a decrease of vitamin D levels by 8 ng ml(-1 ) between summer and winter . After 1 month , none of the measured parameters was influenced by vitamin substitution . CONCLUSION In this pilot study , most patients with PAD were vitamin D deficient . Vitamin D supplementation  increased serum 25-hydroxyvitamin D without influencing endothelial function , arterial stiffness , coagulation and inflammation parameters , although the study was underpowered for definite conclusions
Conclusions Vitamin D supplementation did not improve EF .
The significant effect of vitamin D in diabetics and a tendency for an association with BMI may indicate a role of excess adiposity and insulin resistance in modulating the effects of vitamin D on vascular function .
Abstract Background In addition to regulating calcium homoeostasis and bone health , vitamin D influences vascular and metabolic processes including endothelial function ( EF ) and insulin signalling .