Low vitamin D status: definition, prevalence, consequences, and correction

Integrating Endocrine, Genomic, and Extra-Skeletal Benefits of Vitamin D into National and Regional Clinical Guidelines

BACKGROUND/OBJECTIVES

Vitamin D is essential for bone health, immune function, and overall well-being. Numerous ecological, observational, and prospective studies, including randomized controlled clinical trials (RCTs), report an inverse association between higher serum 25-hydroxyvitamin D [25(OH)D; calcifediol] levels in various conditions, including cardiovascular disease, metabolic disorders such as diabetes and obesity, susceptibility to infection-related complications, autoimmune diseases, and all-cause mortality.

RESULTS

Vitamin D operates through two distinct systems. The endocrine system comprises the renal tubular cell-derived circulatory calcitriol, which primarily regulates calcium homeostasis and muscular functions. In contrast, intracellularly generated calcitriol in peripheral target cells is responsible for intracrine/paracrine system signaling and calcitriol-vitamin D receptor-mediated genomic effects. Government-appointed committees and health organizations have developed various clinical practice guidelines for vitamin D supplementation and management. However, these guidelines heavily relied on the 2011 Institute of Medicine (IoM) report, which focused solely on the skeletal effects of vitamin D, ignoring other body systems. Thus, they do not represent maintaining good overall health and aspects of disease prevention. Additionally, the IoM report was intended as a public health recommendation for the government and is not a clinical guideline.

DISCUSSION

New country- and regional-specific guidelines must focus on healthy nations through disease prevention and reducing healthcare costs. They should not be restricted to bone effect and must encompass all extra-skeletal benefits. Nevertheless, due to misunderstandings, medical societies and other governments have used faulty IoM report as a foundation for creating vitamin D guidelines. Consequently, they placed disproportionate emphasis on bone health while largely overlooking its benefits for other bodily systems, making current guidelines, including 2024, the Endocrine Society less applicable to the public. As a result, the utility of published guidelines has been significantly reduced for clinical practice and RCTs that designed on bone-centric are generate misleading information and remain suboptimal for public health and disease prevention.

CONCLUSIONS

This review and its recommendations address the gaps in current vitamin D clinical practice guidelines and propose a framework for developing more effective, country and region-specific recommendations that capture the extra-skeletal benefits of vitamin D to prevent multiple diseases and enhance public health.

Infections and Autoimmunity-The Immune System and Vitamin D: A Systematic Review

Both 25-autoimmunity and(25(OH)D: calcifediol) and its active form, 1,25-dihydroxyvitamin D (1,25(OH)2D: calcitriol), play critical roles in protecting humans from invasive pathogens, reducing risks of autoimmunity, and maintaining health. Conversely, low 25(OH)D status increases susceptibility to infections and developing autoimmunity. This systematic review examines vitamin D's mechanisms and effects on enhancing innate and acquired immunity against microbes and preventing autoimmunity. The study evaluated the quality of evidence regarding biology, physiology, and aspects of human health on vitamin D related to infections and autoimmunity in peer-reviewed journal articles published in English. The search and analyses followed PRISMA guidelines. Data strongly suggested that maintaining serum 25(OH)D concentrations of more than 50 ng/mL is associated with significant risk reduction from viral and bacterial infections, sepsis, and autoimmunity. Most adequately powered, well-designed, randomized controlled trials with sufficient duration supported substantial benefits of vitamin D. Virtually all studies that failed to conclude benefits or were ambiguous had major study design errors. Treatment of vitamin D deficiency costs less than 0.01% of the cost of investigation of worsening comorbidities associated with hypovitaminosis D. Despite cost-benefits, the prevalence of vitamin D deficiency remains high worldwide. This was clear among those who died from COVID-19 in 2020/21-most had severe vitamin D deficiency. Yet, the lack of direction from health agencies and insurance companies on using vitamin D as an adjunct therapy is astonishing. Data confirmed that keeping an individual's serum 25(OH)D concentrations above 50 ng/mL (125 nmol/L) (and above 40 ng/mL in the population) reduces risks from community outbreaks, sepsis, and autoimmune disorders. Maintaining such concentrations in 97.5% of people is achievable through daily safe sun exposure (except in countries far from the equator during winter) or taking between 5000 and 8000 IU vitamin D supplements daily (average dose, for non-obese adults, ~70 to 90 IU/kg body weight). Those with gastrointestinal malabsorption, obesity, or on medications that increase the catabolism of vitamin D and a few other specific disorders require much higher intake. This systematic review evaluates non-classical actions of vitamin D, with particular emphasis on infection and autoimmunity related to the immune system.

The Chemoprotective Role of Vitamin D in Skin Cancer: A Systematic Review

Introduction

Research in mice showed that vitamin D receptor deficiency was correlated with an increased rate of non-melanoma skin cancer. Therapeutic supplemental vitamin D has also been reported to reduce cell growth in both melanoma and non-melanoma skin cancer. This paper aims to describe the existing research studies that discuss the potential and role of vitamin D in the management of skin cancer.

Methods

Articles were searched from three databases (PubMed, ScienceDirect, Scopus) and manual search. 18 articles were included. These were further divided into in vivo and in vitro studies. The literature search was based on the following Patients, Intervention, Control, and Outcome (PICO) criteria: Patients with any types of skin cancer; Vitamin D and their derivates as the intervention; placebo or standard regimen as control, and survival rate or response rate as primary outcome.

Results

From the three databases, we obtained 802 studies. Prior to screening of the literature obtained, several studies were excluded. In the eligibility assessment, seven studies were excluded due to their outcomes being not eligible for analysis, and two studies were excluded due to inaccessible full texts. The remaining 18 studies were included. Five studies had a clinical research design (randomized controlled trial or interventional study), which use vitamin D3 as vitamin D derivatives and the results showed that the administration of vitamin D3 reduces the proliferation of skin cancer cells. Similar results were also reported in studies with pre-clinical research designs, either in vivo or in vitro, where six were in vivo studies and nine studies were in vitro studies.

Conclusion

Our literature review revealed that that vitamin D derivatives, such as 1,25(OH)2D3 or 20(OH)D3 can effectively reduce the proliferation of skin cancer cells by contributing in the inhibition of cell growth and development, highlighting vitamin D's role as good prognostic factor.

Associations of Serum Total 25OHD, 25OHD3, and epi-25OHD3 with Insulin Resistance: Cross-Sectional Analysis of the National Health and Nutrition Examination Survey, 2011–2016

Background: Vitamin D may have a role in insulin sensitivity. However, the data on the association between various metabolites of Vitamin D and insulin-related parameters have been limited. Methods: We identified 6026 adults aged 20–80 years who participated in the 2011–2016 National Health and Nutrition Examination Survey (NHANES). Serum total 25OHD, 25OHD3, and epi-25OHD3, fasting glucose, insulin, and HOMA2-IR were obtained from the NHANES data. The association between serum Vitamin D-related values and insulin resistance was analyzed using a generalized linear model. For risk analysis, multifactorial logistic regression was used. Results: The median total 25-hydroxyvitamin D level, 25-hydroxyvitamin D3 level, and 3-epi-25-hydroxyvitamin D3 level were 62.5 nmol/L, 58.8 nmol/L, and 3.3 nmol/L, respectively. After adjustment for sex, age, race, ethnicity, and education status, the ORs for the insulin resistance of participants of total 25-hydroxyvitamin D, 25-hydroxyvitamin D3, and 3-epi-25-hydroxyvitamin D3 were 0.32 (95% CI 0.24, 0.43), 0.34 (95% CI 0.26, 0.44), and 0.64 (95% CI 0.53, 0.77), respectively. After an adjustment for body mass index, diabetes, and drinking and smoking, the ORs for the insulin resistance of the participants for total 25-hydroxyvitamin D, 25-hydroxyvitamin D3, and 3-epi-25-hydroxyvitamin D3 were 0.56 (95% CI 0.40, 0.78), 0.63 (95% CI 0.46, 0.85), and 0.99 (95% CI 0.80, 1.24), respectively. Conclusions: Our study provides suggestive evidence for the association between Vitamin D concentrations and a lower risk of insulin resistance. Evidence from larger and more adequately powered cohort studies is needed to confirm our results.

Bone mineral density and explanatory factors in children and adults with juvenile dermatomyositis at long term follow-up; a cross sectional study

BACKGROUND

Juvenile dermatomyositis (JDM) is the most common idiopathic inflammatory myopathy in children and adolescents. Both the disease and its treatment with glucocorticoids may negatively impact bone formation. In this study we compare BMD in patients (children/adolescence and adults) with long-standing JDM with matched controls; and in patients, explore how general/disease characteristics and bone turnover markers are associated with BMD.

METHODS

JDM patients (n = 59) were examined median 16.8y (range 6.6-27.0y) after disease onset and compared with 59 age/sex-matched controls. Dual-energy X-ray absorptiometry (DXA) was used to measure BMD of the whole body and lumbar spine (spine) in all participants, and of ultra-distal radius, forearm and total hip in participants ≥20y only. Markers of bone turnover were analysed, and associations with outcomes explored.

RESULTS

Reduced BMD Z-scores (<-1SD) were found in 19 and 29% of patients and 7 and 9% of controls in whole body and spine, respectively (p-values < 0.05). BMD and BMD Z-scores for whole body and spine were lower in all patients and for < 20y compared with their respective controls. In participants ≥20y, only BMD and BMD Z-score of forearm were lower in the patients versus controls. In patients, BMD Z-scores for whole body and/or spine were found to correlate negatively with prednisolone use at follow-up (yes/no) (age < 20y), inflammatory markers (age ≥ 20y) and levels of interferon gamma-induced protein 10 (IP-10) (both age groups). In all patients, prednisolone use at follow-up (yes/no) and age ≥ 20y were independent correlates of lower BMD Z-scores for whole body and spine, respectively.

CONCLUSION

In long-term JDM, children have more impairment of BMD than adults in spine and whole-body. Associations with BMD were found for both prednisolone and inflammatory markers, and a novel association was discovered with the biomarker of JDM activity, IP-10.

Hypovitaminosis D in migrant children in Switzerland: a retrospective study

Cholecalciferol (vitamin D₃) is essentially known for its role in the phosphocalcic metabolism and its associated pathologies, such as rickets. In Switzerland, 35 to 50% of children are vitamin D deficient. Due to skin colour, poor nutrition, living conditions and cultural practices, migrant population is particularly at risk. Our aim is to attest the prevalence of hypovitaminosis D in children arriving in Switzerland. We retrospectively assessed 528 children's vitamin D status and parathyroid hormone, phosphate and calcium levels between 2015 and 2018 by electrochemiluminescence and spectrophotometry. Cholecalciferol was considered insufficient under 50 nmol/L and severely deficient below 25 nmol/L. Seventy-three percent of children showed hypovitaminosis D and 28% had a severe deficiency. Highest prevalence of deficiency was found in children from Eastern Mediterranean (80%) and African regions (75%). Severe deficiency was more prevalent in the South East Asian (39%) and Eastern Mediterranean regions (33%) and more frequent in females. Deficiency was more frequent and more severe in winter. Hypovitaminosis D increased with age. Two children presented with all three biological manifestations associated to severe hypovitaminosis D (hyperparathyroidism, hypocalcaemia and hypophosphatemia).Conclusion: A majority of migrant children presented with hypovitaminosis D. They should be supplemented to prevent complications. A strategy could be to supplement all children at arrival and during wintertime without regular vitamin D level checks. What is Known: Hypovitaminosis D is frequent in children and can lead to bone-related complications. Migrant children are particularly at risk of deficiency. What is New: Three-quarters of migrant children evaluated at our migrant clinic in Geneva's children hospital are deficient in vitamin D, one third severely. A strategy to correct the deficiency would be to supplement all migrant children at arrival and in winter.

Continued Interest and Controversy: Vitamin D in HIV

PURPOSE OF REVIEW

Vitamin D (VitD) deficiency is highly prevalent among HIV-infected individuals. Given the overlapping risk for several chronic disease and immunomodulatory outcomes from both long-standing HIV and VitD deficiency, there is great interest in clarifying the clinical role of VitD for this population.

RECENT FINDINGS

Recent studies have expanded our knowledge regarding the epidemiology and mechanisms of VitD deficiency-associated outcomes in the setting of HIV. Clinical trials focusing on VitD supplementation have demonstrated a positive impact on bone mineral density in subgroups of HIV-infected individuals initiating ART or on suppressive ART regimens; however, significant heterogeneity exists between studies and data are less consistent with other clinical outcomes. Further research is needed to clarify uncertainly in several domains, including identifying patients at greatest risk for poor outcomes from VitD deficiency, standardizing definitions and measurement techniques, and better quantifying the benefits and risks of VitD supplementation across different demographic strata for skeletal and extra-skeletal outcomes.

Vitamin D Deficiency: Effects on Oxidative Stress, Epigenetics, Gene Regulation, and Aging

Recent advances in vitamin D research indicate that this vitamin, a secosteroid hormone, has beneficial effects on several body systems other than the musculoskeletal system. Both 25 dihydroxy vitamin D [25(OH)₂D] and its active hormonal form, 1,25-dihydroxyvitamin D [1,25(OH)₂D] are essential for human physiological functions, including damping down inflammation and the excessive intracellular oxidative stresses. Vitamin D is one of the key controllers of systemic inflammation, oxidative stress and mitochondrial respiratory function, and thus, the aging process in humans. In turn, molecular and cellular actions form 1,25(OH)₂D slow down oxidative stress, cell and tissue damage, and the aging process. On the other hand, hypovitaminosis D impairs mitochondrial functions, and enhances oxidative stress and systemic inflammation. The interaction of 1,25(OH)₂D with its intracellular receptors modulates vitamin D–dependent gene transcription and activation of vitamin D-responsive elements, which triggers multiple second messenger systems. Thus, it is not surprising that hypovitaminosis D increases the incidence and severity of several age-related common diseases, such as metabolic disorders that are linked to oxidative stress. These include obesity, insulin resistance, type 2 diabetes, hypertension, pregnancy complications, memory disorders, osteoporosis, autoimmune diseases, certain cancers, and systemic inflammatory diseases. Vitamin D adequacy leads to less oxidative stress and improves mitochondrial and endocrine functions, reducing the risks of disorders, such as autoimmunity, infections, metabolic derangements, and impairment of DNA repair; all of this aids a healthy, graceful aging process. Vitamin D is also a potent anti-oxidant that facilitates balanced mitochondrial activities, preventing oxidative stress-related protein oxidation, lipid peroxidation, and DNA damage. New understandings of vitamin D-related advances in metabolomics, transcriptomics, epigenetics, in relation to its ability to control oxidative stress in conjunction with micronutrients, vitamins, and antioxidants, following normalization of serum 25(OH)D and tissue 1,25(OH)₂D concentrations, likely to promise cost-effective better clinical outcomes in humans.

Non-musculoskeletal benefits of vitamin D

The aim of this study is to determine and critically evaluate the plausible relationships of vitamin D with extra-skeletal tissues in humans. Severe vitamin D deficiency results in rickets in children and osteomalacia in adults; these beneficial effects in the musculoskeletal system and certain physiological functions are well understood. Nevertheless, mounting reports support additional beneficial effects of vitamin D, outside the musculoskeletal system. This review explores the recent advances in knowledge about the non-skeletal effects of vitamin D. Peer-reviewed papers were extracted from research databases using key words, to assess correlations between vitamin D and extra-skeletal diseases and conditions. As per the guidelines of the Preferred Reporting Items for Systematic Reviews (PRISMA); general interpretations of results are included; taking into consideration the broader evidence and implications. This review summarizes current knowledge of the effects of vitamin D status on extra-skeletal tissues with special attention given to relationships between vitamin D status and various diseases commonly affecting adults; the effects of intervention with vitamin D and exposure to sunlight. Evidence suggests that vitamin D facilitates the regulation of blood pressure; and cardiac; endothelial; and smooth muscle cell functions; playing an important role in cardiovascular protection. In addition; 1,25(OH)₂D improves immunity; subdues inflammation; and reduces the incidence and severity of common cancers; autoimmune diseases and infectious diseases. Almost all adequately powered; epidemiological and biological studies that use; adequate doses of vitamin D supplementation in D-deficient populations have reported favorable outcomes. These studies have concluded that optimizing 25(OH)D status improves the functionality of bodily systems; reduces comorbidities; improves the quality of life; and increases survival. Although accumulating evidence supports biological associations of vitamin D sufficiency with improved physical and mental functions; no definitive evidence exists from well-designed; statistically powered; randomized controlled clinical trials. Nevertheless, most studies point to significant protective effects of vitamin D in humans when the minimum 25(OH)D serum level exceeds 30ng/mL and is maintained throughout the year.

Vitamin D Deficiency and Its Association with Inflammatory Markers, Lipid Profile and Regulatory T-cells in Pediatric Sickle Cell Disease Patients

We investigated vitamin D deficiency in pediatric sickle cell disease patients and its association with selected bone, lipid and inflammatory parameters. The study included 64 patients (33 SS and 31 SB) and 21 carriers (AS). Blood was obtained to assess levels of vitamin D, WBC, CRP, Ca, P, ALP, PTH, triglyceride, total cholesterol, LDL, VLDL, HDL, IL-2, IL-12, TNF-α, IL-4, IL-6, IL-10 and regulatory T cells. The patients were grouped according to their genotype (SS, SB) and vitamin D status (low or normal). Carriers were also grouped as low or normal vitamin D. Laboratory findings were similar between low and normal Vit D groups in SS, SB and AS genotypes except a lower IL-12 in SB-low vitamin D compared SB-normal vitamin D group. Acute chest syndrome was more frequent in SS-low Vit D (63%) compared to SS-normal Vit D (25%), SB-low Vit D (21%) and SB-normal Vit D (33%) (P = 0.045). Both SS and SB with low vitamin D had higher VLDL (P = 0.006 and P = 0.022), TNF-α (P = 0.001) and regulatory T cells (P = 0.000) compared to AS-low vitamin D. Both SS and SB with normal vitamin D had higher levels of regulatory T cells (P = 0.000) compared to AS-normal vitamin D. Vit D was not a modifier of selected inflammation, bone and lipid parameters in sickle cell disease. Acute chest syndrome was comparably more frequent in SS-low vitamin D. Increase of regulatory T cells in the patients was a result of chronic inflammation in sickle cell disease.

Development of an Improved Standard Reference Material for Vitamin D Metabolites in Human Serum

The National Institute of Standards and Technology (NIST) has developed Standard Reference Material (SRM) 972a Vitamin D Metabolites in Frozen Human Serum as a replacement for SRM 972, which is no longer available. SRM 972a was developed in collaboration with the National Institutes of Health's Office of Dietary Supplements. In contrast to the previous reference material, three of the four levels of SRM 972a are composed of unmodified human serum. This SRM has certified and reference values for the following 25-hydroxyvitamin D [25(OH)D] species: 25(OH)D2, 25(OH)D3, and 3-epi-25(OH)D3. The value assignment and certification process included three isotope-dilution mass spectrometry approaches, with measurements performed at NIST and at the Centers for Disease Control and Prevention (CDC). The value assignment methods employed have been modified from those utilized for the previous SRM, and all three approaches now incorporate chromatographic resolution of the stereoisomers, 25(OH)D3 and 3-epi-25(OH)D3.

Vitamin D status in patients attending a Danish migrant health clinic: a clinical retrospective study

Non-western migrants and ethnic minority populations in western countries are particularly at risk of vitamin D deficiency due to darker skin color and low sun exposure. The aim of this study was to examine levels of 25-OH vitamin D in patients attending a Danish health clinic for migrants. Patients attending the clinic represent a distinct group of migrants with longstanding, unresolved symptoms and often multiple illnesses. In this retrospective study, data on patient demographics and vitamin D levels were extracted from the medical records of 156 patients attending a Migrant Health Clinic in 2008-2011 who were considered at-risk for low vitamin D, mainly due to symptoms of diffuse pain in the muscles, bones or joints. Over the follow-up period of 1 year, the number of patients with vitamin D below 50 nmol/L decreased from 80 to 56%. The median vitamin D level increased from 27 nmol/L [(interquartile ranges (IQR 14.5-45.0)] at baseline to 45 nmol/L (IQR 26.5-64.5) at follow-up. Patient consultations with a holistic approach and close follow-up can help patients with complex symptoms and language barriers to overcome barriers to treatment and adherence, thus leading to improved levels of vitamin D.

Sunbed use and cutaneous melanoma in Norway

Aims: Incidence rates of cutaneous melanoma (CM) in light skinned people in Norway are among the highest in the world. Sunbed use has increased in Norway since 1980. We will try to elucidate whether there is any correlation between the increase in sunbed use and the CM incidence rates, whether the increase in CM risk is similar for all age groups, and whether the possible difference between young and old persons can inform future healthcare strategies. Methods: The frequency of sunbed use by different age groups in the time period 1980–2011 and incidence rates (1980–2009) of CM at different age groups in Norway were studied. Time in minutes per day spent in front of screen of computers or TVs for boys and girls was also analysed. Results: The number of sunbed sessions per year in Norway increased throughout the entire period. The number of men and women diagnosed with CM per year, all ages combined, also increased. Sunbed use increased at a similar rate for three age groups (0–19, 20–50, and >50 years old), while the age-adjusted CM incidence rate increased only for the oldest group. Time spent in front of the screen of computers or TVs increased from 1985 to 2005 and is still increasing. Conclusions: CM incidence is decreasing while sunbed use is increasing in younger age groups. The present data indicate that more work needs to be done before one can know whether the overall health effects of sunbed exposure are positive or negative.

[Vitamin D and breast cancer: is there a link?]

OBJECTIVE

The aim of this review is to know the relationship between breast cancer and vitamin D, synthesised by skin or brought by food or supplementation.

MATERIAL AND METHODS

The selected articles were extracted from the Pubmed database between 1998 and 2012. The keywords used were: "25-hydroxyvitamin D", "breast cancer recurrence", "breast cancer risk", "serum levels of vitamin D", "vitamin D intake". A total of 37 articles were selected.

RESULTS

The sun exposure, via the skin vitamin D synthesis, is associated with a decreased risk of breast cancer. This decrease seems also likely for food contributions and an over 400IU per day vitamin D supplementation. An inverse relationship between plasma 25-hydroxyvitamin D (25-OH-D) level and breast cancer risk has been suggested. An increased 25-OH-D level seems associated with a decreased risk of breast cancer recurrence.

CONCLUSION

Recommendations concerning a vitamin D supplementation could be established, but should be supported by additional studies.

2012 European thyroid association guidelines for genetic testing and its clinical consequences in medullary thyroid cancer

Twenty-five percent of medullary thyroid cancers (MTC) are familial and inherited as an autosomal dominant trait. Three different phenotypes can be distinguished: multiple endocrine neoplasia (MEN) types 2A and 2B, in which the MTC is associated with other endocrine neoplasias, and familial MTC (FMTC), which occurs in isolation. The discovery that germline RET oncogene activating mutations are associated with 95-98% of MEN 2/FMTC syndromes and the availability of genotyping to identify mutations in affected patients and their relatives has revolutionized the diagnostic and therapeutic strategies available for the management of these patients. All patients with MTC, both those with a positive familial history and those apparently sporadic, should be submitted to RET genetic screening. Once an RET mutation has been confirmed in an index patient, first-degree relatives should be screened rapidly to identify the 50% who inherited the mutation and are therefore at risk for development of MTC. Relatives in whom no RET mutation is identified can be reassured and discharged from further follow-up, whereas RET-positive subjects (i.e. gene carriers) must be investigated and a therapeutic strategy initiated. These guideline recommendations are derived from the most recent studies identifying phenotype-genotype correlations following the discovery of causative RET gene mutations in MEN 2 eighteen years ago. Three major points will be discussed: (a) identification of patients and relatives who should have genetic screening for RET mutations, (b) management of asymptomatic gene carriers, and (c) ethics.