Effect of vitamin D deficiency and replacement on endothelial function in asymptomatic subjects.
BACKGROUND
Vitamin D receptors are present in many tissues. Hypovitaminosis D is considered to be a risk factor for atherosclerosis.


OBJECTIVE
This study explores the effects of vitamin D replacement on insulin sensitivity, endothelial function, inflammation, oxidative stress, and leptin in vitamin D-deficient subjects.


METHODS
Twenty-three asymptomatic vitamin D-deficient subjects with 25-hydroxyvitamin D [25(OH)D] levels below 25 nmol/liter were compared with a control group that had a mean 25(OH)D level of 75 nmol/liter. The vitamin D-deficient group received 300,000 IU im monthly for 3 months. The following parameters were evaluated before and after treatment: vitamin D metabolites, leptin, endothelial function by brachial artery flow mediated dilatation (FMD), insulin sensitivity index based on oral glucose tolerance test, and lipid peroxidation as measures of thiobarbituric acid reactive substances (TBARS).


RESULTS
FMD measurements were significantly lower in 25(OH)D-deficient subjects than controls (P = 0.001) and improved after replacement therapy (P = 0.002). Posttreatment values of TBARS were significantly lower than pretreatment levels (P < 0.001). A positive correlation between FMD and 25(OH)D (r = 0.45; P = 0.001) and a negative correlation between FMD and TBARS (r = -0.28; P < 0.05) were observed. There was a significant increase in leptin levels after therapy, and the leptin levels were positively correlated with 25(OH)D levels (r = 0.45; P < 0.05).


CONCLUSIONS
This study shows that 25(OH)D deficiency is associated with endothelial dysfunction and increased lipid peroxidation. Replacement of vitamin D has favorable effects on endothelial function. Vitamin D deficiency can be seen as an independent risk factor of atherosclerosis. Hypovitaminosis D-associated endothelial dysfunction may predispose to higher rates of cardiovascular disease in the winter.
Tarcin
Ozlem
O
Section of Endocrinology and Metabolism, Marmara University School of Medicine, 34060 Istanbul, Turkey. ozlemtarcin@yahoo.com
Yavuz
Dilek Gogas
DG
Ozben
Beste
B
Telli
Ahu
A
Ogunc
Ayliz Velioglu
AV
Yuksel
Meral
M
Toprak
Ahmet
A
Yazici
Dilek
D
Sancak
Seda
S
Deyneli
Oguzhan
O
Akalin
Sema
S
D000328:Adult; D050197:Atherosclerosis / Q000209:etiology / Q000503:physiopathology; D015415:Biomarkers / Q000097:blood; D001783:Blood Flow Velocity; D001794:Blood Pressure; D001916:Brachial Artery / Q000503:physiopathology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D020738:Leptin / Q000097:blood; D016014:Linear Models; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects; D012307:Risk Factors; D016896:Treatment Outcome; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000627:therapeutic use; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D049629:Waist-Hip Ratio
D015415:Biomarkers; D020738:Leptin; D014807:Vitamin D; C104450:25-hydroxyvitamin D