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 short-term vitamin D supplementation on markers of vascular health in South Asian women living in the UK--a randomised controlled trial.
OBJECTIVE Low vitamin D levels and risk factors for vascular disease are both common in South Asian women . This trial evaluated whether vitamin D supplementation could improve markers of vascular health in South Asian women with low 25-hydroxyvitamin D levels . METHODS Parallel-group , double-blind , r and omised placebo-controlled trial . Healthy South Asian women with baseline serum 25-hydroxyvitamin D levels of < 75 nmol/L were r and omised to receive a single dose of 100,000 units oral vitamin D3 or matching placebo . Outcomes were measured at baseline , 4 and 8 weeks . The primary outcome was change in endothelial function measured using brachial artery flow-mediated dilatation . Secondary outcomes included blood pressure , arterial stiffness , microvascular function measured using laser Doppler iontophoresis , insulin resistance , serum lipids , circulating markers of inflammation , thrombosis and adipokines . RESULTS 50 women were r and omised , 25 to each group . Mean age was 41 years ; mean baseline 25-hydroxyvitamin D level was 27 nmol/L.  25-Hydroxyvitamin D levels rose in the vitamin D group relative to the placebo group by 4 weeks ( 16 nmol/L , 95 % CI 11 to 21 , p < 0.001 ) . There was no improvement in flow-mediated dilatation in the vitamin D group relative to placebo at 4 weeks ( 0.1 % , 95 % CI -0.9 to 1.1 , p = 0.84 ) or 8 weeks ( 0.0 % , 95 % CI -1.4 to 1.4 , p = 0.98 ) . There was no improvement in cholesterol , insulin resistance or markers of inflammation . Both platelet activation inhibitor-1 and tissue plasminogen activator levels fell significantly in the vitamin D group relative to placebo at 8 weeks . CONCLUSION A single large dose of vitamin D3 did not improve blood pressure or endothelial function in South Asian women with low baseline 25-hydroxyvitamin D levels . TRIAL REGISTRATION IS RCT N75081811
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 .