The Association of 25 Hydroxyvitamin D and Parathyroid Hormone with Metabolic Syndrome in Two Ethnic Groups in South Africa (original) (raw)
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Background: A strong relationship exists between hypertension and body weight. Research has linked both higher blood pressure and body weight with lower vitamin D status. Objective: This study assessed the vitamin D status of a low-income, urban, black community in South Africa, to examine whether serum levels of 25-hydroxy vitamin D [25(OH)D] are associated with hypertension and body mass index (BMI). Methods: Data collected from 339 adults (25–64 years) from the Assuring Health for All in the Free State (AHA-FS) study were analysed. Variables measured include serum 25(OH)D, blood pressure, weight and height to determine BMI, and HIV status. Results: Mean 25(OH)D level was 38.4 ± 11.2 ng/mL for the group; 43.5 ± 11.8 ng/mL and 37.0 ± 10.6 ng/mL for males and females, respectively. Approximately 40% of the participants were HIV-positive and 63.4% hypertensive. Based on BMI, 11.8% were underweight, 33.0% normal weight, 23.0% overweight and 32.1% obese. HIV status showed no correlation with 25(OH)D levels when controlling for BMI. Poor inverse relationships were found between BMI and 25(OH)D (p = 0.01), and between mean arterial blood pressure and 25(OH)D (p = 0.05). When controlling for BMI, no correlation was found between 25(OH)D and the prevalence of hypertension or mean arterial blood pressure. Conclusion: Approximately 96% of participants had an adequate vitamin D status, which could be attributed to latitude, sunny conditions and expected high levels of sun exposure because of living conditions. Results confirmed a poor inverse relationship between vitamin D status and hypertension, which seems to be dependent on BMI.
British Journal of Nutrition, 2014
Vitamin D deficiency has been implicated in the aetiology of infectious diseases and metabolic syndrome. These diseases are prevalent in the African and Asian-Indian populations of South Africa; however, there is limited data on 25-hydroxyvitamin D (25(OH)D) concentrations in these populations. The aim of the present study was to assess the vitamin D status and its predictors in healthy adults in Johannesburg. We assessed the vitamin D status of 730 adult African and Asian-Indian subjects residing in Johannesburg. The contributions of sun exposure, season, dietary intake of Ca and vitamin D, total body fat and body fat distribution to 25(OH)D concentrations were assessed. The concentrations of 25(OH)D were measured by HPLC. The contribution of 25(OH)D 3 to total 25(OH)D concentrations was assessed. The mean age of the subjects was 42·6 (SD 13·1) years (range: 18-65). Concentrations of 25(OH)D , 30 nmol/l were found in 28·6 % of the Asian-Indian subjects in comparison with 5·1 % of the African subjects (P,0·0001). Parathyroid hormone (PTH) concentrations were negatively associated with 25(OH)D concentrations, while season and sun exposure were positive predictors explaining 16 % of the variance in 25(OH)D concentrations (P, 0·0001) in the African subjects. In the Asian-Indian subjects, PTH concentrations were negatively associated with 25(OH)D concentrations, while male sex, season and Ca supplementation were positive predictors and explained 17 % of the variance in 25(OH)D concentrations (P,0·0001). In the multivariate regression analysis, neither total body fat nor body fat distribution was predictive of 25(OH)D concentrations in either group. In conclusion, factors such as sun exposure, dietary supplement use and ethnicity are important determinants of plasma 25(OH)D concentrations.
Vitamin D, parathyroid hormone and the metabolic syndrome in middle-aged and older European men
2009
Background: Vitamin D (VitD) and parathyroid hormone (PTH) play important roles in calcium metabolism and skeletal homeostasis. Estimates of the VitD status in several European countries show large variations between them. In addition, no national population-based estimate has been published. VitD and PTH may also play important roles in cardiovascular risk, which has been suggested to be associated with metabolic syndrome (MetS) and is very prevalent in Portugal. The goal of our study was to evaluate the prevalence of hypovitaminosis D and its determinants as well as PTH serum level determinants and associations of the 25-hydroxyvitamin D and PTH serum levels with MetS and its individual components in a sample of the Portuguese mainland population. Methods: PORMETS is a national cross-sectional study that includes a total sample of 4095 adults. A subsample, including 500 participants, was randomly selected for the present study. A structured questionnaire was administered to collect information on personal medical histories and socio-demographic and behavioral characteristics. Blood pressure and anthropometrics measurements were performed. Fasting venous samples were collected and PTH and 25hydroxyvitamin D were measured. VitD adequacy was classified according to the Institute of Medicine, and MetS was classified according to the Joint Interim Statement recommendations. Multiple linear regression and unconditional logistic regression models were used to estimate the associations between the levels of PTH and 25-hydroxyvitamin D and with MetS and its individual components. Results: The prevalence of VitD deficiency was 37.7%, and MetS was present in 191 participants (38.4%). The serum PTH levels showed a positive association (OR: 1.014; 95%CI: 1.002, 1.026) with the waist circumference component of MetS. The serum 25-hydroxyvitamin D levels were negatively associated with MetS (OR: 0.957; 95%CI: 0.922, 0.993) as well as with its blood pressure (OR: 0.949; 95%CI: 0.912, 0.987) and triglycerides (OR: 0. 930; 95%CI: 0.892, 0.969) components. Conclusion: This study showed a high national prevalence of hypovitaminosis D. The PTH levels showed a significant positive association with the WC component of MetS, and the VitD levels were negatively associated with the BP and triglycerides components as well as with the MetS.
PLoS ONE, 2010
Background: Increasing evidence suggests a role for mineral metabolism in cardiovascular disease risk. 25-hydroxyvitamin D (25(OH)D), parathyroid hormone (PTH), and calcium may be directly associated with cardiovascular risk factors or mediated by each other. Methodology/Principal Findings: We combined data for adult participants in three cycles of the National Health and Nutrition Examination Survey (2001-2, 2003-4, 2005-6), a representative sample of the civilian, non-institutionalized US population (N = 3,958). Using this data we examined joint associations of 25(OH)D, PTH and calcium with a range of cardiovascular risk factors. 25(OH)D was inversely associated with fasting insulin (mean difference in insulin per 1 standard deviation 25(OH)D: 20.053 (95%CI: 20.091, 20.015)), glucose (20.046 95%CI: 20.081, 20.012) and systolic blood pressure (SBP) (20.032 95%CI: 20.062, 20.001), and positively associated with high density lipoprotein cholesterol HDL-c (0.088 95%CI: 0.044, 0.148), after adjustment for ethnicity, smoking, socioeconomic status and waist circumference. PTH was positively associated with diastolic blood pressure (0.110, 95%CI: 0.055, 0.164) in confounder adjusted models, but was not associated with other cardiovascular risk factors. Albumin adjusted calcium was associated with triglycerides (0.
Annals of Nutrition and Metabolism, 2018
Background/Aims: Asian Indians have a high prevalence of vitamin D deficiency and metabolic syndrome. Vitamin D deficiency is associated with an increased risk of cardiovascular disease and diabetes. Methods: We performed a cross-sectional study of 150 Asian Indians (50% male) from the San Francisco Bay Area. We assessed the association between 25-OH vitamin D (25-OHD) levels and vitamin D deficiency with body composition (anthropometric and radiographic measures) and metabolic outcomes. Results: In both men and women, the presence of vitamin D deficiency was associated with higher systolic (p = 0.004) and diastolic (p = 0.01) blood pressure, and fasting glucose (p = 0.01). Only in women, vitamin D deficiency status was associated with higher body mass index (BMI), waist-to-hip ratio, visceral fat area, and hepatic fat content after adjusting for age, income, and physical activity level. In women, 25-OHD was also associated with fasting glucose after adjusting for age, income, and p...
Vitamin D status and cardiometabolic disease risk among healthy adults of Northern Ghana
Cardiometabolic Disease (CMD) is a cluster of conditions that increase the risk for cardiovascular events, but its relationship with vitamin D status has not been studied in Ghana. A cross-sectional study design was conducted to investigate the relationship between serum vitamin D status and CMD risk (obesity, type 2 diabetes mellitus, hypertension, and dyslipidemia) among 302 apparently healthy adults, aged 25 to 59 and of northern decent in Ghana. Biochemical analysis was done to determine serum total cholesterol (TC), Triglycerides (TG), High Density Lipoprotein (HDL), Low Density Lipoprotein (LDL), Fasting Blood Glucose (FBG), Glycated Haemoglobin (HbA1c) and serum vitamin D levels of participants. Anthropometric assessment was also done and BMI, WC, HC, Blood Pressure, WHR, Body Fat (BF) and visceral fat percentages were obtained. Analysis was done using SPSS (version 25). We evaluated CMD risk factors to predict vitamin D status using binary and multiple linear logistics regre...
2010
Background: Circulating 25-hydroxyvitamin D [25(OH)D] and parathyroid hormone (PTH) concentrations have been shown to be associated with insulin sensitivity; however, adiposity may confound this relation. Furthermore, African Americans (AAs) have lower insulin sensitivity and 25(OH)D concentrations than do European Americans (EAs); whether these differences are associated in a cause-and-effect manner has not been determined. Objectives: The objectives of this study were to examine the relation of 25(OH)D and PTH concentrations with whole-body insulin sensitivity and to determine whether lower 25(OH)D concentrations in AAs compared with EAs contribute to the lower insulin sensitivity of AAs relative to that of EAs. Design: This was a cross-sectional study of 25 AA and 25 EA women. We determined the whole-body insulin sensitivity index (S I) with an intravenous glucose tolerance test and minimal modeling. Percentage body fat was determined with dual-energy X-ray absorptiometry, and intraabdominal adipose tissue (IAAT) was determined with computed tomography. Results: Multiple linear regression analysis indicated that 25(OH)D and PTH concentrations were independent determinants of S I [standardized b = 0.24 (P = 0.04) and 20.36 (P = 0.002), respectively] after adjustment for age, race, and IAAT. The mean ethnic difference in S I decreased from 2.70 [Á 10 24 Á min 21 /(lIU/mL)] after adjustment for IAAT and percentage body fat to 1.80 [Á 10 24 Á min 21 /(lIU/mL)] after further adjustment for 25(OH)D and PTH concentrations. Conclusions: 25(OH)D and PTH concentrations were independently associated with whole-body insulin sensitivity in a cohort of healthy women, which suggested that these variables may influence insulin sensitivity through independent mechanisms. Furthermore, ethnic differences in 25(OH)D concentrations may contribute to ethnic differences in insulin sensitivity.
2016
In type 2 diabetic patients, the relationships between 25-hydroxyvitamin D and parathyroid hormone levels, and glycemic control, remain unclear. We evaluated associations between 25-hydroxyvitamin D, parathyroid hormone, and hemoglobin A 1c levels after adjusting for other covariates, including log transformed 25-hydroxyvitamin D levels and log transformed parathyroid hormone levels, in Korean patients with type 2 diabetes. In total, 1,175 patients with type 2 diabetes were selected from 8,857 individuals who completed the baseline survey of the Dong-gu study, conducted in Korea from 2007 to 2010. After adjusting for other covariates, we found that the mean hemoglobin A 1c level was inversely associated with the 25-hydroxyvitamin D level (Q1: 7.
The Journal of Clinical Endocrinology & Metabolism, 2014
Context and Objective: There are few data on the contribution of body composition to bone mineral density (BMD) in non-Caucasian populations. We therefore studied the contribution of body composition, and possible confounding of 25-hydroxyvitamin D and PTH, to BMD at various skeletal sites in black African (BA) and Asian Indian (AI) subjects. Design and Setting: This was a cross-sectional study in Johannesburg, South Africa. Participants: BMD, body fat, and lean mass were measured using dual x-ray absorptiometry and abdominal fat distribution by ultrasound in 714 healthy subjects, aged 18–65 years. Results: Whole-body (subtotal), hip, femoral neck, and lumbar spine (lumbar) BMD were significantly higher in BA than AI subjects (P < .001 for all). Whole-body lean mass positively associated with BMD at all sites in both ethnic groups (P < .001 for all) and partially explained the higher BMD in BA females compared with AI females. Whole-body fat mass correlated positively with lum...