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  • Abstract: Hypoparathyroidism x
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  • Abstract: Vitamin D x
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Glenville Jones Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada

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Vitamin D has many physiological functions including upregulation of intestinal calcium and phosphate absorption, mobilization of bone resorption, renal reabsorption of calcium as well as actions on a variety of pleiotropic functions. It is believed that many of the hormonal effects of vitamin D involve a 1,25-dihydroxyvitamin D3-vitamin D receptor-mediated transcriptional mechanism involving binding to the cellular chromatin and regulating hundreds of genes in many tissues. This comprehensive historical review provides a unique perspective of the many steps of the discovery of vitamin D and its deficiency disease, rickets, stretching from 1650 until the present. The overview is divided into four distinct historical phases which cover the major developments in the field and in the process highlighting the: (a) first recognition of rickets or vitamin D deficiency; (b) discovery of the nutritional factor, vitamin D and its chemical structure; (c) elucidation of vitamin D metabolites including the hormonal form, 1,25-dihydroxyvitamin D3; (d) delineation of the vitamin D cellular machinery, functions and vitamin D-related diseases which focused on understanding the mechanism of action of vitamin D in its many target cells.

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Marcela Moraes Mendes Department of Nutrition, Faculty of Health Sciences, University of Brasília, Distrito Federal, Brazil
Department of Nutrition, Institute of Life Sciences, Federal University of Juiz de Fora, Governador Valadares, Minas Gerais, Brazil
Department of Nutrition, Faculty of Health and Medical Sciences, University of Surrey, University of Surrey, Guildford, UK

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Patricia Borges Botelho Department of Nutrition, Faculty of Health Sciences, University of Brasília, Distrito Federal, Brazil

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Helena Ribeiro Department of Environmental Health, Faculty of Public Health, University of São Paulo, São Paulo, Brazil

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Vitamin D enhances calcium absorption and bone mineralisation, promotes maintenance of muscle function, and is crucial for musculoskeletal health. Low vitamin D status triggers secondary hyperparathyroidism, increases bone loss, and leads to muscle weakness. The primary physiologic function of vitamin D and its metabolites is maintaining calcium homeostasis for metabolic functioning, signal transduction, and neuromuscular activity. A considerable amount of human evidence supports the well-recognised contribution of adequate serum 25-hydroxyvitamin D concentrations for bone homeostasis maintenance and prevention and treatment strategies for osteoporosis when combined with adequate calcium intake. This paper aimed to review the literature published, mainly in the last 20 years, on the effect of vitamin D and its supplementation for musculoskeletal health in order to identify the aspects that remain unclear or controversial and therefore require further investigation and debate. There is a clear need for consistent data to establish realistic and meaningful recommendations of vitamin D status that consider different population groups and locations. Moreover, there is still a lack of consensus on thresholds for vitamin D deficiency and optimal status as well as toxicity, optimal intake of vitamin D, vitamin D supplement alone as a strategy to prevent fractures and falls, recommended sun exposure at different latitudes and for different skin pigmentations, and the extra skeletal effects of vitamin D.

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Johanna Öberg Tromso Endocrine Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromso, Norway

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Rolf Jorde Tromso Endocrine Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromso, Norway

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Yngve Figenschau Tromso Endocrine Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromso, Norway
Diagnostic Clinic, University Hospital of North Norway, Tromso, Norway

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Per Medbøe Thorsby Hormone Laboratory, Department of Medical Biochemistry and Biochemical Endocrinology and Metabolism Research Group, Oslo University Hospital, Aker, Oslo, Norway

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Sandra Rinne Dahl Hormone Laboratory, Department of Medical Biochemistry and Biochemical Endocrinology and Metabolism Research Group, Oslo University Hospital, Aker, Oslo, Norway

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Anne Winther Division of Neurosciences, Orthopedics and Rehabilitation Services, University Hospital of North Norway, Tromso, Norway

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Guri Grimnes Tromso Endocrine Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromso, Norway
Division of Internal Medicine, University Hospital of North Norway, Tromso, Norway

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Objective

Combined hormonal contraceptive (CHC) use has been associated with higher total 25-hydroxyvitamin D (25(OH)D) levels. Here, we investigate the relation between CHC use and vitamin D metabolism to elucidate its clinical interpretation.

Methods

The cross-sectional Fit Futures 1 included 1038 adolescents. Here, a subgroup of 182 girls with available 25(OH)D, 1,25-dihydroxyvitamin D (1,25(OH)2D), 24,25-dihydroxyvitamin D (24,25(OH)2D), vitamin D-binding protein (DBP) and measured free 25(OH)D levels, in addition to parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23), was investigated. Vitamin D metabolites were compared between girls using (CHC+) and not using CHC (CHC−). Further, the predictability of CHC on 25(OH)D levels was assessed in a multiple regression model including lifestyle factors. The ratios 1,25(OH)2D/25(OH)D and 24,25(OH)2D/25(OH)D (vitamin D metabolite ratio (VMR)) in relation to 25(OH)D were presented in scatterplots.

Results

CHC+ (n  = 64; 35% of the girls) had higher 25(OH)D levels (mean ± s.d., 60.3 ± 22.2) nmol/L) than CHC- (n  = 118; 41.8 ± 19.3 nmol/L), P -values <0.01. The differences in 25(OH)D levels between CHC+ and CHC− were attenuated but remained significant after the adjustment of lifestyle factors. CHC+ also had higher levels of 1,25(OH)2D, 24,25(OH)2D, DBP and calcium than CHC−, whereas 1,25(OH)2D/25(OH)D, PTH, FGF23 and albumin were significantly lower. Free 25(OH)D and VMR did not statistically differ, and both ratios appeared similar in relation to 25(OH)D, irrespective of CHC status.

Conclusion

This confirms a clinical impact of CHC on vitamin D levels in adolescents. Our observations are likely due to an increased DBP-concentration, whereas the free 25(OH)D appears unaltered.

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A Chinoy Royal Manchester Children’s Hospital, Manchester, UK

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M Skae Royal Manchester Children’s Hospital, Manchester, UK

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A Babiker King Abdullah Specialized Children’s Hospital, Riyadh, Saudi Arabia

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D Kendall Royal Preston Hospital, Preston, UK

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M Z Mughal Royal Manchester Children’s Hospital, Manchester, UK

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R Padidela Royal Manchester Children’s Hospital, Manchester, UK

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Background

Hypoparathyroidism is characterised by hypocalcaemia, and standard management is with an active vitamin D analogue and adequate oral calcium intake (dietary and/or supplements). Little is described in the literature about the impact of intercurrent illnesses on calcium homeostasis in children with hypoparathyroidism.

Methods

We describe three children with hypoparathyroidism in whom intercurrent illnesses led to hypocalcaemia and escalation of treatment with alfacalcidol (1-hydroxycholecalciferol) and calcium supplements.

Results

Three infants managed with standard treatment for hypoparathyroidism (two with homozygous mutations in GCMB2 gene and one with Sanjad-Sakati syndrome) developed symptomatic hypocalcaemia (two infants developed seizures) following respiratory or gastrointestinal illnesses. Substantial increases in alfacalcidol doses (up to three times their pre-illness doses) and calcium supplementation were required to achieve acceptable serum calcium concentrations. However, following resolution of illness, these children developed an increase in serum calcium and hypercalciuria, necessitating rapid reduction to pre-illness dosages of alfacalcidol and oral calcium supplementation.

Conclusion

Intercurrent illness may precipitate symptomatic hypocalcaemia in children with hypoparathyroidism, necessitating increase in dosages of alfacalcidol and calcium supplements. Close monitoring is required on resolution of the intercurrent illness, with timely reduction of dosages of active analogues of vitamin D and calcium supplements to prevent hypercalcaemia, hypercalciuria and nephrocalcinosis.

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Gabriella Oliveira Lima Laboratory of Pharmacology and Toxicology of Natural Products, Institute of Biological Sciences, Federal University of Pará, Belém, Pará, Brazil

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Alex Luiz Menezes da Silva Laboratory of Pharmacology and Toxicology of Natural Products, Institute of Biological Sciences, Federal University of Pará, Belém, Pará, Brazil

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Julianne Elba Cunha Azevedo Laboratory of Pharmacology and Toxicology of Natural Products, Institute of Biological Sciences, Federal University of Pará, Belém, Pará, Brazil

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Chirlene Pinheiro Nascimento Laboratory of Pharmacology and Toxicology of Natural Products, Institute of Biological Sciences, Federal University of Pará, Belém, Pará, Brazil

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Luana Rodrigues Vieira Laboratory of Pharmacology and Toxicology of Natural Products, Institute of Biological Sciences, Federal University of Pará, Belém, Pará, Brazil

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Akira Otake Hamoy Laboratory of Pharmacology and Toxicology of Natural Products, Institute of Biological Sciences, Federal University of Pará, Belém, Pará, Brazil

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Luan Oliveira Ferreira Laboratory of Experimental Neuropathology, Institute of Biological Sciences, Federal University of Pará, Belém, Pará, Brazil

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Verônica Regina Lobato Oliveira Bahia Multidisciplinary Laboratory of Animal Morphology, Institute of Biological Sciences, Federal University of Pará, Belém, Pará, Brazil

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Nilton Akio Muto Amazon Bioactive Compounds Valorization Center, Institute of Biological Sciences, Federal University of Pará, Belém, Pará, Brazil

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Dielly Catrina Favacho Lopes Laboratory of Experimental Neuropathology, Institute of Biological Sciences, Federal University of Pará, Belém, Pará, Brazil

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Moisés Hamoy Laboratory of Pharmacology and Toxicology of Natural Products, Institute of Biological Sciences, Federal University of Pará, Belém, Pará, Brazil

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Low plasma levels of vitamin D causes bone mineral change that can precipitate osteopenia and osteoporosis and could aggravate autoimmune diseases, hypertension and diabetes. The demand for vitamin D supplementation becomes necessary; however, the consumption of vitamin D is not without risks, which its toxicity could have potentially serious consequences related to hypervitaminosis D, such as hypercalcemia and cerebral alterations. Thus, the present study describes the electroencephalographic changes caused by supraphysiological doses of vitamin D in the brain electrical dynamics and the electrocardiographic changes. After 4 days of treatment with vitamin D at a dose of 25,000 IU/kg, the serum calcium levels found were increased in comparison with the control group. The electrocorticogram analysis found a reduction in wave activity in the delta, theta, alpha and beta frequency bands. For ECG was observed changes with shortened QT follow-up, which could be related to serum calcium concentration. This study presented important evidence about the cerebral and cardiac alterations caused by high doses of vitamin D, indicating valuable parameters in the screening and decision-making process for diagnosing patients with symptoms suggestive of intoxication.

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Jane Fletcher Nutrition Nurses, University Hospitals Birmingham NHS Trust, Queen Elizabeth Hospital Birmingham, Mindelsohn Way, Edgbaston, Birmingham, UK
School of Nursing, Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham, UK

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Emma L Bishop Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK

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Stephanie R Harrison Leeds Institute of Rheumatic and Musculoskeletal Medicine, Chapel Allerton Hospital, Leeds, UK

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Amelia Swift School of Nursing, Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham, UK

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Sheldon C Cooper Gastroenterology Department, University Hospitals Birmingham NHS Trust, Queen Elizabeth Hospital Birmingham, Mindelsohn Way, Edgbaston, Birmingham, UK

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Sarah K Dimeloe Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK

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Karim Raza Institute of Inflammation and Ageing, University of Birmingham, Birmingham, UK

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Martin Hewison Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK

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Vitamin D has well-documented effects on calcium homeostasis and bone metabolism but recent studies suggest a much broader role for this secosteroid in human health. Key components of the vitamin D system, notably the vitamin D receptor (VDR) and the vitamin D-activating enzyme (1α-hydroxylase), are present in a wide array of tissues, notably macrophages, dendritic cells and T lymphocytes (T cells) from the immune system. Thus, serum 25-hydroxyvitamin D (25D) can be converted to hormonal 1,25-dihydroxyvitamin D (1,25D) within immune cells, and then interact with VDR and promote transcriptional and epigenomic responses in the same or neighbouring cells. These intracrine and paracrine effects of 1,25D have been shown to drive antibacterial or antiviral innate responses, as well as to attenuate inflammatory T cell adaptive immunity. Beyond these mechanistic observations, association studies have reported the correlation between low serum 25D levels and the risk and severity of human immune disorders including autoimmune diseases such as inflammatory bowel disease, multiple sclerosis, type 1 diabetes and rheumatoid arthritis. The proposed explanation for this is that decreased availability of 25D compromises immune cell synthesis of 1,25D leading to impaired innate immunity and over-exuberant inflammatory adaptive immunity. The aim of the current review is to explore the mechanistic basis for immunomodulatory effects of 25D and 1,25D in greater detail with specific emphasis on how vitamin D-deficiency (low serum levels of 25D) may lead to dysregulation of macrophage, dendritic cell and T cell function and increase the risk of inflammatory autoimmune disease.

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Natércia Neves Marques de Queiroz University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Franciane Trindade Cunha de Melo University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Fabrício de Souza Resende University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Luísa Corrêa Janaú University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Norberto Jorge Kzan de Souza Neto University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Manuela Nascimento de Lemos University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Ana Carolina Lobato Virgolino University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Maria Clara Neres Iunes de Oliveira University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Angélica Leite de Alcântara University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Lorena Vilhena de Moraes University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Tiago Franco David University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Wanderson Maia da Silva University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Scarlatt Souza Reis University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Márcia Costa dos Santos University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Ana Carolina Contente Braga de Souza University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Pedro Paulo Freire Piani University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Neyla Arroyo Lara Mourão University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Karem Mileo Felício University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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João Felício Abrahão Neto University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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João Soares Felício University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Objective:

Investigate the prevalence of vitamin D deficiency in an equatorial population through a large-sample study.

Methods:

Cross-sectional study with 30,224 healthy individuals from the North Region, in Brazil (Amazônia – state of Pará), who had 25-hydroxy-vitamin D (25(OH)D) and intact parathyroid hormone (PTH) serum levels measured by immunoassay method. Those with history of acute or chronic diseases were excluded. Abnormal levels of calcium, creatinine, glycemia and albumin were also exclusion criteria.

Results:

25(OH)D levels were 29.1 ± 8.2 ng/mL and values <12.7 ng/mL were equal to < −2 s.d. below average. Hypovitaminosis D was present in 10% of subjects according to the Institute of Medicine (values <20 ng/mL) and in 59%, in consonance with Endocrine Society (values 20–30 ng/mL as insufficiency and <20 ng/mL as deficiency) criteria. Individuals were divided according to four age brackets: children, adolescents, adults and elderly, and their 25(OH)D levels were: 33 ± 9; 28.5 ± 7.4; 28.3 ± 7.7; 29.3 ± 8.5 ng/mL, respectively. All groups differed in 25(OH)D, except adolescents vs adults. Regression model showed BMI, sex, living zone (urban or rural) and age as independent variables to 25(OH)D levels. Comparing subjects with vitamin D deficiency (<20 ng/mL) to those with vitamin D insufficiency (20–30 ng/mL), a difference between PTH levels in these two groups was observed (95.9 ± 24.7 pg/mL vs 44.2 ± 64.5 pg/mL; P < 0.01). Additionally, the most accurate predictive vitamin D level for subclinical hyperparathyroidism in ROC curve was 26 ng/mL.

Conclusion:

Our equatorial population showed low prevalence of vitamin D hypovitaminosis ranging with age bracket. The insufficient category by Endocrine Society was corroborated by our PTH data.

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Mateo Amaya-Montoya School of Medicine, Universidad de los Andes, Bogotá, Colombia

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Daniela Duarte-Montero School of Medicine, Universidad de los Andes, Bogotá, Colombia

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Luz D Nieves-Barreto School of Medicine, Universidad de los Andes, Bogotá, Colombia

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Angélica Montaño-Rodríguez School of Medicine, Universidad de los Andes, Bogotá, Colombia

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Eddy C Betancourt-Villamizar Team Foods, Bogotá, Colombia

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María P Salazar-Ocampo School of Medicine, Universidad de los Andes, Bogotá, Colombia

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Carlos O Mendivil School of Medicine, Universidad de los Andes, Bogotá, Colombia
Fundación Santa Fe de Bogotá, Section of Endocrinology, Bogotá, Colombia

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Data on dietary calcium and vitamin D intake from Latin America are scarce. We explored the main correlates and dietary sources of calcium and vitamin D in a probabilistic, population-based sample from Colombia. We studied 1554 participants aged 18–75 from five different geographical regions. Dietary intake was assessed by employing a 157-item semi-quantitative food frequency questionnaire and national and international food composition tables. Daily vitamin D intake decreased with increasing age, from 230 IU/day in the 18–39 age group to 184 IU/day in the 60–75 age group (P -trend < 0.001). Vitamin D intake was positively associated with socioeconomic status (SES) (196 IU/day in lowest vs 234 in highest SES, P-trend < 0.001), and with educational level (176 IU/day in lowest vs 226 in highest education level, P-trend < 0.001). Daily calcium intake also decreased with age, from 1376 mg/day in the 18–39 age group to 1120 mg/day in the 60–75 age group (P -trend < 0.001). Calcium intake was lowest among participants with only elementary education, but the absolute difference in calcium intake between extreme education categories was smaller than for vitamin D (1107 vs 1274 mg/day, P-trend = 0.023). Daily calcium intake did not correlate with SES (P -trend = 0.74). Eggs were the main source of overall vitamin D, albeit their contribution decreased with increasing age. Dairy products contributed at least 48% of dietary calcium in all subgroups, mostly from cheese-containing traditional foods. SES and education were the key correlates of vitamin D and calcium intake. These findings may contribute to shape public health interventions in Latin American countries.

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Mirjam M Oosterwerff Departments of Internal Medicine, Epidemiology and Biostatistics, Public and Occupational Health, Endocrine Section

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Rosa Meijnen Departments of Internal Medicine, Epidemiology and Biostatistics, Public and Occupational Health, Endocrine Section

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Natasja M Van Schoor Departments of Internal Medicine, Epidemiology and Biostatistics, Public and Occupational Health, Endocrine Section

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Dirk L Knol Departments of Internal Medicine, Epidemiology and Biostatistics, Public and Occupational Health, Endocrine Section

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Mark H H Kramer Departments of Internal Medicine, Epidemiology and Biostatistics, Public and Occupational Health, Endocrine Section

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Mireille N M Van Poppel Departments of Internal Medicine, Epidemiology and Biostatistics, Public and Occupational Health, Endocrine Section

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Paul Lips Departments of Internal Medicine, Epidemiology and Biostatistics, Public and Occupational Health, Endocrine Section

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E Marelise W Eekhoff Departments of Internal Medicine, Epidemiology and Biostatistics, Public and Occupational Health, Endocrine Section

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Vitamin D deficiency is highly prevalent among non-western immigrants in The Netherlands and associated with poor physical performance. The aim of this study was to assess the effect of vitamin D supplementation on physical performance, exercise capacity, and daily physical activity in vitamin D-deficient, overweight non-western immigrants. A randomized double-blind, placebo-controlled trial was conducted to assess the effect of vitamin D on physical performance. A total of 130 participants were included. Eligibility criteria included overweight (BMI >27 kg/m2), 25-hydroxy vitamin D (25(OH)D) ≤50 nmol/l, and an age range of 20–65 years. The intervention group received 1200 IU vitamin D3 daily for 4 months; the control group received placebo. Both groups received 500 mg calcium daily. Outcome measures included physical performance (physical performance score), exercise capacity (a 6-min walk test (6-MWT)), and daily physical activity (questionnaire and accelerometer). There was no significant effect on physical performance, exercise capacity, or physical activity in the intention to treat analysis. In an explorative post hoc analysis restricted to participants reaching a serum 25(OH)D concentration of >60 nmol/l after intervention, there was an improvement of 19 m in the 6-MWT compared with the control group (P=0.053). Moderate dose vitamin D supplementation did not significantly improve physical performance, exercise capacity, or physical activity. However, when 25(OH)D concentrations reached >60 nmol/l after intervention, there was a borderline significant improvement in exercise capacity. Although the clinical relevance is not clear, this is a promising result, as all participants were overweight and did not improve their overall activity levels.

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Stan Ursem Department of Clinical Chemistry, Amsterdam Gastroenterology & Metabolism, Amsterdam UMC, Vrije Universiteit Amsterdam, Endocrine Laboratory, Amsterdam, Netherlands

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Vito Francic Division of Endocrinology and Diabetology, Department of Internal Medicine, Endocrinology Lab Platform, Medical University of Graz, Graz, Austria

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Martin Keppel University Institute for Medical and Chemical Laboratory Diagnostics, Paracelsus Medical University, Salzburg, Austria

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Verena Schwetz Division of Endocrinology and Diabetology, Department of Internal Medicine, Endocrinology Lab Platform, Medical University of Graz, Graz, Austria

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Christian Trummer Division of Endocrinology and Diabetology, Department of Internal Medicine, Endocrinology Lab Platform, Medical University of Graz, Graz, Austria

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Marlene Pandis Division of Endocrinology and Diabetology, Department of Internal Medicine, Endocrinology Lab Platform, Medical University of Graz, Graz, Austria

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Felix Aberer Division of Endocrinology and Diabetology, Department of Internal Medicine, Endocrinology Lab Platform, Medical University of Graz, Graz, Austria

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Martin R Grübler Division of Endocrinology and Diabetology, Department of Internal Medicine, Endocrinology Lab Platform, Medical University of Graz, Graz, Austria

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Nicolas D Verheyen Division of Cardiology, Department of Internal Medicine, Medical University of Graz, Graz, Austria

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Winfried März Synlab Academy, Synlab Holding Germany GmbH, München, Germany

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Andreas Tomaschitz Specialist Clinic of Rehabilitation Bad Gleichenberg, Bad Gleichenberg, Austria

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Stefan Pilz Division of Endocrinology and Diabetology, Department of Internal Medicine, Endocrinology Lab Platform, Medical University of Graz, Graz, Austria

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Barbara Obermayer-Pietsch Division of Endocrinology and Diabetology, Department of Internal Medicine, Endocrinology Lab Platform, Medical University of Graz, Graz, Austria

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Annemieke C Heijboer Department of Clinical Chemistry, Amsterdam Gastroenterology & Metabolism, Amsterdam UMC, Vrije Universiteit Amsterdam, Endocrine Laboratory, Amsterdam, Netherlands
Department of Clinical Chemistry, Amsterdam Gastroenterology & Metabolism, Amsterdam UMC, University of Amsterdam, Endocrine Laboratory, Amsterdam, Netherlands

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Objective

PTH can be oxidised in vivo, rendering it biologically inactive. Non-oxidised PTH (n-oxPTH) may therefore give a better image of the hormonal status of the patient. While vitamin D supplementation decreases total PTH (tPTH) concentration, the effect on n-oxPTH concentration is unexplored. We investigated the effect of vitamin D on n-oxPTH concentration in comparison to tPTH and compared the correlations between parameters of calcium, bone and lipid metabolism with n-oxPTH and tPTH.

Methods

N-oxPTH was measured in 108 vitamin D-insufficient (25(OH)D <75 nmol/L) hypertensive patients, treated with vitamin D (2800 IE daily) or placebo for 8 weeks in the Styrian Vitamin D Hypertension Trial (NCT02136771). We calculated the treatment effect and performed correlation analyses of n-oxPTH and tPTH with parameters of calcium, bone and lipid metabolism and oxidative stress.

Results

After treatment, compared to placebo, 25(OH)D concentrations increased, tPTH decreased by 9% (P < 0.001), n-oxPTH by 7% (P = 0.025) and the ratio of n-oxPTH/tPTH increased (P = 0.027). Changes in phosphate and HDL concentration correlated with changes in n-oxPTH, but not tPTH.

Conclusions

tPTH and n-oxPTH decrease upon vitamin D supplementation. Our study suggests that vitamin D supplementation reduces the oxidation of PTH, as we observed a small but significant increase in the non-oxidised proportion of PTH upon treatment. In addition, we found that changes in phosphate and HDL concentration showed a relationship with changes in n-oxPTH, but not tPTH. This may be explained by the biological activity of n-oxPTH. Further research should be carried out to establish the clinical relevance of n-oxPTH.

Open access