Vitamin D deficiency

Calcitriol Impairs the Secretion of IL-4 and IL-13 in Th2 Cells via Modulating the VDR-Gata3-Gfi1 Axis

Calcitriol, the bioactive form of vitamin D, exerts its biological functions by binding to its cognate receptor, the vitamin D receptor (VDR). The indicators of the severity of allergies and asthma have been linked to low vitamin D levels. However, the role of calcitriol in regulating IL-4 and IL-13, two cytokines pivotal to allergic inflammation, remained unclear. Our study observed diminished IL-4 and IL-13 secretion in murine and human Th2 cells treated with calcitriol. In murine Th2 cells, Gata3 expression was attenuated by calcitriol. However, the expression of the transcriptional repressor Gfi1, too, was attenuated in the presence of calcitriol. Ectopic expression of either Gfi1 or VDR impaired the secretion of IL-13 in Th2 cells. In murine Th2 cells, VDR interacted with Gata3 but not Gfi1. Gfi1 significantly impaired Il13 promoter activation, which calcitriol failed to restore. Conversely, calcitriol augmented Gfi1 recruitment to the Il13 promoter. Ecr, a conserved region between these two genes, which enhanced the transactivation of Il4 and Il13 promoters, is essential for calcitriol-mediated suppression of both the genes. Calcitriol augmented the recruitment of VDR to the Il13 promoter and Ecr regions. Gata3 recruitment was significantly impaired at the Il13 and Ecr loci in the presence of calcitriol but increased at the Il4 promoter. Furthermore, the recruitment of the histone deacetylase HDAC1 was universally increased at the promoters of Il4, Il13, and Ecr when calcitriol was present. Together, our data clearly elucidate that calcitriol modulates VDR, Gata3, and Gfi1 to suppress IL-4 and IL-13 production in Th2 cells.

Deletion of vitamin D receptor exacerbated temporomandibular joint pathological changes under abnormal mechanical stimulation

AIMS

Temporomandibular disorder can cause degenerative pathological changes by aseptic inflammation in the temporomandibular joint (TMJ). Vitamin D (VD) is known for maintaining calcium homeostasis, and recent studies indicated that VD and the vitamin D receptor (VDR) are important in inflammatory responses. In this study, we explored the anti-inflammatory effect of VD-VDR signaling axis in TMJ pathological degeneration.

MAIN METHODS

Mice ablated for Vdr (Vdr-/-res) were fed with a rescue diet to avoid hypocalcemia. With abnormal mechanical stimulation, unilateral anterior crossbite (UAC) induced temporomandibular disorders in mice. Histological staining, immunohistochemistry staining, and micro-CT analysis were performed to evaluate TMJ pathological changes. To identify the mechanisms in the aseptic inflammatory process, in vitro experiments were conducted on wild-type (WT) and Vdr-/- chondrocytes with compressive mechanical stress loading, and the related inflammatory markers were examined.

KEY FINDINGS

Vdr-/-res mice did not develop rickets with a high calcium rescue diet. The TMJ cartilage thickness in Vdr-/-res mice was significantly decreased with mechanical stress stimulation compared to WT mice. UAC-induced bone resorption was obvious, and the number of osteoclasts significantly increased in Vdr-/-res mice. The proliferation was inhibited and the gene expression of Il1b, Mmp3, and Mmp13 was significantly increased in Vdr-/- chondrocytes. However, WT chondrocytes showed significantly increased Tnfa gene expression as a response to mechanical stress but not in Vdr-/- chondrocytes.

SIGNIFICANCE

VD-VDR is crucial in TMJ pathological changes under abnormal mechanical stimulation. Deletion of Vdr exacerbated inflammatory response excluding TNFα, inhibited chondrocyte proliferation, and promoted bone resorption in TMJ.

Enhancing vitamin D levels in care homes: the role of healthy building design in preventing respiratory infections

The recent article by Willcox et al. in the Journal of Public Health highlights the effectiveness of antiviral prophylaxis and high-dose vitamin D supplementation in reducing acute respiratory infections (ARIs) in care homes. This correspondence extends the discussion by emphasizing the critical role of healthy building design in enhancing vitamin D levels, which is vital for immune function and ARI prevention. Many care home residents suffer from vitamin D deficiency due to limited sunlight exposure. Incorporating architectural elements such as large windows, skylights, and outdoor spaces can significantly increase natural light exposure, thereby boosting vitamin D levels and potentially reducing ARI susceptibility. Despite the benefits of supplementation, addressing environmental factors through healthy building design offers a sustainable, long-term strategy that aligns with public health goals of preventive care and environmental sustainability. Prioritizing such design principles in care home planning and renovation can enhance residents' health and resilience against infections like influenza and COVID-19.

Selective Oxidation of Vitamin D3 Enhanced by Long-Range Effects of a Substrate Channel Mutation in Cytochrome P450BM3 (CYP102A1)

Vitamin D deficiency affects nearly half the population, with many requiring or opting for supplements with vitamin D3 (VD3), the precursor of vitamin D (1α,25-dihydroxyVD3). 25-HydroxyVD3, the circulating form of vitamin D, is a more effective supplement than VD3 but its synthesis is complex. We report here the engineering of cytochrome P450BM3 (CYP102A1) for the selective oxidation of VD3 to 25-hydroxyVD3. Long-range effects of the substrate-channel mutation Glu435Ile promoted binding of the VD3 side chain close to the heme, enhancing VD3 oxidation activity that reached 6.62 g of 25-hydroxyVD3 isolated from a 1-litre scale reaction (69.1 % yield; space-time-yield 331 mg/L/h).

Cardioprotective effect of Vitamin D on cardiac hypertrophy through improvement of mitophagy and apoptosis in an experimental rat model of levothyroxine -induced hyperthyroidism

BACKGROUND

Mitochondria are known to be involved in mediating the calorigenic effects of thyroid hormones. With an abundance of these hormones, alterations in energy metabolism and cellular respiration take place, leading to the development of cardiac hypertrophy. Vitamin D has recently gained attention due to its involvement in the regulation of mitochondrial function, demonstrating promising potential in preserving the integrity and functionality of the mitochondrial network. The present study aimed to investigate the therapeutic potential of Vitamin D on cardiac hypertrophy induced by hyperthyroidism, with a focus on the contributions of mitophagy and apoptosis as possible underlying molecular mechanisms.

METHODS AND RESULTS

The rats were divided into three groups: control; hyperthyroid; hyperthyroid + Vitamin D. Hyperthyroidism was induced by Levothyroxine administration for four weeks. Serum thyroid hormones levels, myocardial damage markers, cardiac hypertrophy indices, and histological examination were assessed. The assessment of Malondialdehyde (MDA) levels and the expression of the related genes were conducted using heart tissue samples. Vitamin D pretreatment exhibited a significant improvement in the hyperthyroidism-induced decline in markers indicative of myocardial damage, oxidative stress, and indices of cardiac hypertrophy. Vitamin D pretreatment also improved the downregulation observed in myocardial expression levels of genes involved in the regulation of mitophagy and apoptosis, including PTEN putative kinase 1 (PINK1), Mitofusin-2 (MFN2), Dynamin-related Protein 1 (DRP1), and B cell lymphoma-2 (Bcl-2), induced by hyperthyroidism.

CONCLUSIONS

These results suggest that supplementation with Vitamin D could be advantageous in preventing the progression of cardiac hypertrophy and myocardial damage.

Vitamin D Deficiency after Anterior Cruciate Ligament Reconstruction Associates with Knee Osteoarthritis: A Retrospective Study

BACKGROUND/OBJECTIVES

The objective of this study was to test the hypothesis that vitamin D deficiency (i.e., serum 25-hydroxyvitamin D (25(OH)D) ≤ 20 ng/mL) associates with the increased occurrence and shortened time to a knee osteoarthritis (OA) diagnosis after anterior cruciate ligament reconstruction (ACLR).

METHODS

This study consisted of a retrospective, case-control design. The inclusion criteria consisted of (1) patients (≥18 y) who underwent arthroscopic ACLR with (cases; n = 28) and without (controls; n = 56) a subsequent knee OA diagnosis (≥90 d from the date of ACLR) and (2) with a documented serum 25(OH)D concentration after ACLR (and before a knee OA diagnosis for the cases). Controls were matched (2:1) to cases based on sex, age at ACLR, date of ACLR, and body mass index. After matching, patients were separated into two groups: (1) vitamin D deficient (serum 25(OH)D ≤ 20 ng/mL) or (2) non-vitamin D deficient (serum 25(OH)D > 20 ng/mL). Data were extracted from the medical records.

RESULTS

Thirty-one percent (n = 26) of patients included were vitamin D deficient. Fifty percent (n = 13) of the vitamin D deficient and twenty-six percent (n = 15) of the non-vitamin D deficient patients were subsequently diagnosed with knee OA (p = 0.03). Time from ACLR to a knee OA diagnosis was significantly (p = 0.02) decreased in the vitamin D deficient (OA-free interval, 95% confidence interval [CI] = 7.9 to 10.9 y) compared to the non-vitamin D deficient group (OA-free interval, 95% CI = 10.5 to 12.5 y).

CONCLUSIONS

Vitamin D deficiency after ACLR may serve as a prognostic biomarker for knee OA following ACLR.

Vitamin D and Sarcopenia in the Senior People: A Review of Mechanisms and Comprehensive Prevention and Treatment Strategies

This article reviews the mechanisms and prevention strategies associated with vitamin D and sarcopenia in older adults. As a geriatric syndrome, sarcopenia is defined by a notable decline in skeletal muscle mass and strength, which increases the risk of adverse health outcomes such as falls and fractures. Vitamin D, an essential fat-soluble vitamin, is pivotal in skeletal muscle health. It affects muscle function through various mechanisms, including regulating calcium and phosphorus metabolism, promoting muscle protein synthesis, and modulation of muscle cell proliferation and differentiation. A deficiency in vitamin D has been identified as a significant risk factor for the development of sarcopenia in older adults. Many studies have demonstrated that low serum vitamin D levels are significantly associated with an increased risk of sarcopenia. While there is inconsistency in the findings, most studies support the importance of vitamin D in maintaining skeletal muscle health. Vitamin D influences the onset and progression of sarcopenia through various pathways, including the promotion of muscle protein synthesis, the regulation of mitochondrial function, and the modulation of immune and inflammatory responses. Regarding the prevention and treatment of sarcopenia, a combination of nutritional, exercise, and pharmacological interventions is recommended. Further research should be conducted to elucidate the molecular mechanism of vitamin D in sarcopenia, to study genes related to sarcopenia, to perform large-scale clinical trials, to investigate special populations, and to examine the combined application of vitamin D with other nutrients or drugs. A comprehensive investigation of the interconnection between vitamin D and sarcopenia will furnish a novel scientific foundation and productive strategies for preventing and treating sarcopenia. This, in turn, will enhance the senior people's quality of life and health.

Dietary vitamin D intake and risk of colorectal cancer according to vitamin D receptor expression in tumors and their surrounding stroma

BACKGROUND

Colorectal Cancer (CRC) has been molecularly classified into several subtypes according to tumor, stromal, and immune components. Here, we investigated whether the preventive effect of vitamin D on CRC varies with subtypes defined by Vitamin D receptor (VDR) expression in tumors and their surrounding stroma, along with the association of somatic mutations in CRC.

METHODS

In a population-based prospective study of 22,743 Japanese participants, VDR expression levels in tumors and their surrounding stroma were defined in 507 cases of newly diagnosed CRC using immunohistochemistry. Hazard ratios of CRC and its subtypes according to dietary vitamin D intake were estimated using multivariable Cox proportional hazards models.

RESULTS

Dietary vitamin D intake was not associated with CRC or its subtypes defined by VDR expression in tumors. However, an inverse association was observed for CRC with high VDR expression in the stroma (the highest tertile vs the lowest tertile: 0.46 [0.23-0.94], Ptrend = 0.03), but not for CRC with low VDR expression in the stroma (Pheterogeneity = 0.02). Furthermore, CRC with high VDR expression in the stroma had more somatic TP53 and BRAF mutations and fewer APC mutations than those with low VDR expression in the stroma.

CONCLUSIONS

This study provides the first evidence that the preventive effect of vitamin D on CRC depends on VDR expression in the stroma rather than in the tumors. CRC with high VDR expression in the stroma is likely to develop through a part of the serrated polyp pathway, which tends to occur with BRAF but not with APC mutations.

Vitamin D deficiency: A forgotten aspect in sleep disorders? A critical update

Over the past few years, there has been a surge in interest regarding the connection between sleep duration and quality, sleep disorders, mainly Obstructive sleep apnoea (OSA) and Vitamin D. There is growing evidence to support a new role of Vitamin D in the maintenance and regulation of optimal sleep. Furthermore, a notable link has been identified between OSA and a decrease in serum Vitamin D levels, which appears to intensify as the severity of sleep apnea worsens. Vitamin D status could also potentially serve as a mediator or provide an explanation for the association between OSA and cardiometabolic morbidity, but the current state of research in this area is inadequate. Studies have indicated that the supplementation of Vitamin D can optimize sleep quality, presenting more proof of the connection between insufficient vitamin D levels and sleep disorders. However, it is unclear whether low serum Vitamin D levels are a contributing factor to OSA development or if OSA predisposes individuals to Vitamin D deficiency. As a result, various studies have endeavored to examine the complex relationship between OSA and Vitamin D deficiency. In children and adolescents, while data is limited, there seems also to be a link between sleep disorders and Vitamin D levels. Therefore, the objective of this review is to provide a comprehensive overview of the current evidence on the association between Vitamin D and sleep disorders in both adults and children.

To Study the Correlation of Maternal Serum Vitamin D Levels and Infant Serum Vitamin D Levels With Infant Birth Weight: A Single-Centre Experience From the Bundelkhand Region, India

BACKGROUND

Vitamin D deficiency during pregnancy can have severe effects on both the mother and the newborn child. The main aim of this study was to assess the impact of maternal vitamin D levels on the birth weight of the newborn by analysing the vitamin D levels in pregnant women at full term and their newborn.

MATERIAL AND METHODS

The cross-sectional, hospital-based study was conducted with 150 consecutive women in labour presenting with a singleton term pregnancy at a large tertiary centre in the Bundelkhand region, India. Maternal and infant blood samples were obtained at the time of delivery. Umbilical cord blood was collected from infants, while maternal venous blood was drawn simultaneously. All relevant data were gathered, including the assessment of 25-hydroxy vitamin D3 levels in both mother and infant. The birth weight of the infant was measured, and statistical analysis was performed to find an association between maternal vitamin D level to birth weight and vitamin D level of the infant.

RESULT

Most pregnant women had low vitamin D levels in this study. The results revealed a significant positive correlation between maternal serum vitamin D levels and infant birth weight (p < 0.001), suggesting that lower maternal vitamin D levels were associated with low birth weight in infants. Additionally, infant serum vitamin D levels showed a positive correlation with maternal vitamin D levels (p < 0.001), indicating that higher maternal vitamin D levels tend to have infants with higher vitamin D levels at birth.

CONCLUSION

These findings suggest a potential correlation of maternal vitamin D status to birth weight and vitamin D level of newborns, and further research is needed to confirm and better understand this relationship. Additionally, other factors such as maternal nutrition, genetics, lifestyle factors, and environmental influences may contribute to birth weight outcomes.

Assessment of Vitamin D, Vitamin B12, and Folate Levels in Recently Identified Pregnant Females

Background: Pregnancy is a critical period where optimal maternal and fetal health depends on adequate nutritional status. Deficiencies in essential vitamins, such as vitamin D, vitamin B12, and folate, can result in adverse health outcomes. Objective: This study aims to assess the serum levels of vitamin D, vitamin B12, and folate in early pregnancy. Methodology: This cross-sectional research was conducted at Kurdistan Private Hospital in Duhok, Kurdistan Region of Iraq, from September 2022 to October 2023. The study included 150 pregnant women, with ages ranging from 18 to 45 years. Serum levels of vitamin D, vitamin B12, and folate were measured using the Automatic Clinical Chemistry Analyzer COBAS e 411 (Roche Diagnostics, Basel, Switzerland). Results: The mean age of the participants was 29 years (standard deviation [SD] = 6.2 years), with ages ranging from 18 to 45 years. The average serum human chorionic gonadotropin (HCG) level was 4,292 mIU/mL (SD = 3,947 mIU/mL), with a range of 98 to 10,000 mIU/mL. The mean serum levels were 17.8 ng/mL (SD = 11.6) for vitamin D, 367 pg/mL (SD = 245) for vitamin B12, and 11.5 ng/mL (SD = 4.6) for folate. The prevalence of vitamin D deficiency was significant, with 92 participants (61.3%) having levels below 20 ng/mL, 39 participants (26%) having insufficient levels ranging from 20 to 29 ng/mL, and only 19 participants (12.7%) having sufficient levels between 30 and 100 ng/mL. No cases of vitamin D toxicity (>150 ng/mL) were observed. Regarding vitamin B12, 32 participants (21.3%) had deficient levels (<200 pg/mL), while 118 participants (78.7%) had normal levels. Folate analysis revealed that 3 participants (2%) had moderate deficiency (2-3 ng/mL), 14 participants (9.3%) had mild deficiency (3-6 ng/mL), and there were no cases of severe folate deficiency (<2 ng/mL). Pearson correlation analysis showed weak correlations between the study variables, with the strongest being a weak negative correlation between age and serum folate levels (-0.18). Conclusions: The study found a high prevalence of vitamin D deficiency among the pregnant women included in the study, while the levels of folate and vitamin B12 were comparable to worldwide estimates. These findings focus attention on the importance of monitoring and addressing nutritional deficiencies at the beginning and throughout pregnancy. They also underline the need for preventive health interventions to correct these deficiencies and achieve the best outcomes for both maternal and fetal health.

Relationship between serum vitamin D concentration and parameters of gonadal function in infertile male patients

Background

Vitamin D (vitD) deficiency could affect male reproductive function. Our objective was to investigate the relationship between serum vitD concentrations and hormonal and seminal parameters in infertile patients and to compare the results with those in healthy controls.

Materials and methods

Infertile patients (n = 29) and normozoospermic healthy donors (n = 27) were recruited for the study. Serum concentrations of vitD, total testosterone, estradiol, and sex hormone-binding globulin were determined using chemiluminescence assays, and free testosterone concentration was determined by radioimmunoassay. Semen analysis was performed as suggested by the World Health Organization. Statistical analysis was conducted using Student's t test, contingency tables, and linear regression studies.

Results

VitD concentrations were lower in patients than in controls (p < 0.001). A significant association (p < 0.001) was observed between vitD concentrations <20ng/mL and infertility. In the control group, significant correlations were reported between vitD concentrations >30 ng/mL and the concentrations of testosterone (p < 0.05), free testosterone (p < 0.01), and estradiol (p < 0.05). A direct correlation was found between vitD concentration and percentage of sperm vitality (p = 0.01). VitD also positively correlated with the percentage of progressive sperm motility (p <0.05) and sex hormone-binding globulin concentrations (p < 0.01).

Conclusions

VitD may affect male reproductive parameters, and its deficiency could be associated with infertility.

Optimizing vitamin D status in polycystic ovary syndrome: a systematic review and dose-response meta-analysis

CONTEXT

Polycystic ovary syndrome (PCOS) is a common and complex endocrine disorder in women of reproductive age. Vitamin D supplementation is a promising complementary therapy for PCOS, yet there is no consensus on an optimal dose, leading to a lack of evidence-based supplementation guidelines.

OBJECTIVE

The objective of this study was to conduct a vitamin D dose-response meta-analysis among women with PCOS.

DATA SOURCES

MEDLINE, CINAHL, and EMBASE databases from inception to November 2022 were searched for relevant articles.

DATA EXTRACTION

Study screening and bias assessment were conducted by 2 independent reviewers. Eight relevant studies were identified; data for serum 25(OH)D (nmol/L) at baseline and at 12 weeks in each intervention group (mean ± SD) and vitamin D dose were extracted.

DATA ANALYSIS

Estimates across studies were used to create a pooled curve, using restricted cubic splines with knots at the 10th, 50th, and 90th percentiles of the distribution of doses, to estimate the mean difference in effect for serum 25(OH)D at each dose compared with 0 IU/day. Sensitivity analyses were conducted fixing knots at 4000 IU/day and 7000 IU/day, which were a priori identified as potentially important thresholds, and to assess model fit and estimate heterogeneity. The pooled analysis demonstrated strong evidence of a dose-response relationship (P < .001), suggesting an increasing effect with increasing dose. An initial increase in serum 25(OH)D was evident until doses of approximately 3000 IU/day; this was followed by a plateau in effect between approximately 3000 IU/day and 5000 IU/day. The effect of supplementation with >5000 IU/day was unclear, given the minimal data at higher doses. The curve produced robust results for moderate doses (3000 IU/day to 4000 IU/day), which were not sensitive to model specification.

CONCLUSION

Women with PCOS are responsive to vitamin D supplementation, but the benefit of providing doses of >3000 IU/day appears minimal. Further data is required to determine dose-response at doses of >5000 IU/day, and whether higher intakes provide a clinically meaningful advantage in this population.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42021259396.

Seasonal variation and Vitamin-D status in ostensibly healthy Indian population: An experience from a tertiary care institute

Background

25-hydroxy vitamin-D (25(OH)D) deficiency is prevalent worldwide including India. Earlier some cross-sectional studies have discussed 25(OH)D deficiency and its prevalence. The correlation of 25(OH)D with seasonal variation has been reported rarely in India. To determine the 25(OH)D levels and seasonal changes of 25(OH)D status at a tertiary care hospital in North-western India.

Materials and methods

25(OH)D assessments performed in laboratories between 2018 and 2020 was acquired using hospital records. A total of 11,428 assays of serum 25(OH)D were analyzed in the study. Subjects were divided into three groups based on the International Endocrine Society's recommendation for serum 25(OH)D level. The 25(OH)D deficiency <20 ng/ml, insufficiency 20-29 ng/mL and sufficiency ≥30 ng/mL was defined. The months have been separated into the following seasons to analyze seasonal trends: Summer/monsoon (April-September), and winter/spring (October-March).

Results

The median 25(OH)D was 17.2 ng/mL. We observed the prevalence of 60 %, 24.1 % & 15.9 % of 25(OH)D deficiency, 25(OH)D insufficiency, and sufficiency respectively in the total number of individuals tested. 56 % male and 63 % females were 25(OH)D deficient. Notably, the lowest median 25(OH)D value was found in the 21-30 age group (14.8 ng/mL). A significant difference in 25(OH)D levels between the summer (18.7 ng/mL) and winter (15.8 ng/mL) seasons has been noticed.

Discussion

Current study revealing that 25(OH)D deficiency is common in all age groups and genders, according to our findings. Surprisingly, the lowest levels were reported in young adults. Seasonal variation has an impact on 25(OH)D status, however in all seasons 25(OH)D levels are lower than reference intervals. These findings suggest that the criteria for determining the state of 25(OH)D insufficiency and deficiency in the Indian population should be reconsidered.

Vitamin D metabolism is altered during aging alone or combined with obesity in male mice

Aging and obesity are associated with a decrease in plasma 25-hydroxyvitamin D (25(OH)D) levels. In the context of a growing aging population and the rising incidence of obesity, we hypothesized that aging process, either independently or in combination with obesity, could influence vitamin D (VD) metabolism, consequently resulting in the reduced 25(OH)D plasma concentrations. C57BL/6JRJ young (6 months) and old (23 months) mice fed with control (CD) or high fat diet (HF) were compared. Plasma and adipose concentration of cholecalciferol and 25(OH)D and mRNA expression of genes coding for the main VD actors were analyzed. Aging was associated with a decrease in plasma 25(OH)D levels, whereas combined effect of obesity and aging did not generate a cumulative effect on plasma 25(OH)D levels. The mRNA expression of Cyp27a1, Cyp3a11, and Cyp2j6 were decreased in the liver during aging. Together, these regulations could explain the reduced 25-hydroxylation. Interestingly, the lack of cumulative reduction of 25(OH)D in aged and obese mice could be related to the strong induction of Cyp2j6. In kidneys, a complex modulation of Cyp27b1 and Cyp24a1 could contribute to the reduced 25-hydroxylation in the liver. In white adipose tissue, an induction of Cyp2r1 was observed during aging and obesity, together with an increase of 25(OH)D quantity, suggesting an exacerbated storage that may participated to the reduced plasma 25(OH)D levels. These findings support the notion that aging alone or combined with obesity, induces regulation of VD metabolism in the organs, beyond the classical reduction of epidermal VD precursor, which may contribute to the decrease in 25(OH)D levels.

Are sun exposure time, dietary patterns, and vitamin D intake related to the socioeconomic status of Portuguese children?

OBJECTIVES

To investigate the association among sun exposure time, vitamin D intake, dietary patterns, and socioeconomic status in Portuguese children.

METHODS

Participants aged 3-11 years (50.1% females) were recruited from public and private schools (n = 118) in the districts of Coimbra (n = 2980), Lisbon (n = 3066), and Porto (n = 2426). Parents reported their children's daily sun exposure time during the summer season and reported children's food consumption, including vitamin D food sources, using standardized questionnaires. Parents' education level was used as a proxy measure to the socioeconomic status (SES). The principal component factor analysis (PCA) method was used to identify dietary patterns. The eight dietary patterns identified were labeled in: "fast food", "rich in vitamin D", "sugary drinks", "vitamin D", "candies", "supplements", "rich in calcium" and "vegetables/healthy". Linear regression analyses were performed to investigate the association between sun exposure time and dietary patterns according to SES.

RESULTS

A total of 4755 children were included. Children from high SES had significantly longer sun exposure time (p < .001) and more frequently consumed vitamin D supplements (p < .001). "Fast food" pattern showed a negative association with sun exposure time in medium and high SES (p = .014 and p < .001, respectively).

CONCLUSION

Children with lower SES spend less time exposed to the sun, consume fewer dietary sources of vitamin D, and consume more foods rich in fat and sugar.

Prevalence of Vitamin D Deficiency in Orthopedic Trauma Patients: A Cross-Sectional Survey From a Tertiary Care Trauma Center

Background Vitamin D deficiency is prevalent globally, with potential consequences for bone health and trauma outcomes. This study aimed to assess the prevalence of vitamin D deficiency in orthopedic trauma patients and investigate its correlation with various demographic and injury-related factors. Methodology A cross-sectional investigation was undertaken at a tertiary care center. An evaluation of serum 25-hydroxyvitamin D3 levels was conducted on 124 individuals, aged 20 to 70 years, who were hospitalized with orthopedic injuries. Demographic information, the injury method, the bone involvement pattern, and socioeconomic status were documented. Statistical analysis was employed to evaluate the correlations between vitamin levels D and these variables. Results The overall prevalence of vitamin D deficiency was 54 (43.6%) cases, with nine (7.3%) cases exhibiting severe deficiency and 45 (36.3%) cases exhibiting moderate deficiency. Higher rates of deficiency were associated with lower socioeconomic status (p = 0.044) and low-velocity trauma (p = 0.037). No significant association was found with age, sex, or residence. Interestingly, patients with multiple fractures were more prone to deficiency compared to those with single fractures. Conclusions This survey revealed a significant vitamin D deficiency among orthopedic trauma patients. Factors such as socioeconomic status and the nature of the injury emerged as significant risk factors. While conducting routine vitamin D assessments might pose challenges in developing nations, consistent supplementation could prove advantageous in enhancing fracture healing and overall health outcomes among this demographic. There is a call for future research to delve deeper into the role of vitamin D in trauma management and refine supplementation strategies.

Association of maternal serum vitamin D level with fetal pulmonary artery Doppler indices and neonatal respiratory distress syndrome

PURPOSE

Respiratory distress syndrome (RDS) is potentially fatal in infants. The present study investigated the association of maternal serum vitamin D level with fetal pulmonary artery Doppler indices and neonatal RDS.

METHODS

This cross-sectional-analytical study was conducted on 260 mothers admitted for delivery. The maternal serum 25-hydroxyvitamin D level was measured and fetal main pulmonary artery Doppler indices were evaluated. The neonate's weight, apgar score, RDS, Umbilical cord arterial pH and neonatal intensive care unit admission were recorded.

RESULTS

There was a significant relationship between RDS and the low level of vitamin D in the mother's serum. Mothers with low vitamin D had higher fetal pulmonary artery pulsatility index (PI) and peak systolic velocity (PSV) and lower acceleration time (AT) to ejection time (ET) ratio. Also, in neonates with RDS, pulmonary artery PI was higher, and PSV and the ratio of AT to ET were significantly lower than neonates without RDS. Neonates with lower one and 5-min apgar scores were born from mothers with lower vitamin D levels.

CONCLUSION

Serum levels of vitamin D in pregnant mothers as well as fetal pulmonary artery Doppler indices are correlated to RDS. There is a significant relationship between the serum level of vitamin D in pregnant mothers and fetal pulmonary artery Doppler indices.

Effects of Vitamin D Supplementation and Baseline Vitamin D Status on Acute Respiratory Infections and Cathelicidin: A Randomized Controlled Trial

Background

Vitamin D supplementation may lower the risk of acute respiratory infection (ARI), and the effects may be mediated through the induction of cathelicidin production.

Objective

To study the effect of vitamin D supplementation on ARI and cathelicidin concentration in a randomized controlled trial (RCT) and to study the associations between baseline serum 25 hydroxyvitamin D (25(OH)D) and ARIs and cathelicidin concentrations in a 14-week follow-up study.

Methods

In the RCT study, the participants were randomized into 2 groups to receive either 20 µg of vitamin D3 or an identical placebo daily. Blood samples were obtained 3 times, at the beginning (study week 0), mid-term (study week 6), and at the end of the study period (study week 14). The follow-up study had 412 voluntary young men from 2 different locations and seasons (January and July). The primary outcomes were the number of ARIs diagnosed and the number of days off because of ARI.

Results

In the RCT, vitamin D supplementation had no effect on ARI or days off because of ARI. However, regardless of the group, vitamin D insufficiency (<50 nmol/L) was associated with increased ARI. In the 14-week follow-up study, insufficient serum 25(OH)D at baseline was also associated with increased risk of ARI (odds ratio [OR], 2.1; 95% confidence interval [CI], 1.2-3.7) and also days-off duty (OR, 2.3; 95% CI, 1.3-4.0) and was inversely associated with cathelicidin concentration (OR, 0.49; 95% CI, .24-.99).

Conclusions

Sufficient serum 25(OH)D may be preventive against acute respiratory infection and the preventive effect could be mediated through the induction of cathelicidin production. Clinical Trial Registry number: NCT05014048. https://clinicaltrials.gov/study/NCT05014048?term=NCT05014048&rank=1.

Why do patients with urinary diversions have an increased risk of bone fracture? A systematic review on risk factors for osteoporosis and bone mineral density loss in this group of patients

INTRODUCTION

Patients undergoing radical cystectomy with urinary diversions (UD) are at increased risk of bone fractures compared to the general population. Although a loss of bone mineral density (BMD) has been described in patients with UD, we still do not know with certainty why these patients follow this tendency.

OBJECTIVE

We performed a systematic review of the available literature to analyze the prevalence of osteoporosis and bone alterations in patients with ileal UD and the possible associated risk factors.

EVIDENCE ACQUISITION

We systematically searched PubMed® and Cochrane Library for original articles published before December 2022 according to PRISMA guidelines.

EVIDENCE SYNTHESIS

A total of 394 publications were identified. We selected 12 studies that met the inclusion criteria with 496 patients included. Six of the twelve studies showed decreased BMD values. Prevalence of osteoporosis was specified in three articles, with values ranging ​​from 0% to 36%. Risk factors such as age, sex, body mass index, metabolic acidosis and renal function appear to have an impact on bone tissue reduction, while type of UD, follow-up, 25-hydroxyvitamin D and parathormone had less evidence or contradictory data. The heterogeneity of the studies analyzed could led to interpretation bias.

CONCLUSIONS

UD are associated with multiple risk factors for osteoporosis and bone fractures. Identifying patients at highest risk and establishing diagnostic protocols in routine clinical practice are essential to reduce the risk of fractures and the resulting complications.

Serum 25-hydroxyvitamin D levels and risk of all-cause and cause-specific mortality: A 14-year prospective cohort study

BACKGROUND & AIMS

The circulating vitamin D level that is optimal for health is unknown. This study aimed to examine the association between circulating vitamin D level and risk of all-cause and cause-specific mortality.

METHODS

This prospective cohort study included 18,797 Korean adults aged 40 years or older, living in rural areas, with no history of cancer or cardiovascular disease (CVD) at baseline. Serum 25-hydroxyvitamin D (25(OH)D) levels were measured at baseline. Participants were followed-up from the survey date (2005-2012) until December 31, 2021. Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for mortality by baseline vitamin D level. Restricted cubic splines were used to explore the nonlinearity.

RESULTS

The median (interquartile range) of 25(OH)D level was 55.8 (40.8-71.8) nmol/L. During a median follow-up of 14.3 years, 2250 deaths were recorded. Compared with participants with a 25(OH)D level <30 nmol/L, higher vitamin D levels (30 to < 50, 50 to < 75, and ≥75 nmol/L) were associated with a lower risk of all-cause mortality: HR (95% CI) of 0.82 (0.69-0.98), 0.74 (0.62-0.88), and 0.69 (0.57-0.84), respectively. A nonlinear relationship between vitamin D level and all-cause mortality was observed, with the risk plateauing between 50 and 60 nmol/L (p for nonlinearity = 0.009). The association was more pronounced for cancer-related mortality. HR 0.55 (95% CI: 0.39-0.77) for a 25(OH)D level ≥75 nmol/L compared with <30.0 nmol/L. Low vitamin D levels were associated with increased CVD mortality in men.

CONCLUSIONS

Vitamin D level was inversely associated with all-cause and cause-specific mortality in middle-aged and older adults. Maintaining a serum 25(OH)D level of approximately 50-60 nmol/L may contribute to longevity and warrants further investigation.

Maternal exposure to airborne particulate matter during pregnancy and lactation induces kidney injury in rat dams and their male offspring: the role of vitamin D in pregnancy and beyond

BACKGROUND

Little is known about the transgenerational effects of maternal exposure to fine particulate matter (PM2.5) on offspring kidney health. This study investigated the effect of maternal administration of PM2.5 or PM2.5 with vitamin D during pregnancy and lactation on renal injury in rat dams and their offspring.

METHODS

Nine pregnant Sprague-Dawley rats received oral administration of normal saline, airborne PM2.5, or PM2.5 with vitamin D from gestational day 11 to postpartum day 21. Kidneys of rat dams (n = 3 for each group) and their male offspring (n = 5 for each group) were taken for analysis on postpartum or postnatal day 21.

RESULTS

Maternal PM2.5 exposure increased glomerular damage, tubulointerstitial injury, and cortical macrophage infiltration in both dams and pups; all increases were attenuated by vitamin D administration. In dam kidneys, PM2.5 increased the protein expression of vitamin D receptor (VDR), klotho, and tumor necrosis factor-α; vitamin D lessened these changes. The expressions of renin, nuclear factor erythroid 2-related factor 2 (Nrf2), and nuclear factor-kappa B (NF-κB) p50 decreased in rat dams exposed to PM2.5. In offspring kidneys, exposure to maternal PM2.5 reduced the expression of VDR, renin, angiotensin-converting enzyme (ACE), Nrf2, and NF-κB p50, but increased cytochrome P450 24A1 expression. Maternal vitamin D administration with PM2.5 enhanced VDR, ACE, and NF-κB p50 activities in pup kidneys.

CONCLUSION

PM2.5 exposure during nephrogenesis may exert transgenerational renal impairment, and maternal vitamin D intake could attenuate PM2.5-induced kidney damage in mothers and their offspring.

Calcium Disorders

This article provides a comprehensive overview of calcium physiology, clinical presentation with physical examination findings, laboratory assessment, differential diagnosis, and management of hypocalcemia and hypercalcemia for the primary care provider.

Association between vitamin D, depression, and sleep health in the National Health and Nutrition Examination Surveys: a mediation analysis

OBJECTIVE

This study aimed to assess the association between vitamin D and sleep health and to investigate whether depression could mediate this relationship.

METHODS

A cross-sectional analysis was performed using the 2005-2014 US National Health and Nutrition Examination Survey (NHANES) data. The logistic regression models were conducted to evaluate association of serum vitamin D concentrations with sleep health and depression. Mediation analyses were conducted to investigate the mediated effects of depression on the association of vitamin D with sleep health.

RESULTS

In multivariate logistic models, vitamin D was found to be negatively associated with an increased risk of poor sleep health, with an odds ratio (OR) of vitamin D deficiency versus sufficiency was 1.256 (95% CI = 1.084-1.455). Additionally, univariate logistic models showed that vitamin D was also negatively associated with depression risk (vitamin D deficiency vs. sufficiency: OR = 1.699, 95% CI = (1.373-2.103). Further mediation analyses showed that the association of vitamin D with sleep health was mediated by depression, with the mediating effects of depression accounted for 44.56% of the total effects.

CONCLUSION

Vitamin D affects sleep health directly and indirectly through depression. The results suggest that interventions increasing intake of vitamin D should be prioritized to promote sleep health of persons with or at risk of depression.

Effects of vitamin D supplementation on the glycaemic indices, lipid profile and liver function tests in patients with cirrhosis: a double-blind randomised controlled trial

Background

Liver cirrhosis is considered a progressive disease that can eventually result in death. Vitamin D deficiency is prevalent in patients with cirrhosis. Few studies have been conducted on the effect of vitamin D supplementation in patients with cirrhosis.

Objectives

The aim of this study was to identify the effect of vitamin D supplementation on lipid profile, glycaemic indices and liver function tests in patients with cirrhosis.

Methods

Sixty patients with cirrhosis were involved in this double-blind, randomised controlled clinical trial. During the intervention, patients received one 50 000 IU pearl of vitamin D supplement or placebo per week for 12 weeks. Before and after supplementation, we assessed serum 25-hydroxy-vitamin-D3 (25(OH) D3), glycaemic indices (insulin, haemoglobin A1c, fasting blood glucose (FBG) and homeostatic model assessment for insulin resistance (HOMA-IR)), lipid profile and liver function tests.

Results

Baseline variables were not significantly different between groups. The present study indicated that over the 12 weeks, vitamin D supplementation significantly increased serum 25(OH) D3 (p<0.001), and also significantly decreased FBG (p=0.006), and HOMA-IR (p=0.001).

Conclusions

Vitamin D supplementation significantly improves FBG and HOMA-IR as well as serum 25(OH) D3 in patients with cirrhosis.

Trial registration number

The protocol of the study was registered at the Iranian Registry of Clinical Trials (IRCT) (IRCT20140502017522N2).

Prevalence of low vitamin D status in an urban district in Sri Lanka: a population-based study

BACKGROUND

Vitamin D deficiency (VDD) is conventionally associated with inadequate sunlight exposure. Ironically, recent evidence suggests a rising prevalence in urban areas of tropical regions like Sri Lanka, where comprehensive data are unavailable. This study aimed to estimate the prevalence of low vitamin D status in urban adults and its impact on serum calcium.

METHODS

A population-based cross-sectional study was conducted among 1260 adults aged 35-74 years, living in Colombo, the most urban district in Sri Lanka. They were recruited from 63 administrative divisions, using multi-stage, probability-proportionate-to-size, cluster sampling. Non-fasting venous blood was collected without tourniquet. Low vitamin D (< 30.0 ng/mL), VDD (< 20 ng/mL) and vitamin D insufficiency (20.0-29.9 ng/mL) were determined using chemiluminescence assay method, and serum calcium using Calcium Gen2 reagent.

RESULTS

Among the population (53.3% females; mean age = 51.8 years), the prevalence of low vitamin D was 93.9% (95% CI: 92.5-95.2). This was primarily due to VDD (67.5%; 95% CI: 64.9.0-70.1%), with some insufficiency (26.4%; 95% CI: 24.0-28.9%). Most VDD cases (53.9.0%) were 'mild' (10.0- < 20.0 ng/mL) in severity, with fewer 'moderate' (12.8%) and 'severe' (0.8%) cases. Prevalence of VDD was highest in females, aged 35-44-years, living in 'highly urban' areas and of Tamil ethnicity. Further, VDD showed a decreasing trend with older age groups, while it was significantly more prevalent in females than males (72.6% vs. 61.7%; p < 0.01), across all age groups. Low serum calcium levels were observed in 9.8% of adults with low vitamin D, compared to 22.4% with normal vitamin D, implying that there could be factors other than vitamin D in maintaining serum calcium levels.

CONCLUSIONS

Colombo District, representing urban settings in Sri Lanka faces a high prevalence of low vitamin D, primarily VDD, with higher rates in females, younger individuals and highly urban areas. These findings challenge assumptions about tropical regions being guaranteed of optimal vitamin D levels; and underscore the need for national vitamin D supplementation and food fortification programs, especially in high-risk urban settings in South Asian countries like Sri Lanka.

Inverted U-shaped relationship between serum 25-hydroxyvitamin D concentrations and Toxoplasma gondii infection: a cross-sectional study

Background

Toxoplasma gondii (T. gondii) is a widespread zoonotic parasite transmitted through contaminated food or water. It poses a significant public health threat, especially to pregnant women and immunocompromised individuals. 25-Hydroxyvitamin D [25(OH)D] plays a critical role in regulating both innate and adaptive immune responses, particularly in its anti-infective capacity. However, the relationship between serum 25(OH)D concentrations and T. gondii infection remains uncertain.

Methods

We analyzed the data from the National Health and Nutrition Examination Survey (NHANES) spanning 2009-2014 to explore the association between serum 25(OH)D concentrations and T. gondii infection. Extensive demographic, comorbidity, and dietary data were collected. The status of T. gondii infection was determined using serum anti-IgG antibodies. Serum 25(OH)D levels were measured using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). In addition, weighted logistic regression and restricted cubic spline analyses were performed.

Results

Our analysis included 10,157 participants (mean [SE] age, 45.38 [0.39] years; 49.73% female) who met the inclusion criteria. Serum 25(OH)D levels were categorized into quintiles, with the second quintile serving as the reference group. The final model, adjusted for age, sex, race, education level, poverty income ratio, body mass index, smoking status, hypertension, diabetes, chronic kidney disease, depression, physical activity, alcohol intake, seasonal testing, and dietary vitamin D, revealed the following adjusted odds ratios (ORs) for the quintiles: 0.75 (95% confidence interval [CI]: 0.60-0.93) for the first, 0.87 (95% CI: 0.69-1.10) for the third, 0.75 (95% CI: 0.58-0.95) for the fourth, and 0.66 (95% CI: 0.49-0.91) for the fifth. Additionally, a restricted cubic spline analysis revealed an inverted U-shaped relationship between serum 25(OH)D and T. gondii infection, with an inflection point at approximately 51.29 nmol/L. Odds ratios to the left and right of the inflection point were 1.17 (95% CI: 1.03-1.32) and 0.94 (95% CI, 0.90-0.98) per 10 nmol/L, respectively.

Conclusion

Our study uncovers an inverted U-shaped relationship between serum 25(OH)D concentrations and T. gondii infection, with an inflection point around 51.29 nmol/L.

Nutritional Strategies for Chronic Craniofacial Pain and Temporomandibular Disorders: Current Clinical and Preclinical Insights

This narrative review provides an overview of current knowledge on the impact of nutritional strategies on chronic craniofacial pain associated with temporomandibular disorders (TMDs). Individuals experiencing painful TMDs alter their dietary habits, avoiding certain foods, possibly due to chewing difficulties, which might lead to nutrient deficiencies. Our literature investigation revealed that the causal links between nutritional changes and craniofacial pain remain unclear. However, clinical and preclinical studies suggest that nutraceuticals, including vitamins, minerals, polyphenols, omega-3 fatty acids, isoprenoids, carotenoids, lectins, polysaccharides, glucosamines, and palmitoylethanolamides, could have beneficial effects on managing TMDs. This is described in 12 clinical and 38 preclinical articles since 2000. Clinical articles discussed the roles of vitamins, minerals, glucosamine, and palmitoylethanolamides. The other nutraceuticals were assessed solely in preclinical studies, using TMD models, mostly craniofacial inflammatory rodents, with 36 of the 38 articles published since 2013. Our investigation indicates that current evidence is insufficient to assess the efficacy of these nutraceuticals. However, the existing data suggest potential for therapeutic intervention in TMDs. Further support from longitudinal and randomized controlled studies and well-designed preclinical investigations is necessary to evaluate the efficacy of each nutraceutical intervention and understand their underlying mechanisms in TMDs.

Effects of vitamin D supplementation on muscle strength in middle-aged and elderly individuals: a retrospective, propensity score-matched study

Introduction

The aim of this study is to investigate the impact of vitamin D supplementation on the muscle strength of the elderly.

Methods

This retrospective, propensity score-matched study included 160 middle-aged and elderly individuals from a community in Beijing, China. The control group (n=110) received health education and lifestyle guidance, while the intervention group (n=50) was given oral vitamin D supplementation in addition to health education and lifestyle guidance. All participants underwent laboratory tests, muscle function, and physical function at baseline and follow-up.

Results

In the propensity score-matched cohort of 41 patients per group, the levels of serum calcium and 25-hydroxyvitamin D in both groups were improved significantly by the end of the study (p<0.05), with the intervention group showing a more significant improvement. The muscle strength of the left lower limb in the intervention group significantly increased after the intervention (p<0.05). The results also showed that the grip strength and pinch strength of the patients in both groups increased after the intervention, and the difference between the two groups was statistically significant (p<0.05).

Discussion

The findings of this study suggest that vitamin D supplementation, in conjunction with lifestyle guidance and health education, is beneficial for enhancing the upper and lower limb strength of patients.

Role of Vitamin D in Oral Lichen Planus: A Case Control Study

BACKGROUND

It has been reported that vitamin D deficiency may be associated with the development of oral lichen planus (OLP). Given the high prevalence of vitamin D deficiency in many countries, we sought to determine whether it constitutes a comorbidity of OLP.

METHODS

One hundred and twenty patients clinically and histologically diagnosed with OLP were evaluated for their serum vitamin D levels. The results were compared to results from a control series of the same number of subjects matched for age and sex.

RESULTS

Vitamin D deficiency was diagnosed in 45% (n = 54) of OLP patients and in 26.7% (n = 32) of the control group. Vitamin D supplements were being taken by 32 (26.7%) OLP patients and 15 (12.5%) subjects in the control group. A multivariate logistic regression model showed that OLP was associated with vitamin D deficiency [OR: 2.24 (1.28-3.98, p = 0.005)] and vitamin D supplementation [OR: 2.51 (1.25-5.22, p = 0.011)], even after controlling for confounding variables such as sex, age ≤60>, tobacco, and alcohol.

CONCLUSION

The association between OLP patients and vitamin D deficiency or vitamin D supplementation suggests that further research might explore the benefits of vitamin D supplements in managing OLP patients.

Antioxidant Functions of Vitamin D and CYP11A1-Derived Vitamin D, Tachysterol, and Lumisterol Metabolites: Mechanisms, Clinical Implications, and Future Directions

Evidence is increasing that vitamin D and CYP11A1-derived vitamin D, tachysterol, and lumisterol metabolites play a significant antioxidant role beyond its classical functions in bone health and calcium metabolism. Several recent studies have linked these elements to reduced oxidative stress as well as improved immune, cardiovascular, and neurological functions as a result of chronic kidney disease and cancer. Additionally, supplementation with this vitamin has been shown to be one of the most cost-effective micronutrient interventions worldwide, highlighting its potential as a therapeutic approach. The underlying mechanisms and implications of this antioxidant function of vitamin D or CYP11A1-derived vitamin D, tachysterol, and lumisterol metabolites are not well understood. This comprehensive and narrative review is aimed at summarizing the current evidence regarding the molecular mechanisms implicated in this antioxidant function of vitamin D, as well as to provide a general overview and to identify key research areas for the future, offering an extensive perspective that can guide both researchers and clinicians in the management of diseases associated with oxidative stress and/or insufficient vitamin D status.

Target Values for 25-Hydroxy and 1,25-Dihydroxy Vitamin D Based on Their Associations with Inflammation and Calcium-Phosphate Metabolism

Target values for 25-hydroxy vitamin D and 1,25(OH)2D or 1,25-dihydroxy vitamin D remain a topic of debate among clinicians. We analysed data collected from December 2012 to April 2020 from two cohorts. Cohort A, comprising 455,062 subjects, was used to investigate the relationship between inflammatory indicators (white blood cell [WBC] count and C-reactive protein [CRP]) and 25(OH)D/1,25(OH)2D. Cohort B, including 47,778 subjects, was used to investigate the connection between 25(OH)D/1,25(OH)2D and mineral metabolism markers (phosphate, calcium, and intact parathyroid hormone [iPTH]). Quadratic models fit best for all tested correlations, revealing U-shaped relationships between inflammatory indicators and 25(OH)D and 1,25(OH)2D. Minimal CRP and WBC counts were observed at 1,25(OH)2D levels of 60 pg/mL and at 25(OH)D levels of 32 ng/mL, as well as of 42 ng/mL, respectively. iPTH correlated inversely with both 1,25(OH)2D and 25(OH)D, while phosphate as well as calcium levels positively correlated with both vitamin D forms. Calcium-phosphate product increased sharply when 25(OH)D was more than 50 ng/mL, indicating a possible risk for vascular calcification. Multiple regression analyses confirmed that these correlations were independent of confounders. This study suggests target values for 25(OH)D between 30-50 ng/mL and for 1,25(OH)2D between 50-70 pg/mL, based particularly on their associations with inflammation but also with mineral metabolism markers. These findings contribute to the ongoing discussion around ideal levels of vitamin D but require support from independent studies with data on clinical endpoints.

Association between serum vitamin D status and severity of liver cirrhosis: implications for therapeutic targeting in Nigerian patients

BACKGROUND

Liver cirrhosis is a chronic and progressive liver disease with significant global health implications. Recent evidence suggests an association between serum vitamin D levels and the severity of liver cirrhosis, potentially serving as a therapeutic target. This study aimed to investigate the relationship between serum vitamin D status and the severity of liver cirrhosis in a population of Nigerian patients.

METHODS

This analytical, cross-sectional study involved 201 participants, including 103 with liver cirrhosis and 98 age- and sex-matched controls. Serum vitamin D was measured using ELISA, with deficiency defined as < 20 ng/ml. Cirrhosis severity was assessed using Child-Pugh and MELD scores. Spearman's correlation was used to assess the relationship between vitamin D and severity of liver cirrhosis while ordinal regression analysis assessed its performance as an indicator of the disease severity.

RESULT

Among cirrhotic patients, 36.9% were deficient, 31.1% insufficient, and 32.0% had sufficient vitamin D levels. Serum vitamin D showed strong negative correlations with Child-Pugh and MELD scores (r = -0.696, p < 0.001; r = -0.734, p < 0.001, respectively). Ordinal regression showed that higher vitamin D levels were associated with lower severity scores (Child-Pugh: OR = 0.856, 95% CI: 0.815-0.900, p < 0.001; MELD: OR = 0.875, 95% CI: 0.837-0.915, p < 0.001).

CONCLUSION

Lower serum vitamin D levels correlated with increased liver cirrhosis severity, suggesting its potential as both a prognostic marker and therapeutic target. Further studies should investigate the efficacy of vitamin D supplementation in improving cirrhosis outcomes.

Serum 25-Hydroxyvitamin D and Five-Year Survival in Primary Colon Cancer: A Retrospective Cohort Study

This study examined the link between serum 25-hydroxyvitamin D (25(OH)D) and mortality in patients with colon cancer. Using a clinical database from the University of California, serum 25(OH)D measures were averaged for the time following diagnosis until either the time of death or 5 years had elapsed. Analytical methods included the use of Generalized Additive Models (GAM), logistic regression, and Cox proportional hazards models to examine non-linear relationships and the impact of 25(OH)D on 5-year mortality. This study assessed 1,602 patients with colon cancer having a median 25(OH)D of 31.8 ng/mL and a 5-year mortality rate of 22.7%. A significant association between higher post-diagnosis vitamin D levels and decreased 5-year mortality was observed. This association persisted after adjusting for disease severity and significant demographic confounders, in both a logistic regression model for 5-year mortality (OR = 0.79, 95% CI: 0.66-0.92, p < 0.001) and a cox proportional hazards model for survival (HR = 0.94, CI: 0.88-0.99, p = 0.048). GAM illustrated a steep increase in survival probability up to a plateau, suggesting a threshold effect beyond roughly 50.0 ng/mL. This study found a potential protective role of vitamin D in the survival of colon cancer patients, supporting the correction of levels below 25 ng/mL but ideally above 50 ng/mL.

Association between serum vitamin D and the risk of diabetic kidney disease in patients with type 2 diabetes

Aims

This investigation explored the potential correlation between serum vitamin D concentration and diabetic kidney disease (DKD) among patients with type 2 diabetes mellitus (T2DM).

Methods

This cross-sectional study assessed 4,570 patients with T2DM drawn from the National Health and Nutrition Examination Survey (NHANES) dataset. Restricted cubic splines were utilized to examine the dose-response relationship between serum vitamin D levels and the risk of DKD in patients with T2DM. Serum vitamin D concentrations were divided into quartiles for multivariable logistic regression analysis to evaluate the association between varying serum vitamin D levels and DKD risk in patients with T2DM. Additionally, sex-stratified analyses were conducted to determine consistency of the results. The influence of vitamin D concentrations on mortality risk was assessed using a Cox regression model.

Results

Of the patients with T2DM, 33% were diagnosed with DKD. Restricted cubic spline plots revealed a U-shaped relationship between vitamin D levels and DKD risk, with a protective effect noted in the mid-range, indicating optimal serum vitamin D concentrations between 59.6 nmol/L and 84.3 nmol/L. The multivariate Cox regression analysis suggested that higher VID levels were associated with a reduced mortality risk, particularly in male patients.

Conclusion

The regulation and monitoring of serum vitamin D levels within an optimal range may play a pivotal role in the prevention of DKD in patients with T2DM. Public health strategies should emphasize the regular monitoring of vitamin D levels, especially among populations at elevated risk, to mitigate the progression of DKD and decrease the associated mortality rates.

The prognosis of patients with myocardial infarction after light therapy: A preliminary study

BACKGROUND

Patients with myocardial infarction (MI) can have disturbed sleep, but little is known about the efficacy of light therapy on sleep and the prognosis of patients with MI. We conducted a randomized controlled study to investigate its efficacy.

MATERIAL AND METHODS

This preliminary study included 34 patients with MI. They were randomized into the blue light and the white light groups during their stay in intensive care unit. 17 age and gender-matched healthy controls were also enrolled. Actigraphy was used to evaluate objective sleep since enrollment. Delirium scales were used to screen delirium. Lab work-up, including vitamin D level was performed at the baseline and discharge. We used the Mann-Whitney U test or Wilcoxon signed-rank test to compare the difference between the MI group and the healthy control group, and the group difference after receiving light therapy.

RESULTS

Patients with MI had significantly lower vitamin D levels than healthy controls (p < 0.001). They also had significantly poorer sleep, as indicated by actigraphy parameters, including sleep onset latency (p = 0.01), sleep efficiency (p = 0.002), wake after sleep onset (p < 0.001), and awake times (p = 0.002). No significant group difference was found by actigraphy after light therapy except a non-significant higher relative amplitude of the blue light group (p = 0.061). Besides, the vitamin D level of the blue light group increased significantly (p1 = 0.047, p2 = 0.045).

CONCLUSIONS

Patients with MI had poorer sleep, highlighting the need to develop interventions. Significantly increased vitamin D levels and a non-significant better rest-active rhythm after light therapy suggest its potential with sleep and prognosis, which warrants further investigation.

Changes in vitamin D status among adults from the COVID-19 pandemic to post-pandemic normality

Introduction

The COVID-19 pandemic has prompted widespread lockdown measures globally, significantly impacting daily activities and outdoor exposure. This study investigates the effect of the pandemic on vitamin D levels and the prevalence of vitamin D deficiency in the adult population, with a focus on gender-specific differences.

Methods

A total of 1525 adults from Henan Provincial People's Hospital were included. Serum 25-hydroxyvitamin D (25(OH)D) levels were measured using the Elecsys® Vitamin D total kit on the Roche Cobas® 8000 analyzer. The Clinical Application Consensus on Vitamin D and Its Analogs defined deficiency as 25(OH)D levels below 20 ng/ml. Statistical analysis was performed using SPSS 23.0 and GraphPad Prism 8 software.

Results

The overall 25(OH)D levels increased from 18.14 ng/ml [IQR: 13.78, 23.68] in 2022 to 19.15 ng/ml [IQR: 14.88, 25.01] in 2023 (p=0.004). Males exhibited significant improvement in 25(OH)D levels from 18.01 ng/ml [IQR: 14.10, 23.53] in 2022 to 20.49 ng/ml [IQR: 16.11, 26.01] in 2023 (p<0.001). The prevalence of vitamin D deficiency decreased from 62% in 2022 to 54.9% in 2023 (p=0.009), with a notable reduction in males (64.1% in 2022 to 47.2% in 2023). Among 168 individuals tested in both years, 25(OH)D levels increased from 20.73 ± 9.37 ng/ml in 2022 to 22.28 ± 8.59 ng/ml in 2023 (p=0.012), and the deficiency rate decreased from 58.3% in 2022 to 47.0% in 2023 (p=0.038). The 40-49 age group showed significant improvement in 25(OH)D levels from 16.10 ng/ml [IQR: 12.41, 21.18] in 2022 to 18.28 ng/ml [IQR: 13.91, 23.86] in 2023 (p=0.005), with a reduction in deficiency rate from 72.8% to 59.9% (p=0.02). Furthermore, in February, March, and April, 2022, 25(OH)D levels were significantly lower compared to 2023 (p<0.001, p=0.002, p<0.001, respectively), accompanied by a higher prevalence of vitamin D deficiency (p<0.001, p=0.015, p<0.001, respectively).

Discussion

This study demonstrates that the COVID-19 pandemic significantly impacted vitamin D levels, leading to an increased prevalence of deficiency, particularly among males. These findings highlight the critical importance of maintaining sufficient outdoor activities to ensure adequate vitamin D levels. The data underscore the need for public health strategies to address potential deficiencies during prolonged periods of limited outdoor exposure.

Vitamin D deficiency and the risk of diabetic retinopathy in patients with type 2 diabetes in Tibet: a cross-sectional analysis

BACKGROUND

Diabetic retinopathy (DR) is one of the most common complications of diabetes worldwide. The aim of this study was to assess the prevalence of DR in hospitalized patients with type 2 diabetes (T2DM) in Tibet and to identify risk factors that may influence the occurrence of DR.

METHODS

This was a cross-sectional study conducted in a third-class hospital in the Tibet Autonomous Region. The prevalence of DR in hospitalized patients with T2DM was measured. Univariate and multivariate logistic regression, restricted cubic spline (RCS) analysis and receiver-operating characteristic curve analysis were used to investigate the risk factors for DR.

RESULTS

The prevalence of DR was 29.3%. The duration of diabetes; concentrations of 25-OH-VitD3, hemoglobin, fasting insulin, alanine aminotransferase, total bilirubin, and creatinine; and HOMA-IR were significantly different between DR patients and non-DR patients (all P < 0.05). Univariate and multivariate logistic regression revealed that a longer duration of diabetes and lower 25-OH-VitD3 levels were associated with increased DR risk. RCS analysis suggested overall positive associations of the duration of diabetes and 25-OH-VitD3 concentrations with DR risk (P nonlinearity < 0.05). The turning points for the duration of diabetes and 25-OH-VitD3 concentrations were 5.1 years and 10.6 ng/mL, respectively. The sensitivity, specificity, and area under the receiver-operating characteristic curve for the combination of the duration of diabetes and 25-OH-VitD3 levels were 79.4%, 69.4% and 0.764, respectively.

CONCLUSIONS

Given the high prevalence of DR in hospitalized patients with T2DM in Tibet, vitamin D supplementation seems to be important in the prevention of DR to some degree.

Unraveling the Relationship Between Vitamin D and Oxidative Stress: A Cross-Sectional Study

INTRODUCTION

Vitamin D, beyond bone metabolism, has played a significant role in various physiological processes, including modulation of oxidative stress and maintenance of vascular architecture. Oxidative stress, a state of altered balance between reactive oxygen species (ROS) and antioxidants, is a critical factor in the pathogenesis of various chronic diseases. Our study aims to explore the intricate relationship between serum vitamin D levels and markers of oxidative stress in normotensive and hypertensive individuals.

MATERIALS AND METHODS

A total of 108 age-matched participants (35 to 50 years) of both genders (54 males and 54 females) were included in this cross-sectional study according to the study design and assessed for their serum vitamin D level by using enzyme-linked immunosorbent assay (ELISA) method and serum malondialdehyde (MDA) level by using a spectrophotometer at 540 nm after measurement of the blood pressure. The data were entered in a Microsoft Excel sheet and analyzed using Statistical Package for Social Science (SPSS) software version 20.

RESULTS

Our findings demonstrate a significant inverse correlation between serum vitamin D levels and MDA (r = -0.71, p < 0.001), indicating lower lipid peroxidation with higher vitamin D levels. Our study concludes by evident higher serum vitamin D levels associated with reduced oxidative stress, reflected by lower MDA.

CONCLUSION

These findings suggest a potential protective role of vitamin D against oxidative damage, which could have implications for the prevention of oxidative stress-related diseases.

Vitamin D3 improves glucose metabolism and attenuates inflammation in prediabetic human and mice

Prediabetes is a crucial stage for prevention and treatment of diabetes, and vitamin D (VD) has been found to be linked to the development of prediabetes and diabetes. Thus, we aimed to identify the effect of VD supplementation on glucose metabolism in prediabetic participants and mice. A 1:1 paired design of randomized, placebo-controlled trial with 1600 IU/day VD3 or placebo was administered to individuals with prediabetes, two-way repeated-measures ANCOVA was used to analyze glycolipid and inflammatory factors. A high-fat diet induced prediabetic KKay mice were utilized to evaluate the effects of VD3 with 16 weeks supplementation. Generalized estimation equation, one way ANOVA were used to analyze continuous monitoring indexes and terminal indexes, respectively. Exercise capacity, skeletal muscle pathological features and relevant proteins were examined. The clinical results showed that VD3 could improve insulin secretion and decrease inflammation. Results of KKay mice exhibited that VD3 not only ameliorate glycolipid metabolism and inflammatory indicators, but also regulated pathological changes of skeletal muscle and exercise capacity. Mechanistically, our results demonstrated that VD3 could inhibit the TLR4/NFκB and activate PI3K/AKT signaling pathway. Collectively, the study indicated that VD3 exerts its beneficial effects by inhibiting TLR4/NFκB to decrease inflammatory response, and activating PI3K/AKT signaling pathway to regulate glucose homeostasis.

The neuroprotective effect of vitamin D in Parkinson's disease: association or causation

Parkinson's disease (PD) is a chronic neurodegenerative disease (NDD) due to the degeneration of dopaminergic neurons (DNs) in the substantia nigra (SN). PD is characterized by diverse motor symptoms such as rigidity, resting tremors, and bradykinesia, and non-motor symptoms such as cognitive dysfunction and sleep disturbances. Vitamin D (VD), VD receptor (VDR), and VD metabolites are present in the brain and play a role in maintaining the development, differentiation, and functions of the DNs. VDRs exert protective effects against PD neuropathology by modulating functional capacity and DNs neurotransmission in the SN. In virtue of its anti-inflammatory and antioxidant activities, VD could be effective in the prevention and treatment of PD. VD exerts a neuroprotective effect by reducing oxidative stress and mitochondrial dysfunction, and by increasing autophagy and brain-derived neurotrophic factor (BDNF). Low VD serum level is connected with cognitive dysfunction and the development of dementia in PD. The VD-mediated cognitive augmenting effect is interrelated to the safeguarding of synaptic plasticity and modulation of neurotransmitter release. VD deficiency is linked with the severity of olfactory dysfunction which precedes the progression of symptomatic PD. However, the precise role of VD in PD remains unidentified, and there is a conflict about whether treatment with VD can ameliorate PD or not.

Uterine fibroids: current research on novel drug targets and innovative therapeutic strategies

INTRODUCTION

Uterine fibroids, the most common nonmalignant tumors affecting the female genital tract, are a significant medical challenge. This article focuses on the most recent studies that attempted to identify novel non-hormonal therapeutic targets and strategies in UF therapy.

AREAS COVERED

This review covers the analysis of the pharmacological and biological mechanisms of the action of natural substances and the role of the microbiome in reference to UFs. This study aimed to determine the potential role of these compounds in UF prevention and therapy.

EXPERT OPINION

While there are numerous approaches for treating UFs, available drug therapies for disease control have not been optimized yet. This review highlights the biological potential of vitamin D, EGCG and other natural compounds, as well as the microbiome, as promising alternatives in UF management and prevention. Although these substances have been quite well analyzed in this area, we still recommend conducting further studies, particularly randomized ones, in the field of therapy with these compounds or probiotics. Alternatively, as the quality of data continues to improve, we propose the consideration of their integration into clinical practice, in alignment with the patient's preferences and consent.

Serum vitamin D concentrations and sleep disorders: insights from NHANES 2011-2016 and Mendelian Randomization analysis

OBJECTIVE

This investigation seeks to examine the association between serum vitamin D concentrations and the prevalence of sleep disorders, additionally elucidating the causal relationship via Mendelian Randomization (MR) analysis.

MATERIALS AND METHODS

This research employed data from the National Health and Nutrition Examination Survey (NHANES) 2011-2016, focusing on adults aged 20-50 years reporting sleep disorders. The research encompassed 4913 American adults. Weighted multivariable logistic regression models and cubic spline analyses were utilized to evaluate the association between serum vitamin D concentrations and the incidence of sleep disorders. Additionally, a two-sample Mendelian Randomization analysis was performed to evaluate the potential causal link between serum vitamin D concentrations and the risk of sleep disorders.

RESULTS

Within the 2011-2016 NHANES cohort of the U.S. population, a notable inverse association was detected between serum vitamin D concentrations and sleep disorders (β =  - 3.81, 95% CI: - 6.10 to - 1.52, p = 0.003). After multivariate adjustments, a higher incidence of sleep disorders was associated with lower vitamin D Concentrations (OR 1.52, 95% CI 1.10-2.10, trend p = 0.014). Restricted cubic spline regression analysis indicated a linear association between serum vitamin D concentrations and sleep disorders(non-linearity p > 0.05). Lastly, the two-sample MR analysis yielded evidence supporting a potential causal connection between serum vitamin D concentrations and sleep disorders, with each unit increase in genetically predicted serum vitamin D reducing the odds ratio to 0.78 (95% CI 0.61-0.99, p = 0.044).

CONCLUSIONS

These results imply that lower vitamin D concentrations in the population might correlate with a heightened risk of sleep disorders, suggesting the importance of considering vitamin D supplementation when treating sleep disorders.

Intravenous calcitriol administration improves the liver redox status and attenuates ferroptosis in mice with high-fat diet-induced obesity complicated with sepsis

Obesity aggravates ferroptosis, and vitamin D (VD) may inhibit ferroptosis. We hypothesized that weight reduction and/or calcitriol administration have benefits against the sepsis-induced liver redox imbalance and ferroptosis in obese mice. Mice were fed a high-fat diet for 11 weeks, then half of the mice continued to consume the diet, while the other half were transferred to a low-energy diet for 5 weeks. After feeding the respective diets for 16 weeks, sepsis was induced by cecal ligation and puncture (CLP). Septic mice were divided into four experimental groups: OS group, obese mice injected with saline; OD group, obese mice with calcitriol; WS group, weight-reduction mice with saline; and WD group, weight-reduction mice with calcitriol. Mice in the respective groups were euthanized at 12 or 24 h after CLP. Results showed that the OS group had the highest inflammatory mediators and lipid peroxide levels in the liver. Calcitriol treatment reduced iron content, enhanced the reduced glutathione/oxidized glutathione ratio, upregulated nuclear factor erythroid 2-related factor 2, ferroptosis-suppressing protein 1, and solute carrier family 7 member 11 expression levels. Also, mitochondrion-associated nicotinamide adenine dinucleotide phosphate oxidase 1, peroxisome proliferator-activated receptor-γ coactivator 1, hypoxia-inducible factor-1α, and heme oxidase-1 expression levels increased in the late phase of sepsis. These results were not noted in the WS group. These findings suggest that calcitriol treatment elicits a more-balanced glutathione redox status, alleviates liver ferroptosis, and enhances mitochondrial biogenesis-associated gene expressions. Weight reduction alone had minimal influences on liver ferroptosis and mitochondrial biogenesis in obese mice with sepsis.

Emerging role of vitamin D deficiency as a risk factor for retinal venous occlusions and need for public health measures for its prevention

Purpose

To estimate levels of serum vitamin D in patients of retinal vein occlusion (RVO) and compare with age- and sex-matched controls.

Methods

A prospective case-control study of 54 patients of RVO and 54 age- and sex-matched attendants of patients presenting to a tertiary care hospital in Delhi was performed. Patients on vitamin D supplementations and RVO due to infective or immunological causes or patients of glaucoma were excluded. Serum vitamin D levels of all the study participants along with relevant blood investigations with history and examination were documented. Vitamin D deficiency was defined as <20 ng/ml.

Results

The mean serum vitamin D levels seen in RVO patients and the control group were 14.19 ± 5.23 ng/ml and 19.42 ± 10.27 ng/ml, respectively (P value = 0.001) with an odds ratio of 10.558 (CI = 2.34-47.50), indicating vitamin D deficiency to be strongly correlated with RVO. Maximum patients of RVO (46.3%) were seen during the winter season. The study noted hypertension [odds ratio 20.22 (CI = 5.812-70.347)], dyslipidemia, and anemia [odds ratio 4.107 (CI = 0.62-26.90)] to be the risk factors for RVO as previously proved in the literature. Smoking, diabetes, alcohol intake, and body mass index did not emerge as risk factors for RVO.

Conclusion

Vitamin D deficiency is associated with RVO; hence, estimation of serum vitamin D levels should be advised as a part of routine investigations while looking for the cause of RVOs. Public health measures like food fortification with vitamin D micronutrients and public awareness towards increased sunlight exposure in the community are simple, inexpensive measures that can decrease the burden of sight-threatening disease of RVO in the community.

Imiglucerase, cholecalciferol, and bone-diet in skeletal health management of type I Gaucher disease patients: a pilot study and systematic review

Skeletal anomalies represent a characteristic feature of type 1 Gaucher disease (GD1). Here we evaluated the impact of an integrated therapy comprising enzyme-replacement therapy (ERT), cholecalciferol, and a normocalcemic-normocaloric-hyposodic diet (bone diet) on bone health in GD1 patients. We also performed a systematic review to compare our results with available data. From January 1, 2015 to February 28, 2019, all GD1 patients referred to Federico II University were enrolled and treated with the integrated therapy. Bone turnover markers and bone mineral density (BMD) were evaluated at baseline (T0) and after 24 months (T24). We enrolled 25 GD1 patients, all showing 25-hydroxy vitamin D (25OHD) levels < 50 nmol/l (hypovitaminosis D) at T0. Response to cholecalciferol treatment was effective, showing a direct relationship between 25OHD levels before and after treatment. At T0, 2 GD1 patients showed fragility fractures, 5 the Erlenmeyer flask deformity, 3 osteonecrosis, and 7 a BMD Z-score ≤ -2. Overall, GD1 patients with bone anomalies showed higher C-terminal telopeptide levels compared with those without bone anomalies. No new bone anomalies occurred during 2 years of follow-up. At T24, BMD remained stable across the entire study cohort, including in patients with bone anomalies. The systematic review showed that our study is the first that evaluated all bone health parameters. Hypovitaminosis D is prevalent in GD1 patients. The response to cholecalciferol treatment was effective but different to healthy subjects and in patients with metabolic bone disorders. Integrated therapy including ERT, cholecalciferol, and bone diet guarantees bone health.

Dietary Supplements as Concentrated Sources of Nutrients with a Nutritional or Physiological Effect for Children with Inflammatory Bowel Disease

The consequences of inflammatory bowel disease (IBD) in children are connected to possible detrimental impacts on growth, development, psychosocial function, and general well-being. Therefore, the primary management plan in pediatric IBD is to achieve the long-term control of intestinal inflammation while also monitoring potential disease complications and therapeutic adverse effects, where nutritional management is of utmost importance. This review explores the role of dietary supplements as concentrated sources of nutrients with nutritional and/or physiological effects on children with IBD. While dietary supplements are commonly used in pediatric IBD management, their efficacy and, for some of them, safety remain subjects of debate. We provide an overview of the types of dietary supplements available and their potential benefits and risks in pediatric IBD patients. Additionally, we discuss the evidence supporting the use of specific supplements, their mechanisms of action, and considerations for clinical practice. Understanding the role of dietary supplements in pediatric IBD management is crucial for optimizing patient care and outcomes.

Vitamin D supplementation for women during pregnancy

BACKGROUND

Vitamin D supplementation during pregnancy may help improve maternal and neonatal health outcomes (such as fewer preterm birth and low birthweight babies) and reduce the risk of adverse pregnancy outcomes (such as severe postpartum haemorrhage).

OBJECTIVES

To examine whether vitamin D supplementation alone or in combination with calcium or other vitamins and minerals given to women during pregnancy can safely improve certain maternal and neonatal outcomes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Trials Register (which includes results of comprehensive searches of CENTRAL, MEDLINE, Embase, CINAHL, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform, and relevant conference proceedings) (3 December 2022). We also searched the reference lists of retrieved studies.

SELECTION CRITERIA

Randomised and quasi-randomised trials evaluating the effect of supplementation with vitamin D alone or in combination with other micronutrients for women during pregnancy in comparison to placebo or no intervention.

DATA COLLECTION AND ANALYSIS

Two review authors independently i) assessed the eligibility of studies against the inclusion criteria, ii) assessed trustworthiness based on pre-defined criteria of scientific integrity, iii) extracted data from included studies, and iv) assessed the risk of bias of the included studies. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

The previous version of this review included 30 studies; in this update, we have removed 20 of these studies to 'awaiting classification' following assessments of trustworthiness, one study has been excluded, and one new study included. This current review has a total of 10 included studies, 117 excluded studies, 34 studies in awaiting assessment, and seven ongoing studies. We used the GRADE approach to assess the certainty of the evidence. This removal of the studies resulted in evidence that was downgraded to low-certainty or very low-certainty due to study design limitations, inconsistency between studies, and imprecision. Supplementation with vitamin D compared to no intervention or a placebo A total of eight studies involving 2313 pregnant women were included in this comparison. We assessed four studies as having a low risk of bias for most domains and four studies as having high risk or unclear risk of bias for most domains. The evidence is very uncertain about the effect of supplementation with vitamin D during pregnancy compared to placebo or no intervention on pre-eclampsia (risk ratio (RR) 0.53, 95% confidence interval (CI) 0.21 to 1.33; 1 study, 165 women), gestational diabetes (RR 0.53, 95% CI 0.03 to 8.28; 1 study, 165 women), preterm birth (< 37 weeks) (RR 0.76, 95% CI 0.25 to 2.33; 3 studies, 1368 women), nephritic syndrome (RR 0.17, 95% CI 0.01 to 4.06; 1 study, 135 women), or hypercalcaemia (1 study; no cases reported). Supplementation with vitamin D during pregnancy may reduce the risk of severe postpartum haemorrhage; however, only one study reported this outcome (RR 0.68, 95% CI 0.51 to 0.91; 1 study, 1134 women; low-certainty evidence) and may reduce the risk of low birthweight; however, the upper CI suggests that an increase in risk cannot be ruled out (RR 0.69, 95% CI 0.44 to 1.08; 3 studies, 371 infants; low-certainty evidence). Supplementation with vitamin D + calcium compared to no intervention or a placebo One study involving 84 pregnant women was included in this comparison. Overall, this study was at moderate to high risk of bias. Pre-eclampsia, gestational diabetes, and maternal adverse events were not reported. The evidence is very uncertain about the effect of supplementation with vitamin D and calcium on preterm birth (RR not estimable; very low-certainty evidence) or for low birthweight (RR 1.45, 95% CI 0.14 to 14.94; very low-certainty evidence) compared to women who received placebo or no intervention. Supplementation with vitamin D + calcium + other vitamins and minerals versus calcium + other vitamins and minerals (but no vitamin D) One study involving 1298 pregnant women was included in this comparison. We assessed this study as having a low risk of bias in all domains. Pre-eclampsia was not reported. The evidence is very uncertain about the effect of supplementation with vitamin D, calcium, and other vitamins and minerals during pregnancy compared to no vitamin D on gestational diabetes (RR 0.42, 95% CI 0.10 to 1.73; very low-certainty evidence), maternal adverse events (hypercalcaemia no events and hypercalciuria RR 0.25, 95% CI 0.02 to 3.97; very low-certainty evidence), preterm birth (RR 1.04, 95% CI 0.68 to 1.59; low-certainty evidence), or low birthweight (RR 1.12, 95% CI 0.82 to 1.51; low-certainty evidence).

AUTHORS' CONCLUSIONS

This updated review using the trustworthy assessment tool removed 21 studies from the previous update and added one new study for a total of 10 included studies. In this setting, supplementation with vitamin D alone compared to no intervention or a placebo resulted in very uncertain evidence on pre-eclampsia, gestational diabetes, preterm birth, or nephritic syndrome. It may reduce the risk of severe postpartum haemorrhage; however, only one study reported this outcome. It may also reduce the risk of low birthweight; however, the upper CI suggests that an increase in risk cannot be ruled out. Supplementation with vitamin D and calcium versus placebo or no intervention resulted in very uncertain evidence on preterm birth and low birthweight. Pre-eclampsia, gestational diabetes, and maternal adverse events were not reported in the only study included in this comparison. Supplementation with vitamin D + calcium + other vitamins and minerals versus calcium + other vitamins and minerals (but no vitamin D) resulted in very uncertain evidence on gestational diabetes and maternal adverse events (hypercalciuria) and uncertain evidence on preterm birth and low birthweight. Pre-eclampsia was not reported in the only study included in this comparison. All findings warrant further research. Additional rigorous, high-quality, and larger randomised trials are required to evaluate the effects of vitamin D supplementation in pregnancy, particularly in relation to the risk of maternal adverse events.

Skin pigmentation related variants in Mexican population and interaction effects on serum 25(OH)D concentration and vitamin D deficiency

Skin pigmentation is negatively associated with circulating vitamin D (VD) concentration. Therefore, genetic factors involved in skin pigmentation could influence the risk of vitamin D deficiency (VDD). We evaluated the impact genetic variants related to skin pigmentation on VD in Mexican population. This cross-sectional analysis included 848 individuals from the Health Worker Cohort Study (ratio males to females ~ 1:3). Eight genetic variants: rs16891982 (SLC45A2), rs12203592 (IRF4), rs1042602 and rs1126809 (TYR), rs1800404 (OCA2), rs12913832 (HERC2), rs1426654 (SLC24A5), and rs2240751 (MFSD12); involved in skin pigmentation were genotyped. Skin pigmentation was assessed by self-report. Linear and logistic regression were used to assess the association between the variants of interest and VD and VDD, as appropriate. In our study, eight genetic variants were associated with skin pigmentation. A genetic risk score built with the variants rs1426654 and rs224075 was associated with lower VD levels (β = - 1.38, 95% CI - 2.59, - 0.17, p = 0.025). Nevertheless, when examining gene-gene interactions, we observed that rs2240751 × rs12203592 were associated with VD levels (P interaction = 0.021). Whereas rs2240751 × rs12913832 (P interaction = 0.0001) were associated with VDD. Our results suggest that skin pigmentation-related gene variants are associated with lower VD levels in Mexican population. These results underscore the importance of considering genetic interactions when assessing the impact of genetic polymorphisms on VD levels.