Intestinal absorption of vitamin D: a systematic review

Comprehensive nutrition guidelines and management strategies for enteropathy in children

Protein-losing enteropathy (PLE) describes a syndrome of excessive protein loss into the gastrointestinal tract, which may be due to a wide variety of etiologies. For children in whom the protein loss is associated with lymphangiectasia, medical nutrition therapy focused on restricting enteral long-chain triglycerides and thus intestinal chyle production is an integral component of treatment. This approach is based on the principle that reducing intestinal chyle production will concurrently decrease enteric protein losses of lymphatic origin. In patients with ongoing active PLE or those who are on a fat-restricted diet, particularly in infants and young children, supplemental calories may be provided with medium-chain triglycerides (MCT). MCT are absorbed directly into the bloodstream, bypassing intestinal lymphatics and not contributing to intestinal chyle production. Patients with active PLE or who are on dietary fat restriction should be monitored for associated micronutrient deficiencies. In this paper, we seek to formally present recommended nutrition interventions, principles of dietary education and patient counseling, and monitoring parameters in pediatric populations with PLE based on our experience in a busy clinical referral practice focused on this population.

Mini-encyclopedia of mitochondria-relevant nutraceuticals protecting health in primary and secondary care-clinically relevant 3PM innovation

Despite their subordination in humans, to a great extent, mitochondria maintain their independent status but tightly cooperate with the "host" on protecting the joint life quality and minimizing health risks. Under oxidative stress conditions, healthy mitochondria promptly increase mitophagy level to remove damaged "fellows" rejuvenating the mitochondrial population and sending fragments of mtDNA as SOS signals to all systems in the human body. As long as metabolic pathways are under systemic control and well-concerted together, adaptive mechanisms become triggered increasing systemic protection, activating antioxidant defense and repair machinery. Contextually, all attributes of mitochondrial patho-/physiology are instrumental for predictive medical approach and cost-effective treatments tailored to individualized patient profiles in primary (to protect vulnerable individuals again the health-to-disease transition) and secondary (to protect affected individuals again disease progression) care. Nutraceuticals are naturally occurring bioactive compounds demonstrating health-promoting, illness-preventing, and other health-related benefits. Keeping in mind health-promoting properties of nutraceuticals along with their great therapeutic potential and safety profile, there is a permanently growing demand on the application of mitochondria-relevant nutraceuticals. Application of nutraceuticals is beneficial only if meeting needs at individual level. Therefore, health risk assessment and creation of individualized patient profiles are of pivotal importance followed by adapted nutraceutical sets meeting individual needs. Based on the scientific evidence available for mitochondria-relevant nutraceuticals, this article presents examples of frequent medical conditions, which require protective measures targeted on mitochondria as a holistic approach following advanced concepts of predictive, preventive, and personalized medicine (PPPM/3PM) in primary and secondary care.

Consensus Statement on Vitamin D Status Assessment and Supplementation: Whys, Whens, and Hows

The 6th International Conference, "Controversies in Vitamin D," was convened to discuss controversial topics, such as vitamin D metabolism, assessment, actions, and supplementation. Novel insights into vitamin D mechanisms of action suggest links with conditions that do not depend only on reduced solar exposure or diet intake and that can be detected with distinctive noncanonical vitamin D metabolites. Optimal 25-hydroxyvitamin D (25(OH)D) levels remain debated. Varying recommendations from different societies arise from evaluating different clinical or public health approaches. The lack of assay standardization also poses challenges in interpreting data from available studies, hindering rational data pooling and meta-analyses. Beyond the well-known skeletal features, interest in vitamin D's extraskeletal effects has led to clinical trials on cancer, cardiovascular risk, respiratory effects, autoimmune diseases, diabetes, and mortality. The initial negative results are likely due to enrollment of vitamin D-replete individuals. Subsequent post hoc analyses have suggested, nevertheless, potential benefits in reducing cancer incidence, autoimmune diseases, cardiovascular events, and diabetes. Oral administration of vitamin D is the preferred route. Parenteral administration is reserved for specific clinical situations. Cholecalciferol is favored due to safety and minimal monitoring requirements. Calcifediol may be used in certain conditions, while calcitriol should be limited to specific disorders in which the active metabolite is not readily produced in vivo. Further studies are needed to investigate vitamin D effects in relation to the different recommended 25(OH)D levels and the efficacy of the different supplementary formulations in achieving biochemical and clinical outcomes within the multifaced skeletal and extraskeletal potential effects of vitamin D.

The Power of Vitamin D: Is the Future in Precision Nutrition through Personalized Supplementation Plans?

In the last few decades, vitamin D has undeniably been one of the most studied nutrients. Despite our ability to produce vitamin D through sunlight exposure, its presence in several natural food sources and fortified foods, and its widespread availability as a dietary supplement, vitamin D deficiency is a serious public health problem, affecting nearly 50% of the global population. Low serum levels of vitamin D are being associated with increased susceptibility to numerous health conditions, including respiratory infections, mental health, autoimmune diseases, and different cancer types. Although the association between vitamin D status and health is well-established, the exact beneficial effects of vitamin D are still inconclusive and indefinite, especially when considering the prevention and treatment of different health conditions and the determination of an appropriate dosage to exert those beneficial effects in various population groups. Therefore, further research is needed. With constant improvements in our understanding of individual variations in vitamin D metabolism and requirements, in the future, precision nutrition and personalized supplementation plans could prove beneficial.

Vitamin D and Cardiovascular Diseases: From Physiology to Pathophysiology and Outcomes

Vitamin D is rightly recognized as an essential key factor in the regulation of calcium and phosphate homeostasis, affecting primary adequate bone mineralization. In the last decades, a more complex and wider role of vitamin D has been postulated and demonstrated. Cardiovascular diseases have been found to be strongly related to vitamin D levels, especially to its deficiency. Pre-clinical studies have suggested a direct role of vitamin D in the regulation of several pathophysiological pathways, such as endothelial dysfunction and platelet aggregation; moreover, observational data have confirmed the relationship with different conditions, including coronary artery disease, heart failure, and hypertension. Despite the significant evidence available so far, most clinical trials have failed to prove any positive impact of vitamin D supplements on cardiovascular outcomes. This discrepancy indicates the need for further information and knowledge about vitamin D metabolism and its effect on the cardiovascular system, in order to identify those patients who would benefit from vitamin D supplementation.

Vitamin A, D, E, and K as Matrix Metalloproteinase-2/9 Regulators That Affect Expression and Enzymatic Activity

Fat-soluble vitamins (vitamin A, D, E, and K) assume a pivotal role in maintaining human homeostasis by virtue of their enzymatic functions. The daily inclusion of these vitamins is imperative to the upkeep of various physiological processes including vision, bone health, immunity, and protection against oxidative stress. Current research highlights fat-soluble vitamins as potential therapeutics for human diseases, especially cancer. Fat-soluble vitamins exert their therapeutic effects through multiple pathways, including regulation of matrix metalloproteinases' (MMPs) expression and enzymatic activity. As MMPs have been reported to be involved in the pathology of various diseases, such as cancers, cardiovascular diseases, and neurological disorders, regulating the expression and/or activity of MMPs could be considered as a potent therapeutic strategy. Here, we summarize the properties of fat-soluble vitamins and their potential as promising candidates capable of effectively modulating MMPs through multiple pathways to treat human diseases.

Supplementation of vitamin D isolated or calcium-associated with bone remodeling and fracture risk in postmenopausal women without osteoporosis: A systematic review of randomized clinical trials

Menopause and vitamin D deficiency increase bone reabsorption and bone fracture risk in women in postmenopause, and vitamin D supplementation may improve bone health and decrease bone fracture risk. This study aims to discuss the effect of vitamin D supplementation, isolated or calcium-associated, on remodeling and fracture risk bone in women in postmenopause without osteoporosis. This study was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PROSPERO database registration: CRD42022359796). A search was conducted in four databases and gray literature using MeSH and similar terms related to supplements, vitamin D, calcium, remodeling, and fracture bone, without the restriction of language and year of publication. A total of 3460 studies were identified, and nine were selected. Vitamin D supplementation increased 25-hydroxyvitamin D levels ≥10 ng/mL and decreased parathyroid hormone secretion dependent on baseline levels. The doses of 400 IU of vitamin D improved the percentage of carboxylated osteocalcin, whereas 800 to 1000 IU combined with calcium resulted in reduced, improved, or maintained bone mineral density and reduced alkaline phosphatase levels. However, 4000 IU alone or combined with calcium for 6 mo did not improve C-telopeptide and procollagen type 1 peptide levels. Additionally, 15 000 IU/wk increased the cortical area of metacarpal bone, whereas 500 000 IU of vitamin D annually for 5 y did not contribute to reducing the fracture risk and falls. Only one study found a reduction in fracture risk (dose of 800 IU of vitamin D plus 1200 mg of calcium). Thus, the vitamin D supplementation, alone or calcium-associated, improved the status of 25-hydroxyvitamin D and bone remodeling, but it was not possible to assert that it reduced fracture bone risk in postmenopausal women.

Hypovitaminosis D in Haematological Malignancies: Cause or Consequence?

Vitamin D is a pleiotropic hormone, widely controversial for its role in the development of chronic diseases and cancers, including haematological malignancies, and also for its impact on overall survival. Observational and interventional studies are being conducted on hypovitaminosis D and haematological malignancies and their subtypes in order to improve the therapeutic management of patients. We carried out a prospective observational study over three years on a population of 251 patients followed up for newly diagnosed haematological malignancies to investigate the impact of vitamin D deficiency on this category of patients. Our population was dominated by the lymphoproliferative syndrome and included 125 patients (49.8%). Anthropometric data showed a significant difference in body mass index between the sexes with a p value of 0.001. Vitamin D levels at diagnosis were inadequate in more than half the patients (56%). This hypovitaminosis was linked to the female sex (p = 0.006), obesity (p = 0.031) and the digestive involvement of the lymphoma (p = 0.03). There was also a relationship between vitamin D deficiency and hypoalbuminemia (p = 0.02). This relationship was confirmed in multivariate analysis, with hypoalbuminemia being a factor associated with the deficiency (p = 0.022, OR = 0.95, IC95% 0.91-0.93). However, we did not find any impact on overall survival.

Calcifediol: Mechanisms of Action

Due to its essential role in calcium and phosphate homeostasis, the secosteroid hormone calcitriol has received growing attention over the last few years. Calcitriol, like other steroid hormones, may function through both genomic and non-genomic mechanisms. In the traditional function, the interaction between the biologically active form of vitamin D and the vitamin D receptor (VDR) affects the transcription of thousands of genes by binding to repeated sequences present in their promoter region, named vitamin D-responsive elements (VDREs). Non-transcriptional effects, on the other hand, occur quickly and are unaffected by inhibitors of transcription and protein synthesis. Recently, calcifediol, the immediate precursor metabolite of calcitriol, has also been shown to bind to the VDR with weaker affinity than calcitriol, thus exerting gene-regulatory properties. Moreover, calcifediol may also trigger rapid non-genomic responses through its interaction with specific membrane vitamin D receptors. Membrane-associated VDR (mVDR) and protein disulfide isomerase family A member 3 (Pdia3) are the best-studied candidates for mediating these rapid responses to vitamin D metabolites. This paper provides an overview of the calcifediol-related mechanisms of action, which may help to better understand the vitamin D endocrine system and to identify new therapeutic targets that could be important for treating diseases closely associated with vitamin D deficiency.

Optimized vitamin D repletion with oral thin film cholecalciferol in patients undergoing stem cell transplant

Vitamin D deficiency is common in childhood, pervasive before and after bone marrow transplant, and is associated with increased incidence of graft-versus-host disease (GVHD) and decreased survival in patients undergoing hematopoietic stem cell transplant (HSCT). Numerous barriers impede replacement, including malabsorption secondary to gut GVHD, mucositis, inability to take capsules, kidney disease, liver disease, and infection; many patients remain refractory despite vitamin D therapy. We hypothesized that a different formulation of cholecalciferol, administered on the tongue as a readily dissolving oral thin film (OTF), would ease administration and facilitate therapeutic vitamin D levels (>35 ng/mL) in patients who are refractory. In this prospective pilot study, we evaluated 20 patients after HSCT (range, day +21 - day +428 at enrollment) with serum vitamin D levels ≤35 ng/mL. Cholecalciferol OTF strips were administered for 12 weeks. Dosing was based on patient body weight and titrated per individual pharmacokinetics. Wilcoxon matched-pairs signed-rank test demonstrated marked improvement in all 20 patients who were formerly refractory, increasing from a median baseline vitamin D level of 29.2 ng/mL to 58 ng/mL at end of study (P < .0001). All patients demonstrated improvement in serum vitamin D level by week 4 on study, some of whom had been refractory for years prior. Median dose was 1 OTF strip (40 000 IU) per week. No toxicity was observed. This formulation proved to be safe, effective, efficient, and well received. We are eager to explore other patient populations, which might benefit from this promising development, and other therapeutics that might be optimized using this mode of delivery. This trial was registered at www.clinicaltrials.gov as #NCT04818957.

The Pathophysiology, Identification and Management of Fracture Risk, Sublesional Osteoporosis and Fracture among Adults with Spinal Cord Injury

BACKGROUND

The prevention of lower extremity fractures and fracture-related morbidity and mortality is a critical component of health services for adults living with chronic spinal cord injury (SCI).

METHODS

Established best practices and guideline recommendations are articulated in recent international consensus documents from the International Society of Clinical Densitometry, the Paralyzed Veterans of America Consortium for Spinal Cord Medicine and the Orthopedic Trauma Association.

RESULTS

This review is a synthesis of the aforementioned consensus documents, which highlight the pathophysiology of lower extremity bone mineral density (BMD) decline after acute SCI. The role and actions treating clinicians should take to screen, diagnose and initiate the appropriate treatment of established low bone mass/osteoporosis of the hip, distal femur or proximal tibia regions associated with moderate or high fracture risk or diagnose and manage a lower extremity fracture among adults with chronic SCI are articulated. Guidance regarding the prescription of dietary calcium, vitamin D supplements, rehabilitation interventions (passive standing, functional electrical stimulation (FES) or neuromuscular electrical stimulation (NMES)) to modify bone mass and/or anti-resorptive drug therapy (Alendronate, Denosumab, or Zoledronic Acid) is provided. In the event of lower extremity fracture, the need for timely orthopedic consultation for fracture diagnosis and interprofessional care following definitive fracture management to prevent health complications (venous thromboembolism, pressure injury, and autonomic dysreflexia) and rehabilitation interventions to return the individual to his/her pre-fracture functional abilities is emphasized.

CONCLUSIONS

Interprofessional care teams should use recent consensus publications to drive sustained practice change to mitigate fracture incidence and fracture-related morbidity and mortality among adults with chronic SCI.

Prevalence of vitamin D deficiency and associated risk of all-cause and cause-specific mortality among middle-aged and older adults in the United States

Introduction

The prevalence of vitamin D deficiency varied among populations and regions worldwide. In addition, the association between vitamin D deficiency and health outcomes remained controversial. Our study aimed to investigate the prevalence of vitamin D deficiency and its association with mortality risk among non-institutional middle-aged and older adults in the United States.

Method

The study population included 11,119 adult participants aged between 50 and 79 years in the 2007-2016 National Health and Nutrition Examination Survey (NHANES). Vitamin D status was divided as ≤ 30 (severely deficient), 30.1-50 (moderately deficient), 50.1-75 (insufficient), 75.1-100 (sufficient), and > 100 nmol/L (very sufficient). NHANES data were linked to National Death Index to ascertain the survival status and cause of death.

Results

The population aged 61.5 years (survey-weighted) and 47.9% were men. Among them, 4.6% were severely vitamin D deficient, 15.2% moderately deficient, and 33.6% insufficient. Individuals with higher vitamin D levels tended to be female, older, white people, non-smoker, non-single, more educated, with higher family income, and lower body mass index. During a median follow-up of 97.0 months, a total of 1,585 participants died (15.9 per 10,000 person-months). The crude analysis showed that vitamin D deficiency, but not vitamin D insufficiency, correlated to higher all-cause mortality risk. The association remained similar after adjusting for potential confounders, showing that vitamin D deficiency (HR: 1.38, 95% CI 1.15-1.66), but not vitamin D insufficiency (HR: 1.03, 95% CI 0.88-1.20), correlated to higher all-cause mortality risk. In addition, we showed that vitamin D deficiency was an independent risk factor for death from pneumonia (HR: 3.82, 95% CI 1.14-12.86) but not from cardiovascular diseases, cancer, or cerebrovascular diseases.

Conclusion

In summary, among middle-aged and older adults in the United States, nearly 20% were vitamin D deficient. Vitamin D deficiency, but not vitamin D insufficiency, correlated to increased mortality risk.

Nutrition in children with exocrine pancreatic insufficiency

Exocrine pancreatic insufficiency (EPI) is a condition defined as pancreatic loss of exocrine function, including decreased digestive enzymes and bicarbonate secretion, which leads to maldigestion and malabsorption of nutrients. It is a common complication in many pancreatic disorders. If left undiagnosed, EPI can cause poor digestion of food, chronic diarrhea, severe malnutrition and related complications. Nutritional status and fat-soluble vitamins should be carefully assessed and monitored in patients with EPI. Early diagnosis of EPI is clinically important for appropriate nutritional support and initiating pancreatic enzyme replacement therapy (PERT) which could significantly improve patient outcomes. The evaluation of nutritional status and related unique management in children with EPI will be discussed in this review.

ABCG2 plays a central role in the dysregulation of 25-hydrovitamin D in Crohn's disease

Vitamin D (VD) deficiency, as indicated by the main circulating form of VD metabolite 25-hydrovitamin D₃ (25(OH)D₃), in patients with Crohn's disease (CD) has been well documented, but the reasons for this remain unclear. In this study, 367 patients with CD and 57 healthy individuals who were enrolled, and the association between 25(OH)D₃ level and clinical biochemical characteristics including hepatic and renal functions, inflammatory response was analyzed with binary logistic regression models. VD metabolic enzymes and transporters were screened with bioinformatical analysis and identified with qRT-PCR and western blot. Compared to the healthy controls, serum 25(OH)D₃ was significantly reduced in patients with CD, but the protein level of adenosine triphosphate (ATP)-binding cassette efflux transporter G2 (ABCG2) was evidently increased in the ileum and colon. Meanwhile, in lipopolysaccharide (LPS)-treated CaCO2 cells, the mRNA and protein levels of ABCG2 were significantly increased, and the overexpression of ABCG2 obviously promoted 25(OH)D₃ efflux, but, Ko143, an ABCG2 inhibitors, substantially prevented the efflux of 25(OH)D₃. In addition, in 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced CD model mice, the ABCG2 protein levels were significantly increased in the ileum, colon, kidney and liver, and administration of Ko143 significantly inhibited the efflux of 25 (OH) D₃in vivo. All of these findings suggest that VD deficiency in patients with CD may be associated with an abnormal increase in ABCG2 expression, but not directly implicated in hepatic and renal function, and inflammatory response in patients with CD.

Novel Approach for the Approximation of Vitamin D3 Pharmacokinetics from In Vivo Absorption Studies

The changing environment and modified lifestyles have meant that many vitamins and minerals are deficient in a significant portion of the human population. Therefore, supplementation is a viable nutritional approach, which helps to maintain health and well-being. The supplementation efficiency of a highly hydrophobic compound such as cholecalciferol (logP > 7) depends predominantly on the formulation. To overcome difficulties associated with the evaluation of pharmacokinetics of cholecalciferol, a method based on the short time absorption data in the clinical study and physiologically based mathematical modeling is proposed. The method was used to compare pharmacokinetics of liposomal and oily formulations of vitamin D3. The liposomal formulation was more effective in elevating calcidiol concentration in serum. The determined AUC value for liposomal vitamin D3 formulation was four times bigger than that for the oily formulation.

Dry Eye Disease: What Is the Role of Vitamin D?

Dry eye disease (DED) is a multifactorial condition resulting from reduced tear secretion from the lacrimal glands, increased tear water evaporation or the production of poor-quality tears. Such tear instability can lead to inflammation and damage of the ocular surface, as well as to abnormal nociception. Historically, tear substitutes and corticosteroids have been the bastion of DED therapy, but a substantial number of patients still suffer from residual symptoms even after being treated with traditional treatments. Aiming to find safe and effective alternative therapies, recent efforts have been focused on the role of vitamin D in the cellular physiology of the eye. Possibly because of its positive effect in modulating the immune and inflammatory responses, the systemic supplementation of vitamin D seems, indeed, to be an effective therapeutic strategy, especially, but not only, for patients affected by DED that does not respond to conventional treatments. In this context, this review focuses on the literature reporting on the pathogenesis and treatment of DED, with a special emphasis on the recent investigations reporting on the potential role of the systemic administration of vitamin D as a therapeutic approach in the management of such condition.

Vitamin D Fortification and Its Effect on Athletes' Physical Improvement: A Mini Review

Poor vitamin D status is a widespread problem regardless of age and sex, emphasizing the necessity of new food sources to improve vitamin D levels. Currently, approximately 60% of dietary vitamin D consumption occurs via fortified foods. Vitamin D insufficiency (50-90%) is widespread according to age and region, despite different levels of sunlight exposure. The food industry must identify more effective strategies to increase normal dietary vitamin D intake and improve overall health. Strategies for vitamin D fortification include bioaddition, wherein a vitamin D-rich food source is added to staple foods during processes. These bioadditive strategies expand the range of vitamin D-containing foods and appeal to different preferences, cultures, and economic statuses. In several countries, vitamin D deficiency places athletes at a high risk of disease susceptibility. Due to low sun exposure, athletes in countries with higher and lower levels of sunlight have similar risks of vitamin D deficiency. In this review, we summarize recent technical advances to promote vitamin D utilization by humans during sports activities and in relation to the normal practices of athletes.

Vitamin D Deficiency in Both Oral and Systemic Manifestations in SARS-CoV-2 Infection: Updated Review

The specialized literature emphasizes the fact that vitamin D has a potentially beneficial effect in the context of the current COVID-19 pandemic. The purpose of this article is to highlight the role of vitamin D, both prophylactic and curative, in the treatment of patients diagnosed with COVID-19. Even though its relevance is still unknown and causes various controversies, there is currently no specific treatment for patients diagnosed with COVID-19. There are various prevention strategies with new vaccination schedules, but additional randomized and clinical trials are still needed to combat this pandemic. In addition to the systemic manifestations of SARS-CoV-2 infection, oral manifestations of this disease have also been described in the literature. The etiology of oral manifestations associated with COVID-19 infection and vitamin D deficiency remains controversial. In the present studies, oral manifestations such as salivary gland infections, aphthae, erythema, gingivitis, ulcers, etc. have been reported. This is a new topic, and the prevalence of manifestations is described in only a few studies, which is inconsistent with the number of COVID-19 cases reported since the beginning of the pandemic. The clinical symptomatology in patients with current COVID-19 infection is polymorphic. Whether the oral manifestation is directly caused by SARS-CoV-2 or a secondary manifestation remains an important topic to analyze and discuss.

Vitamin D Metabolic Pathway Components in Orthopedic Patientes-Systematic Review

Vitamin D takes part in the functioning of many processes that ensure the homeostasis of the body. In orthopedics, it is indicated as an inseparable element ensuring proper bone growth and functioning, and its deficiencies are indicated in various diseases, mainly in the proper structure and function of the skeleton. In this review, we focus on the most important components of the vitamin D metabolic pathway, in correlation with selected orthopedic conditions. Records were obtained from the PubMed database in a timeline of 2010-2022. The keywords were as follows: vitamin D/cholesterol/vitamin D binding protein/ VDBP/Cytochrome/CYP24A1/CYP 27B1/Vitamin D receptor/VDR/ + diseases (ACL reconstruction, rotator cuff, arthroplasty knee/hip/shoulder). The recent original studies were analyzed, discussed, and the most important data were shown. The vast majority of articles concern the metabolite of vitamin D (25(OH)D), which is measured as a standard in diagnostic laboratories. Even though there is a lot of valuable information in the literature, we believe that the other elements of the vitamin D pathway also deserve attention and suggest their research in correlation with orthopedic disorders to supplement the missing knowledge on this topic.

Radiosynthesis, Preclinical, and Clinical Positron Emission Tomography Studies of Carbon-11 Labeled Endogenous and Natural Exogenous Compounds

The presence of positron emission tomography (PET) centers at most major hospitals worldwide, along with the improvement of PET scanner sensitivity and the introduction of total body PET systems, has increased the interest in the PET tracer development using the short-lived radionuclides carbon-11. In the last few decades, methodological improvements and fully automated modules have allowed the development of carbon-11 tracers for clinical use. Radiolabeling natural compounds with carbon-11 by substituting one of the backbone carbons with the radionuclide has provided important information on the biochemistry of the authentic compounds and increased the understanding of their in vivo behavior in healthy and diseased states. The number of endogenous and natural compounds essential for human life is staggering, ranging from simple alcohols to vitamins and peptides. This review collates all the carbon-11 radiolabeled endogenous and natural exogenous compounds synthesised to date, including essential information on their radiochemistry methodologies and preclinical and clinical studies in healthy subjects.

The Effect of Vitamin D Supplementation on Serum 25-Hydroxy Vitamin D in the Patients Undergoing Bariatric Surgery: a Systematic Review and Meta-Analysis of Randomized Clinical Trials

Currently, there is no consensus on the optimal vitamin D administration in bariatric patients. The present systematic review and meta-analysis were conducted to examine the effect of vitamin D supplements on serum level of 25(OH) vitamin D in the patients undergoing bariatric surgery (BS).Random model effects were used to estimate standardized mean difference (SMD) with a 95% confidence interval (CI). Nine clinical trials were included in the meta-analysis. Vitamin D supplementation in patients undergoing BS modestly improves vitamin D status (SMD, 0.53; 95% CI, 0.28, 0.77) particularly, in the dosages above 2850 IU/day and in the patients with BMI greater than 50 kg/m². Vitamin D supplementation was associated with prevention of raising of the PTH serum concentration and without impact on serum calcium levels.

The Effect of Vitamin D Supplementation on the Severity of Symptoms and the Quality of Life in Irritable Bowel Syndrome Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Irritable bowel syndrome (IBS), a gastrointestinal disorder affecting 7–12% of the population, is characterized by abdominal pain, bloating, and alternating bowel patterns. Data on risk and protective influences have yielded conflicting evidence on the effects of alternative interventions, such as vitamin D. This review focuses on the effects of vitamin D on IBS. A systematic review and meta-analysis considered all articles published until 4 April 2022. The search for randomized controlled trials assessing vitamin D efficacy in IBS with outcomes, primary (Irritable Bowel Severity Scoring System (IBS-SSS)) and secondary (IBS quality of life (IBS-QoL) and serum level of calcifediol (25(OH)D)), was performed on six databases, Google Scholar, Web of Science, SCOPUS, EMBASE, PubMed (MEDLINE), and Cochrane Central Register of Controlled Trials. We included six trials with 616 patients. The pooled analysis found no difference between vitamin D and placebo in improving IBS-SSS (MD: −45.82 with 95% CI [−93.62, 1.98], p = 0.06). However, the pooled analysis favored vitamin D over placebo in improving the IBS-Qol (MD: 6.19 with 95% CI [0.35, 12.03], p = 0.04) and serum 25(OH)D (MD: 25.2 with 95% CI [18.41, 31.98], p = 0.00001). Therefore, further clinical trials are required to reach clinically applicable and generalizable findings.

Alterations in the composition of the gut microbiota affect absorption of cholecalciferol in severe osteoporosis

INTRODUCTION

To evaluate the relationship between the gut microbial composition and intestinal cholecalciferol absorption in patients with severe osteoporosis (SOP).

MATERIALS AND METHODS

Eighteen patients with primary osteoporosis (OP) and 18 with SOP were included. Their clinical data were collected and their circulating concentrations of cholecalciferol and 25(OH)D₃ were measured. Fecal samples were collected and their microbial contents were analyzed using 16S rDNA sequencing.

RESULTS

The age, sex, body mass index, and body mass of the participants did not differ between the groups. The prevalence of gastrointestinal symptoms in the participants with SOP was significantly higher than that in the participants with OP. There were significant differences in the 25(OH)D₃ and cholecalciferol concentrations between participants with SOP or OP and there was a significant positive correlation between the concentrations of these substance. The diversity of the gut microbiota in participants with SOP was significantly higher than that in participants with OP. Firmicutes was more abundant in the SOP group and the ratio of Firmicutes/Bacteroidetes in participants with SOP was higher. Conversely, Bifidobacterium was significantly less abundant, as were the order and family it belongs to. At the species level, Bifidobacterium was the most significant difference between the two groups.

CONCLUSION

Differences in the intestinal microecology, especially Bifidobacterium, are associated with differences in the absorption of cholecalciferol and in the circulating 25(OH)D₃ concentration, which may influence the progression of OP to SOP.

Vitamin D as therapeutic modulator in cerebrovascular diseases: a mechanistic perspectives

Vitamin D deficiency has been linked to several major chronic diseases, such as cardiovascular and neurodegenerative diseases, diabetes, and cancer, linked to oxidative stress, inflammation, and aging. Vitamin D deficiency appears to be particularly harmful to the cardiovascular system, as it can cause endothelial dysfunctioning and vascular abnormalities through the modulation of various downstream mechanisms. As a result, new research indicates that therapeutic approaches targeting vitamin D inadequacies or its significant downstream effects, such as impaired autophagy, abnormal pro-inflammatory and pro-oxidant reactions, may delay the onset and severity of major cerebrovascular disorders such as stroke and neurologic malformations. Vitamin D modulates the various molecular pathways, i.e., Nitric Oxide, PI3K-Akt Pathway, cAMP pathway, NF-kB Pathway, Sirtuin 1, Nrf2, FOXO, in cerebrovascular disorder. The current review shows evidence for vitamin D's mitigating or slowing the progression of these cerebrovascular disorders, which are significant causes of disability and death worldwide.

Physiological significance of vitamin D produced in skin compared with oral vitamin D

Since the discovery of vitamin D, it has been accepted that its physiological supply is either from food or by endogenous synthesis in skin exposed to solar UV light. Yet vitamin D is a component of very few foods and its supply as a natural nutrient is unable to maintain good vitamin D status for human populations. One aspect of vitamin D physiology that has been ignored is that the mechanisms for its transport and processing from these two sources are quite different. Excess intake of vitamin D causes hypercalcaemic toxicity. However, experiments with different animal species have shown that long-term supply of oral vitamin D in apparently non-toxic amounts causes atherosclerosis in large arteries. A mechanism for this toxicity is proposed. Alternative strategies for addressing widespread vitamin D deficiency by food fortification should be considered in light of the angiotoxicity caused by oral vitamin D in animal experiments.

Safety Assessment of Vitamin D and Its Photo-Isomers in UV-Irradiated Baker's Yeast

Vitamin D deficiency due to, e.g., nutritional and life style reasons is a health concern that is gaining increasing attention over the last two decades. Vitamin D₃, the most common isoform of vitamin D, is only available in food derived from animal sources. However, mushrooms and yeast are rich in ergosterol. This compound can be converted into vitamin D₂ by UV-light, and therefore act as a precursor for vitamin D. Vitamin D₂ from UV-irradiated mushrooms has become an alternative source of vitamin D, especially for persons pursuing a vegan diet. UV-irradiated baker’s yeast (Saccharomyces cerevisiae) for the production of fortified yeast-leavened bread and baked goods was approved as a Novel Food Ingredient in the European Union, according to Regulation (EC) No. 258/97. The Scientific Opinion provided by the European Food Safety Authority Panel on Dietetic Products, Nutrition, and Allergies has assessed this Novel Food Ingredient as safe under the intended nutritional use. However, recent findings on the formation of side products during UV-irradiation, e.g., the photoproducts tachysterol and lumisterol which are compounds with no adequate risk assessment performed, have only been marginally considered for this EFSA opinion. Furthermore, proceedings in analytics can provide additional insights, which might open up new perspectives, also regarding the bioavailability and potential health benefits of vitamin D-fortified mushrooms and yeast. Therefore, this review is intended to give an overview on the current status of UV irradiation in mushrooms and yeast in general and provide a detailed assessment on the potential health effects of UV-irradiated baker’s yeast.

Influence of Vitamin D3 Supplementation on Infliximab Effectiveness in Chinese Patients With Crohn's Disease: A Retrospective Cohort Study

Background: It remains uncertain whether vitamin D3 (vitD3) supplementation is beneficial for remission of Crohn's disease (CD). The influence of vitD3 supplementation on Infliximab (IFX) effectiveness was analyzed in Chinese CD patients.

Methods: In this retrospective cohort study, moderate-to-severe CD patients, who were bio-naïve and prescribed with IFX treatment for at least 54 weeks, were recorded from January 2014 to December 2019. VitD3 supplementation was defined as patients additionally took oral vitD3 (125 IU/d) within 3 days after the first infusion and persisted in the whole follow-up period. Disease activity was assessed using Harvey-Bradshaw Index (HBI). Serum cytokine profiles (IL-2, IL-4, IL-6, IL-10, TNF-α, and IFN-γ) were quantitatively analyzed in a subset of all patients at baseline and 54-week after intervention.

Results: Among 73 enrolled patients, 37 took vitD3 regularly (D3-patients), the others (non-D3-patients) did not. At 54-week, the mean 25-hydroxyvitaminD level increased in D3-patients (20.33 vs. 15.07 ng/mL, P < 0.001). The clinical remission rate was higher in D3-patients compared to non-D3-patients (83.8 vs. 61.6%, P = 0.030). The decrease of HBI from baseline to 54-week was more in D3-patients than non-D3-patients (7.41 ± 3.0 vs. 6.28 ± 2.75, P = 0.023). Furthermore, vitD3 supplementation was independently related to the increase of remission rate at 54-week in D3-patients (β = −1.667, P = 0.015). The benefit of vitD3 supplementation was significant only in patients with deficient vitD3 (all P < 0.05), but not in non-deficient vitD3. A total of nine patients (four non-D3-patients and five D3-patients) were selected to determine serum cytokine profiles after 54-week IFX treatment. In non-D3-patients, the decreases of TNF-α and IL-6 at 54-week were more obvious than at baseline (P = 0.032, 0.022, respectively). In D3-patients, however, only IL-10 increased at 54-week compared with its baseline value (P = 0.037).

Conclusions: VitD3 supplementation could improve IFX effectiveness in CD patients, especially for patients with vitD3 deficiency. This beneficial effect of vitD3 supplementation probably arose from the up-regulation of IL-10.

Trial Registration: NCT04606017.

Vitamin D toxicity related to its physiological and unphysiological supply

Vitamin D is defined as a nutrient despite its rare occurrence in food. Vitamin D status is determined mainly by solar UV light action in skin. However, the strategy to combat vitamin D deficiency has been to increase oral intake of vitamin D in greater amounts than could be obtained from food. Persistent large intakes of vitamin D can cause hypercalcaemic toxicity. Although the amounts recommended to prevent deficiency are far less than those causing such toxicity, the possibility of other toxic actions from increased intake of vitamin D has been ignored. Animal experiments have demonstrated that moderate amounts of oral vitamin D over time result in atherosclerosis. Differences in the fate of vitamin D could explain this angiotoxicity.

Sources of vitamin D for humans

Both vitamin D insufficiency and deficiency are now well-documented worldwide in relation to human health, and this has raised interest in vitamin D research. The aim of this article is therefore to review the literature on sources of vitamin D. It can be endogenously synthesised under ultraviolet B radiation in the skin, or ingested through dietary supplements and dietary sources, which include food of animal and plant origin, as well as fortified foods. Vitamin D is mainly found in two forms, D₃ (cholecalciferol) and D₂ (ergocalciferol). In addition to the D₃ and D₂ forms of vitamin D, 25-hydroxy vitamin D also contributes significantly to dietary vitamin D intake. It is found in many animal-derived products. Fortified food can contain D₃ or D₂ forms or vitamin D metabolite 25-hydroxy vitamin D. Not many foods are a rich source (> 4 μg/100 g) of vitamin D (D represents D₃ and/or D₂), e.g., many but not all fish (5-25 μg/100 g), mushrooms (21.1-58.7 μg/100 g), Reindeer lichen (87 μg/100 g) and fish liver oils (250 μg/100 g). Other dietary sources are cheese, beef liver and eggs (1.3-2.9 μg/100 g), dark chocolate (4 μg/100 g), as well as fortified foods (milk, yoghurt, fat spreads, orange juice, breakfast grains, plant-based beverages). Since an adequate intake of vitamin D (15 μg/day set by the European Food Safety Authority) is hard to achieve through diet alone, dietary supplements of vitamin D are usually recommended. This review summarizes current knowledge about different sources of vitamin D for humans.

Osteoporosis therapies and their mechanisms of action (Review)

Osteoporosis is a common disease that affects millions of patients worldwide and is most common in menopausal women. The main characteristics of osteoporosis are low bone density and increased risk of fractures due to deterioration of the bone architecture. Osteoporosis is a chronic disease that is difficult to treat; thus, investigations into novel effective therapeutic methods are required. A number of studies have focused on determining the most effective treatment options for this disease. There are several treatment options for osteoporosis that differ depending on the characteristics of the disease, and these include both well-established and newly developed drugs. The present review focuses on the various drugs available for osteoporosis, the associated mechanisms of action and the methods of administration.

Revisiting food-sourced vitamins for consumer diet and health needs: a perspective review, from vitamin classification, metabolic functions, absorption, utilization, to balancing nutritional requirements

The significant attention gained by food-sourced vitamins has provided insights into numerous current researches; for instance, the potential reversal of epigenetic age using a diet and lifestyle intervention, the balance between food and dietary supplements in the general population, the role of diet and food intake in age-related macular degeneration, and the association of dietary supplement use, nutrient intake and mortality among adults. As relevant literature about food-sourced vitamin increases, continuous synthesis is warranted. To supplement existing information, this perspective review discussed food-sourced vitamins for consumer diet and health needs, scoping from vitamin absorption, metabolic functions, utilization, to balancing nutritional requirements. Relevant literatures were identified through a search of databases like Google Scholar, Web of Science, the Interscience Online Library, ScienceDirect, and PubMed. We demonstrated that vitamins whether from plant- and animal-based sources are prerequisites for the metabolic functions of the human body. The fat- and water-soluble classification of vitamins remains consistent with their respective absorption and dissolution potentials, underpinned by numerous physiological functions. Vitamins, largely absorbed in the small intestine, have their bioavailability dependent on the food composition, its associated interactions, as well as alignment with their metabolic functions, which involves antioxidants, coenzymes, electron acceptor/donor, and hormones. Moreover, vitamin deficiencies, in every form, pose a serious threat to human health. Vitamin toxicities remain rare, but can still occur mainly from supplementation, although it appears much less in water-soluble vitamins of which some excesses get readily removed by the human body, different from the fat-soluble ones that are stored in tissues and organs. Besides discussions of absorption, transport, and cellular uptake of vitamins, this perspective review also included approaches to meeting vitamin requirements and therapeutic strategies against micronutrient deficiency and COVID-19. We have also attempted on how to strike the balance between food-sourced vitamins and dietary supplements.

Independent and interactive associations of season, dietary vitamin D, and vitamin D-related genetic variants with serum 25(OH)D in Korean adults aged 40 years or older

Only limited information is available on the inter-relationships between genetic and non-genetic factors such as diet and sunlight exposure with serum 25-hydroxyvitamin D [25(OH)D] concentration. This cross-sectional study aimed to examine the independent and interactive associations of season, dietary vitamin D intake, and SNPs of 11 vitamin D-related candidate genes with serum 25(OH)D concentration among 2,721 adults aged ≥40 years at baseline from the Yangpyeong cohort, a part of the Korean Genome Epidemiology Study (KoGES). The interactions between season or dietary vitamin D and 556 SNPs were evaluated using 2-degree of freedom joint tests. Season was strongly (p_difference = 1.00 × 10^-12) and dietary vitamin D intake was slightly but significantly associated with serum 25(OH)D concentration (p_difference = 0.0119). Among five SNPs (rs11723621-GC, rs7041-GC, rs10500804-CYP2R1, rs7129781-CYP2R1, and rs2852853-DHCR7) identified in the screening steps, only one, rs10500804-CYP2R1, significantly interacted with season (p_interaction = 8.01 × 10^-5). The inverse association between number of minor alleles of rs10500804-CYP2R1 and concentration of 25(OH)D was significant only in summer/fall. Conversely, dietary vitamin D intake was positively associated only in winter/spring. In conclusion, season, dietary vitamin D intake, and four SNPs in GC, CYP2R1, and DHCR7 are independently and rs10500804-CYP2R1 is interactively associated with serum 25(OH)D concentration. Serum 25(OH)D is influenced by genotype of rs10500804-CYP2R1 in summer/fall when sunlight exposure is high, while dietary vitamin D intake is an important determinant of serum 25(OH)D during the seasons with low cutaneous vitamin D synthesis.

Effects of Vitamin D2 and 25-Hydroxyvitamin D2 Supplementation on Plasma Vitamin D Epimeric Metabolites in Adult Cats

Feline vitamin D status is based on dietary consumption but metabolism of this essential nutrient and the efficacy of supplementation forms are poorly described in cats. The aim of this study was to further elucidate the metabolites of vitamin D2 in cats and to compare the effectiveness of vitamin D2 and 25(OH)D2 for increasing feline vitamin D status. Eight adult male castrated domestic shorthair cats received vitamin D2 or 25(OH)D2 in a single crossover design. Vitamin D2 was dosed daily in a molar equivalent dosage to vitamin D3 ingested in the diet while 25(OH)D2 was provided at a daily dose of 20% molar equivalent intake of dietary vitamin D3 based on its expected higher potency. Plasma concentrations of 25-hydroxyvitamin D epimers were evaluated at baseline then every 2 weeks for a total of 10 weeks. Analysis of multiple vitamin D metabolite concentrations was completed at the end of each supplementation period, followed by a washout period preceding the second phase of the crossover trial. Results showed that supplementation with 25(OH)D2 more effectively and rapidly raised circulating 25(OH)D2 levels in cat plasma compared to vitamin D2. Formation of C-3 epimers of 25(OH)D3, 25(OH)D2, and 24,25R(OH)2D3, but not 24,25(OH)2D2, were observed in feline plasma. The abundant concentrations of epimeric forms of vitamin D metabolites found in circulation suggest that these metabolites should be considered during vitamin D analyses in cats. Further studies using 25(OH)D and vitamin D2 forms are needed to conclude safety and efficacy of these vitamers for supplementation in this species.

Vitamin D: Current Challenges between the Laboratory and Clinical Practice

Vitamin D is a micronutrient with pleiotropic effects in humans. Due to sedentary lifestyles and increasing time spent indoors, a growing body of research is revealing that vitamin D deficiency is a global problem. Despite the routine measurement of vitamin D in clinical laboratories and many years of efforts, methods of vitamin D analysis have yet to be standardized and are burdened with significant difficulties. This review summarizes several key analytical and clinical challenges that accompany the current methods for measuring vitamin D. According to an external quality assessment, methods and laboratories still produce a high degree of variability. Structurally similar metabolites are a source of significant interference. Furthermore, there is still no consensus on the normal values of vitamin D in a healthy population. These and other problems discussed herein can be a source of inconsistency in the results of research studies.

The impact of emulsion droplet size on in vitro lipolysis rate and in vivo plasma uptake kinetics of triglycerides and vitamin D3 in rats

Emulsions play an important role in the process of triglyceride (TG) digestion (lipolysis). Through emulsification, the oil-water interface is increased by orders of magnitude. This often leads to faster and more efficient lipolysis, which is potentially beneficial for the intestinal uptake of oils and lipophilic compounds. In this paper, we first examined the effect of emulsion droplet size on the in vitro lipolysis rate. Then an in vivo experiment was performed, to examine the plasma uptake kinetics of TGs and vitamin D₃ (vitD₃) over a 24 hours period after oral administration of the emulsions in rats. Basic corn oil emulsions loaded with vitD₃ were prepared using polysorbate 80 as the emulsifier, with three different droplet sizes (D[3,2]): ∼3 μm (large), ∼1 μm (medium) and ∼0.3 μm (small). In vitro lipolysis experiments showed, as expected, that smaller droplets were lipolyzed more rapidly. However, the medium emulsion had by far the highest rate of lipolysis per surface area. This was attributed to bile salt limitation, polysorbate 80 lipolysis inhibition and TG digestion product accumulation. In vivo, the two smallest emulsions showed the highest uptake (C_max and AUC) of vitD₃ and TG, while the largest emulsion and bulk oil control showed lower values. However, only the (incremental) TG plasma values and kinetics displayed some statistically significant differences. These findings may have relevance for the formulation of functional foods/beverages or delivery units containing oils or lipophilic bioactives.

The Relationship between Low Serum Vitamin D Levels and Altered Intestinal Barrier Function in Patients with IBS Diarrhoea Undergoing a Long-Term Low-FODMAP Diet: Novel Observations from a Clinical Trial

Decreased serum vitamin D (VD) levels have been associated with gastrointestinal (GI) disorders, including irritable bowel syndrome (IBS). VD can also modulate the intestinal barrier. Given the link between the GI barrier’s alterations and diet, attention has aroused the positive effects of the Low FODMAP Diet (LFD) on IBS patients’ symptom profile. We evaluated the GI symptoms and the urinary and circulating markers of GI barrier function, the markers of inflammation and intestinal dysbiosis in 36 IBS patients with predominant diarrhea (IBS-D) (5 men and 31 women, 43.1 ± 1.7 years) categorized for their circulating VD levels in low (L-VD) and normal (N-VD) (cutoff = 20 ng/mL). Evaluations were performed before and after 12 weeks of LFD. At the baseline, L-VD patients showed a significantly worse symptom profile and altered small intestinal permeability (s-IP) than N-VD. After LFD, a significant increase in the circulating VD levels in both the subgroups and a significant improvement of s-IP in L-VD patients occurred. Finally, VD levels negatively correlated with the symptom score and fecal zonulin. These data highlight the close relationship between VD and the intestinal barrier and support their involvement in IBS-D pathophysiology. Moreover, the potentially positive role of LFD in the management of IBS-D was confirmed.

Rapid improvement in vitamin D status with dietary 25-hydroxycholecalciferol in vitamin D insufficient dogs

Vitamin D insufficiency is associated with various disease processes. We determined whether consumption of a diet supplemented with HyD^®, a 25-hydroxycholecalciferol (25(OH)D₃) source, would safely increase plasma 25(OH)D₃ concentrations in Golden Retrievers with low vitamin D status. We hypothesised that dietary supplementation with HyD^® would rapidly increase and sustain plasma 25(OH)D₃ levels in healthy Golden Retrievers with low vitamin D status compared with supplementation with vitamin D₃. Of fifty-seven privately owned dogs recruited with written owner consent, eighteen dogs with low vitamin D status were identified and sorted between two groups to have similar initial plasma 25(OH)D₃ concentrations, sex distributions, ages and body weights. Dogs of each group were fed a dry dog food supplemented with either 16 μg/kg of 25(OH)D₃ as HyD^® (n 10) or 81 μg/kg of cholecalciferol (D₃) (n 8) for 4 months. Plasma 25(OH)D₃ concentrations were determined monthly. A significant time effect (P < 0⋅001) and time by group interaction (P = 0⋅0045) were found for monthly determined plasma 25(OH)D₃ concentrations. Dogs fed the HyD^®-supplemented diet experienced a 40⋅5 % rise in plasma 25(OH)D₃ values after 1 month (P < 0⋅001) and no change thereafter. Plasma 25(OH)D₃ values of dogs supplemented with vitamin D₃ did not increase (P > 0⋅05) and were less than values of dogs supplemented with HyD^® (P = 0⋅044). With few exceptions, average haematologic, biochemical and urinalyses results remained within the reference range for both groups. Dietary supplementation with HyD^® is sufficient to safely increase and sustain plasma 25(OH)D₃ levels in healthy dogs.

Improving the bioavailability of oil-soluble vitamins by optimizing food matrix effects: A review

The potency of oil-soluble vitamins (vitamins A, D, E and K) in fortified foods can be improved by understanding how food matrices impact their bioavailability. In this review, the major food matrix effects influencing the bioavailability of oil-soluble vitamins are highlighted: oil content, oil composition, particle size, interfacial properties, and food additives. Droplet size and aggregation state in the human gut impact vitamin bioavailability by modulating lipid digestion, vitamin release, and vitamin solubilization. Vitamins in small isolated oil droplets typically have a higher bioavailability than those in large or aggregated ones. Emulsifiers, stabilizers, or texture modifiers can therefore affect bioavailability by influencing droplet size or aggregation. The dimensions of the hydrophobic domains in mixed micelles depends on lipid type: if the domains are too small, vitamin bioavailability is low. Overall, this review highlights the importance of carefully designing food matrices to improve vitamin bioavailability.

Vitamin D Metabolism and Guidelines for Vitamin D Supplementation

Vitamin D is essential for bone health and is known to be involved in immunomodulation and cell proliferation. Vitamin D status remains a significant health issue worldwide. However, there has been no clear consensus on vitamin D deficiency and its measurement in serum, and clinical practice of vitamin D deficiency treatment remains inconsistent. The major circulating metabolite of vitamin D, 25-hydroxyvitamin D (25(OH)D), is widely used as a biomarker of vitamin D status. Other metabolic pathways are recognised as important to vitamin D function and measurement of other metabolites may become important in the future. The utility of free 25(OH)D rather than total 25(OH)D needs further assessment. Data used to estimate the vitamin D intake required to achieve a serum 25(OH)D concentration were drawn from individual studies which reported dose-response data. The studies differ in their choice of subjects, dose of vitamin D, frequency of dosing regimen and methods used for the measurement of 25(OH)D concentration. Baseline 25(OH)D, body mass index, ethnicity, type of vitamin D (D₂ or D₃) and genetics affect the response of serum 25(OH)D to vitamin D supplementation. The diversity of opinions that exist on this topic are reflected in the guidelines. Government and scientific societies have published their recommendations for vitamin D intake which vary from 400-1000 IU/d (10-25 μg/d) for an average adult. It was not possible to establish a range of serum 25(OH)D concentrations associated with selected non-musculoskeletal health outcomes. To recommend treatment targets, future studies need to be on infants, children, pregnant and lactating women.

Increased calcium intake is associated lower serum 25-hydroxyvitamin D levels in subjects with adequate vitamin D intake: a population-based observational study

BACKGROUND

There are indications that an increased intake of calcium has a vitamin D sparing effect, which might be explained by a decreased catabolism of 25-hydroxyvitamin D (25(OH)D). However, there are only a few studies where this has been examined.

METHOD

In the seventh survey of the Tromsø study, serum 25(OH)D and parathyroid hormone were measured, and questionnaires on calcium and vitamin D intakes filled in.

RESULTS

There were significant interactions between sex, calcium and vitamin D intakes regarding serum 25(OH)D level. The analyses were therefore done stratified. In males there was, regardless of vitamin D intake, a significant decrease in serum 25(OH)D with increasing calcium intake. The difference in serum 25(OH)D between those with the highest and lowest calcium intakes was approximately 10%. In the females, there was in subjects with low vitamin D intake (< 7 μg/d) a significant increase in serum 25(OH)D with increasing calcium intake, which could not be explained by secondary hyperparathyroidism. In females with higher vitamin D intakes, increasing calcium intake was associated with lower serum 25(OH)D levels.

CONCLUSIONS

There is, at least in subjects with an adequate vitamin D intake, a negative association between calcium intake and serum 25(OH)D.

Natural Products: Evidence for Neuroprotection to Be Exploited in Glaucoma

Glaucoma, a leading cause of irreversible blindness worldwide, is an optic neuropathy characterized by the progressive death of retinal ganglion cells (RGCs). Elevated intraocular pressure (IOP) is recognized as the main risk factor. Despite effective IOP-lowering therapies, the disease progresses in a significant number of patients. Therefore, alternative IOP-independent strategies aiming at halting or delaying RGC degeneration is the current therapeutic challenge for glaucoma management. Here, we review the literature on the neuroprotective activities, and the underlying mechanisms, of natural compounds and dietary supplements in experimental and clinical glaucoma.

Vitamin D Signaling in Inflammation and Cancer: Molecular Mechanisms and Therapeutic Implications

Vitamin D and its active metabolites are important nutrients for human skeletal health. UV irradiation of skin converts 7-dehydrocholesterol into vitamin D3, which metabolized in the liver and kidneys into its active form, 1α,25-dihydroxyvitamin D3. Apart from its classical role in calcium and phosphate regulation, scientists have shown that the vitamin D receptor is expressed in almost all tissues of the body, hence it has numerous biological effects. These includes fetal and adult homeostatic functions in development and differentiation of metabolic, epidermal, endocrine, neurological and immunological systems of the body. Moreover, the expression of vitamin D receptor in the majority of immune cells and the ability of these cells to actively metabolize 25(OH)D3 into its active form 1,25(OH)₂D3 reinforces the important role of vitamin D signaling in maintaining a healthy immune system. In addition, several studies have showed that vitamin D has important regulatory roles of mechanisms controlling proliferation, differentiation and growth. The administration of vitamin D analogues or the active metabolite of vitamin D activates apoptotic pathways, has antiproliferative effects and inhibits angiogenesis. This review aims to provide an up-to-date overview on the effects of vitamin D and its receptor (VDR) in regulating inflammation, different cell death modalities and cancer. It also aims to investigate the possible therapeutic benefits of vitamin D and its analogues as anticancer agents.

[Hypoparathyroidism - un underestimated problem?]

BACKGROUND

Hypoparathyroidism is a rare and disabilitating disorder characterized by hypocalcemia and low parathyroid hormone levels. Most of the cases occur as a result of the removal of parathyroid glands or damage to the glands during neck surgery. More rare causes include nonsurgical causes such as autoimmune or genetic diseases.

METHOD

In this review, a panel of experts presents the current state of diagnosis and therapy of hypoparathyroidism and explains practical aspects of caring for the affected patients.

RESULTS

Common signs and symptoms are abnormal sensations and increased excitability in the lower limbs, paresthesia of perioral areas and nocturnal leg cramps. Renal complications frequently occur, but also basal ganglia calcification. Treatment consists of administration of vitamin D analogs in combination with 0.5-1.0 g calcium daily. An adjunctive treatment with the in April 2017 approved recombinant human parathyroid hormone (1-84) is an option for patients whose hypoparathyroidism is difficult to control by conventional treatment alone. Initially and after dose changes follow-up controls should be performed at least every 2 weeks, in well-controlled patients or in the case of chronic progression every 3-6 months.

Efficacy of Vitamin D3 Buccal Spray Supplementation Compared to Other Delivery Methods: A Systematic Review of Superiority Randomized Controlled Trials

(1) Background: Vitamin D deficiency is an important public health concern and supplementation is common for this deficiency. Many different modes of delivering supplementation have been proposed in order to enhance absorption and utilization. The present review compared the efficacy of vitamin D₃ buccal spray against other forms of supplementation delivery. (2) Methods: The protocol was registered at PROSPERO (CRD42019136146). Medline/PubMed, CENTRAL and clinicaltrials.gov were searched from their inception until September 2019, for randomized controlled trials (RCTs) that compare vitamin D₃ delivery via sublingual spray against other delivery methods. Eligible RCTs involved humans, of any age and health status, published in any language that evaluated changes in plasma 25(OH)D concentrations. Three reviewers independently extracted data, assessed risk of bias (RoB) and the quality of the trials. (3) Results: Out of 9759 RCTs, four matched the predefined criteria. Intervention duration ranged from 30 days to 3 months whereas vitamin D₃ dosage ranged between 800 and 3000 IU/day. One RCT advocated for the superiority of buccal spray in increasing plasma 25(OH)D concentrations, although several limitations were recorded in that trial. The rest failed to report differences in post-intervention 25(OH)D concentrations between delivery methods. Considerable clinical heterogeneity was observed due to study design, intervention duration and dosage, assays and labs used to perform the assays, population age and health status, not allowing for synthesis of the results. (4) Conclusions: Based on the available evidence, delivery of vitamin D₃ via buccal spray does not appear superior to the other modes of delivery. Future RCTs avoiding the existing methodological shortcomings are warranted.

A Potential Linking between Vitamin D and Adipose Metabolic Disorders

Vitamin D has been discovered centuries ago, and current studies have focused on the biological effects of vitamin D on adipogenesis. Besides its role in calcium homeostasis and energy metabolism, vitamin D is also involved in the regulation of development and process of metabolic disorders. Adipose tissue is a major storage depot of vitamin D. This review summarized studies on the relationship between vitamin D and adipogenesis and furthermore focuses on adipose metabolic disorders. We reviewed the biological roles and functionalities of vitamin D, the correlation between vitamin D and adipose tissue, the effect of vitamin D on adipogenesis, and adipose metabolic diseases. Vitamin D is associated with adipogenesis, and vitamin D supplements can reduce the burden caused by metabolic diseases. The review provides new insights and basis for medical therapy on adipose metabolic diseases.

Genetic variation in GC and CYP2R1 affects 25-hydroxyvitamin D concentration and skeletal parameters: A genome-wide association study in 24-month-old Finnish children

Vitamin D is important for normal skeletal homeostasis, especially in growing children. There are no previous genome-wide association (GWA) studies exploring genetic factors that influence vitamin D metabolism in early childhood. We performed a GWA study on serum 25-hydroxyvitamin D (25(OH)D) and response to supplementation in 761 healthy term-born Finnish 24-month-old children, who participated in a randomized clinical trial comparing effects of 10 μg and 30 μg of daily vitamin D supplementation from age 2 weeks to 24 months. Using the Illumina Infinium Global Screening Array, which has been optimized for imputation, a total of 686085 markers were genotyped across the genome. Serum 25(OH)D was measured at the end of the intervention at 24 months of age. Skeletal parameters reflecting bone strength were determined at the distal tibia at 24 months using peripheral quantitative computed tomography (pQCT) (data available for 648 children). For 25(OH)D, two strong GWA signals were identified, localizing to GC (Vitamin D binding protein) and CYP2R1 (Vitamin D 25-hydroxylase) genes. The GWA locus comprising the GC gene also associated with response to supplementation. Further evidence for the importance of these two genes was obtained by comparing association signals to gene expression data from the Genotype-Tissue Expression project and performing colocalization analyses. Through the identification of haplotypes associated with low or high 25(OH)D concentrations we used a Mendelian randomization approach to show that haplotypes associating with low 25(OH)D were also associated with low pQCT parameters in the 24-month-old children. In this first GWA study on 25(OH)D in this age group we show that already at the age of 24 months genetic variation influences 25(OH)D concentrations and determines response to supplementation, with genome-wide significant associations with GC and CYP2R1. Also, the dual association between haplotypes, 25(OH)D and pQCT parameters gives support for vertical pleiotropy mediated by 25(OH)D.

Immunohistochemical Detection of Vasa Antigen and Apoptosis-Related DNA Fragmentation in Ovaries of Sheep Fetuses Prenatally Exposed to Vitamin D Deficiency

The primordial germ cells (PGCs) in female animals are comprised of diplotene oocytes arrested in the first meiotic prophase. Expression of Vasa is one of the key factors required for subsequent resumption of development and recruitment of PGCs into the growing follicle class. Since vitamin D regulates recruitment of PGCs and developmental competence of ovarian follicles, this study was designed to investigate the expression of Vasa and rate of apoptosis in foetal ovaries prenatally restricted from dietary vitamin D. Nineteen sexually mature Welsh mountain ewes were randomly assigned to vitamin D deficient (VDD) and vitamin D control (VDC) diets from 17d before mating, up to 125d of gestation, when fetal ovaries were collected and fixed in formalin for immunohistochemistry and TUNEL assay. VDD ovaries had fewer healthy oocytes that could stain positive for Vasa as well as a lower integrated density value for DAB staining intensity. Conversely, TUNNEL staining in VDD animals showed a higher integrated density value and percentage of affected area (P<0.05). The present findings indicate that Vasa expression is decreased, while the rate of apoptosis increased in VDD fetal ovaries, and this may adversely affect resumption of growth and development of PGCs reserve.

Comparative effectiveness of vitamin D supplementation via buccal spray versus oral supplements on serum 25-hydroxyvitamin D concentrations in humans: a systematic review protocol

REVIEW QUESTIONS

The questions of this review are.

Use of carotenoids in feed mixtures for poultry: a review

Carotenoids are present in ingredients of feed for poultry. Their content can be further increased by supplementation of feed mixtures with synthetic or natural carotenoids. The present paper recapitulates knowledge on the use of carotenoids in broiler chickens and laying hens, and deals with synthetic or natural carotenoids derived from plants. The review describes effects of carotenoids on productive performance, oxidative stability of poultry products, colouring of yolks and accumulation of carotenoids in yolks. There are several alternatives to synthetic carotenoids which are usable in poultry diets and satisfy the interest of consumers in poultry products free of undesirable side effects.