Article

Circulating Vitamin D, Supplement Use, and Cardiovascular Disease Risk: The MrOS Sleep Study

The Journal of Clinical Endocrinology and Metabolism (Impact Factor: 6.21). 03/2014; 99(9):jc20134178. DOI: 10.1210/jc.2013-4178
Source: PubMed

ABSTRACT

Context: Evidence suggests an inverse association between circulating 25(OH) vitamin D and cardiovascular disease (CVD). Objective: Determine the association between serum 25(OH) vitamin D and risk for CVD events. Design: From March 2000 to April 2002, participants were recruited for the Osteoporotic Fractures in Men (MrOS) study; between December 2003 and March 2005, members of the MrOS cohort were invited to participate in the MrOS Sleep Study. We followed participants from the sleep study cohort for a mean of 5.9 years. Setting: Clinical centers at six recruitment sites across the United States. Patients: 3,135 men aged 65 and older from the MrOS cohort, of whom 116 were excluded for missing vitamin D or CVD data. Interventions: Participants were divided into two groups based on serum 25(OH) vitamin D levels: <20 ng/mL and ≥20 ng/mL. Main Outcome Measure: Participants were followed for CVD endpoints: coronary heart disease (CHD) and cerebrovascular events. We calculated age- and multivariable adjusted hazard ratios and stratified by use of vitamin D containing supplements. Results: We observed no significant association between circulating 25(OH) vitamin D and risk of CVD event (HR=0.91, 95% CI=0.73-1.13) and CHD event (HR=0.81, 95% CI=0.61-1.07). For cerebrovascular events, men with vitamin D deficiency appeared to exhibit a higher risk (HR=1.44, 95% CI=1.00-2.08) using the minimally adjusted model and after excluding supplement users (HR=1.70, 95% CI=1.02-2.83). Conclusions: 25(OH) vitamin D was not associated with risk of CVD and CHD events. However, vitamin D deficiency may be associated with an increased risk of cerebrovascular events.

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    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. This systematic review and meta-analysis of randomised clinical trials (RCTs) were conducted to investigate the effect of vitamin D supplementation on EF and to examine whether the effect size was modified by health status, study duration, dose, route of vitamin D administration, vitamin D status (baseline and post-intervention), body mass index (BMI), age and type of vitamin D. Methods: We searched the Medline, Embase, Cochrane Library and Scopus databases from inception until March 2015 for studies meeting the following criteria: (1) RCT with adult participants, (2) vitamin D administration alone, (3) studies that quantified EF using commonly applied methods including ultrasound, plethysmography, applanation tonometry and laser Doppler. Results: Sixteen articles reporting data for 1177 participants were included. Study duration ranged from 4 to 52 weeks. The effect of vitamin D on EF was not significant (SMD: 0.08, 95 % CI -0.06, 0.22, p = 0.28). Subgroup analysis showed a significant improvement of EF in diabetic subjects (SMD: 0.31, 95 % CI 0.05, 0.57, p = 0.02). A non-significant trend was found for diastolic blood pressure (β = 0.02; p = 0.07) and BMI (β = 0.05; p = 0.06). 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. This remains to be tested in future studies.
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