Vitamin D3 and calcium absorption in the chick.
Ontology highlight
ABSTRACT:
SUBMITTER: Holdsworth ES
PROVIDER: S-EPMC1207062 | biostudies-other | 1965 Aug
REPOSITORIES: biostudies-other
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Project description:This study is a pilot study to determine whether patients with TNFα excess have decreased calcium absorption in response to calcitriol (1,25-dihydroxyvitamin D, the active form of vitamin D) compared to normal controls. This initial pilot study is being done to determine if it is feasible to conduct a study where TNFα could be blocked (e.g., by anti-TNFα therapy such as Enbrel or Remicade) to improve vitamin D dependant calcium absorption and thus bone health.
| 2036554 | ecrin-mdr-crc
Project description:1. Chick intestinal nuclei were isolated, with practically no contamination from other organelles and whole cells, by centrifugation through 2.4m-sucrose. 2. The proportions of RNA, DNA and protein of the isolated nuclei were unaffected by the vitamin D status of the birds. The RNA/DNA ratio was 0.15. 3. The incorporation of [5-(3)H]orotic acid into the rapidly labelled intestinal nuclear RNA, after a 10min. pulse of the orotic acid, was increased in vitamin D-deficient chicks only 10min. after a 125mug. dose of cholecalciferol. 4. There was no stimulation of the DNA-dependent RNA polymerase activity of the isolated nuclei from birds treated with cholecalciferol. 5. The results are discussed in relation to the changes occurring during the lag period, after administration of cholecalciferol and before Ca(2+) transport is detected, and the function of the vitamin.
| S-EPMC1185098 | biostudies-other
Project description:PurposeIn Caco-2 cells, folate uptake via the proton-coupled folate transporter (PCFT) increases significantly by a 3-day treatment with 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). Additionally, mRNA content and protein expression of the transporter OATP1A2 were increased up to ninefold with 1,25(OH)2D3. We investigated whether these in vitro findings can be confirmed in humans in vivo.MethodsTen healthy volunteers (six women) received 5 mg folic acid orally once before and once together with the last intake of a 10-day course of 0.5 μg 1,25(OH)2D3 orally. One hundred twenty milligrams fexofenadine, an OATP1A2 substrate, was taken in 1 day before the first folic acid intake, and again on the ninth day of 1,25(OH)2D3 intake. Duodenal biopsies were taken for transporter mRNA assessments once before and once on the ninth or tenth day of the vitamin D3 course. Serum folic acid and fexofenadine concentrations were quantified with a chemiluminescence immunoassay and LC-MS/MS, respectively. Pharmacokinetics were compared between periods with standard bioequivalence approaches.ResultsWhile geometric mean folic acid AUC0-2h, which mainly reflects absorption, was 0.403 and 0.414 mg/L·h before and after the vitamin D3 course (geometric mean ratio (GMR), 1.027; 90 % confidence interval (90 % CI), 0.788-1.340), the geometric mean fexofenadine AUC0-2h was 1.932 and 2.761 mg/L·h, respectively (GMR, 1.429; 90 % CI, 0.890-2.294). PCFT- and OATP1A2-mRNA expressions in duodenal biopsies were essentially unchanged.ConclusionsNo significant changes in folic acid and fexofenadine absorption were observed after a 10-day course of 1,25(OH)2D3 in humans in vivo. This study underlines the importance of confirming in vitro findings in vivo in humans.
| S-EPMC4909797 | biostudies-literature
Project description:ContextVitamin 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.ObjectiveOur objective was to study the effect of increasing doses of vitamin D3 on calcium absorption.Design and settingWe conducted a randomized double-blind placebo-controlled trial at Creighton University Medical Center, Omaha, NE.ParticipantsParticipants included 163 postmenopausal Caucasian women with vitamin D insufficiency, defined as a serum 25-hydroxyvitamin D (25OHD) below 20 ng/ml (50 nmol/liter).InterventionParticipants 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.Main outcomeWe evaluated the change in calcium absorption on vitamin D.ResultsMean 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).ConclusionsThere 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).
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Project description:The objective of this study was to assess side effects and satisfaction about OsteoCalVitFort (500 mg calcium and 400 I.U. of vitamin D3) usage.A total 186 people were participated with range age from 18 to 65 years old. Each participant received 1 pack that contains 60 OsteoCalVitFort tablet and used two tablet OsteoCalVitFort daily (1 tablet after breakfast and 1 after dinner). By a phone call, side effects and satisfaction about OsteoCalVitFort were assessed.The rate of constipating (8.0 %) and bloating (12.5 %) were decreased significantly after OsteoCalVitFort supplement intake (1.2 %, and 0.6 %, respectively). Similar results were observed in metallic taste in mouth, tiredness, weakness, loss of appetite, bone/muscle pain and mental/mood change after Calcium Vitamin D3 supplementation intake. Totally, 94 % of patients were satisfied about OsteoCalVitFort usage.The results of the research indicate despite the high quality of OsteoCalVitFort supplement, there are no side effects which have been seen in other supplements.
| S-EPMC4785726 | biostudies-other
Project description:The objective of this study was to assess side effects and satisfaction about OsteoCalVitFort (500 mg calcium and 400 I.U. of vitamin D3) usage.A total 186 people were participated with range age from 18 to 65 years old. Each participant received 1 pack that contains 60 OsteoCalVitFort tablet and used two tablet OsteoCalVitFort daily (1 tablet after breakfast and 1 after dinner). By a phone call, side effects and satisfaction about OsteoCalVitFort were assessed.The rate of constipating (8.0 %) and bloating (12.5 %) were decreased significantly after OsteoCalVitFort supplement intake (1.2 %, and 0.6 %, respectively). Similar results were observed in metallic taste in mouth, tiredness, weakness, loss of appetite, bone/muscle pain and mental/mood change after Calcium Vitamin D3 supplementation intake. Totally, 94 % of patients were satisfied about OsteoCalVitFort usage.The results of the research indicate despite the high quality of OsteoCalVitFort supplement, there are no side effects which have been seen in other supplements.
| S-EPMC4812639 | biostudies-other
Project description:High dietary intake of calcium has been classified as a probable cause of prostate cancer, although the mechanism underlying the association between dietary calcium and prostate cancer risk is unclear. The vitamin D receptor (VDR) is a key regulator of calcium absorption. In the small intestine, VDR expression is regulated by the CDX-2 transcription factor, which binds a polymorphic site in the VDR gene promoter. We examined VDR Cdx2 genotype and calcium intake, assessed by a food frequency questionnaire, in 533 African-American prostate cancer cases (256 with advanced stage at diagnosis, 277 with localized stage) and 250 African-American controls who participated in the California Collaborative Prostate Cancer Study. We examined the effects of genotype, calcium intake, and diet-gene interactions by conditional logistic regression. Compared with men in the lowest quartile of calcium intake, men in the highest quartile had an approximately twofold increased risk of localized and advanced prostate cancer (odds ratio [OR]?=?2.20, 95% confidence interval [CI]?=?1.40, 3.46), with a significant dose-response. Poor absorbers of calcium (VDR Cdx2 GG genotype) had a significantly lower risk of advanced prostate cancer (OR?=?0.41, 95% CI?=?0.19, 0.90). The gene-calcium interaction was statistically significant (p?=?0.03). Among men with calcium intake below the median (680?mg/day), carriers of the G allele had an approximately 50% decreased risk compared with men with the AA genotype. These findings suggest a link between prostate cancer risk and high intestinal absorption of calcium.
| S-EPMC3234334 | biostudies-literature
Project description:Rickets and hyperparathyroidism caused by a defective vitamin D receptor (VDR) can be prevented in humans and animals by high calcium intake, suggesting that intestinal calcium absorption is critical for 1,25(OH)(2) vitamin D [1,25(OH)(2)D(3)] action on calcium homeostasis. We assessed the rate of serum (45)Ca accumulation within 10 min of oral gavage in two strains of VDR-knockout (KO) mice (Leuven and Tokyo KO) and observed a 3-fold lower area under the curve in both KO strains. Moreover, we evaluated the expression of intestinal candidate genes involved in transcellular calcium transport. The calcium transport protein1 (CaT1) was more abundantly expressed at mRNA level than the epithelial calcium channel (ECaC) in duodenum, but both were considerably reduced (CaT1>90%, ECaC>60%) in the two VDR-KO strains on a normal calcium diet. Calbindin-D(9K) expression was decreased only in the Tokyo KO, whereas plasma membrane calcium ATPase (PMCA(1b)) expression was normal in both VDR-KOs. In Leuven wild-type mice, a high calcium diet inhibited (>90%) and 1,25(OH)(2)D(3) injection or low calcium diet induced (6-fold) duodenal CaT1 expression and, to a lesser degree, ECaC and calbindin-D(9K) expression. In Leuven KO mice, however, high or low calcium intake decreased calbindin-D(9K) and PMCA(1b) expression, whereas CaT1 and ECaC expression remained consistently low on any diet. These results suggest that the expression of the novel duodenal epithelial calcium channels (in particular CaT1) is strongly vitamin D-dependent, and that calcium influx, probably interacting with calbindin-D(9K), should be considered as a rate-limiting step in the process of vitamin D-dependent active calcium absorption.
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Project description:Low vitamin D status has been associated with multiple sclerosis (MS) prevalence and risk, but the therapeutic potential of vitamin D in established MS has not been explored. Our aim was to assess the tolerability of high-dose oral vitamin D and its impact on biochemical, immunologic, and clinical outcomes in patients with MS prospectively.An open-label randomized prospective controlled 52-week trial matched patients with MS for demographic and disease characteristics, with randomization to treatment or control groups. Treatment patients received escalating vitamin D doses up to 40,000 IU/day over 28 weeks to raise serum 25-hydroxyvitamin D [25(OH)D] rapidly and assess tolerability, followed by 10,000 IU/day (12 weeks), and further downtitrated to 0 IU/day. Calcium (1,200 mg/day) was given throughout the trial. Primary endpoints were mean change in serum calcium at each vitamin D dose and a comparison of serum calcium between groups. Secondary endpoints included 25(OH)D and other biochemical measures, immunologic biomarkers, relapse events, and Expanded Disability Status Scale (EDSS) score.Forty-nine patients (25 treatment, 24 control) were enrolled [mean age 40.5 years, EDSS 1.34, and 25(OH)D 78 nmol/L]. All calcium-related measures within and between groups were normal. Despite a mean peak 25(OH)D of 413 nmol/L, no significant adverse events occurred. Although there may have been confounding variables in clinical outcomes, treatment group patients appeared to have fewer relapse events and a persistent reduction in T-cell proliferation compared to controls.High-dose vitamin D (approximately 10,000 IU/day) in multiple sclerosis is safe, with evidence of immunomodulatory effects.This trial provides Class II evidence that high-dose vitamin D use for 52 weeks in patients with multiple sclerosis does not significantly increase serum calcium levels when compared to patients not on high-dose supplementation. The trial, however, lacked statistical precision and the design requirements to adequately assess changes in clinical disease measures (relapses and Expanded Disability Status Scale scores), providing only Class level IV evidence for these outcomes.
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