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Zhu A, Kuznia S, Niedermaier T, Holleczek B, Schöttker B, Brenner H. Consistent Inverse Associations of Total, “Bioavailable”, Free, and “Non-Bioavailable” Vitamin D with Incidence of Diabetes among Older Adults with Lower Baseline HbA1c (≤6%) Levels. Nutrients 2022; 14:nu14163282. [PMID: 36014788 PMCID: PMC9413175 DOI: 10.3390/nu14163282] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 08/04/2022] [Accepted: 08/08/2022] [Indexed: 11/16/2022] Open
Abstract
Background: Serum 25-hydroxyvitamin (25(OH)D) levels are inversely associated with risk of diabetes. The “free hormone hypothesis” suggests potential effects to be mainly related to concentrations of “bioavailable” and free rather than total 25(OH)D. We assessed associations of serum concentrations of vitamin D-binding protein (VDBP), as well as total “bioavailable”, complementary “non-bioavailable”, and free 25(OH)D, with the risk of developing diabetes among non-diabetic older adults in a large population-based cohort study in Germany. Methods: We included 4841 non-diabetic older adults aged 50–75 years at the baseline exam from the ESTHER cohort conducted in Saarland, Germany, in 2001–2002. Concentrations of “bioavailable” and free 25(OH)D were derived from serum concentrations of VDBP, total 25(OH)D, and albumin. Incidence of diabetes was ascertained during up to 14 years of follow-up. Associations were quantified by multivariable Cox proportional hazards regression models with comprehensive confounder adjustment. Results: During a median follow-up of 10.6 years, 837 non-diabetic participants developed diabetes. We observed similar inverse associations with developing diabetes for VDBP (hazard ratio (HR) for lowest versus highest quintile: 1.37, 95% confidence interval (CI): 1.09, 1.72), total 25(OH)D (HR: 1.31, 95% CI: 1.03, 1.66), and “non-bioavailable” 25(OH)D (HR: 1.30, 95% CI: 1.02, 1.65). Associations were smaller and statistically insignificant for “bioavailable” and free 25(OH)D. However, associations of total “non-bioavailable”, “bioavailable”, and free 25(OH)D with incidence of diabetes were much stronger among, and essentially restricted to, participants with lower baseline HbA1c (≤6%) levels. Conclusions: This large prospective cohort study of older Caucasian adults, in agreement with results from randomized trials and Mendelian randomization studies, supports a protective effect of vitamin D against development of diabetes. The “free hormone theory” may not be relevant in this context. However, our results underline the importance of adequate vitamin D status among those who have not yet shown any sign of impaired glucose tolerance.
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Affiliation(s)
- Anna Zhu
- Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
- Medical Faculty Heidelberg, Heidelberg University, 69120 Heidelberg, Germany
| | - Sabine Kuznia
- Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
- Medical Faculty Heidelberg, Heidelberg University, 69120 Heidelberg, Germany
| | - Tobias Niedermaier
- Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | | | - Ben Schöttker
- Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
- Network Aging Research, Heidelberg University, 69115 Heidelberg, Germany
| | - Hermann Brenner
- Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
- Network Aging Research, Heidelberg University, 69115 Heidelberg, Germany
- Division of Preventive Oncology, German Cancer Research Center (DKFZ) and National Center for Tumor Diseases (NCT), 69120 Heidelberg, Germany
- German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
- Correspondence: ; Tel.: +49-6221421300
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Karacan Küçükali G, Gülbahar Ö, Özalkak Ş, Dağlı H, Ceylaner S, Aycan Z, Savaş Erdeve Ş. Is Bioavailable Vitamin D Better Than Total Vitamin D to Evaluate Vitamin D Status in Obese Children? J Clin Res Pediatr Endocrinol 2021; 13:391-399. [PMID: 34013709 PMCID: PMC8638623 DOI: 10.4274/jcrpe.galenos.2020.2021.0230] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
INTRODUCTION Free hormones are biologically more active in target tissues. Thus, measurement of vitamin D taking into account bioavailability and free vitamin D may be preferable, especially when evidence is contradictory, as in obese children. In order to assess bioavailablity and free vitamin D, using a previously reported formula, vitamin D-binding protein (VDBP) level was measured and VDBP polymorphisms were also evaluated because of variations in binding affinity. METHODS Eighty-four obese and 78 healthy children were included. Anthropometry, calcium, phosphorus, alkaline-phosphatase, parathyroid hormone (PTH), 25 hydroxyvitamin D [25(OH)D], bioavailable-free vitamin D, and VDBP concentration and polymorphism were evaluated in the whole group. RESULTS Obese girls had significantly higher PTH than normal weight girls (p=0.001). Regardless of gender, obese children had significantly higher concentrations of VDBP (p=0.008) and PTH (p=0.002). When samples taken in winter were analyzed, PTH and VDBP were found to be higher and bioavailable and free vitamin D lower in the obese group. There was no difference in terms of total vitamin D between groups during the winter season. CONCLUSION While total, free, and bioavailable vitamin D in the obese group was similar to the control group in autumn, free and bioavailable vitamin D in the winter was lower in the obese than the control group. In addition, PTH was higher in the obese group in both autumn and winter. Therefore, more research is needed to evaluate the variability of free and bioavailable vitamin D according to body habitus, season and the effect any differences may have.
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Affiliation(s)
- Gülin Karacan Küçükali
- University of Health Science Turkey, Dr. Sami Ulus Maternity, Child Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey,* Address for Correspondence: University of Health Science Turkey, Dr. Sami Ulus Maternity, Child Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey Phone: +90 533 764 84 26 E-mail:
| | - Özlem Gülbahar
- Gazi University Faculty of Medicine, Department of Clinical Biochemistry, Ankara, Turkey
| | - Şervan Özalkak
- University of Health Science Turkey, Dr. Sami Ulus Maternity, Child Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey
| | - Hasan Dağlı
- Gazi University Faculty of Medicine, Department of Clinical Biochemistry, Ankara, Turkey
| | | | - Zehra Aycan
- University of Health Science Turkey, Dr. Sami Ulus Maternity, Child Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey
| | - Şenay Savaş Erdeve
- University of Health Science Turkey, Dr. Sami Ulus Maternity, Child Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey
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Rivera-Paredez B, Hidalgo-Bravo A, León-Reyes G, León-Maldonado LS, Aquino-Gálvez A, Castillejos-López M, Denova-Gutiérrez E, Flores YN, Salmerón J, Velázquez-Cruz R. Total, Bioavailable, and Free 25-Hydroxyvitamin D Equally Associate with Adiposity Markers and Metabolic Traits in Mexican Adults. Nutrients 2021; 13:nu13103320. [PMID: 34684322 PMCID: PMC8539380 DOI: 10.3390/nu13103320] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/24/2021] [Accepted: 09/15/2021] [Indexed: 12/17/2022] Open
Abstract
Epidemiological studies suggest a relationship between total 25-hydroxyvitamin D [25(OH)D], adiposity, and metabolic traits. The bioavailability of 25(OH)D is regulated by the albumin, vitamin D binding protein (VDBP), and variants of the GC gene. Therefore, it is not clear if bioavailable or free 25(OH)D offer additional benefits compared to total 25(OH)D when estimating the magnitude of these associations. Our aim was to evaluate the association between 25(OH)D (total, free and bioavailable) with adiposity and metabolic traits. This was a cross-sectional study of 1904 subjects from the Health Workers Cohort Study from Mexico. Free and bioavailable 25(OH)D were calculated based on VDBP and albumin determinations, using a formula adjusted for the GC gene diplotypes. Adiposity and metabolic traits were measured with standardized procedures. Free and bioavailable 25(OH)D levels correlated with total 25(OH)D, r = 0.71 and 0.70, respectively (p < 0.001). Total, bioavailable and free 25(OH)D levels were negatively associated with the adiposity marker (visceral adiposity index) and metabolic traits (metabolic syndrome, type 2 diabetes, triglycerides, triglycerides/HDL-c ratio, and triglycerides/glucose index) in multivariate regression models (ORs = 0.73 to 0.96). Our findings suggest that free and bioavailable 25(OH)D do not offer additional advantages over total 25(OH)D regarding its association with adiposity and several metabolic traits in Mexican adults.
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Affiliation(s)
- Berenice Rivera-Paredez
- Research Center in Policies, Population and Health, School of Medicine, National Autonomous University of Mexico (UNAM), Mexico City 04510, Mexico; (B.R.-P.); (J.S.)
| | - Alberto Hidalgo-Bravo
- Department of Genetics, National Institute of Rehabilitation (INR), Mexico City 014389, Mexico;
| | - Guadalupe León-Reyes
- Genomics of Bone Metabolism Laboratory, National Institute of Genomic Medicine (INMEGEN), Mexico City 14610, Mexico;
| | - Leith S. León-Maldonado
- National Council for Science and Technology (CONACyT)—Center for Population Health Research, National Institute of Public Health (INSP), Cuernavaca 62100, Morelos, Mexico;
| | - Arnoldo Aquino-Gálvez
- National Institute of Respiratory Diseases “Ismael Cosío Villegas” (INER), Mexico City 14080, Mexico; (A.A.-G.); (M.C.-L.)
| | - Manuel Castillejos-López
- National Institute of Respiratory Diseases “Ismael Cosío Villegas” (INER), Mexico City 14080, Mexico; (A.A.-G.); (M.C.-L.)
| | - Edgar Denova-Gutiérrez
- Nutrition and Health Research Center, National Institute of Public Health (INSP), Cuernavaca 62000, Morelos, Mexico;
| | - Yvonne N. Flores
- Epidemiological and Health Services Research Unit, Mexican Institute of Social Security, Cuernavaca 62000, Morelos, Mexico;
- UCLA Department of Health Policy and Management and Kaiser Permanente Center for Health Equity, Fielding School of Public Health, Los Angeles, CA 90095, USA
- UCLA Cancer Prevention and Control Research Center, Fielding School of Public Health and Jonsson Comprehensive Cancer Center, Los Angeles, CA 90095, USA
| | - Jorge Salmerón
- Research Center in Policies, Population and Health, School of Medicine, National Autonomous University of Mexico (UNAM), Mexico City 04510, Mexico; (B.R.-P.); (J.S.)
| | - Rafael Velázquez-Cruz
- Genomics of Bone Metabolism Laboratory, National Institute of Genomic Medicine (INMEGEN), Mexico City 14610, Mexico;
- Correspondence: ; Tel.: +52-(55)-5350-1900; Fax: +52-(55)-5350-1999
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Wang D, Yu S, Zou Y, Zhang Y, Qiu L, Chen L. Distribution of free 25OHD in elderly population based on LC-MS/MS. J Steroid Biochem Mol Biol 2020; 200:105672. [PMID: 32311429 DOI: 10.1016/j.jsbmb.2020.105672] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 04/04/2020] [Accepted: 04/06/2020] [Indexed: 02/09/2023]
Abstract
Vitamin D deficiency is a global health problem in all age groups, especially in the elderly population. Serum 25(OH)D is the biomarker to assess vitamin D nutrition status. However, the free hormone hypothesis proposes that free vitamin D might be a more reliable marker of vitamin D nutrition status. Thus, the aims of this study were to (1) evaluate the distribution of free 25OHD in elderly individuals, and (2) to assess the association between free 25OHD and total 25(OH)D, 1,25(OH)2D, 24,25(OH)2D, calcium (Ca), alkaline phosphatase (ALP), and phosphorus (P) in elderly population. A total of 312 healthy elderly individuals were enrolled in this study and residual serum samples were collected. Free 25OHD, total 25(OH)D, 24,25(OH)2D, and 1,25(OH)2D were measured using LC-MS/MS. Other biochemical analytes were measured using automatic analyzers. Our results showed that with an increase in the levels of total 25(OH)D, the levels of 25(OH)D3, 1,25(OH)2D, 24,25(OH)D, and free 25OHD increased, whereas the levels of 25(OH)D/24,25(OH)2D decreased. Further, we observed that the level of free 25OHD was significantly positively correlated with the total 25(OH)D (r = 0.226, P < 0.001), 25(OH)D (r = 0.221, P < 0.001), and 24,25(OH)2D (r = 0.231, P < 0.001) but was negatively correlated with 25(OH)D/24,25(OH)2D (r = -0.185, P < 0.01). Moreover, the total 25(OH)D, 25(OH)D3, 24,25(OH)2D, and 25(OH)D/24,25(OH)2D were correlated with 1,25(OH)2D. Furthermore, free 25OHD was positively correlated with creatinine (Cr) (r = 0.227, P <0.001). Our results showed a narrower distribution for free 25OHD than that reported by direct measurement techniques and confirmed the correlation between free 25OHD and total 25(OH)D.
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Affiliation(s)
- Danchen Wang
- Department of Laboratory Medicine, Peking Union Medical College Hospital, Peking Union Chinese Academy of Medical Sciences, No. 1 Shuaifu Yuan, Dongcheng District, Beijing 100730, PR China
| | - Songlin Yu
- Department of Laboratory Medicine, Peking Union Medical College Hospital, Peking Union Chinese Academy of Medical Sciences, No. 1 Shuaifu Yuan, Dongcheng District, Beijing 100730, PR China
| | - Yutong Zou
- Department of Laboratory Medicine, Peking Union Medical College Hospital, Peking Union Chinese Academy of Medical Sciences, No. 1 Shuaifu Yuan, Dongcheng District, Beijing 100730, PR China
| | - Yuanyuan Zhang
- Shanghai AB Sciex Analytical Instrument Trading Co., Ltd., Beijing, PR China
| | - Ling Qiu
- Department of Laboratory Medicine, Peking Union Medical College Hospital, Peking Union Chinese Academy of Medical Sciences, No. 1 Shuaifu Yuan, Dongcheng District, Beijing 100730, PR China.
| | - Limeng Chen
- Department of Nephrology, Peking Union Medical College Hospital, Peking Union Chinese Academy of Medical Sciences, No. 1 Shuaifu Yuan, Dongcheng District, Beijing 100730, PR China.
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Al-Khalidi B, Kuk JL, Ardern CI. Lifetime risk of cardiometabolic mortality according to vitamin D status of middle and older-aged adults: NHANES III mortality follow-up. J Steroid Biochem Mol Biol 2019; 186:34-41. [PMID: 30219735 DOI: 10.1016/j.jsbmb.2018.09.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 08/26/2018] [Accepted: 09/12/2018] [Indexed: 12/20/2022]
Abstract
The predictive value of total 25-hydroxyvitamin D (25(OH)D, a biomarker of vitamin D status) in relation to lifetime risk of cardiometabolic mortality is not known. The purpose of this study was to determine the association between standardized and annualized total 25(OH)D levels and lifetime risk for cardiometabolic mortality in middle- to older-aged adults. In this study, we followed up 7958 participants in the Third National Health and Nutrition Examination Survey from 1988 to 1994 (NHANES III) until the occurrence of cardiometabolic death or attainment of 95 years of age (median follow-up 17.9 years, 1371 cardiometabolic-deaths). Lifetime risks were estimated according to recommended total 25(OH)D cutoffs by national guidelines, and a combination of total 25(OH)D status and traditional risk factor burden. We also explored variation in lifetime risk estimates by levels of body mass index (BMI). The results of this study showed that annualized total 25(OH)D <30 nmol/L was associated with high lifetime risk of cardiometabolic mortality (40%). Lifetime risks of cardiometabolic mortality were similar for annualized levels between 30-< 50 nmol/L, 50-< 75 nmol/L and ≥75 nmol/L (31-33%). Lifetime risk was highest among participants with annualized total 25(OH)D <30 nmol/L and ≥2 major traditional risk factors (45%), whereas lifetime risk was lowest among participants with annualized 25(OH)D ≥30 nmol/L and low-intermediate risk factors (28%). Lifetime risk estimates were similar across BMI categories. In conclusion, a single measurement of vitamin D deficiency (annualized levels <30 nmol/L) in middle- to older-aged adults is a strong predictor of high lifetime risk for cardiometabolic mortality, particularly among those with high burden of traditional risk factors.
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Affiliation(s)
- Banaz Al-Khalidi
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada.
| | - Jennifer L Kuk
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada
| | - Chris I Ardern
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada
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Abstract
OBJECTIVE Vitamin D plays an important role in bone metabolism. There is now evidence that a higher serum level of 25-hydroxyvitamin D (25[OH]D) is associated with a lower risk of developing type 2 diabetes mellitus, because it provides better glycemic control, possibly by promoting greater insulin sensitivity, and also by improving pancreatic beta cell function. The objective of the present study was to evaluate the possible association between 25(OH)D sufficiency and glycemia. METHODS This was a cross-sectional study involving 680 women, 35 to 74 years of age, selected through systematic sampling. From each participant, fasting blood samples were collected for the determination of 25(OH)D and glucose levels. RESULTS The mean fasting blood glucose level was 105 mg/dL (range 26-401 mg/dL). Fasting serum levels of 25(OH)D were <30 ng/mL in 65.4% of the participants and <20 ng/mL in 25.6%. A serum 25(OH)D level <30 ng/mL was positively associated with a blood glucose level ≥100 mg/dL (odds ratio [OR] 1.29, 95% confidence interval [CI] 1.05-1.57), as was a serum 25(OH)D level <20 ng/mL (OR 1.25, 95% CI 1.04-1.50). CONCLUSIONS Lower serum 25(OH)D concentrations appear to be associated with a high blood glucose levels.
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Chun RF, Shieh A, Gottlieb C, Yacoubian V, Wang J, Hewison M, Adams JS. Vitamin D Binding Protein and the Biological Activity of Vitamin D. Front Endocrinol (Lausanne) 2019; 10:718. [PMID: 31708871 PMCID: PMC6821678 DOI: 10.3389/fendo.2019.00718] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 10/04/2019] [Indexed: 12/15/2022] Open
Abstract
Vitamin D has a long-established role in bone health. In the last two decades, there has been a dramatic resurgence in research interest in vitamin D due to studies that have shown its possible benefits for non-skeletal health. Underpinning the renewed interest in vitamin D was the identification of the vital role of intracrine or localized, tissue-specific, conversion of inactive pro-hormone 25-hydroxyvitamin D [25(OH)D] to active 1,25-dihydroxyvitamin D [1,25(OH)2D]. This intracrine mechanism is the likely driving force behind vitamin D action resulting in positive effects on human health. To fully capture the effect of this localized, tissue-specific conversion to 1,25(OH)2D, adequate 25(OH)D would be required. As such, low serum concentrations of 25(OH)D would compromise intracrine generation of 1,25(OH)2D within target tissues. Consistent with this is the observation that all adverse human health consequences of vitamin D deficiency are associated with a low serum 25(OH)D level and not with low 1,25(OH)2D concentrations. Thus, clinical investigators have sought to define what concentration of serum 25(OH)D constitutes adequate vitamin D status. However, since 25(OH)D is transported in serum bound primarily to vitamin D binding protein (DBP) and secondarily to albumin, is the total 25(OH)D (bound plus free) or the unbound free 25(OH)D the crucial determinant of the non-classical actions of vitamin D? While DBP-bound-25(OH)D is important for renal handling of 25(OH)D and endocrine synthesis of 1,25(OH)2D, how does DBP impact extra-renal synthesis of 1,25(OH)2D and subsequent 1,25(OH)2D actions? Are their pathophysiological contexts where total 25(OH)D and free 25(OH)D would diverge in value as a marker of vitamin D status? This review aims to introduce and discuss the concept of free 25(OH)D, the molecular biology and biochemistry of vitamin D and DBP that provides the context for free 25(OH)D, and surveys in vitro, animal, and human studies taking free 25(OH)D into consideration.
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Affiliation(s)
- Rene F. Chun
- Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
- *Correspondence: Rene F. Chun
| | - Albert Shieh
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Carter Gottlieb
- Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Vahe Yacoubian
- Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Jeffrey Wang
- Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Martin Hewison
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom
| | - John S. Adams
- Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
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Jorde R. The Role of Vitamin D Binding Protein, Total and Free 25-Hydroxyvitamin D in Diabetes. Front Endocrinol (Lausanne) 2019; 10:79. [PMID: 30837950 PMCID: PMC6389604 DOI: 10.3389/fendo.2019.00079] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 01/30/2019] [Indexed: 12/16/2022] Open
Abstract
Vitamin D is important for bone health, but may also have extra-skeletal effects. Vitamin D and its binding protein DBP have immunological effects and may therefore be important in the development of type 1 diabetes (T1DM), and low serum levels of 25-hydroxyvitamin D (25(OH)D) are associated with later development of type 2 diabetes (T2DM). However, it has so far been difficult to convincingly show an effect of vitamin D supplementation on prevention or treatment of diabetes. The serum level of 25(OH)D has traditionally been used as a marker of a subject's vitamin D status. This measurement includes both 25(OH)D bound to DBP and albumin as well as the free from of 25(OH)D. However, according to the free hormone hypothesis, the free form is the biologically active. Previously the free form of 25(OH)D had to be calculated based on measurements of 25(OH)D, DBP, and albumin, but recently a method for direct measurement of free 25(OH)D has become commercially available. This is important in clinical conditions where the amount of DBP is affected, and has caused a renewed interest in which vitamin D metabolite to measure in clinical situations. In the present review the relations between DBP, total and free 25(OH)D in T1DM and T2DM are described.
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Affiliation(s)
- Rolf Jorde
- Tromsø Endocrine Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway
- Division of Internal Medicine, University Hospital of North Norway, Tromsø, Norway
- *Correspondence: Rolf Jorde
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Pilz S, Obeid R, Schwetz V, Trummer C, Pandis M, Lerchbaum E, Pieber TR, Obermayer-Pietsch B, Wilhelm M, Hahn A, Schön C. Hormonal Contraceptive Use Is Associated With Higher Total but Unaltered Free 25-Hydroxyvitamin D Serum Concentrations. J Clin Endocrinol Metab 2018; 103:2385-2391. [PMID: 29672719 DOI: 10.1210/jc.2018-00336] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 04/11/2018] [Indexed: 11/19/2022]
Abstract
CONTEXT Intake of hormonal contraceptives (HC) is associated with higher total 25-hydroxyvitamin D [25(OH)D] concentrations, but the effect of HC on free 25(OH)D is unclear. OBJECTIVE We investigated whether free 25(OH)D concentrations differ according to use of HC. DESIGN This is a post hoc analysis of a randomized open trial. SETTING This study was conducted from 13 January to 9 May, 2016, at a clinical research organization in Esslingen, Germany. PARTICIPANTS We included 201 apparently healthy women of childbearing age. INTERVENTION Participants were randomly assigned to receive a daily multimicronutrient supplement for 8 weeks; the supplement contained 200 IU (n =100) or 800 IU (n = 101) of vitamin D3. MAIN OUTCOME MEASURES Primary outcome was the difference in free 25(OH)D between users and nonusers of HC. RESULTS Overall, 176 participants [median (25th to 75th percentiles) age: 25 (22 to 29) years] with available free 25(OH)D were included in the present analysis. At baseline, total 25(OH)D was significantly higher in users (n = 110) than in nonusers (n = 66) of HC [49.2 (33.4 to 63.4) vs 39.1 (23.8 to 52.5) nmol/L; P < 0.001], whereas there was no difference in free 25(OH)D [7.87 (6.50 to 10.11) vs 7.88 (6.35 to 10.12) pmol/L; P = 0.923]. These results were confirmed after multimicronutrient supplementation and in subgroups according to treatment allocation. CONCLUSIONS Use of HC was associated with, on average, 26% higher total 25(OH)D, whereas free 25(OH)D values did not differ according to use of HC. These findings are relevant for epidemiological studies, but the physiological implications remain to be clarified.
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Affiliation(s)
- Stefan Pilz
- Department of Internal Medicine, Division of Endocrinology and Diabetology, Medical University of Graz, Graz, Austria
| | - Rima Obeid
- Department of Clinical Chemistry, Saarland University Hospital, Homburg, Germany
| | - Verena Schwetz
- Department of Internal Medicine, Division of Endocrinology and Diabetology, Medical University of Graz, Graz, Austria
| | - Christian Trummer
- Department of Internal Medicine, Division of Endocrinology and Diabetology, Medical University of Graz, Graz, Austria
| | - Marlene Pandis
- Department of Internal Medicine, Division of Endocrinology and Diabetology, Medical University of Graz, Graz, Austria
| | - Elisabeth Lerchbaum
- Department of Internal Medicine, Division of Endocrinology and Diabetology, Medical University of Graz, Graz, Austria
| | - Thomas R Pieber
- Department of Internal Medicine, Division of Endocrinology and Diabetology, Medical University of Graz, Graz, Austria
- Center for Biomarker Research in Medicine, Graz, Austria
| | - Barbara Obermayer-Pietsch
- Department of Internal Medicine, Division of Endocrinology and Diabetology, Medical University of Graz, Graz, Austria
- Center for Biomarker Research in Medicine, Graz, Austria
| | - Manfred Wilhelm
- Department of Mathematics, Natural and Economic Sciences, University of Applied Sciences Ulm, Ulm, Germany
| | - Andreas Hahn
- 5Institute of Food Science and Human Nutrition, Leibniz University of Hannover, Hannover, Germany
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No effect of vitamin D supplementation on cardiovascular risk factors in subjects with metabolic syndrome: a pilot randomised study. ACTA ACUST UNITED AC 2017; 2:e52-e60. [PMID: 29242845 PMCID: PMC5728078 DOI: 10.5114/amsad.2017.70504] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Accepted: 07/31/2017] [Indexed: 12/17/2022]
Abstract
Introduction Patients with metabolic syndrome (MetS) may have lower 25-hydroxyvitamin D (25(OH)VitD) serum levels compared with non-MetS individuals. Vitamin D (VitD) deficiency is associated with various cardiovascular disease (CVD) risk factors. Yet, the effect of VitD supplementation on MetS remains uncertain. Our aim was to examine the effect of VitD supplementation on CVD risk factors in MetS subjects. Material and methods This pilot study had a PROBE (prospective, randomised, open-label, blinded end-point) design. Fifty patients with MetS were included and randomised either to dietary instructions (n = 25) (control group) or dietary instructions plus VitD 2000 IU/day (n = 25) (VitD group) for 3 months. This study is registered in ClinicalTrials.gov (NCT01237769). Results In both groups a similar small weight reduction was achieved. In the VitD group serum 25(OH)VitD levels significantly increased by 91% (from 16.0 (3.0–35.0) to 30.6 (8.4–67.0) ng/ml, p < 0.001), while in the control group no significant change was observed (from 10.0 (4.0–39.6) to 13.0 (3.5–37.0) ng/ml). In both groups triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, fasting glucose, haemoglobin A1c, homeostasis model assessment index and diastolic blood pressure did not significantly change. Systolic blood pressure decreased by 3.7% (from 134 ±14 to 129 ±13 mm Hg, p = 0.05) in the VitD group, while it decreased by 1.5% (from 132 ±13 to 130 ±16 mm Hg, p = NS) in the control group (p = NS between groups). In the VitD group serum 25(OH)VitD increase was negatively correlated with SBP decrease (r = –0.398, p = 0.049). Conclusions VitD supplementation (2000 IU/day) did not affect various CVD risk factors in patients with MetS.
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