Cross-sectional evaluation of the relationship between vitamin D status and supplement use across levels of kidney function in adults.
ABSTRACT: OBJECTIVES:The objective of this study was to assess vitamin D status of US non-pregnant adults using a standardised assay across 15 mL/min/1.73 m2 increments of kidney function, report the use of dietary supplements containing vitamin D and assess relationships between vitamin D and markers of bone resorption. DESIGN:This study is a cross-sectional evaluation. SETTING:The study is from the US National Health and Nutrition Evaluation Survey in 2001-2012. PARTICIPANTS:The participants were non-institutionalised, non-pregnant adults, age ≥20 years. PRIMARY AND SECONDARY OUTCOME MEASURES:The primary outcome measure was serum 25OHD evaluated using liquid chromatography-tandem mass spectroscopy traceable to international reference standards. Secondary outcome measures were use of dietary supplements containing vitamin D and the serum intact parathyroid hormone and bone-specific alkaline phosphatase in a subset of participants. RESULTS:The median 25OHD concentration in 27 543 US non-pregnant adults was 25.7 ng/mL (range, 2.2-150.0 ng/mL). Vitamin D supplements were used by 38.0%; mean (SE)=757 (43) international units/day. The range of 25OHD concentration across groups, stratified by kidney function, was 23.0-28.1 ng/mL. The lowest concentration of 25OHD observed was in people with higher kidney function (23.0 ng/mL for estimated glomerular filtration rate >105 mL/min/1.73 m2). Only 24% of people not taking a dietary supplement had a 25OHD concentration >30 ng/mL. Serum intact parathyroid hormone inversely correlated with 25OHD within all kidney function groups. Bone-specific alkaline phosphatase was also negatively associated with 25OHD concentration. CONCLUSIONS:These data indicate that 25OHD concentrations and supplement use may be suboptimal in a significant proportion of the population, across all kidney function levels. The response of bone resorption markers further suggests that 25OHD levels could be improved. Together, these data support a re-evaluation of the 25OHD concentration associated with health in adults.
Project description:Vitamin D is often recommended for use with calcium supplements to increase absorption. There are no systematic studies of vitamin D on calcium absorption that indicate what dose should be recommended.Our objective was to study the effect of increasing doses of vitamin D3 on calcium absorption.We conducted a randomized double-blind placebo-controlled trial at Creighton University Medical Center, Omaha, NE.Participants included 163 postmenopausal Caucasian women with vitamin D insufficiency, defined as a serum 25-hydroxyvitamin D (25OHD) below 20 ng/ml (50 nmol/liter).Participants were randomized to receive one of the vitamin D3 doses, 400, 800, 1600, 2400, 3200, 4000, or 4800 IU/d, or placebo for 1 yr. Calcium intake was increased to 1200-1400 mg daily by giving daily calcium citrate.We evaluated the change in calcium absorption on vitamin D.Mean serum 25OHD increased from baseline 15.6 ng/ml (39 nmol/liter) to 46.5 ng/ml (112 nmol/liter) in subjects randomized to the highest dose of vitamin D (4800 IU). Calcium absorption was more significantly related to serum 25OHD (R2=0.50; P=0.001) than dose (R2=0.47; P=0.033). Calcium absorption of a 100-mg dose increased from 52-58% (6 mg) over a serum 25OHD range of 20-66 ng/ml (50-165 nmol/liter).There was no evidence of a threshold for reduced calcium absorption in the serum 25OHD range of 10-66 ng/ml (25-165 nmol/liter). The increase in absorbed calcium of 6% on high doses of vitamin D is so small that the same amount could be obtained from half a glass of milk (100 ml) or 100 mg elemental calcium. The results challenge assumptions about the value of adding vitamin D to increase calcium absorption except when serum 25OHD is very low that is less than 10 ng/ml (25 nmol/liter).
Project description:<h4>Context</h4>Serum 25-hydroxyvitamin D (25OHD) is lower in women with darker skin color. Is it due to lower skin production, lower absorption, or different metabolism of vitamin D?<h4>Objectives</h4>The objective of the study was to measure the effect of vitamin D3 on serum 25OHD and serum PTH in older African American women with vitamin D insufficiency and the serum 25OHD 20 ng/mL or less (<50 nmol/L). The results can be used to estimate the Recommended Dietary Allowance (RDA).<h4>Design and setting</h4>This was a randomized, double-blind placebo trial at Creighton University Medical Center and Indiana University Medical Center.<h4>Participants</h4>Participants were 110 healthy older African American women.<h4>Interventions</h4>The intervention consisted of participants randomly assigned to placebo, vitamin D3 400, 800, 1600, 2400, 3200, 4000, or 4800 IU daily; calcium supplements were given to maintain total calcium intake of 1200-1400 mg/d.<h4>Main outcome measurements</h4>Change in serum 25OHD and serum PTH levels at 12 months was measured.<h4>Results</h4>Mean baseline serum 25OHD was 13 ng/mL (33 nmol/L). On 4800 IU, serum 25OHD averaged 50 ng/mL (125 nmol/L) compared with 47 ng/mL (117 nmol/L) in Caucasian women. Serum PTH at 12 months decreased significantly (P = .008) when related to serum 25OHD but not dose. Hypercalcemia occurred in 7% and hypercalciuria in 15%. Events were unrelated to vitamin D dose.<h4>Conclusion</h4>Vitamin D3 800 IU increased serum 25OHD greater than 20 ng/mL (>50 nmol/L) in 97.5% of the African American women just as it did in the Caucasian women, and therefore, the RDA is the same for both groups. Because absorption and metabolism of oral vitamin D absorption is similar in both groups, lower levels of serum 25OHD in African Americans must be due to lower production of vitamin D in skin.
Project description:Vitamin D deficiency and insufficiency may contribute to musculoskeletal symptoms and bone loss observed in women taking aromatase inhibitors (AIs). This study was conducted to determine the prevalence of suboptimal vitamin D levels in women initiating adjuvant letrozole for breast cancer and to determine whether supplementation with 50,000 IU of vitamin D3 weekly could reduce musculoskeletal symptoms and fatigue in women who have suboptimal vitamin D levels. Sixty women about to begin an adjuvant AI were enrolled. Baseline 25OHD levels were obtained, and women completed symptom questionnaires. They were then started on letrozole, along with standard dose calcium and vitamin D. Four weeks later, women with baseline 25OHD levels </=40 ng/ml started additional vitamin D3 supplementation at 50,000 IU per week for 12 weeks. 25OHD levels were re-assessed at 4, 10, and 16 weeks; the questionnaires were repeated at weeks 4 and 16. At baseline, 63% of women exhibited vitamin D deficiency (<20 ng/ml) or insufficiency (20-31 ng/ml). 25OHD levels >40 ng/ml were achieved in all 42 subjects who received 12 weeks of supplementation with 50,000 IU vitamin D3 weekly, with no adverse effects. After 16 weeks of letrozole, more women with 25OHD levels >66 ng/ml (median level) reported no disability from joint pain than did women with levels <66 ng/ml (52 vs. 19%; P = 0.026). Vitamin D deficiency and insufficiency are prevalent in post-menopausal women initiating adjuvant AI. Vitamin D3 supplementation with 50,000 IU per week is safe, significantly increases 25OHD levels, and may reduce disability from AI-induced arthralgias.
Project description:Vitamin D levels have been linked to various health outcomes including reproductive disorders. The purpose of this study was to explore the association between serum vitamin D level (25-hydroxy-vitamin D, or 25OHD) and semen and hormonal parameters. This is a cross-sectional study that included 170 healthy men recruited for the study of spermatogenesis from the general population. Men completed general and reproductive health questionnaires, and donated blood and semen samples. The main measures were hormonal (total and free testosterone, sex hormone-binding globulin, estradiol, follicle-stimulating hormone and luteinizing hormone) and semen parameters, adjusted (n=147) for age, body mass index (BMI), season, alcohol intake and smoking, in relation to categories of vitamin D levels, determined a priori. The mean age of the study population was 29.0±8.5 years and mean BMI was 24.3±3.2 kg m(-2). The mean 25OHD was 34.1±15.06 ng ml(-1). BMI showed a negative association with 25OHD. Sperm concentration, sperm progressive motility, sperm morphology, and total progressively motile sperm count were lower in men with '25OHD≥50 ng ml(-1)' when compared to men with '20 ng ml(-1)≤25OHD<50 ng ml(-1)'. Total sperm count and total progressive motile sperm count were lower in men with '25OHD<20 ng ml(-1)' when compared to men with '20 ng ml(-1)≤25OHD<50 ng ml(-1)'. The adjusted means of various hormonal parameters did not show statistical difference in the different categories of 25OHD. In conclusion, serum vitamin D levels at high and low levels can be negatively associated with semen parameters.
Project description:Background. ?Vitamin D insufficiency is prevalent in human immunodeficiency virus-positive (HIV+) persons. Human immunodeficiency virus and antiretroviral therapy (ART) may create unique risk factors, and the optimal vitamin D repletion and maintenance regimen in HIV+ persons remains unclear. Methods. ?Human immunodeficiency virus-positive adults on suppressive ART underwent routine serum 25-hydroxyvitamin D (25OHD) screening. Persons with vitamin D insufficiency (25OHD <30 ng/mL) received open-label, oral vitamin D3 50 000 international units (IU) twice weekly for 5 weeks, then 2000 IU daily to complete 12 weeks. We predicted 70% (95% confidence interval, 60%-80%) repletion to 25OHD ?30 ng/mL compared with 85% among historical HIV-negative controls. Eighty participants provided 91% power to detect this difference. Ability to maintain 25OHD ?30 ng/mL after 24 weeks was also assessed. Results. ?Baseline characteristics were similar between the 82 vitamin D insufficient and 40 sufficient persons enrolled: 95% male, 60% white, 88% nonsmokers, median age 49 years, body mass index 26 kg/m(2), and CD4(+) T lymphocyte count 520 cells/mm(3). After 12 weeks, 81% (66 of 82) of insufficient persons achieved 25OHD ?30 ng/mL (P = .32 vs historical controls), with only older age (odds ratio [OR] = 1.06; P = .06), higher baseline 25OHD (OR = 1.14; P < .01), white race (OR = 3.39; P = .04), and current smoking (OR = 0.25; P = .06) associated with successful repletion. After 24 weeks, 73% (48 of 66) maintained 25OHD ?30 ng/mL, with tenofovir (OR = 5.00; P = .01) and abacavir use (OR = 0.23; P = .02) associated with success and failure, respectively, to maintain 25OHD levels. Conclusions. ?The 25OHD repletion rates were comparable between HIV+ adults on suppressive ART and historical HIV-negative controls, indicating that successful oral repletion can be achieved in this population.
Project description:Vitamin D insufficiency [serum 25-hydroxyvitamin D (25OHD) concentration less than 20 ng/ml] is prevalent among children with inflammatory bowel disease (IBD), and its treatment has not been studied.The aim of this study was to compare the efficacy and safety of three vitamin D repletion regimens.We conducted a randomized, controlled clinical trial from November 2007 to June 2010 at the Clinical and Translational Study Unit of Children's Hospital Boston. The study was not blinded to participants and investigators.Eligibility criteria included diagnosis of IBD, age 5-21, and serum 25OHD concentration below 20 ng/ml. Seventy-one patients enrolled, 61 completed the trial, and two withdrew due to adverse events.Patients received orally for 6 wk: vitamin D(2), 2,000 IU daily (arm A, control); vitamin D(3), 2,000 IU daily (arm B); vitamin D(2), 50,000 IU weekly (arm C); and an age-appropriate calcium supplement.We measured the change in serum 25OHD concentration (?25OHD) (ng/ml). Secondary outcomes included change in serum intact PTH concentration (?PTH) (pg/ml) and the adverse event occurrence rate.After 6 wk, ?25OHD ± se was: 9.3 ± 1.8 (arm A); 16.4 ± 2.0 (arm B); 25.4 ± 2.5 (arm C); P (A vs. C) = 0.0004; P (A vs. B) = 0.03. ?PTH ± SE was -5.6 ± 5.5 (arm A); -0.1 ± 4.2 (arm B); -4.4 ± 3.9 (arm C); P = 0.57. No participant experienced hypercalcemia or hyperphosphatemia, and the prevalence of hypercalciuria did not differ among arms at follow-up.Oral doses of 2,000 IU vitamin D(3) daily and 50,000 IU vitamin D(2) weekly for 6 wk are superior to 2,000 IU vitamin D(2) daily for 6 wk in raising serum 25OHD concentration and are well-tolerated among children and adolescents with IBD. The change in serum PTH concentration did not differ among arms.
Project description:Hematopoietic cell transplantation (HCT) may be detrimental to bone health and vitamin D status in children.We conducted a prospective, multicenter cohort study to identify changes in bone health markers during the first 100 days after allogeneic HCT in 26 children. Bone mineral density (BMD), bone mineral content (BMC), and serum 25-hydroxyvitamin D (25OHD) concentrations were measured at baseline, 30 days, and 100 days after HCT.Mean (SD) BMD and BMC Z-scores (-0.48 ± 1.09 and -0.98 ± 1.26, respectively) were normal at baseline. Repeated-measures analysis revealed significant declines in BMD and BMC Z-scores over the 100 day study period, when adjusted for age, sex, Tanner stage, lean mass, fat mass, resting energy expenditure, total energy intake, insulin sensitivity, serum phosphorus, and inpatient steroid intake. Adjusted mean (SE) 25OHD concentrations declined from 29.2 (3.1)?ng/ml at baseline, to 17.7 (1.8)?ng/ml at 100 days after HCT. Vitamin D deficiency (25OHD <20?ng/ml) was present in 50% of patients 100 days after HCT.Significant bone loss and vitamin D deficiency occur in children in the first 100 days following allogeneic HCT. Strategies to diminish acute bone loss during HCT in children are needed.
Project description:Objectives:Obese, African-American (AA) adolescents are at increased risk for vitamin D deficiency. The primary objective of this pilot study was to examine the effect of vitamin D supplementation upon 25-hydroxy vitamin D (25OHD) levels in obese, AA adolescents. Methods:A randomized, double-blinded, controlled pilot study included 26 obese (BMI???95%ile), vitamin D deficient (25OHD?<?20?ng/mL), pubertal AA adolescents (ages 12-17). Subjects received cholecalciferol 1000?IU or 5000?IU daily for 3?months. Serum 25OHD, vitamin D binding protein, parathyroid hormone, and cardiometabolic risk markers were obtained at baseline and post-treatment. Results:Of 39 subjects enrolled, 26 (67%) were vitamin D deficient (mean 25OHD 12.0?±?3.8?ng/mL) at baseline and were randomized, with 22 completing the study. Sex, age, season, pubertal stage, BMI, insulin resistance (HOMA-IR) and 25OHD were similar at baseline between the 1000?IU and 5000?IU groups. Post-treatment, 25OHD increased less in the 1000?IU group (5.6?ng/mL, p?=?0.03) vs. the 5000?IU group (15.6?ng/mL, p?=?0.002). 83% of the 5000?IU group and 30% of the 1000?IU group reached post-treatment 25OHD???20?ng/mL (p?=?0.01); 50% of the 5000?IU group, but no subject from the 1000?IU group, achieved 25OHD???30?ng/mL (p?=?0.009). We detected no group differences in mineral metabolites or cardiometabolic risk markers following supplementation. Conclusions:Cholecalciferol dosing in excess of the current Institute of Medicine dietary reference intakes was required to achieve 25OHD levels ?20?ng/mL in obese, AA adolescents. Supplementation of 5000?IU may be required to achieve the desired goal.
Project description:<h4>Background</h4>Vitamin D is a fat-soluble hormone necessary for calcium homeostasis. Recently, studies have demonstrated that vitamin D may be important to the health of the cardiovascular system.<h4>Methods</h4>Adults ? 50 years of age with heart failure were recruited for assessment of serum 25-hydroxyvitamin D (25OHD) concentrations. Cardiopulmonary exercise testing was used to assess functional capacity. Proximal muscle strength was evaluated with a Biodex isokinetic dynamometer [corrected] (Biodex, Shirley, NY), and health status was assessed with the Kansas City Cardiomyopathy Questionnaire. Univariate associations between physical performance and health status measures and 25OHD followed by a linear regression model were used to study associations, adjusting for other potential explanatory variables.<h4>Results</h4>Forty adults 67.8 ± 10.9 years of age (55% women and 57.5% African American) with mean ejection fraction 40% were analyzed (New York Heart Association class II in 70% and class III in 30%). Comorbidities included 77.5% hypertension and 47.5% diabetes. The mean 25OHD concentration was 18.5 ± 9.1 ng/mL, and mean peak Vo?, 14 ± 4 mL/kg/min. In univariate regression analysis, 25OHD was positively associated with peak Vo? (P = .045). Multivariable regression analysis sustained positive association between 25OHD and peak Vo? (P = .044) after adjusting for age, race, and respiratory exchange ratio (adjusted R² = 0.32). Association between proximal muscle strength with the 25OHD concentration was not significant. The Kansas City Cardiomyopathy Questionnaire physical limitation domain score was negatively associated with 25OHD (P = .04) but was not sustained in multivariable analysis.<h4>Conclusions</h4>25-Hydroxyvitamin D may be an important marker or modulator of functional capacity in patients with heart failure. Randomized controlled trials are needed to assess the effect of vitamin D repletion on functional performance.
Project description:<h4>Objectives</h4>Our study aimed at assessing the prevalence and determinants of vitamin D deficiency (25-hydroxy-vitamin D [25(OH)D]?<?20?ng/mL) in pregnant women in the first trimester living in Switzerland.<h4>Methods</h4>From September 2014 through December 2015, 204 pregnant women were conveniently recruited during their first clinical appointment at the Clinic of Obstetrics of the University Hospital Zurich (between week 6 and 12 of pregnancy). Blood samples were collected and a questionnaire focusing on lifestyle and skin colour was completed face-to-face with the responsible physician. Logistic regression analyses were performed with vitamin D status as dependent variable.<h4>Results</h4>63.2% of the participating women were vitamin D deficient, and the median vitamin D concentration in the overall sample was 17.1?ng/mL [Q1, Q3: 9.78, 22.3]. The highest proportions of vitamin D deficiency were detected in women originating from Africa and Middle East (91.4% deficient, median vitamin D concentration of 10.7?ng/mL [Q1, Q3: 6.55, 14.45]) and from South-East Asia/Pacific (88.5% deficient, median vitamin D concentration of 8.4?ng/mL [Q1, Q3: 6.10, 14.88]). Multivariable logistic regression showed that significant risk factors of vitamin D deficiency were country of origin (women born in Switzerland and Germany had a lower risk than women born in other countries), smoking status (lower risk for former smokers) and intake of vitamin D supplements.<h4>Conclusions</h4>Our results confirm a high prevalence of vitamin D deficiency in this Swiss cohort, in particular in women coming from Asian and African countries, and underline the importance of appropriate counseling and vitamin D supplementation in early pregnancy.