Abstract 1723: Vitamin D Levels Are Associated With Exercise Capacity and Measures of Endothelial Function in Healthy Humans
Introduction: Vitamin D deficiency is associated with incident CVD. Vascular cells express receptors for vitamin D and are able to metabolize it to its active moiety. Exercise capacity and measures of vascular function determine cardiovascular performance and predict future risk. We hypothesized that Vitamin D status is associated with exercise capacity and measures of vascular function.
Methods: Serum levels of total 25-hydroxyvitamin D (25-OH D) were measured in 163 healthy white subjects free of all risk factors (age 44 ± 13 yrs, BMI 22 ± 3 kg/m2, male 53%). Levels of peak oxygen uptake at
maximal effort (PVO2) and
the anaerobic threshold (AT) were derived from cardiopulmonary exercise testing (CPET, METTEST®).
Endothelial function was assessed by arterial tonometry derived reactive hyperemia index (PAT-RHI, Itamar Medical).
Results: Mean 25-OH D level was 39 ± 15 ng/ml. There were significant correlations between PVO2 and 25-OH D levels (r = 0.35, p < 0.01) and between AT and 25-OH D levels (r = 0.37, p < 0.01). Thus, subjects with higher PVO2 and AT had higher 25-OH D levels. This remained significant after adjusting for age, gender and BMI. Moreover, higher 25-OH D levels were associated with higher RHI (r = 0.21, p = 0.02), even after correcting for exercise capacity, age, gender and BMI, indicating that lower levels of 25-OH D were associated with lower hyperemia and endothelial dysfunction.
Conclusion: In a population free of risk factors, improved fitness and vascular function are associated with higher vit. D levels. Further research is needed to determine whether vitamin D levels reflect cardiovascular fitness (biomarker) or if they determine vascular health (risk factor).