Evolutionary formation of melatonin and vitamin D in early life forms: insects take centre stage.

Melatonin, a product of tryptophan metabolism via serotonin, is a molecule with an indole backbone that is widely produced by bacteria, unicellular eukaryotic organisms, plants, fungi and all animal taxa. Aside from its role in the regulation of circadian rhythms, it has diverse biological actions including regulation of cytoprotective responses and other functions crucial for survival across different species. The latter properties are also shared by its metabolites including kynuric products generated by reactive oxygen species or phototransfomation induced by ultraviolet radiation. Vitamins D and related photoproducts originate from phototransformation of ∆5,7 sterols, of which 7-dehydrocholesterol and ergosterol are examples. Their ∆5,7 bonds in the B ring absorb solar ultraviolet radiation [290-315 nm, ultraviolet B (UVB) radiation] resulting in B ring opening to produce previtamin D, also referred to as a secosteroid. Once formed, previtamin D can either undergo thermal-induced isomerization to vitamin D or absorb UVB radiation to be transformed into photoproducts including lumisterol and tachysterol. Vitamin D, as well as the previtamin D photoproducts lumisterol and tachysterol, are hydroxylated by cyochrome P450 (CYP) enzymes to produce biologically active hydroxyderivatives. The best known of these is 1,25-dihydroxyvitamin D (1,25(OH)2D) for which the major function in vertebrates is regulation of calcium and phosphorus metabolism. Herein we review data on melatonin production and metabolism and discuss their functions in insects. We discuss production of previtamin D and vitamin D, and their photoproducts in fungi, plants and insects, as well as mechanisms for their enzymatic activation and suggest possible biological functions for them in these groups of organisms. For the detection of these secosteroids and their precursors and photoderivatives, as well as melatonin metabolites, we focus on honey produced by bees and on body extracts of Drosophila melanogaster. Common biological functions for melatonin derivatives and secosteroids such as cytoprotective and photoprotective actions in insects are discussed. We provide hypotheses for the photoproduction of other secosteroids and of kynuric metabolites of melatonin, based on the known photobiology of ∆5,7 sterols and of the indole ring, respectively. We also offer possible mechanisms of actions for these unique molecules and summarise differences and similarities of melatoninergic and secosteroidogenic pathways in diverse organisms including insects.

Efficacy, safety, and dose-response effects of calcifediol supplementation on 25-hydroxyvitamin D, parathyroid hormone, and 1,25-dihydroxyvitamin D levels in healthy adults: An open-label, interventional pilot study.

BACKGROUND: Vitamin D deficiency (VDD) is highly prevalent across the globe. Cholecalciferol (Vitamin D3) fails to attain sufficient serum concentrations of 25-hydroxyvitamin D (25(OH)D) in a significant proportion of supplemented individuals. Calcifediol (25-hydroxyvitamin D3) is less studied in healthy adults and its effects on 25(OH)D, parathyroid hormone (PTH), and 1,25-dihydroxyvitamin D (1,25(OH)2D) at higher doses are not well known. MATERIALS AND METHODS: The study was an open-label, interventional trial recruiting consecutive participants with VDD who were allocated to receive either 2 capsules (50 µg-group) or 1 capsule (25 µg-group) daily doses of calcifediol. Baseline assessment included clinicodemographic parameters, dietary calcium, calcemic (calcium, inorganic phosphate, albumin, alkaline phosphatase, urine spot calcium/creatinine), and hormonal parameters (25(OH)D, PTH, and 1,25(OH)2D). Participants were followed up at 4 and 8 weeks with repeat assessments of calcemic and hormonal parameters. RESULTS: There were 64 participants, 35 (50 µg-group) and 29 (25 µg-group), without any significant difference in any of the baseline parameters. 97.1% participants in the 50 µg-group (at 4 and 8 weeks) and 93.1% (at 4 weeks) and 96.5% (at 8 weeks) in the 25 µg-group attained 25(OH)D sufficiency (≥30 ng/ml) with calcifediol. The mean serum 25(OH)D was 84.0 ± 27.7 ng/ml in the 50 µg-group and 58.0 ± 23.6 ng/ml in the 25 µg-group group at 4 weeks, which later rose to 94.3 ± 21.8 ng/ml and 76.0 ± 16.4 ng/ml, respectively, at 8 weeks. PTH levels decreased in both groups at both time points. 1,25(OH)2D rose significantly in both groups at 4 and 8 weeks but was not significantly different between both groups. There was no case of incident hypercalcemia or symptomatic nephrolithiasis. CONCLUSION: Calcifediol is a safe and efficacious alternative for oral Vitamin D supplementation in young adults. Increment in 25(OH)D levels is rapid and dose-dependent.

Calcifediol: a review of its pharmacological characteristics and clinical use in correcting vitamin D deficiency.

BACKGROUND: In addition to the role of vitamin D in bone mineralization, calcium and phosphate homeostasis, and skeletal health, evidence suggests an association between vitamin D deficiency and a wide range of chronic conditions. This is of clinical concern given the substantial global prevalence of vitamin D deficiency. Vitamin D deficiency has traditionally been treated with vitamin D3 (cholecalciferol) or vitamin D2 (ergocalciferol). Calcifediol (25-hydroxyvitamin D3) has recently become available more widely. METHODS: By means of targeted literature searches of PubMed, this narrative review overviews the physiological functions and metabolic pathways of vitamin D, examines the differences between calcifediol and vitamin D3, and highlights clinical trials conducted with calcifediol in patients with bone disease or other conditions. RESULTS: For supplemental use in the healthy population, calcifediol can be used at doses of up to 10 µg per day for children ≥ 11 years and adults and up to 5 µg/day in children 3-10 years. For therapeutic use of calcifediol under medical supervision, the dose, frequency and duration of treatment is determined according to serum 25(OH)D concentrations, condition, type of patient and comorbidities. Calcifediol differs pharmacokinetically from vitamin D3 in several ways. It is independent of hepatic 25-hydroxylation and thus is one step closer in the metabolic pathway to active vitamin D. At comparable doses to vitamin D3, calcifediol achieves target serum 25(OH)D concentrations more rapidly and in contrast to vitamin D3, it has a predictable and linear dose-response curve irrespective of baseline serum 25(OH)D concentrations. The intestinal absorption of calcifediol is relatively preserved in patients with fat malabsorption and it is more hydrophilic than vitamin D3 and thus is less prone to sequestration in adipose tissue. CONCLUSION: Calcifediol is suitable for use in all patients with vitamin D deficiency and may be preferable to vitamin D3 for patients with obesity, liver disease, malabsorption and those who require a rapid increase in 25(OH)D concentrations.

The One-Hundred-Year Anniversary of the Discovery of the Sunshine Vitamin D3: Historical, Personal Experience and Evidence-Based Perspectives.

The discovery of a fat-soluble nutrient that had antirachitic activity and no vitamin A activity by McCollum has had far reaching health benefits for children and adults. He named this nutrient vitamin D. The goal of this review and personal experiences is to give the reader a broad perspective almost from the beginning of time for how vitamin D evolved to became intimately involved in the evolution of land vertebrates. It was the deficiency of sunlight causing the devastating skeletal disease known as English disease and rickets that provided the first insight as to the relationship of sunlight and the cutaneous production of vitamin D3. The initial appreciation that vitamin D could be obtained from ultraviolet exposure of ergosterol in yeast to produce vitamin D2 resulted in the fortification of foods with vitamin D2 and the eradication of rickets. Vitamin D3 and vitamin D2 (represented as D) are equally effective in humans. They undergo sequential metabolism to produce the active form of vitamin D, 1,25-dihydroxyvitamin D. It is now also recognized that essentially every tissue and cell in the body not only has a vitamin D receptor but can produce 1,25-dihydroxyvitamin D. This could explain why vitamin D deficiency has now been related to many acute and chronic illnesses, including COVID-19.

Guidelines for Preventing and Treating Vitamin D Deficiency: A 2023 Update in Poland.

Introduction: All epidemiological studies suggest that vitamin D deficiency is prevalent among the Polish general population. Since vitamin D deficiency was shown to be among the risk factors for many diseases and for all-cause mortality, concern about this problem led us to update the previous Polish recommendations. Methods: After reviewing the epidemiological evidence, case-control studies and randomized control trials (RCTs), a Polish multidisciplinary group formulated questions on the recommendations for prophylaxis and treatment of vitamin D deficiency both for the general population and for the risk groups of patients. The scientific evidence of pleiotropic effects of vitamin D as well as the results of panelists' voting were reviewed and discussed. Thirty-four authors representing different areas of expertise prepared position statements. The consensus group, representing eight Polish/international medical societies and eight national specialist consultants, prepared the final Polish recommendations. Results: Based on networking discussions, the ranges of total serum 25-hydroxyvitamin D concentration indicating vitamin D deficiency [<20 ng/mL (<50 nmol/L)], suboptimal status [20-30 ng/mL (50-75 nmol/L)], and optimal concentration [30-50 ng/mL (75-125 nmol/L)] were confirmed. Practical guidelines for cholecalciferol (vitamin D3) as the first choice for prophylaxis and treatment of vitamin D deficiency were developed. Calcifediol dosing as the second choice for preventing and treating vitamin D deficiency was introduced. Conclusions: Improving the vitamin D status of the general population and treatment of risk groups of patients must be again announced as healthcare policy to reduce a risk of spectrum of diseases. This paper offers consensus statements on prophylaxis and treatment strategies for vitamin D deficiency in Poland.

Genomic or Non-Genomic? A Question about the Pleiotropic Roles of Vitamin D in Inflammatory-Based Diseases.

Vitamin D (vit D) is widely known for its role in calcium metabolism and its importance for the bone system. However, various studies have revealed a myriad of extra-skeletal functions, including cell differentiation and proliferation, antibacterial, antioxidant, immunomodulatory, and anti-inflammatory properties in various cells and tissues. Vit D mediates its function via regulation of gene expression by binding to its receptor (VDR) which is expressed in almost all cells within the body. This review summarizes the pleiotropic effects of vit D, emphasizing its anti-inflammatory effect on different organ systems. It also provides a comprehensive overview of the genetic and epigenetic effects of vit D and VDR on the expression of genes pertaining to immunity and anti-inflammation. We speculate that in the context of inflammation, vit D and its receptor VDR might fulfill their roles as gene regulators through not only direct gene regulation but also through epigenetic mechanisms.

Bone Fragility in Hereditary Connective Tissue Disorders: A Systematic Review and Meta-Analysis.

OBJECTIVE: To investigate bone fragility in patients with hereditary connective tissue disorders (HCTD), including Ehlers-Danlos syndrome (EDS), Marfan's syndrome (MFS) and Loeys-Dietz syndrome (LDS). METHODS: From inception to June 2022, potentially eligible studies were identified in the Medline and EMBASE databases using search strategy that included terms for "HCTD", "Fracture" and "Osteoporosis". Eligible studies must consist of a group of patients with HCTD and report prevalence/incidence of fracture/osteoporosis in their participants, with or without comparison with healthy individuals. Point estimates with standard errors were obtained from each study and combined using the generic inverse variance method. RESULTS: Among the 4206 articles identified, 19 studies were included. The pooled prevalence of fracture in EDS, MFS, and LDS were 44% (95% confidence interval [CI], 25% to 65%, I2 88%), 17% (95% CI, 11% to 26%, I2 68%), 69% (95% CI, 47% to 85%, I2 83%), respectively. The pooled prevalence of osteoporosis in EDS was 17% (95% CI, 8% to 34%, I2 96%). EDS was associated with fracture [pooled odds ratio {OR} 4.90 (95% CI, 1.49 - 16.08, I2 86%)], but not osteoporosis [pooled OR 1.34 (95% CI, 0.28 - 6.36, I2 87%). One study reported a 5% (95% CI, 3% to 8%) prevalence of osteoporosis in MFS, which was associated with fracture [incidence rate ratio 1.35 (95% CI, 1.18 - 1.55)] and osteoporosis [subhazard ratio 3.97 (95% CI, 2.53 - 6.25)]. CONCLUSION: EDS was associated with fracture, which could be independent of osteoporosis status. MFS had a milder degree of increased risk of fracture and osteoporosis. Despite no data from cohort studies, there was a significantly higher rate of fracture in LDS.

Effect of supplemental vitamin D3 on bone mineral density: a systematic review and meta-analysis.

CONTEXT: There is still controversy over the effect of vitamin D3 supplementation on bone health. OBJECTIVE: The effects of vitamin D3 supplementation on bone mineral density (BMD) and markers of bone turnover, as well as the dose-response relationship between vitamin D3 and bone health in adults, were evaluated. DATA SOURCES: The PubMed, Scopus, Cochrane, Web of Science, and AGRIS databases were searched for articles published through April 30, 2022. Thirty-nine of the 6409 records identified met the inclusion criteria. DATA EXTRACTION: Data were extracted from articles by 2 authors, and data extraction was cross-checked independently. A random-effects model was used to estimate the pooled effect size and the associated 95%CI for the effect of vitamin D3 for each outcome. A one-stage random-effects dose-response model was used to estimate the dose-response relationship between vitamin D3 supplementation and BMD. DATA ANALYSIS: Results of meta-analysis showed a beneficial effect of vitamin D3 at the lumbar spine (standardized mean difference [SMD] = 0.06; 95%CI, 0.01-0.12) and femoral neck (SMD = 0.25; 95%CI, 0.09-0.41). Dose-response analysis revealed a linear relationship between vitamin D3 supplementation doses and BMD at the femoral neck, lumbar spine, and total hip sites. No significant effect of vitamin D3 supplementation on whole-body or total hip BMD was observed (P > 0.05). Vitamin D3 supplementation significantly decreased BMD at both proximal and distal forearm (SMD = -0.16; 95%CI, -0.26 to -0.06). The variables of ethnicity, age, baseline 25-hydroxyvitamin D (25[OH]D), menopause status, vitamin D3 dosing frequency, and bone health status (P interaction = 0.02) altered the effect of vitamin D3 supplementation on BMD. Additionally, a nonlinear relationship between vitamin D3 supplement doses and markers of bone turnover was found. CONCLUSION: A protective effect of vitamin D3 supplementation on BMD of the lumbar spine, femoral neck, and total hip is implicated. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration number CRD42017054132.

Mosquitoes Exposed to Sunlight in Florida Are Capable of Making Vitamin D3.

BACKGROUND/AIM: This study aimed to determine whether mosquitoes exposed to natural sunlight are able to produce vitamin D3 Materials and Methods: Mosquito eggs obtained from adult Aedes aegypti mosquitoes were raised to adulthood. Approximately 1,200 male and female mosquitoes were divided among six cages. Four cages were placed on the roof on sunny days, 10-Sep-2021 and 12-Oct-2021. Two of the cages were exposed to sunlight from 8:30-18:00 and brought inside during rainstorms in the midday that lasted approximately 2 hours, while the other two cages were placed in deep shade and served as a control. After the exposure, the mosquitoes were collected and frozen at -80°C. The mosquitoes were thawed and then extracted in methanol followed by high-performance liquid chromatography analysis. RESULTS: The mosquitoes that were exposed to sunlight produced vitamin D3 whereas the mosquitoes kept in deep shade and not exposed to any sunlight did not produce significant vitamin D3 Conclusion: Mosquitoes exposed to sunlight have the ability to produce vitamin D3 Therefore, mosquitoes exposed to sunlight provide an excellent dietary source of vitamin D3 for insect eating vertebrates including birds and especially bats that avoid sun exposure and require vitamin D for their skeletal health.

Evaluation of 14-day Concentration-time Curves of Vitamin D3 and 25-Hydroxyvitamin D3 in Healthy Adults With Varying Body Mass Index.

BACKGROUND/AIM: To analyze the concentration-time curves of single-dose oral 25(OH)D3 in comparison with vitamin D3 in healthy adults. PATIENTS AND METHODS: The pharmacokinetics observed over two weeks after orally administering single 900 µg doses of vitamin D3 and 25(OH)D3 to six otherwise healthy vitamin D insufficient/deficient adults participating in a broader randomized, double-blind, crossover, single center trial was analyzed. The study protocol was approved by the institutional review board (H-37167). RESULTS: Individual concentration-time curves revealed that vitamin D3 took longer than 25(OH)D3 to reach its maximal concentration after ingestion in five participants. After 25(OH)D3 ingestion, 25(OH)D3 reached its maximal concentration, dropped rapidly, and plateaued before starting to decrease slowly. There were observable inter-individual variations in the bioavailability of vitamin D3 and 25(OH)D3 and the pattern of changes in 25(OH)D3 concentration after their ingestion. CONCLUSION: Pharmacokinetics of 25(OH)D3 in comparison with vitamin D3 was illustrated and described in this study.

A Novel Immunomodulatory Mechanism by Which Vitamin D Influences Folate Receptor 3 Expression to Reduce COVID-19 Severity.

BACKGROUND/AIM: Identify potential mechanisms involving gene expression changes through which vitamin D supplementation could be beneficial in preventing adverse COVID-19 outcomes. MATERIALS AND METHODS: We performed a literature review to identify differentially expressed genes (DEGs) in the blood between severe and mild COVID-19 patients. We compared these with the top DEGs induced by 6 months of 10,000 IU/day vitamin D supplementation in healthy adults who were vitamin D deficient/insufficient. We used bioinformatic tools to look for a vitamin D response element (VDRE) in DEGs. RESULTS: FOLR3, RGS1, GPR84, and LRRN3 were the most significantly altered genes by 6 months of 10,000 IU/day vitamin D supplementation whose expression levels were also involved in COVID-19 severity. FOLR3 and GPR84 were found to be consistently up-regulated and RGS1 and LRRN3 consistently down-regulated in severe COVID-19 infection. FOLR3 and LRRN3 were down-regulated and RGS1 and GPR84 were up-regulated by 10,000 IU/day vitamin D supplementation. CONCLUSION: FOLR3 and RGS1 are expressed in neutrophils and lymphocytes, respectively. Vitamin D supplementation may decrease the neutrophil-lymphocyte ratio as has been reported in patients admitted with severe symptoms. There is evidence that vitamin D directly influences the expression of the RGS1 gene through vitamin D receptor binding. A potential negative VDRE (nVDRE) in an intron of the FOLR3 gene was found, which was homologous with two known nVDREs. Combined with other transcription factor elements near the newly identified nVDRE, these observations may explain the mechanism by which vitamin D regulates these genes, thus influencing COVID-19 outcomes.

An Appraisal to Address Health Consequences of Vitamin D Deficiency With Food Fortification and Supplements: Time to Act!

A symposium entitled "Vitamin D in Prevention and Therapy" was held on May 4-5, 2022, in Homburg, Germany to discuss important new advances in the field, including identification of new vitamin D signaling pathways, of new biologic effects of vitamin D-compounds (e.g., on the microbiome), and convincing proof of the relevance of vitamin D deficiency for the risk and outcome of many chronic diseases, including cancer, cardio-vascular, auto-immune, metabolic, and infectious diseases. Concerning the COVID-19-pandemic, an inverse association between 25(OH)D serum concentrations and SARS-CoV-2-infections, morbidity, and mortality was shown. In relation to cancer, several meta-analyses recently demonstrated an association of vitamin D-supplementation with significantly decreased mortality rates, which presumably would reduce health care costs. Considering the impressive body of evidence and the high safety of oral supplementation and food fortification with vitamin D, it was concluded that there is now an urgent need to act. In many countries worldwide, health care authorities need to increase efforts to address vitamin D deficiency, e.g., via food fortification and/or supplementation with vitamin D, and/or promoting moderate UV-exposure. It was estimated that in many countries, vitamin D intakes of the order of appr. 1,000 IE (25 µg)/day would be needed to bring and/or keep the vast majority of people over a serum 25(OH)D threshold of 20 ng/ml (50 nmol/l), which would be difficult to obtain alone from food fortification. New developments in personalized medicine may represent helpful tools to identify populations at risk for vitamin D deficiency and their responsiveness to vitamin D treatment.

Hereditary Metabolic Bone Diseases: A Review of Pathogenesis, Diagnosis and Management.

Hereditary metabolic bone diseases are characterized by genetic abnormalities in skeletal homeostasis and encompass one of the most diverse groups among rare diseases. In this review, we examine 25 selected hereditary metabolic bone diseases and recognized genetic variations of 78 genes that represent each of the three groups, including sclerosing bone disorders, disorders of defective bone mineralization and disorder of bone matrix and cartilage formation. We also review pathophysiology, manifestation and treatment for each disease. Advances in molecular genetics and basic sciences has led to accurate genetic diagnosis and novel effective therapeutic strategies for some diseases. For other diseases, the genetic basis and pathophysiology remain unclear. Further researches are therefore crucial to innovate ways to overcome diagnostic challenges and develop effective treatment options for these orphan diseases.

Nutritional rickets and vitamin D deficiency: consequences and strategies for treatment and prevention.

INTRODUCTION: Rickets is typically characterized by bone deformities due to defective bone mineralization and chondrocyte maturation in growing bones. However, infantile rickets often goes unrecognized, because the skeletal abnormalities are more subtle and often can only be detected radiologically. Nutritional rickets is a major public health concern in several regions worldwide. It is most commonly caused by vitamin D and/or calcium deficiency. AREA COVERED: We provide an overview of historical perspective, epidemiology, and pathophysiology of nutritional rickets. Additionally, we outline diagnostic approaches and highlight challenges in radiographic diagnosis of rickets. Finally, we present strategies for prevention and treatment of rickets. EXPERT OPINION: Despite the evidence from clinical databases that rickets is a rare disease, it is likely that rickets is clinically underdiagnosed as studies designed to screen healthy children for radiographic evidence of rickets reported surprisingly much higher prevalence. It has been reported that some of the radiologic features of rickets can be misinterpreted as fractures. To prevent nutritional rickets, most if not all infants and young children, should receive vitamin D from formulas and foods that are fortified with vitamin D or supplementation to achieve a serum 25-hydroxyvitamin D of at least 20 ng/mL as recommended by the Institute of Medicine. It has been recommended by the Endocrine Society that to achieve maximum bone health for children and adults, a serum concentration of 25-hydroxyvitamin D should be at least 30 ng/mL and preferably 40-60 ng/mL. Pregnant women who are unable to obtain an adequate amount of vitamin D from sunlight exposure and natural and fortified diets should take a vitamin D supplement of 1500-2000 IUs daily as recommended by the Endocrine Society since it has been demonstrated that 600 IUs daily will not maintain a circulating 25-hydroxyvitamin D of at least 20 ng/mL and most pregnant women. If lactating women take approximately 6400 IUs of vitamin D daily, they provide enough vitamin D in their milk to satisfy their infant's requirement thereby preventing rickets.