Original ArticleFree Vitamin D: Relationship to Insulin Sensitivity and Vascular Health in Youth
Section snippets
Methods
Seventy-nine adolescents were evaluated in this cross-sectional study. Glucose tolerance status was defined according to American Diabetes Association criteria after a 2-hour oral glucose tolerance test (OGTT).12 Normal glucose tolerance was thus defined as glycosylated hemoglobin (HbA1c) <5.7%, fasting glucose <100 mg/dL, and a 2-hour value less than 140 mg/dL during the OGTT; impaired fasting glucose (IFG) as a fasting glucose ≥100 mg/dL, impaired glucose tolerance (IGT) as a 2-hour value
Results
Seventy-nine pubertal youth (34 male and 45 female; 42 Hispanic, 23 black, and 14 white), 15.4 ± 0.2 years in age, underwent study evaluations. Subjects' characteristics are detailed in Table I. Of the 79 subjects, only 17 met the criteria for vitamin D sufficiency, using a cut-off of 20 ng/mL. To evaluate the effect of free 25(OH)D or BioD on outcomes of interest, the subjects were examined according to tertiles of free 25(OH)D (Table I), or tertiles of BioD concentrations (Table II; available
Discussion
Our findings of endothelial dysfunction as measured by RHI in the lowest tertiles of free 25(OH)D and in association with total 25(OH)D deficiency vs sufficiency are consistent with findings of a relationship of low vitamin D concentrations with measures of vascular stiffness,5 intima media thickness,6 and markers of inflammation4 in youth. This is also consistent with adult studies suggesting that vitamin D plays an important role in cardiovascular health and is an independent risk factor for
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Central body fat deposits are associated with poor vitamin D status in Chinese children and adolescents
2022, NutritionCitation Excerpt :Compared with fat stored in the extremities and hips, trunk and abdominal fat have higher lipolytic activity, are more likely to lead to IR, are associated with higher levels of free fatty acids and fatty liver disease, and secrete more proinflammatory and less anti-inflammatory cytokines [31–33]. These adverse metabolic conditions are related to decreased circulating vitamin D concentrations [34–36]. Thus, excess central region fat, but not peripheral region fat, may cause a decline in 25(OH)D synthesis by the liver, leading to reduced vitamin D receptor activity and to vitamin D deficiency symptoms [11,14,37].
Effect of vitamin D supplementation on microvascular reactivity in obese adolescents: A randomized controlled trial
2021, Nutrition, Metabolism and Cardiovascular DiseasesCitation Excerpt :Consistent with this position, vitamin D deficiency in adults has been associated with macrovascular endothelial dysfunction in cross-sectional studies [17,18]; and with microvascular endothelial dysfunction in nephropathy patients, with or without diabetes [19–21]. However, observational studies evaluating the association between vitamin D deficiency and vascular dysfunction in obese children were not concordant [22–26]. Additionally, randomized clinical trials examining the macrovascular effect of vitamin D supplementation in adults have been inconclusive so far [27,28].
Vitamin D deficiency and cardiometabolic risk factors in adolescents: systematic review and meta-analysis
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Supported by the USDA ARS 6250-5100-054 (to F.B.) and Thrasher Research Fund (to F.B.). The authors declare no conflicts of interest. Portions of this study were presented at the Obesity Society Meeting, November 2015, Los Angeles, CA