The delicate balance between vitamin D, calcium and bone homeostasis: Lessons learned from intestinal- and osteocyte-specific VDR null mice

Vitamin D and calcium are considered crucial for the treatment of bone diseases. Both vitamin D and calcium contribute to bone homeostasis but also preserve muscle health by reducing the risk of falls and fractures. Low vitamin D concentrations result in secondary hyperparathyroidism and contribute to bone loss, although the development of secondary hyperparathyroidism varies, even in patients with severe vitamin D deficiency. Findings from observational studies have shown controversial results regarding the association between bone mineral density and vitamin D/calcium status, thus sparking a debate regarding optimum concentrations of 25-hydroxyvitamin D and calcium for the best possible skeletal health. Although most of the intervention studies reported a positive effect of supplementation with calcium and vitamin D on bone in patients with osteoporosis, this therapeutic approach has been a matter of debate regarding potential side effects on the cardiovascular (CV) system. Thus, the aim of this review is to consider the current evidence on the physiological role of vitamin D and calcium on bone and muscle health. Moreover, we provide an overview on observational and interventional studies that investigate the effect of vitamin D and calcium supplementation on bone health, also taking into account the possible CV side-effects. We also provide molecular insights on the effect of calcium plus vitamin D on the CV system.

Download Full-text

Vitamin D and sleep duration: Is there a bidirectional relationship?

Hormone Molecular Biology and Clinical Investigation ◽

10.1515/hmbci-2020-0025 ◽

2020 ◽

Vol 41 (4) ◽

Author(s):

Maryam Mosavat ◽

Aisling Smyth ◽

Diana Arabiat ◽

Lisa Whitehead

Keyword(s):

Vitamin D ◽

Sleep Duration ◽

Vitamin D Supplementation ◽

The Body ◽

Bone Homeostasis ◽

Limited Information ◽

Physiological Processes ◽

Vitamin D Levels ◽

Bidirectional Relationship ◽

Sleep Length

AbstractVitamin D contributes to numerous physiological processes within the body but primarily calcium and bone homeostasis. Emerging evidence highlights a novel role for vitamin D in maintaining and regulating optimal sleep. Sleep is a known regulator of bone health, highlighting the interconnectedness between vitamin D concentrations, sleep duration and bone metabolism. It is possible that the relationship between sleep length and vitamin D is bidirectional, with vitamin D playing a role in sleep health and conversely, sleep affecting vitamin D levels. Nevertheless, limited information on the direction of the interaction is available, and much remains to be learned concerning the complex relationship between insufficient sleep duration and vitamin D deficiency. Given the potential to implement interventions to improve sleep and vitamin D supplementation, understanding this relationship further could represent a novel way to support and improve health.

Download Full-text

Back to the future: a new look at ‘old’ vitamin D

Journal of Endocrinology ◽

10.1677/joe-08-0170 ◽

2008 ◽

Vol 198 (2) ◽

pp. 261-269 ◽

Cited By ~ 56

Author(s):

Rene F Chun ◽

John S Adams ◽

Martin Hewison

Keyword(s):

Vitamin D ◽

Vitamin D Insufficiency ◽

Target Cells ◽

Bone Homeostasis ◽

Immune Disorders ◽

Factors Associated ◽

Dihydroxyvitamin D ◽

High Prevalence ◽

Fresh Perspective ◽

Vitamin D Signaling

Our perception of the vitamin D system continues to evolve. Recent studies have re-evaluated the parameters for adequate vitamin D status in humans, revealing a high prevalence of insufficiency in many populations throughout the world. Other reports have highlighted the potential consequences of vitamin D insufficiency beyond established effects on bone homeostasis. Most notably, there is now strong evidence of a role for vitamin D in modulating innate and adaptive immunities, with insufficiency being linked to infectious disease and other immune disorders. To date, signaling pathways for these new responses to vitamin D have been based on established endocrine models for active 1,25-dihydroxyvitamin D, despite present evidence for more localized, intracrine modes of action. In the following review, we provide a fresh perspective on vitamin D signaling in non-classical target cells such as macrophages by highlighting novel factors associated with the transport and action of this pluripotent secosteroid.

Download Full-text

Potential Beneficial Effects of Vitamin D in Coronary Artery Disease

Nutrients ◽

10.3390/nu12010099 ◽

2019 ◽

Vol 12 (1) ◽

pp. 99 ◽

Cited By ~ 2

Author(s):

Christian Legarth ◽

Daniela Grimm ◽

Marcus Krüger ◽

Manfred Infanger ◽

Markus Wehland

Keyword(s):

Coronary Artery Disease ◽

Vitamin D ◽

Coronary Artery ◽

Vitamin D Supplementation ◽

Diabetic Patients ◽

Inverse Association ◽

Bone Homeostasis ◽

Beneficial Effects ◽

Vitamin D Levels ◽

Artery Disease

Vitamin D plays a pivotal role in bone homeostasis and calcium metabolism. However, recent research has indicated additional beneficial effects of vitamin D on the cardiovascular system. This review aims to elucidate if vitamin D can be used as an add-on treatment in coronary artery disease (CAD). Large-scale epidemiological studies have found a significant inverse association between serum 25(OH)-vitamin D levels and the prevalence of essential hypertension. Likewise, epidemiological data have suggested plasma levels of vitamin D to be inversely correlated to cardiac injury after acute myocardial infarction (MI). Remarkably, in vitro trials have showed that vitamin D can actively suppress the intracellular NF-κB pathway to decrease CAD progression. This is suggested as a mechanistic link to explain how vitamin D may decrease vascular inflammation and atherosclerosis. A review of randomized controlled trials with vitamin D supplementation showed ambiguous results. This may partly be explained by heterogeneous study groups. It is suggested that subgroups of diabetic patients may benefit more from vitamin D supplementation. Moreover, some studies have indicated that calcitriol rather than cholecalciferol exerts more potent beneficial effects on atherosclerosis and CAD. Therefore, further studies are required to clarify these assumptions.

Download Full-text

Bilateral Simultaneous Avulsion Fractures of the Proximal Tibia in a 14-Year-Old Athlete with Vitamin-D Deficiency

Case Reports in Orthopedics ◽

10.1155/2015/783046 ◽

2015 ◽

Vol 2015 ◽

pp. 1-3 ◽

Cited By ~ 3

Author(s):

Ziad Harb ◽

Arfan Malhi

Keyword(s):

Vitamin D ◽

Vitamin D Deficiency ◽

Proximal Tibia ◽

Vital Role ◽

Bone Homeostasis ◽

Avulsion Fractures ◽

Developmental Anatomy ◽

Tibial Epiphysis ◽

Developmental Features ◽

Physeal Fractures

Fractures involving the proximal tibial epiphysis are rare and form 0.5% of all epiphyseal injuries. The specific anatomical and developmental features of the proximal tibial epiphysis make it vulnerable to unique patterns of fractures. Vitamin-D plays a vital role in bone homeostasis and its deficiency has an impact on fracture risk and healing. We present the first ever reported case of simultaneous bilateral proximal tibial physeal fractures in an athlete with vitamin-D deficiency. Treatment consisted of plaster immobilisation, and the patient made a full recovery and returned to preinjury level of activities. We report this case for its uniqueness and as an educational review of the importance of the developmental anatomy of the proximal tibia. We review the literature and discuss how the stages of the growing physis determine the type of fracture sustained.

Download Full-text

The Molecular Mechanisms by Which Vitamin D Prevents Insulin Resistance and Associated Disorders

International Journal of Molecular Sciences ◽

10.3390/ijms21186644 ◽

2020 ◽

Vol 21 (18) ◽

pp. 6644 ◽

Cited By ~ 1

Author(s):

Izabela Szymczak-Pajor ◽

Józef Drzewoski ◽

Agnieszka Śliwińska

Keyword(s):

Insulin Resistance ◽

Vitamin D ◽

Molecular Mechanisms ◽

Cell Types ◽

Review Article ◽

Bone Homeostasis ◽

Glucose And Lipid Metabolism ◽

The University ◽

Chronic Hyperglycaemia

Numerous studies have shown that vitamin D deficiency is very common in modern societies and is perceived as an important risk factor in the development of insulin resistance and related diseases such as obesity and type 2 diabetes (T2DM). While it is generally accepted that vitamin D is a regulator of bone homeostasis, its ability to counteract insulin resistance is subject to debate. The goal of this communication is to review the molecular mechanism by which vitamin D reduces insulin resistance and related complications. The university library, PUBMED, and Google Scholar were searched to find relevant studies to be summarized in this review article. Insulin resistance is accompanied by chronic hyperglycaemia and inflammation. Recent studies have shown that vitamin D exhibits indirect antioxidative properties and participates in the maintenance of normal resting ROS level. Appealingly, vitamin D reduces inflammation and regulates Ca2+ level in many cell types. Therefore, the beneficial actions of vitamin D include diminished insulin resistance which is observed as an improvement of glucose and lipid metabolism in insulin-sensitive tissues.

Download Full-text

The Effect of Ultraviolet B Irradiation Compared with Oral Vitamin D Supplementation on the Well-being of Nursing Home Residents with Dementia: A Randomized Controlled Trial

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17051684 ◽

2020 ◽

Vol 17 (5) ◽

pp. 1684

Author(s):

Bistra I. Veleva ◽

Monique A. A. Caljouw ◽

Jenny T. van der Steen ◽

Bart J. A. Mertens ◽

Victor G. M. Chel ◽

...

Keyword(s):

Vitamin D ◽

Nursing Home ◽

Nursing Home Residents ◽

Well Being ◽

Vitamin D Supplementation ◽

Mean Difference ◽

Ultraviolet B ◽

Control Group ◽

Bone Homeostasis ◽

Randomized Controlled

There are indications that ultraviolet B (UVB) exposure has beneficial effects on well-being through mechanisms other than vitamin D synthesis alone. We conducted a randomized controlled multicenter trial to compare the effects of UVB light and vitamin D supplementation (VD) in terms of the well-being of nursing home residents with dementia. Participants were randomly assigned to the intervention group (UVB group, n = 41; half-body UVB irradiation, twice weekly over 6 months, with 1 standard erythema dose (SED)) or to the control group (VD group, n = 37; 5600 International units (IU) cholecalciferol supplementation once a week). The main outcome was well-being, measured by the Cohen-Mansfield Agitation Inventory (CMAI) and the Cornell scale for depression in dementia at 0, 3, and 6 months. Secondary outcomes were QUALIDEM quality of life domains and biochemical parameters of bone homeostasis. Intention-to-treat analysis with linear mixed modeling showed no significant between-group differences on agitation (p = 0.431) or depressive symptoms (p = 0.982). At six months, the UVB group showed less restless/tense behavior compared to the VD group (mean difference of the mean change scores 2.2, 95% CI 0.8 to 3.6; p = 0.003 for group x time interaction) and lower serum 25(OH)D3 concentration (estimated mean difference - 21.9, 95% CI −32.6 to −11.2; p = 0.003 for group difference). The exposure of nursing home residents with dementia to UVB light showed no positive benefits in terms of wellbeing. UVB treatment may have a positive effect on the restless/tense behavior characteristic of advanced dementia but more research is needed to confirm this finding.

Download Full-text