Role Of Vitamin D3 Research Articles

Protective Effects of Vitamin D on Proteoglycans of Human Articular Chondrocytes through TGF-β1 Signaling.

The extracellular matrix of cartilage primarily constitutes of collagen and aggrecan. Cartilage degradation starts with aggrecan loss in osteoarthritis (OA). Vitamin D (VD) plays an essential role in several inflammation-related diseases and can protect the collagen in cartilage during OA. The present study focused on the role of VD in aggrecan turnover of human articular chondrocytes treated with tumor necrosis factor α (TNF-α) and the possible mechanism. Treatment with different doses of VD and different periods of intervention with TNF-α and TGF-β1 receptor (TGFβR1) inhibitor SB525334 were investigated. The viability of human chondrocytes and extracellular secretion of TGF-β1 were measured. The expression of intracellular TGFβR1 and VD receptor was examined. Transcriptional and translational levels of aggrecan and the related metabolic factors were analyzed. The results showed that TNF-α markedly reduced the viability, TGFβR1 expressions and aggrecan levels of human chondrocytes, and increased disintegrin and metalloproteinase with thrombospondin motifs. The alterations were partially inhibited by VD treatment. Furthermore, the effects of VD were blocked by the TGFβR1 inhibitor SB525334 in TNF-α-treated cells. VD may prevent proteoglycan loss due to TNF-α via TGF-β1 signaling in human chondrocytes.

Role of Vitamin D3 in Chronic Cases of Plantar Fascitis

Role of Vitamin D3 in Chronic Cases of Plantar Fascitis

Vitamin D3 suppresses Npt2c abundance and differentially modulates phosphate and calcium homeostasis in Npt2a knockout mice

Vitamin D3 is clinically used for the treatment of vitamin D3 deficiency or osteoporosis, partially because of its role in regulating phosphate (Pi) and calcium (Ca2+) homeostasis. The renal sodium-phosphate cotransporter 2a (Npt2a) plays an important role in Pi homeostasis; however, the role of vitamin D3 in hypophosphatemia has never been investigated. We administered vehicle or vitamin D3 to wild-type (WT) mice or hypophosphatemic Npt2a−/− mice. In contrast to WT mice, vitamin D3 treatment increased plasma Pi levels in Npt2a−/− mice, despite similar levels of reduced parathyroid hormone and increased fibroblast growth factor 23. Plasma Ca2+ was increased ~ twofold in both genotypes. Whereas WT mice were able to increase urinary Pi and Ca2+/creatinine ratios, in Npt2a−/− mice, Pi/creatinine was unchanged and Ca2+/creatinine drastically decreased, coinciding with the highest kidney Ca2+ content, highest plasma creatinine, and greatest amount of nephrocalcinosis. In Npt2a−/− mice, vitamin D3 treatment completely diminished Npt2c abundance, so that mice resembled Npt2a/c double knockout mice. Abundance of intestinal Npt2b and claudin-3 (tight junctions protein) were reduced in Npt2a−/− only, the latter might facilitate the increase in plasma Pi in Npt2a−/− mice. Npt2a might function as regulator between renal Ca2+ excretion and reabsorption in response to vitamin D3.

Exploring Vitamin D Synthesis and Function in Cardiovascular Health: A Narrative Review

Vitamin D plays a crucial role in the human body, influencing a wide range of physiological processes from bone health to immune function. The complex biochemical pathways involved in the synthesis, metabolism, and action of Vitamin D are explored, emphasizing its importance in nutrition and food technology. This review also investigates the regulatory mechanisms that control Vitamin D metabolism and its systemic effects on calcium homeostasis, cell proliferation, differentiation, and immune modulation. The role of Vitamin D3 in regulating blood pressure and atherosclerosis in the onset of cardiovascular disorders is discussed. Given the importance of Vitamin D in food science and technology, the regulatory mechanisms that control Vitamin D metabolism and its systemic effects on calcium homeostasis are also investigated, integrating innovative approaches and advanced technologies to improve human health through nutrition. Additionally, the review assesses the influence of food processing on Vitamin D levels and discusses cutting-edge technologies as innovative strategies to mitigate Vitamin D loss during food processing. This comprehensive exploration aims to improve our understanding of the biochemical pathways of Vitamin D and its relevance to food science, contributing to the development of new strategies for food fortification and the promotion of optimal health through diet.

Vitamin D regulates COVID-19 associated severity by suppressing the NLRP3 inflammasome pathway.

The role of vitamin D3 (VitD3) in modulating innate and adaptive immunity has been reported in different disease contexts. Since the start of the coronavirus disease-2019 (COVID-19) pandemic, the role of VitD3 has been highlighted in many correlational and observational studies. However, the exact mechanisms of action are not well identified. One of the mechanisms via which VitD3 modulates innate immunity is by regulating the NLRP3-inflammasome pathway, being a main underlying cause of SARS-CoV-2-induced hyperinflammation. Blood specimens of severe COVID-19 patients with or without VitD3 treatment were collected during their stay in the intensive care unit and patients were followed up for 29 days. qPCR, western blot, and ELISA were done to investigate the mechanism of action of VitD3 on the NLRP3 inflammasome activation. We here report the ability of VitD3 to downregulate the NLRP3-inflammsome pathway in severe COVID-19 patients. Lower inflammasome pathway activation was observed with significantly lower gene and protein expression of NLRP3, cleaved caspase-1, ASC and IL-1β among severe COVID-19 patients treated with VitD3. The reduction of the inflammasome pathway was associated with a reduction in disease severity markers and enhancement of type I IFN pathway. Our data reveals an important anti-inflammatory effect of VitD3 during SARS-CoV-2 infection. Further investigations are warranted to better characterize the ability of VitD3 to control disease pathogenesis and prevent progression to severe states. This will allow for a more efficient use of a low cost and accessible treatment like VitD3.

Role of Vitamin D3 in Oral Implantology: A Literature Review

Dental implants integrated in the bone for a long period of time is the main goal of implantology, which in turn depends on many factors such as implant-related and others to the patient. Patient-related risk factors affects the success or failures of implants; this has initiated researchers into finding various mechanisms which control the remodelling of bone in the body of which Vit D3 plays an important role. The present review focuses on the importance of vitamin D3 in oral implantology.

Differential effects of cholecalciferol and calcitriol on muscle proteolysis and oxidative stress in angiotensin II-induced C2C12 myotube atrophy.

Renin-angiotensin system activation contributes to skeletal muscle atrophy in aging individuals with chronic diseases. We aimed to explore the effects of cholecalciferol (VD3) and calcitriol (1,25VD3) on signaling of muscle proteolysis and oxidative stress in myotubes challenged with angiotensin II (AII). The mouse C2C12 myotubes were assigned to vehicle, AII, AII + VD3, AII + 1,25VD3, and AII + losartan groups. The expression levels of muscle-specific E3 ubiquitin ligase proteins, autophagy-related proteins, and oxidative stress markers were investigated. We demonstrated the diverse effects of VD3 and 1,25VD3 on AII-induced myotube atrophy. The myotube diameter was preserved by treatment with 100 nM VD3 and losartan, while 1 and 10 nM 1,25VD3 increased levels of FoxO3a, MuRF1, and atrogin-1 protein expression in myotubes exposed to AII. Treatment with AII + 10 nM 1,25VD3 resulted in the upregulation of LC3B-II, LC3B-II/LC3B-I, and mature cathepsin L, which are autophagic marker proteins. The p62/SQSTM1 protein was downregulated and vitamin D receptor was upregulated after treatment with AII + 10 nM 1,25VD3. A cellular redox imbalance was observed as AII + 10 nM 1,25VD3-induced reactive oxygen species and NADPH oxidase-2 overproduction, and these changes were associated with an inadequate response of antioxidant superoxide dismutase-1 and catalase proteins. Collectively, these findings provide a translational perspective on the role of vitamin D3 in alleviating muscle atrophy related to high levels of AII.

Relationship in development of malocclusions to polymorphisms of selected vitamin D receptors.

The development of malocclusion is related to various factor, many of which are still not fully explained. The steroid hormone, 1,25-dihydroxyvitamin D3, has pleiotropic effects. It plays a key role in skeletal metabolism and the control of cell repair by attaching to the nuclear vitamin D steroid receptor (VDR). This vitamin affects bone turnover through the processes of bone tissue formation and resorption via its action on cells of the osteoblastic and osteoclastic lineage, exerts a modulating effect on the immune system, and is involved in the regulation of cell proliferation and differentiation. The role of vitamin D3 (VD3) and its receptor polymorphisms is a rarely studied topic in dentistry. Due to the proven influence on bone turnover processes and immune responses, the main research topic is its relation to periodontal diseases, but so far, its role in the formation and development of malocclusions has not been assessed. This study aimed to assess the association of selected VDR polymorphisms: Cdx2 (rs11658820), TaqI (rs7975232), BsmI (rs1544410), ApaI (rs7975232), and FokI (rs2228570) with the development of malocclusions. A prospective observational study was performed. The examination consisted of a medical interview, intraand extraoral orthodontic diagnosis, alginate impression, cone beam computed tomography (CBCT), and venous blood sample to obtain genomic DNA and assess VDR polymorphisms. The rs11658820 polymorphism causes an almost 4-fold increase in the probability of the presence of a malocclusion. GT and TT genotypes of rs7975232 are also associated with a similar risk - almost 6 and almost 5 times higher, respectively. In turn, the effect of the rs2228570-AG and GG genotype polymorphisms on the occurrence of transversal anomalies was demonstrated (odds ratio (OR) = 8.46 and OR = 6.92, respectively). The association of individual polymorphisms with specific malocclusions should be carefully assessed, especially since some trends have been indicated.

The Role of Vitamin D3 and Trace Elements of Lumbar Spinal Degeneration in Patients Undergoing Lumbar Spinal Surgery

The Role of Vitamin D3 and Trace Elements of Lumbar Spinal Degeneration in Patients Undergoing Lumbar Spinal Surgery

Vitamin D3 promotes fish oocyte development by directly regulating gonadal steroid hormone synthesis†.

Vitamin D receptors and vitamin D3-metabolizing enzymes have been found to be highly expressed in the ovaries and spermatophores of fish. However, the role of vitamin D3 on fish gonadal development has rarely been reported. In this study, 2-month-old female zebrafish were fed with different concentrations of vitamin D3 diets (0, 700, 1400, and 11200IU/kg) to investigate the effects of vitamin D3 on ovarian development. The diet with 0IU/kg vitamin D3 resulted in elevated interstitial spaces, follicular atresia, and reproductive toxicity in zebrafish ovaries. Supplementation with 700 and 1400IU/kg of vitamin D3 significantly increased the oocyte maturation rate; upregulated ovarian gonadal steroid hormone synthesis capacity; and elevated plasma estradiol, testosterone, and ovarian vitellogenin levels. Furthermore, the current study identified a vitamin D response element in the cyp19a1a promoter and demonstrated that 1.25(OH)2D3-vitamin D response directly activated cyp19a1a production through activating the vitamin D response element. In conclusion, this study shows that an appropriate concentration of vitamin D3 can promote zebrafish ovarian development and affect vitellogenin synthesis through the vdr/cyp19a1a/er/vtg gene axis.

The role of vitamin D3 in modulating the interplay between NLRP3 inflammasome and autophagy in NASH

Damage-associated molecular patterns released upon hepatocyte injury ensuing non-alcoholic steatohepatitis (NASH) can stimulate innate immunity by activating NOD-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome, thereby triggering pro-inflammatory cascades in the liver. Aberrant NLRP3 activation allied to compromised autophagic clearance of its components contributes to the progression of multiple inflammatory diseases. Such intricate interplay, however, was not fully deciphered in NASH. Prior studies have illuminated the ability of vitamin D3 to temper inflammasome activation in several contexts, prompting us to probe the impact of vitamin D3, particularly its active form, calcitriol (CAL), on NLRP3 overactivation in a high-fat diet (HFD)-based NASH model and its potential dependence on autophagy. Hydroxychloroquine (HCQ), an autophagy inhibitor, was co-administered with CAL to examine the likely modulation of the NLRP3/autophagy crosstalk. Our results showed that treatment with CAL countervailed the histopathological derangement reported in the livers of HFD-fed mice that paralleled a restoration of vitamin D receptor gene expression and reduction in sterol regulatory element binding protein 1c levels. Moreover, p62 was curtailed with CAL treatment indicating autophagy induction. CAL also prompted a reduction in NLRP3, caspase-1, gasdermin D, and IL-18 protein levels along with the apoptosis-associated speck-like protein (ASC) gene expression. Treatment with CAL also reduced IL-1β and caspase-3 immunoreactivities compared to control. Intriguingly, CAL modulatory effects on inflammasome activation were curbed in the group that received HCQ, suggesting a potential autophagy dependency. Accordingly, the current study suggests that CAL was capable of ameliorating NASH via inhibiting NLRP3 inflammasome activation in an autophagy-dependent manner.

OR11-06 Biological Activity Of Lumisterol Hydroxymetabolites And Their Mechanism Of Action

Abstract Disclosure: A. Slominski: None. T. Kim: None. E. Podgorska: None. Z. Janjetovic: None. J. Stefan: None. S. Ravichandran: None. R.M. Slominski: None. Y. Song: None. Y. Song: None. J. Szpotan: None. A. Mobley: None. C. Raman: None. E. Tang: None. A.M. Jetten: None. M.F. Holick: None. R. Tuckey: None. While the role of vitamin D3 in body homeostasis is well established, the functions of its photoderivative, lumisterol (L3), are gradually being appreciated. Previously, we reported that L3 can be metabolized by CYP11A1 and CYP27A1 to mono- and dihydroxy-L3. Furthermore, we have shown that 7DHC reductase (DHCR7) does not act on L3 and its metabolites [(OH)nL3]. In the current study, we show the presence of CYP27A1-derived 25(OH)L3, (25R)27(OH)L3 and (25S)27(OH)L3 in human epidermis and serum, and the capability by human keratinocytes to generate them from L3 substrate. Furthermore, these metabolites inhibited keratinocyte proliferation and stimulated cell differentiation. They, together with CYP11A1-derived (OH)nL3 acted as ligands on the human aryl hydrocarbon (AhR), liver X (LXR α and β), and peroxisome proliferator-activated (PPARγ) receptors as demonstrated by functional assays, molecular modeling, and activation of the CYP1A1 and CYP1B1, which are downstream of the AhR. These findings indicate that these hydroxyderivatives can regulate physiological functions by acting on AhR, LXRs and PPARγ receptors and activate respective downstream signaling pathways. Thus, L3 produced in the skin by UVB, can act as a pro-hormone that is metabolized into biologically active metabolites by CYP11A1 and CYP27A1 that can not only regulate skin functions but also other biological functions after their entry into the systemic circulation. These findings open, previously unanticipated, exciting new areas of research on the physiological role of (OH)nL3, and L3 through action on AhR, LXRs and PPARγ receptors. Presentation: Friday, June 16, 2023

Osteoporosis and dermatoporosis: a review on the role of vitamin D.

Osteoporosis (OP) and Dermatoporosis (DP) are expressions of the aging process at the skin and bone levels, respectively. Both conditions are associated with increased morbidity for elderly people, and this requires necessary interventions. They share many common risk factors; among these, vitamin D (VD) deficiency appears to have a role. VD is involved in either disease with many mechanisms, among which immunomodulation. VD deficiency has been linked to OP because it inhibits the body's capacity to absorb calcium and maintain optimal bone health. Available evidence suggests that proper vitaminosis D also appears to be vital in preventing skin age-related issues. DP is often seen in elderly individuals, particularly those with long-term sun exposure and a history of chronic sun damage. VD deficiency can be linked to DP, since its involvement in collagen production, epidermal barrier function, inflammation regulation, wound healing, and sun protection. Aim of this review is to summarize the most updated existing evidence on the role of VD in the development of fragility syndromes such as DP and OP and the possible benefits of VD supplementation as a simple and harmful weapon against aging.

Vitamin D-An Effective Antioxidant in an Animal Model of Progressive Multiple Sclerosis.

Vitamin D (VD) is the most discussed antioxidant supplement for multiple sclerosis (MS) patients and many studies suggest correlations between a low VD serum level and onset and progression of the disease. While many studies in animals as well as clinical studies focused on the role of VD in the relapsing-remitting MS, knowledge is rather sparse for the progressive phase of the disease and the development of cortical pathology. In this study, we used our established rat model of cortical inflammatory demyelination, resembling features seen in late progressive MS, to address the question about whether VD could have positive effects on reducing cortical pathology, oxidative stress, and neurofilament light chain (NfL) serum levels. For this purpose, we used male Dark Agouti (DA) rats, with one group being supplemented with VD (400 IE per week; VD+) from the weaning on at age three weeks; the other group received standard rodent food. The rat brains were assessed using immunohistochemical markers against demyelination, microglial activation, apoptosis, neurons, neurofilament, and reactive astrocytes. To evaluate the effect of VD on oxidative stress and the antioxidant capacity, we used two different oxidized lipid markers (anti- Cu++ and HOCl oxidized LDL antibodies) along with colorimetric methods for protective polyphenols (PP) and total antioxidative capacity (TAC). NfL serum levels of VD+ and VD- animals were analyzed by fourth generation single-molecule array (SIMOA) analysis. We found significant differences between the VD+ and VD- animals both in histopathology as well as in all serum markers. Myelin loss and microglial activation is lower in VD+ animals and the number of apoptotic cells is significantly reduced with a higher neuronal survival. VD+ animals show significantly lower NfL serum levels, a higher TAC, and more PP. Additionally, there is a significant reduction of oxidized lipid markers in animals under VD supplementation. Our data thus show a positive effect of VD on cellular features of cortical pathology in our animal model, presumably due to protection against reactive oxygen species. In this study, VD enhanced remyelination and prevented neuroaxonal and oxidative damage, such as demyelination and neurodegeneration. However, more studies on VD dose relations are required to establish an optimal response while avoiding overdosing.

Local production of active vitamin D3 metabolites in breast cancer cells by CYP24A1 and CYP27B1

The role of vitamin D3 and its metabolites in cancer and especially as a treatment option has been widely disputed. Clinicians noting low serum 25-hydroxyvitamin D3 [25(OH)D3] levels in their patients, recommend vitamin D3 supplementation as a method of reducing the risk of cancer; however, data supporting this are inconsistent. These studies rely on systemic 25(OH)D3 as an indicator of hormone status, but 25(OH)D3 is further metabolized in the kidney and other tissues under regulation by several factors. This study examined if breast cancer cells also possess the ability to metabolize 25(OH)D3, and if so, whether the resulting metabolites are secreted locally; if this ability reflects ERα66 status; and if they possess vitamin D receptors (VDR). To address this question, estrogen receptor alpha (ERα) positive (MCF-7) and ERα negative (HCC38 and MDA-MB-231) breast cancer cell lines were examined for expression of ERα66, ERα36, CYP24A1, CYP27B1, and VDR as well as for local production of 24,25-dihydroxyvitamin D3 [24,25(OH)2D3] and 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] after treatment with 25(OH)D3. The results showed that independent of ER status, breast cancer cells express the enzymes CYP24A1 and CYP27B1, which are responsible for converting 25(OH)D3 into its dihydroxylated forms. Moreover, these metabolites are produced at levels comparable to the levels observed in blood. They are positive for VDR, indicating that they can respond to 1α,25(OH)2D3, which can upregulate CYP24A1. These findings suggest that vitamin D metabolites may contribute to the tumorigenicity of breast cancer via autocrine and/or paracrine mechanisms.

Evaluation of serum levels of vitamin D and CXCL10 in patients with generalized vitiligo and their relation to disease severity

Background Vitiligo is an acquired, common, autoimmune, pigmentary defect of the skin. Vitamin D (VitD) plays a physiological role in photo-induced melanogenesis in the skin. It was found that VitD levels decline in autoimmune illnesses. Recently, there has been growing interest in the role of vitamin D3 in the pathogenesis of vitiligo and its change after treatment. The chemokine CXCL10 was found to be raised in the serum of patients with vitiligo. Few studies have evaluated its relation to the severity of the disease. Aims To establish a link between both serum VitD and serum CXCL10 and vitiligo, besides evaluating their possible relation to disease severity. Patients and methods This study was conducted on 30 patients with generalized vitiligo and 30 healthy individuals without age and sex limitations. Serum VitD and CXCL10 levels were measured for both patients with vitiligo and controls and were re-evaluated after 12 weeks for patients with vitiligo. The Vitiligo Area Scoring Index was calculated for the patient group at baseline and after 12 weeks. Results Serum VitD was found to be significantly lower in patients with vitiligo than controls, whereas serum CXCL10 was significantly higher in patients than healthy controls. Changes in serum CXCL10 at the end of the study period positively correlated with changes in Vitiligo Area Scoring Index of patients with vitiligo. Conclusion There is a strong relationship between both serum VitD and CXCL10 and vitiligo. Serum CXCL10 levels change in relation to disease severity.

Serum Parathyroid Hormone and Vitamin D Levels as Predictors of Hypocalcemia after Total/ Near Total Thyroidectomy

Background: Post-operative Hypocalcaemia is the most-common complication of total and near-total thyroidectomy which is a selective treatment for benign and malignant thyroid diseases. Incidence ranges from 0.5-50%. Objectives: The role of vitamin-D and Parathyroid hormone(PTH) in incidence of Hypocalcemia after thyroidectomy has been taken into consideration. Methods: This is a prospective interventional study is conducted in Kasturba Medical College and hospital, Manipal after taking written informed consent from the participants. It aimed at surveying the serum level of preoperative Vitamin D, PTH and calcium before total-thyroidectomy surgery and its relationship with the incidence of postoperative hypocalcemia after the surgery. The study was done on 70 patients who were-planned for total/near total thyroidectomy. Preoperative Vitamin D, PTH, calcium and Postoperative 4 hours-PTH, Calcium were measured on POD-1, POD-2-4, the results obtained were then analysed. Results: Considering the cut-off of calcium as 8.6mg/dl, 42 patients developed hypocalcemia on POD-1, 28 patients on POD-2. Preoperative calcium and postoperative PTH levels in people having hypocalcaemia where significantly less compared to the patients having normal calcium. 4-hours post-operative PTH measurements showed 51% sensitivity, 100% specificity and strong co-relation between postoperative hypocalcemia and drop in PTH levels- (p=<0.001). Out of 42 patients who developed hypocalcemia 28- (65%) patients had vitamin-D deficiency(p=0.5) on POD-1 and out of 51 patients with hypocalcemia on POD 2-4, 33(78%) had-vitamin-D-deficiency(p=0.3852). Which was not statically significant. Conclusion:4 hours post-operative PTH level is a predictor of early postoperative hypocalcemia, by detecting this we can effectively manage postoperative hypocalcemia

Role of vitamin D3 in selected pulmonary diseases with particular emphasis on lung fibrosis.

For many years vitamin D3 was known only as a regulator of the calcium-phosphate and water-electrolyte balances. Recent studies have paid special attention to other biological effects of calcitriol (the bioactive form of vitamin D3) with particular emphasis on its influence on immune function. Thus, any alterations, especially deficiencies, in the physiological level of calcitriol have serious health consequences. The aim of the study was to summarise the current state of knowledge concerning the role of vitamin D3 in selected pulmonary diseases. The review was based on data obtained from articles published in PubMed between 2000-2022. Papers were reviewed for scientific merit and relevance. In the reviewed literature, much attention was paid to clinical studies focused on the role of vitamin D3 in the pathogenesis of selected respiratory diseases. As revealed in research over the last two decades, vitamin D3 deficiency increases the risk and worsens the course of asthma, cystic fibrosis, chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, as well as COVID-19. Surprisingly, vitamin D supplementation has not always proved to be an effective therapeutic strategy. The review also presents the unique concept of the possibility of using vitamin D3 in the prevention and treatment of pulmonary fibrosis in the course of hypersensitivity pneumonitis. Due to the multiplicity and variety of factors that affect the metabolism of vitamin D3, effective counteracting, and even more eliminating the negative consequences of disorders in the level and activity of calcitriol in the respiratory tract, seems to be a breakneck action. On the other hand, only a deep understanding of the role of calcitriol in the pathogenesis of lung diseases provides the chance to develop an effective therapy.

Vitamin D Knowledge and Awareness Is Associated with Physical Activity among Adults: A Cross-Sectional Survey.

The relation between knowledge and awareness of vitamin D (VD) and physical activity in adults has not been well studied. The present cross-sectional study aims to demonstrate this relation among adults living in Saudi Arabia. A total of 774 adults participated and were stratified based on self-reports of whether they were physically active (PA group, N = 562) or not (non-PA, N = 212). The prevalence of VD awareness and its health effects were significantly higher in the PA group compared with their counterparts (97 vs. 93.4%; p = 0.02 and 92.3 vs. 81.6%; p < 0.001, respectively). Sunlight was the preferred overall source of VD among the PA group (91.1%) followed by food, supplements, and fortified foods. Sardine, salmon, oily fish (63.7%) and eggs (54.6%) were reported as good dietary sources. Other positive attitudes, represented by taking supplement or multivitamins (51.2%), high sun exposure (33.1%), and daily duration of exposure to sunlight (15−30 min; 53.4%) were higher in the PA than the non-PA group (p values < 0.05). The body parts exposed to the sun among the PA group were arms (67.1%), hands (64.1%), face and hands (62.5%), legs (58.5%), and face (53.2%), while sunscreen cream (47.2%) was their preferred sun-protection method. High levels of knowledge and positive attitudes were reported by the PA group compared with the non-PA group in regard to walking outdoors for sun exposure (80.6 vs. 62.7%; p < 0.001). Information about good dietary sources, the role of VD in human health, associated diseases, positive attitudes to sun exposure, and the use of supplements or multivitamins were among the determinants of VD knowledge and awareness. In conclusion, VD knowledge and awareness are positively associated with self-reported physical activity in adults. Further objective classifications of PA may strengthen the results of the present investigation.

Is Vitamin D3 a Worthy Supplement Protecting against Secondary Infections in Dogs with Atopic Dermatitis?

Canine atopic dermatitis (CAD) is a common, chronic, inflammatory skin disease in dogs worldwide. This disease often predisposes for secondary organisms overgrowth and skin infections with pathogens, such as Staphylococcus pseudintermedius and Malassezia pachydermatis. Unfortunately, the causes of this disease in both humans and animals are not fully understood; therefore, the only possible option is a lifelong, symptomatic treatment. The management of CAD is mainly based on limiting contact with allergens and antipruritic therapy, most often with glucocorticoids and antihistamines. A serious problem in this situation is the fact, that long-term administration of glucocorticoids leads to side effects like polyuria, alopecia, increased susceptibility to infection, muscle atrophy, and many others. For this reason, great emphasis is placed on the development of replacement and supportive therapies. It is a well-documented fact that reduced concentrations of serum vitamin D3 contribute to the severity of atopic dermatitis symptoms in humans. Moreover, unlike the most commonly used therapeutic methods, of which the main goal is to ameliorate inflammation and pruritus, namely the symptoms of AD, vitamin D3 supplementation affects some underlying factors of this disease. Therefore, in this review, we summarize the current state of knowledge regarding the role of vitamin D3 in CAD, its protective effect against secondary bacterial and fungal infections, and the potential of its supplementation in dogs.