Effect of a single, oral, high-dose vitamin D supplementation on endothelial function in patients with peripheral...

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.

In this double-blind, placebo-controlled, interventional pilot study, we screened 76 Caucasian patients with PAD for vitamin D deficiency. Sixty-two were randomised 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.

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.

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.