Current evidence indicates that inverse association between leptin level and 25(OH)D concentration was observed in observational studies , which was not demonstrated in intervention studies with high heterogeneity .
We aim ed to investigate the potential association between vitamin D and serum leptin levels by pooling together the results from observational studies and clinical trials .
Effect of vitamin D deficiency and replacement on endothelial function in asymptomatic subjects.
CONTEXT 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 . DESIGN , SETTING , AND PATIENTS 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 i m 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
Current evidence indicates that inverse association between leptin level and 25(OH)D concentration was observed in observational studies , which was not demonstrated in intervention studies with high heterogeneity .
We aim ed to investigate the potential association between vitamin D and serum leptin levels by pooling together the results from observational studies and clinical trials .