Vitamin D supplementation

Objective: The effects of vitamin D in the elderly are inconsistent. The aim of this study was to evaluate the association between vitamin D status and the metabolic syndrome (MetS) in the elderly, as well as between vitamin D status and the components of MetS (i.e. serum glucose, triglycerides (TG), HDL cholesterol (HDL-C), waist circumference (WC), and blood pressure (BP)). Methods: The study was embedded in the Rotterdam Study, a population-based cohort of middle-aged and elderly adults. We analyzed data from 3240 people (median age 71.2 years) who did not have type 2 diabetes mellitus at baseline.

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“…Since that time, vitamin D has been established as a major factor influencing metabolism of bones and calcium metabolism (1,2).…”

Section: Introductionmentioning

confidence: 99%

Vitamin D status and metabolic syndrome in the elderly: the Rotterdam Study

Vitezova

Zillikens

Herpt

et al. 2015

European Journal of Endocrinology

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“…Upon cellular uptake, retinol is converted to retinal by ubiquitous alcohol dehydrogenases, but further conversion to retinoic acid (RA), an active metabolite of vitamin A, requires specialized aldehyde dehydrogenases (ALDH1A). ALDH1A enzymes are expressed by a subset of cells, including gut dendritic cells and epithelial cells lining the upper and lower respiratory tracts (URT and LRT) (5,8). Once converted from retinal, RA in the form of all-trans-RA can be spontaneously isomerized to 9-cis-RA.…”

mentioning

confidence: 99%

“…Individuals with low vitamin levels are particularly vulnerable to infections of the gastrointestinal and respiratory tracts (5)(6)(7)(8), the latter of which are responsible for one-fifth of all deaths among children under the age of five (1,9).…”

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confidence: 99%

Vitamin Supplementation at the Time of Immunization with a Cold-Adapted Influenza Virus Vaccine Corrects Poor Mucosal Antibody Responses in Mice Deficient for Vitamins A and D

Surman

Penkert

Jones

et al. 2016

Clin Vaccine Immunol

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V itamin A deficiencies (VAD) and vitamin D deficiencies (VDD) have long been considered maladies in the developing world, but recent research demonstrates that children and adults of developed countries also suffer from vitamin deficits (1-4). Individuals with low vitamin levels are particularly vulnerable to infections of the gastrointestinal and respiratory tracts (5-8), the latter of which are responsible for one-fifth of all deaths among children under the age of five (1, 9).Vitamin A is ingested in the form of retinyl esters or betacarotene. It is stored in the liver as an ester and is transported through the circulatory system as retinol bound to the retinol binding protein (RBP) (10). Upon cellular uptake, retinol is converted to retinal by ubiquitous alcohol dehydrogenases, but further conversion to retinoic acid (RA), an active metabolite of vitamin A, requires specialized aldehyde dehydrogenases (ALDH1A). ALDH1A enzymes are expressed by a subset of cells, including gut dendritic cells and epithelial cells lining the upper and lower respiratory tracts (URT and LRT) (5, 8). Once converted from retinal, RA in the form of all-trans-RA can be spontaneously isomerized to 9-cis-RA. The two metabolites function as high-affinity ligands, respectively, for the retinoic acid receptor (RAR) and retinoid X receptor (RXR) proteins (11, 12). RAR and RXR are members of the nuclear receptor superfamily. These exist as monomers, homodimers, and heterodimers. DNA motifs for RAR-RXR binding (known as retinoic acid response elements [RARE]) are typically direct repeats of half sites puG(G/T)TCA separated by 2 or 5 nucleotides. RA binding to RAR-RXR (and related heterodimeric receptors) can have profound effects on immune cell development, activation, homing, and function (5,(12)(13)(14).Vitamin D can be synthesized by the body in addition to being obtained through dietary sources. Cholecalciferol (vitamin D 3 ) and ergocalciferol (vitamin D 2 ) are acquired through the diet, but cholecalciferol is also produced photochemically from 7-dehydrocholesterol in the skin. Cholecalciferol is con- Vitamin A and D metabolites are highly interactive. Calcitriol binds the vitamin D receptor (VDR), which like RAR can heterodimerize with RXR (17). The same DNA binding motifs described for RAR-RXR [puG(G/T)TCA] can be recognized by the VDR-RXR complex, but half sites are often separated by 3 nucleotides (17) rather than 2 or 5. Receptor proteins can bind promiscuously to ligands and to noncanonical DNA motifs. In some instances, vitamin receptors (and related members of the nuclear receptor superfamily) behave synergistically, but in other instances, they antagonize one another (e.g., vitamin D exerts a negative effect on the vitamin A-dependent commitment of bone marrow cells to the granulocytic lineage [13,[17][18][19][20]

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“…The controversy has been fuelled by several factors that should be taken into account in interpreting the results of the current literature. These include: the difficulty to distinguish the sole effect of vitamin D as the majority of intervention trials co-administered calcium; the difficulty to exactly measure the relative contribution of sunlight exposure, food fortification, and multivitamins intake; the lack of randomized controlled trials assessing the effect of vitamin D supplementation on health outcomes other than bone; and the complexity to compare studies utilizing different 25(OH)D assays (24,60,61,62,63). On the other hand, it should be emphasized that the two reports are intended for different populations (the general population for the IOM report and the population at risk for deficiency for the ES), and this could partly explain the controversy surrounding their respective recommendations.…”

Section: Vitamin D and The Search For A Thresholdmentioning

confidence: 99%

MANAGEMENT OF ENDOCRINE DISEASE: Value and limitations of assessing vitamin D nutritional status and advised levels of vitamin D supplementation

Romagnoli

Pepe

Piemonte

et al. 2013

European Journal of Endocrinology

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The growing attention to the role of vitamin D in skeletal and extra-skeletal diseases over the last decade induced an increased demand for vitamin D determination as well as a dramatic rise of sales of vitamin D supplement. However, several critical points in this field remain to be clarified. We lack a clear consensus about the definition of vitamin D deficiency, insufficiency, and sufficiency. The identification of different thresholds defining vitamin D status has relevant implications in clinical practice. In fact, the worldwide prevalence of low vitamin D status is highly varying according to the level of 25(OH)D utilized to define sufficiency. Therefore, the assessment of 25-hydroxyvitamin D levels may have a critical role, but a number of different technical problems associated with its determination may interfere in interpreting the results. The hydrophobic nature of vitamin D and the tight binding to its carrier (vitamin D binding protein), the different forms circulating in blood, and the issue of standardization are among the most important factors influencing the measurement of this metabolite. Another controversial point relies on the conflicting guidance on prevention and treatment of vitamin D deficiency endorsed by different medical and scientific communities. In particular, uncertainty exists about how to replete vitamin D stores, how to maintain normal 25(OH)D levels after repletion, which form of vitamin D is preferable for supplementation, and which route of administration and dosing regimens are advisable. Finally, concerns have been raised regarding vitamin D toxicity and its adverse effects.

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Vitamin D supplementation

Cited by 130 publications

References 43 publications

Vitamin D status and metabolic syndrome in the elderly: the Rotterdam Study

Vitamin D status and metabolic syndrome in the elderly: the Rotterdam Study

Vitamin Supplementation at the Time of Immunization with a Cold-Adapted Influenza Virus Vaccine Corrects Poor Mucosal Antibody Responses in Mice Deficient for Vitamins A and D

MANAGEMENT OF ENDOCRINE DISEASE: Value and limitations of assessing vitamin D nutritional status and advised levels of vitamin D supplementation

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