Is vitamin D status a determining factor for metabolic syndrome? A case-control study

This study was undertaken to assess vitamin D status in nonmenopausal women with metabolic syndrome (MeS) and to evaluate its possible role in inflammation and other components of MeS. A case-control study was conducted during late fall and winter 2009–10. A total of 375 women with waist circumference (WC) ≥88 cm were examined to find 100 who met MeS criteria according to the National Cholesterol Education Program (NCEP)/Adult Treatment Panel (ATP) III criteria (NCEP/ATP III). Of those without MeS, 100 age- and residence area-matched women were selected as a control group. Anthropometric and laboratory evaluations were performed. Waist-to-hip ratio (WHR), body mass index (BMI), homeostatic model of insulin resistance (HOMA-IR) and body fat mass (FM) were also evaluated. Women with MeS had significantly higher BMI, waist circumference (WC) and FM but lower serum osteocalcin than controls. There was no significant difference in serum 25 hydroxyvitamin D (25[OH]D), intact parathyroid hormone (iPTH) or vitamin D status between the two groups. Serum highly sensitive C-reactive protein (hsCRP) concentration was significantly higher in the MeS group, compared to the controls (3.4 ± 3.3 vs 2.0 ± 1.9 mg/L, P < 0.001). The difference remained significant even after controlling for BMI (P = 0.011), WC (P = 0.014) and FM (P = 0.005). When comparison was made only in those subjects with insulin resistance (HOMA-IR > 2.4), hsCRP was still higher in the MeS group (n = 79) than in the control group (n = 61) (P < 0.001). When data were categorized according to vitamin D status, in the MeS group significantly higher plasma glucose concentrations were observed in subjects with vitamin D deficiency compared to those with insufficiency or sufficiency (104.0 ± 11.7, 83.0 ± 11.3 and 83.2 ± 9.9 mg/dL, respectively, P < 0.001). Interestingly, their WC or WHR did not show any significant difference. In stepwise regression analysis, 25(OH)D was the main predictor of both hsCRP and plasma glucose. Vitamin D status may, at least in part, be a determining factor of systemic inflammation and the related metabolic derangements of MeS

Efficacy of vitamin D3-fortified-yogurt drink on anthropometric, metabolic, inflammatory and oxidative stress biomarkers according to vitamin D receptor gene polymorphisms in type 2 diabetic patients: a study protocol for a randomized controlled clinical trial

<p>Abstract</p> <p>Background</p> <p>Development of type 2 diabetes mellitus (T2DM) is determined by the interactions of genetic and environmental factors. This study was designed to evaluate the possible role of VDR single nucleotide polymorphisms (SNPs) on different aspects of diabetic host response (anthropometric, metabolic, oxidative stress and inflammatory) to daily intake of vitamin D through fortified yogurt drink for 12 weeks.</p> <p>Methods/Design</p> <p>This study comprises two parts: (i) a case-control study; and (ii) an intervention trial. In the first part, VDR polymorphisms <it>(Taq1</it>, <it>FokI</it>, <it>Apa1</it>, <it>Bsm1</it>, and <it>Cdx2) </it>are determined in 350 T2DM patients and 350 non-diabetic subjects. In the second part, the possible effects of daily intake of two servings of vitamin D3-fortified yogurt drink (FYD; 500 IU vitamin D/250 mL) on some selected metabolic (including insulin resistance), inflammatory and oxidative stress biomarkers in 135 T2DM patients are assessed. To relate the resulted changes in the biomarkers to vitamin D replenishment, another group of diabetic patients (n = 45) are also included in the study who receive 2 servings of plain yogurt drink (PYD) a day. The primary outcome is serum level of 25(OH) D, which it is expected to be elevated only in FYD group. Secondary outcomes include improvements in glycemic, metabolic, inflammatory and oxidative stress biomarkers in FYD group compared to PYD group. Three VDR <it>FokI </it>polymorphisms are determined only in FYD group followed by comparison of changes in the biomarkers among these genotypic variants.</p> <p>Discussion</p> <p>The present study, at least in part, elucidates the discrepancies in the results of different vitamin D-diabetes studies pertaining to the genetic variations of the population. If VDR polymorphisms are found to influence the response to our intervention, then knowing distribution of VDR polymorphisms in both diabetic and non-diabetic populations can give a picture of the proportion of the community in whom up to 1000 IU/d vitamin D may not be effective enough to improve insulin resistance and related morbidities. Therefore, they should ideally receive further nutritional support according to their genotype.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT01236846">NCT01236846</a></p

Regular consumption of vitamin D-fortified yogurt drink (Doogh) improved endothelial biomarkers in subjects with type 2 diabetes: a randomized double-blind clinical trial

<p>Abstract</p> <p>Background</p> <p>Endothelial dysfunction has been proposed as the underlying cause of diabetic angiopathy that eventually leads to cardiovascular disease, the major cause of death in diabetes. We recently demonstrated the ameliorating effect of regular vitamin D intake on the glycemic status of patients with type 2 diabetes (T2D). In this study, the effects of improvement of vitamin D status on glycemic status, lipid profile and endothelial biomarkers in T2D subjects were investigated.</p> <p>Methods</p> <p>Subjects with T2D were randomly allocated to one of the two groups to receive either plain yogurt drink (PYD; containing 170 mg calcium and no vitamin D/250 mL, n₁= 50) or vitamin D3-fortified yogurt drink (FYD; containing 170 mg calcium and 500 IU/250 mL, n₂= 50) twice a day for 12 weeks. Anthropometric measures, glycemic status, lipid profile, body fat mass (FM) and endothelial biomarkers including serum endothelin-1, E-selectin and matrix metalloproteinase (MMP)-9 were evaluated at the beginning and after the 12-week intervention period.</p> <p>Results</p> <p>The intervention resulted in a significant improvement in fasting glucose, the Quantitative Insulin Check Index (QUICKI), glycated hemoglobin (HbA1c), triacylglycerols, high-density lipoprotein cholesterol (HDL-C), endothelin-1, E-selectin and MMP-9 in FYD compared to PYD (<it>P </it>< 0.05, for all). Interestingly, difference in changes of endothelin-1, E-selectin and MMP-9 concentrations in FYD compared to PYD (-0.35 ± 0.63 versus -0.03 ± 0.55, <it>P </it>= 0.028; -3.8 ± 7.3 versus 0.95 ± 8.3, <it>P </it>= 0.003 and -2.3 ± 3.7 versus 0.44 ± 7.1 ng/mL, respectively, <it>P </it>< 0.05 for all), even after controlling for changes of QUICKI, FM and waist circumference, remained significant for endothelin-1 and MMP-9 (<it>P </it>= 0.009 and <it>P </it>= 0.005, respectively) but disappeared for E-selectin (<it>P </it>= 0.092). On the contrary, after controlling for serum 25(OH)D, the differences disappeared for endothelin-1(<it>P </it>= 0.066) and MMP-9 (<it>P </it>= 0.277) but still remained significant for E-selectin (<it>P </it>= 0.011).</p> <p>Conclusions</p> <p>Ameliorated vitamin D status was accompanied by improved glycemic status, lipid profile and endothelial biomarkers in T2D subjects. Our findings suggest both direct and indirect ameliorating effects of vitamin D on the endothelial biomarkers.</p> <p>Trial registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT01236846">NCT01236846</a></p

Evaluation of Iron Bioavailability in Caco-2 cell Culture Model: Modification of the Original Method

Background and Objectives: In the original in vitro method for evaluation of iron bioavailability using caco-2 cell model, ferritin formation by cells is considered as a functional indicator of both absorption and utilization of iron. However, as iron is measured in the tested material and then ferritin concentration is measured in caco-2 cell lysate, it is almost impossible to have a concrete measure of iron bioavailability because the percent of absorbable iron cannot be calculated by the concentration of iron in caco-2 cell lysate. To overcome this problem, the original method was modified by using ferrous sulfate tablet as a standard and also including blank well in the cell culture plate to subtract the baseline ferritin concentration from the ferritin concentration of other wells. Materials and Methods: To evaluate iron bioavailability in this model, one kind of Iranian traditional breads (Sangak) was used. Standard curve was plotted using iron concentration and ferritin/protein ratio in the X and Y axes, respectively. Results: The standard curve showed a linear equation: Ferritin (ng)/protein (mg) = (5.96 &times; bread Fe)+ 11.55, R2=0.989. Using this equation, the bioavailability of iron from the tested bread was 79.76 &plusmn; 11.5% of ferrous sulfate. Considering that the reported iron bioavailability from ferrous sulfate is about 10%, bioavailability of iron from the bread could be regarded 8%. Conclusions: This data can be potentially usable to adjust the amount of absorbable iron in the target population for fortification programs. Keywords: Iron, Bioavailability, Caco-2 cel

The Epidemic of Poor Vitamin D Status among 9-12 Years Old Children in Tehran, 2008, Using HPLC: Need for an Urgent Action

Background and Objectives: Vitamin D deficiency/insufficiency is a global health problem. The importance of this problem is doubled in growing children because of their increased need for skeletal growth. This investigation was performed firstly to assess vitamin D status, and secondly to examine its possible relationship with sex, residing area and duration of sun exposure in 9-12 years old children of Tehran. Materials and Methods: We studied 257 randomly selected children out of 1111 children of a huge study, titled “Vitamin D and Calcium Deficiency Prevalence of Tehran’s Elementary School Children (VDPT)”, performed in fall and winter 2008 in Tehran. The children were without the history of diabetes, allergy or autoimmune disease, and any calcium, vitamin D and fish oil supplement use during the last three months. Venous blood samples were taken, and the sera were analyzed by high performance liquid chromatography (HPLC) for measuring 25-hydroxycalciferol (25(OH)D). Results: The participating children comprised of 53.7% girls and 46.3% boys from different economical areas of Tehran (40.5% poor, 26% middle and 33.5% rich). Their mean age was 10.1±0.7 years, mean duration of sun exposure was 41.2±34.6 min/day, and mean serum 25(OH)D concentration was 21.9±15.6 nmol/L. Duration of sun exposure was not significantly different either between boys and girls (p=0.220), among different residing areas (p= 0.057), or between the girls and boys of different areas. The occurrence of vitamin D deficiency was 72.4% (n=186). Vitamin D status was significantly different between boys and girls (p= 0.01) and among the areas (P= 0.004). There was no significant relation between poor vitamin D status and duration of sun exposure (p=0.411). Conclusions: The findings showed a noticeable occurrence of vitamin D deficiency/insufficiency among 9-12 years old children in Tehran. The data warrants urgent interventions. Keywords: Vitamin D, 25-hydroxycalciferol, School childre

Daily intake of yogurt drink fortified either with vitamin D alone or in combination with added calcium causes a thyroid-independent increase of resting metabolic rate in adults with type 2 diabetes: a randomized double blind clinical trial

We investigated the effect of daily intake of yogurt drink fortified with either vitamin D alone or with added calcium on resting metabolic rate (RMR), thyroid hormones and homeostatic model assessment for insulin resistance (HOMA-IR) in subjects with type 2 diabetes (T2D). A total of 75 adult subjects with T2D were randomly assigned to one of the three groups to receive either D-fortified yogurt drink (DY; 1000 IU vitamin D/d), Ca-D-fortified yogurt drink (CDY; 1000 IU vitamin D plus 500 mg calcium), or plain yogurt drink (PY) for 12 weeks. All assessments were done at the baseline and after the intervention. The concentrations of anti-thyroid peroxidase antibody (anti-TPO-Ab), intact parathyroid hormone (iPTH) and thyroid stimulating hormone (TSH) had significant decline compared with baseline values only in CDY group. The mean RMR increased in both DY and CDY groups (pThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Vitamin D Status of Tehran Taxi Drivers: How Efficient Is the Occupational Exposure to Sun? A Case-control Study

Background and Objectives: Day-shift taxi drivers have a long duration of direct sun exposure. However, the efficiency of this occupational exposure in vitamin D synthesis has not been addressed yet. The aim of this study was to assess the vitamin D status of taxi drivers in Tehran, and examine vitamin D status association with some anthropometric and circulating biomarkers. Materials and Methods: In a case control study, 53 taxi drivers and 80 apparently healthy subjects from other occupations were enrolled. Questionnaires for demographic data, supplement use, and duration of sun exposure were completed. Weight, height and waist circumference were measured. Blood samples were taken from all participants for complete blood cell count, fasting blood glucose (FBG), lipid profile, and 25-hydroxycholecalciferol (25 (OH)D) measurements. Results: Taxi drivers, as compared to the controls, had significantly higher body mass index (BMI), waist circumference (WC), serum triglycerides (TG), and 25(OH)D concentrations. Moreover, 56.6% of the drivers had more than 2 hours of sun exposure during a day. Conclusions: Despite having higher circulating concentrations of 25(OH)D, the taxi drivers had higher cardiometabolic risk factors. These findings indicate a need for nutritional education for taxi drivers. Keywords: Vitamin D, Driving, Sun exposur