Sunlight exposure is just one of the factors which influence vitamin D status

Vitamin D status, vitamin D receptor, CYP2R1, and CYP24A1 profiles in children

Introduction

Vitamin D plays a major role in the musculoskeletal and immune system. Understanding the comprehensive mechanism of vitamin D receptors and the enzyme of vitamin D induction (CYP2R1) and inhibition (CYP24A1) in its metabolism is interesting. This study aims to understand vitamin D metabolism in Indonesian pediatrics, specifically in Jakarta, which has abundant sun exposure.

Methodology

A cross-sectional study with comparative, correlative, and multivariate analysis on vitamin D, vitamin D receptor, CYP2R1, and CYP24A1 levels was conducted on 46 children with no known morbidity.

Result

Subjects were mostly male (52.2%), age group of 2-6 years (34.8%), and had sufficient vitamin D status (43.5%, median 27.55 ng/mL). Age was found to have a negative correlation with vitamin D levels (p < 0.001; r = -0.625) and CYP2R1 (p = 0.035; r = -0.311). Significant positive associations were found between CYP24A1 and CYP2R1 (p = 0.046; r = 0.296). Participants aged 0-2 are more likely to have a higher level of vitamin D status compared to those aged >2 years (OR 42.092, 95% CI [4.532-390.914], p = 0.001). VDR levels were significantly lower in insufficient vitamin D levels than in the sufficient group (p = 0.018). VDR and vitamin D status had a positive relation (OR 7.023, 95% CI [1.864-26.453], p = 0.004).

Conclusion

Vitamin D levels decrease with the increase in age. Vitamin D receptor level has an inline-level progression with vitamin D level. CYP2R1 and CYP24A1 suggest a directly proportional relationship. Vitamin D screening and supplementation in children older than 2 years old are suggested.

Effect of epigenetics on vitamin D levels: a systematic review until December 2020

BACKGROUND

The association between epigenetic modification of the genes involved in the vitamin D metabolic pathway and vitamin D metabolites' status has been elucidated incompletely. This study aims to review the studies on the mentioned association and create a brighter view of this topic.

METHODS

A systematic literature search was conducted in Medline database (PubMed), Scopus, and Web of Science up to the end of November 2020. Original articles which reported the effect of epigenetic alteration-methylation level or its changes-of genes involved in vitamin D regulation on the vitamin D metabolites serum level or its changes were included. The National Institutes of Health (NIH) checklist was used to assess the quality of included articles.

RESULTS

Among 2566 records, nine reports were included in the systematic review according to the inclusion and exclusion criteria. Studies discussed the contribution of methylation status of members of the cytochrome P450 family (CYP2R1, CYP27B1, CYP24A1), and Vitamin D Receptor (VDR) genes to vitamin D level variance. CYP2R1 methylation status could regulate the contributing factors affecting the vitamin D serum level and predict response to vitamin D supplementation. Studies revealed that impaired methylation of CYP24A1 occurs in response to an increase in serum level of 25-hydroxyvitamin D (25(OH)D). It is reported that the association between methylation levels of CYP2R1, CYP24A1, and VDR genes and 25(OH)D level is not affected by the methyl-donors bioavailability.

CONCLUSIONS

The epigenetic modification of the vitamin D-related genes could explain the vitamin D levels variation among populations. Large-scale clinical trials in various ethnicities are suggested to find the effect of epigenetics on vitamin D response variation.

REGISTRATION

The systematic review protocol was registered on PROSPERO (registration number: CRD42022306327).

The role of single nucleotide variant rs3819817 of the Histidine Ammonia-Lyase gene and 25-Hydroxyvitamin D on bone mineral density, adiposity markers, and skin pigmentation, in Mexican population

PURPOSE

Vitamin D (VD) deficiency and osteoporosis have become a global public health problem. A variant in the Histidine Ammonia-Lyase (HAL) gene has been associated with VD levels and bone mineral density (BMD). However, whether this variant has an influence on VD levels and BMD in Mexican adults remain unclear.

METHODS

This cross-sectional analysis included 1,905 adults participating in the Health Worker Cohort Study and 164 indigenous postmenopausal women from the Metabolic Analysis in an Indigenous Sample (MAIS) cohort. The rs3819817 variant was genotyped by TaqMan probe assay. Total 25 hydroxyvitamin D levels were measured by DiaSorin Liaison. BMD at the different sites was assessed through dual-energy X-ray absorptiometry. Linear and logistic regression models were performed to evaluate the associations of interest.

RESULTS

The prevalence of VD deficiency was 41%, showing differences between sexes. Obesity and skin pigmentation were associated with lower levels of VD in males and females. rs3819817-T allele was associated with low levels of 25-hydroxyvitamin D, VD deficiency, and hip and femoral neck BMD values (g/cm²). We found two interactions with VD levels, one between adiposity and rs3819817-T allele (P = 0.017) and another between skin pigmentation and rs3819817-T allele (P = 0.019). In indigenous postmenopausal women, we observed higher VD levels in the southern region compared to the northern region (P < 0.001); however, we did not observe differences by genotype.

CONCLUSION

Our findings confirm that the genetic variant rs3819817 has an essential function in VD levels and BMD and suggests a role in skin pigmentation in the Mexican population.

Association between serum Vitamin D levels and asthma severity and control in children and adolescents

OBJECTIVE

To assess the association of serum Vitamin D (vitD) levels with asthma control and severity in children and adolescents in different seasons of the year.

METHOD

Longitudinal, prospective study with 7- to 17-year-old children and adolescents diagnosed with asthma. All participants underwent two assessments conducted in opposite seasons of the year which included a clinical assessment, a questionnaire for classification of asthma control (Asthma Control Test), spirometry, and blood collection to measure serum vitD levels.

RESULTS

In total, 141 individuals with asthma were evaluated. The mean vitD was lower in females (p = 0.006) and sunlight exposure appears not to be an influencing factor for vitD levels. We found no differences in mean vitD of patients with controlled and uncontrolled asthma (p = 0.703; p = 0.956). However, the severe asthma group had lower mean Vitamin D than the mild/moderate asthma group for both assessments (p = 0.013; p = 0.032). In the first assessment, the group with vitD insufficiency had a higher prevalence of severe asthma (p = 0.015). Vitamin D was positively correlated with FEV₁ in both assessments (p = 0.008; p = 0.006) and with FEF_25-75% in the first assessment (p = 0.038).

CONCLUSION

In a tropical climate zone, there is no evidence of association between seasonality and serum vitD levels or between serum vitD levels and asthma control in children and adolescents. However, vitD and lung function were positively correlated and the group with vitD insufficiency had a higher prevalence of severe asthma.

Determination of vitamin D3 conjugated metabolites: a complementary view on hydroxylated metabolites

Experts typically define vitamin D deficiency levels by the determination of a circulating 25-hydroxyvitamin D₃-calcifediol prohormone. A large part of the population is characterized by deficient vitamin D levels (calcifediol < 20 ng mL^-1) despite individuals not being affected by any disorder. Cholecalciferol (vitamin D₃) and/or calcifediol supplementation is a common practice for vitamin D-deficient individuals as recommended by international scientific societies and official agencies. In the last few years, several studies have reported the presence of conjugated vitamin D₃ metabolites, mainly glucuronidation and sulfation derivatives, although simultaneous quantitative measurements involving phase I and II vitamin D metabolites have not been carried out. A quantitative method based on tandem mass spectrometry detection is proposed here for the combined determination of phase I and phase II vitamin D₃ metabolites in human serum. As phase I and phase II metabolites are preferentially ionized in different modes, a switching polarity mode was adopted to determine both groups of compounds in serum at high sensitivity levels (pg mL^-1). The validation of this proposal was successfully accomplished by following the Center for Drug Evaluation and Research (CDER) guidelines. Its applicability was tested in a cohort of volunteers with mostly deficient baseline levels. Considering the sulfated form of calcifediol, the sum of its concentrations showed sufficient baseline vitamin D levels in all individuals, suggesting that this could be a novel strategy for vitamin D deficiency definition. Therefore, phase II metabolites are proposed to be included when evaluating the vitamin D status since they provide more information about the overall status of the vitamin D endocrine system. Nevertheless, further studies are required to confirm the biological activity of these conjugated metabolites and the suitability of this strategy for the description of vitamin D deficiency.

Vitamin D in Cancer Prevention: Gaps in Current Knowledge and Room for Hope

Intensive epigenome and transcriptome analyses have unveiled numerous biological mechanisms, including the regulation of cell differentiation, proliferation, and induced apoptosis in neoplastic cells, as well as the modulation of the antineoplastic action of the immune system, which plausibly explains the observed population-based relationship between low vitamin D status and increased cancer risk. However, large randomized clinical trials involving cholecalciferol supplementation have so far failed to show the potential of such interventions in cancer prevention. In this article, we attempt to reconcile the supposed contradiction of these findings by undertaking a thorough review of the literature, including an assessment of the limitations in the design, conduct, and analysis of the studies conducted thus far. We examine the long-standing dilemma of whether the beneficial effects of vitamin D levels increase significantly above a critical threshold or if the conjecture is valid that an increase in available cholecalciferol translates directly into an increase in calcitriol activity. In addition, we try to shed light on the high interindividual epigenetic and transcriptomic variability in response to cholecalciferol supplementation. Moreover, we critically review the standards of interpretation of the available study results and propose criteria that could allow us to reach sound conclusions in this field. Finally, we advocate for options tailored to individual vitamin D needs, combined with a comprehensive intervention that favors prevention through a healthy environment and responsible health behaviors.

Maternal Vitamin D Status Correlates to Leukocyte Antigenic Responses in Breastfeeding Infants

It is unknown if vitamin D (vitD) sufficiency in breastfeeding mothers can lead to physiological outcomes for their children that are discernible from infant vitD sufficiency per se. In a 3-month, randomized vitD supplementation study of mothers and their exclusively breastfeeding infants, the effects of maternal vitD sufficiency were determined on infant plasma concentrations of 25-hydroxyvitamin D (i.e., vitD status) and 11 cytokines. An inverse correlation was seen between maternal vitD status and infant plasma TNF concentration (r = −0.27; p < 0.05). Infant whole blood was also subjected to in vitro antigenic stimulation. TNF, IFNγ, IL-4, IL-13, and TGFβ1 responses by infant leukocytes were significantly higher if mothers were vitD sufficient but were not as closely correlated to infants’ own vitD status. Conversely, IL-10 and IL-12 responses after antigenic challenge were more correlated to infant vitD status. These data are consistent with vitD-mediated changes in breast milk composition providing immunological signaling to breastfeeding infants and indicate differential physiological effects of direct-infant versus maternal vitD supplementation. Thus, consistent with many previous studies that focused on the importance of vitD sufficiency during pregnancy, maintenance of maternal sufficiency likely continues to affect the health of breastfed infants.

An investigation of vitamin D nutritional status in children after outbreak of coronavirus disease 2019

OBJECTIVES

To investigate vitamin D nutritional status in children after outbreak of coronavirus disease 2019 (COVID-19), as well as the effect of strict epidemic prevention and control measures for the COVID-19 epidemic on vitamin D nutritional status in children.

METHODS

A total of 7 460 children who underwent routine physical examinations from February to August, 2020 and had normal results were retrospectively enrolled as the observation group, and 10 102 children who underwent routine physical examinations from February to August, 2019 (no epidemic of COVID-19) and had normal results were enrolled as the control group. The serum level of 25-hydroxy vitamin D [25(OH)D] was compared between the two groups. The children in the observation and control groups who underwent physical examinations in March and April were selected as the epidemic prevention subgroup (n=1 710) and non-epidemic subgroup (n=2 877) respectively. The subjects were divided into five age groups (infancy, early childhood, preschool, school age and adolescence), and serum 25(OH)D levels of children of all ages were compared between the epidemic prevention and non-epidemic subgroups.

RESULTS

The observation group had a lower serum level of 25(OH)D than the control group in March and April (P<0.001). The epidemic prevention subgroup had a lower serum level of 25(OH)D than the non-epidemic subgroup in all age groups (P<0.001). The vitamin D sufficiency rate in early childhood, preschool, school and adolescent children from the epidemic prevention subgroup was lower than the non-epidemic subgroup (P<0.001), with a reduction of 10.71%, 18.76%, 59.63% and 56.29% respectively.

CONCLUSIONS

Strict prevention and control measures for the COVID-19 epidemic may lead to a significant reduction in vitamin D level in children, especially school-aged and adolescent children. It is recommended to timely monitor vitamin D level in children, take vitamin D supplements, and increase the time of outdoor sunshine as far as possible under the premise of adherence to epidemic prevention regulations.

Vitamin D oral intermittent treatment (DO IT) study, a randomized clinical trial with individual loading regimen

Comparison of several regimens of oral vitamin D including an individually calculated loading regimen with the aim of achieving serum values > 75 nmol/l. Interventional, randomized, 3-arm study in vitamin D-deficient outpatients. Participants were allocated to supplementation of 24,000 IU vitamin D monthly over three months, using either a monthly drinking solution (Vi-De 3) or capsule (D3 VitaCaps), or an individualized loading regimen with the capsules taken weekly. For the loading regimen, the cumulative dose was calculated according to baseline 25-hydroxy-vitamin D (25(OH)D) serum value and body weight. Main inclusion criteria were age ≥ 18 years and 25(OH)D serum concentration < 50 nmol/l. The primary outcome was 25(OH)D serum concentration one week after treatment termination. Secondary endpoints were patient's preferences and adverse events. Full datasets were obtained from 52 patients. Mean 25(OH)D values were statistically significant higher after a loading regimen compared to a monthly administration of 24,000 IU vitamin D (76.4 ± 15.8 vs 61.4 ± 10.8 nmol/l; p < 0.01). All patients treated with the loading regimen reached sufficient 25(OH)D values > 50 nmol/l. Serum 25(OH)D values > 75 nmol/l were observed more frequently in patients taking the loading regimen (47% vs 11% drinking solution vs 12% capsules). Vitamin D-related adverse effects did not occur in any treatment groups. Capsules were preferred by 88.5% of the patients. Compared to treatments with monthly intake of 24,000 IU vitamin D, the intake of an individually calculated weekly loading regimen was able to raise serum concentrations > 50 nmol/l in all cases within a safe range.

Early-Life Factors Are Associated with Vitamin D Status in Early and Mid-Childhood and May Differ between White and Black Children

BACKGROUND

Suboptimal vitamin D (VitD) status has been associated with poor bone health and other adverse health outcomes and is common among children. Various early-life factors are associated with child VitD, yet few studies have examined multiple factors simultaneously in a single study population.

OBJECTIVES

We aimed to characterize relations of early-life factors with plasma 25-hydroxyvitamin D [25(OH)D] concentrations in early and mid-childhood, and to explore potential differences in these associations between white and black children.

METHODS

We identified associations of various early-life factors with 25(OH)D concentrations in early and mid-childhood among 961 children in Project Viva using linear regression models. All variables associated with 25(OH)D were included together in final multivariable models at each outcome time point: 1 in the overall sample and additional models for children whose mothers identified them as being white or black.

RESULTS

Overall mean ± SD 25(OH)D concentrations were 86 ± 29 nmol/L in early childhood and 68 ± 21 nmol/L in mid-childhood. After accounting for other predictors, children who took VitD supplements (compared with those who did not) had 25(OH)D concentrations 5.6 nmol/L (95% CI: 2.0, 9.2 nmol/L) higher in early childhood and 8.2 nmol/L (95% CI: 4.8, 11.6 nmol/L) higher in mid-childhood. Other factors consistently associated with higher 25(OH)D were blood collection in summer or fall, white race, nonfall birth season, prenatal exposure to higher 25(OH)D, and higher dietary intake of VitD. Greater waist circumference was associated with lower 25(OH)D in early childhood (β: -3.8; 95% CI: -7.4, -0.2 per 1-SD increase) among black children only.

CONCLUSIONS

Our findings may help clinicians better target children at risk of lower 25(OH)D for screening and/or intervention and may inform research focused on associations of 25(OH)D with different exposures and outcomes or causal effects of early-life factors on later VitD status.This trial was registered at clinicaltrials.gov as NCT02820402.

Vitamin D status and blood pressure in children and adolescents: a systematic review of observational studies

BACKGROUND

Childhood hypertension is a growing public health problem. Simultaneously, hypovitaminosis D is widespread in this population and could be associated with hypertension. This study systematically reviewed the literature on the relationship between vitamin D status and blood pressure (BP) in children and adolescents.

METHODS

Following the PRISMA guidelines, PUBMED, MEDLINE, CINAHL, EMBASE, Cochrane Library, and ClinicalTrials.gov and the gray literature without language or time restrictions were searched. We included observational studies, assessed their risk of bias, and extracted data on population characteristics, vitamin D status and BP measurements, and the association between the two variables. A narrative analysis of the studies was performed.

RESULTS

In total, 85 studies were included. Prospective cohort studies showed no association between vitamin D and BP, and generally, they were flawed. Also, the majority of non-prospective cohort studies (cross-sectional, retrospective, case-control) did not report an association between vitamin D and BP. They were mostly flawed regarding BP measurement and adjusting to potential confounders.

CONCLUSION

The results on the relationship between vitamin D status and BP in children and adolescents varied between the studies, and mainly pointed towards lack of association.

Physical Determinants of Vitamin D Photosynthesis: A Review

Vitamin D synthesis by exposure of skin to solar ultraviolet radiation (UVR) provides the majority of this hormone that is essential for bone development and maintenance but may be important for many other health outcomes. This process, which is the only well-established benefit of solar UVR exposure, depends on many factors including genetics, age, health, and behavior. However, the most important factor is the quantity and quality of UVR reaching the skin. Vitamin D synthesis specifically requires ultraviolet B (UVB) radiation that is the minority component (<5%) of solar UVR. This waveband is also the most important for the adverse effects of solar exposure. The most obvious of which is sunburn (erythema), but UVB is also the main cause of DNA damage to the skin that is a prerequisite for most skin cancers. UVB at the Earth's surface depends on many physical and temporal factors such as latitude, altitude, season, and weather. Personal, cultural, and behavioral factors are also important. These include skin melanin, clothing, body surface area exposed, holiday habits, and sunscreen use. There is considerable disagreement in the literature about the role of some of these factors, possibly because some studies have been done by researchers with little understanding of photobiology. It can be argued that vitamin D supplementation obviates the need for solar exposure, but many studies have shown little benefit from this approach for a wide range of health outcomes. There is also increasing evidence that such exposure offers health benefits independently of vitamin D: the most important of which is blood-pressure reduction. In any case, public health advice must optimize risk versus benefit for solar exposure. It is fortunate that the individual UVB doses necessary for maintaining optimal vitamin D status are lower than those for sunburn, irrespective of skin melanin. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

Skeletal Muscle and the Maintenance of Vitamin D Status

Vitamin D, unlike the micronutrients, vitamins A, E, and K, is largely obtained not from food, but by the action of solar ultraviolet (UV) light on its precursor, 7-dehydrocholesterol, in skin. With the decline in UV light intensity in winter, most skin production of vitamin D occurs in summer. Since no defined storage organ or tissue has been found for vitamin D, it has been assumed that an adequate vitamin D status in winter can only be maintained by oral supplementation. Skeletal muscle cells have now been shown to incorporate the vitamin D-binding protein (DBP) from blood into the cell cytoplasm where it binds to cytoplasmic actin. This intracellular DBP provides an array of specific binding sites for 25-hydroxyvitamin D (25(OH)D), which diffuses into the cell from the extracellular fluid. When intracellular DBP undergoes proteolytic breakdown, the bound 25(OH)D is then released and diffuses back into the blood. This uptake and release of 25(OH)D by muscle accounts for the very long half-life of this metabolite in the circulation. Since 25(OH)D concentration in the blood declines in winter, its cycling in and out of muscle cells appears to be upregulated. Parathyroid hormone is the most likely factor enhancing the repeated cycling of 25(OH)D between skeletal muscle and blood. This mechanism appears to have evolved to maintain an adequate vitamin D status in winter.

Effects of vitamin D supplementation on fasting glucose, dyslipidemia, blood pressure, and abdominal obesity among patients with metabolic syndrome: a protocol for systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Vitamin D deficiency can play a role in extraskeletal functions that are involved with a set of risk factors associated with metabolic syndrome (MetS). The purpose of this review is to investigate the impact of vitamin D supplementation on fasting glucose, dyslipidemia, blood pressure, and abdominal obesity among patients with MetS.

METHODS

EMBASE, Medline, Web of Science, Lilacs, the Cochrane Central Register of Controlled Trials, clinicaltrials.gov databases, and grey literature will be systematically searched for randomized controlled trials (RCTs) of vitamin D supplementation compared with placebo, through December 2020. We will include in the study patients with MetS diagnosed by the criteria set forth by the National Cholesterol Education Program Adult Treatment Panel III or the International Diabetes Federation. The effect of oral vitamin D supplementation on lipid profile improvement (triglycerides, high-density lipoprotein cholesterol-HDL-C) is this review's primary outcome. The systematic review will be performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The study screening, data extraction, and quality assessment will be fulfilled by two independent reviewers according to the Cochrane Risk of Bias tool (RoB 2.0). The results of the systematic review will be provided according to the type of intervention, characteristics of the target population, the methods of measurement of vitamin D, the calculated vitamin D concentrations, types of biological samples, and types of outcomes. Meta-analyses will be conducted where appropriate. The Cochran's Q test and the I2-heterogeneity test will be used to assess the presence of heterogeneity and whether the fixed or the random-effects model would be appropriate for combining study results using the inverse variance method or the DerSimonian-Lair method, respectively. Publication bias will be evaluated using funnel plots and Egger's and Begg's tests. The strength of the evidence will be assessed according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE).

DISCUSSION

This systematic review will assess the effects of vitamin D supplementation on fasting glucose and triglyceride levels, waist circumference and mean blood pressure, and HDL-C among individuals with MetS. These findings may assist with decision-making within a clinical setting.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number CRD42019123212.

Vitamin D Synthesis Following a Single Bout of Sun Exposure in Older and Younger Men and Women

Older adults are frequently cited as an at-risk population for vitamin D deficiency that may in part be due to decreased cutaneous synthesis, a potentially important source of cholecalciferol (vitamin D₃). Previous studies found that cutaneous D₃ production declines with age; however, most studies have been conducted ex vivo or in the photobiology lab. The purpose of this study was to characterize the response of vitamin D metabolites following a 30-min bout of sun exposure (15-min each to the dorsal and ventral sides) at close to solar noon in younger and older adults.

METHODS

30 healthy individuals with skin type II/III were recruited; a younger cohort, aged 20-37 (n = 18) and an older cohort (n = 12), age 51-69 years. Exposure was at outer limits of sensible sun exposure designed to enhance vitamin D synthesis without increasing risk of photo ageing and non-melanoma skin cancer. Serum D₃ concentration was measured at baseline, 24, 48 and 72 h post-exposure. Serum 25(OH)D was measured at baseline and 72 h post-exposure plus 168 h post-exposure in the older cohort.

RESULTS

D₃ increased in response to sun exposure (time effect; p = 0.002) with a trend for a difference in D₃ between cohorts (time*group; p = 0.09). By regression modeling of continuous data, age accounted for 20% of the variation in D₃ production. D₃ production decreased by 13% per decade. Despite changes in D₃, however, serum 25(OH)D did not change from baseline to 72 or 168 h post exposure (p > 0.10).

CONCLUSIONS

Serum D₃ concentration increased significantly in response to outdoor sun exposure in younger and older adults. While ageing may dampen cutaneous synthesis, sunlight exposure is still a significant source of vitamin D₃.

Oral intermittent vitamin D substitution: influence of pharmaceutical form and dosage frequency on medication adherence: a randomized clinical trial

Background

To assess adherence to and preference for vitamin D substitution with different pharmaceutical forms and frequencies of administration.

Methods

A focus group of stakeholders aimed at preparing the design of an interventional, randomized, cross-over study with 2 × 2 groups obtaining monthly or weekly vitamin D products in liquid or solid form for 3 months each. Dosage corresponds to cumulated amount of recommended 800 IU daily (5.600 IU weekly / 24.000 IU monthly). Main inclusion criteria were a vitamin D serum value < 50 nmol/l and age ≥ 18 years. Primary endpoint was adherence, secondary endpoints were preferences and vitamin D serum levels.

Results

The focus group reached consensus for preference of a monthly administration of solid forms to adults.

Full datasets were obtained from 97 participants. Adherence was significantly higher with monthly (79.5–100.0%) than weekly (66.4–98.1%) administration. Vitamin D levels increased significantly (p < 0.001) in all participants. An optimal value of > 75 nmol/l was achieved by 32% after 3 months and by 50% after 6 months. Preferred formulation was solid form (tablets, capsules) for 71% of participants, and preferred dosage frequency was monthly for 39% of participants.

Conclusions

Monthly oral vitamin D in solid form lead to the highest adherence, and is preferred by the participants. However, only one third of study participants achieved values in the optimal range of > 75 nmol/l cholecalciferol using weekly or monthly administration providing an average daily cholecalciferol dose of 800 IU.

Trial registration

NCT03121593 | SNCTP000002251. Registered 30. May 2017,. Prospectively registered.

Evaluation of Self-Assessed State of Health and Vitamin D Knowledge in Emirati and International Female Students in United Arab Emirates (UAE)

INTRODUCTION

Globally, vitamin D deficiency is one of the most common deficiencies, affecting nearly half the world's population. The objective of this survey was to assess and compare the knowledge about vitamin D and the perceived state of health in Emirati and international tourist female students in Dubai, United Arab Emirates (UAE).

METHODS

This is a cross-sectional study that took place in universities in Dubai, United Arab Emirates. This survey consisted of 17 multiple choice questions and was adapted from a study recently conducted in Poland. The first part of the survey assessed levels of supplementation, diet and UV exposure. Another section evaluated the participants' self-assessed state of health in terms of vitamin D testing, symptoms related to vitamin D deficiency and general welbeing. The collected data were statistically analyzed using SPSS statistics for windows version 26.0 (SPSS Inc., Chicago, IL, United States). Statistical significance was set at P < 0.05.

RESULTS

105 respondents were Emiratis and 65 were international students. The average age was 21, with an average BMI 23.3 kg/m2. Almost one-third of each group reported using Vitamin D supplements once weekly. The vast majority of both groups reported rarely getting tanned. Almost all participants in both groups reported regular consumption of Vitamin D rich foods. In both groups, more than half reported consuming milk and cheese regularly and up to one-third reported consuming fish in a regular manner. Although more than half of the students rated their health as good; more than two-thirds reported experiencing muscle pain; only half reported having their blood Vitamin D levels measured once; half reported experiencing problems with concentration and more than three-quarters reported experiencing bad mood in the past month. The prevalence of these symptoms was almost similar across different categories of vitamin D supplementation, tanning habits, dietary intake, or nationality. No statistically significant differences were noted between the Emirati and International tourist students regarding any of the studied variables.

CONCLUSION

Notably, more Emirati students were aware of the association between vitamin D and osteoporosis than International tourist students (40% vs. 21.9%, respectively; p < 0.05). On the other hand, both groups had lower knowledge about the relationship between vitamin D deficiency and depression, Rheumatoid Arthritis and Hypertension, and the optimal vitamin D level; however, no statistically significant differences were noted regarding this knowledge of Emiratis and international students.

Seasonal variation and correlation analysis of vitamin D and parathyroid hormone in Hangzhou, Southeast China

This study aimed to describe the 25‐hydroxyvitamin D (25(OH)D) and parathyroid hormone (PTH) status of Southeast Chinese individuals influenced by season. The secondary aim was to determine the cutoff for sufficient 25(OH)D in a four‐season region. From January 2011 to June 2014, a total of 17 646 individuals were evaluated in our study. The serum levels of PTH were detected simultaneously in 5579 cases. A total of 25(OH)D and intact PTH were measured by the electrochemiluminescent immunoassay. The distribution of the concentration, prevalence and seasonal variability of 25(OH)D and PTH were studied. The mean 25(OH)D concentration in our study was 43.00(30.40) nmol/L. The prevalence of insufficiency (25(OH)D < 50 nmol/L) was 62.87% and that of deficiency (<30 nmol/L) was 28.54%. Mean serum 25(OH)D levels revealed a limited sinusoidal profile throughout the year and were significantly higher in Autumn. On the other hand, PTH levels showed an opposite response to seasonal effects relative to 25(OH)D. Age, BMI and daylight were not significantly correlated with 25(OH)D and serum PTH reached a plateau at higher values of serum 25(OH)D of 42.86 nmol/L. This study demonstrated that Vitamin D insufficiency is highly prevalent in Southeast China. The concentration of 25(OH)D in the male group was generally higher than that in the female group. Seasonal variation was an important aspect of 25(OH)D and PTH concentration. This study revealed that the optimal serum threshold of 25(OH)D for bone health should be between 40 and 50 nmol/L for Southeast Chinese individuals.

Oxidative Stress, Diet and Prostate Cancer

Prostate cancer has become the second leading cancer in men worldwide. Androgen plays an important role in normal functioning, development, and differentiation of the prostate, and thus is considered to be the most powerful candidate that mediates reactive oxygen species (ROS) balance in the prostate. The elevation of ROS has been associated with the progression and development of this disease. Conventional therapy has shown a high cure rate in patients with localized prostate cancer. Despite the patients respond favorably initially, this therapy fails to response in the advanced stage of the diseases even in the absence of androgens. Indeed, the onset and progression of prostate cancer could be prevented by changing dietary habits. Much information indicates that oxidative stress and prostate cancer can be modulated by dietary components rich in antioxidants. While there is substantial evidence to suggest an association between prostate cancer risk and ROS-mediated oxidative stress; therefore, the interactions and mechanisms of this phenomenon are worth to discuss further. This review aimed to discuss the mechanisms of action of oxidative stress involved in the progression of prostate cancer. We also highlighted how some of the vital dietary components dampen or exacerbate inflammation, oxidative stress, and prostate cancer. Overall, the reported information would provide a useful approach to the prevention of prostate cancer.

Influence of daily 10-85 μg vitamin D supplements during pregnancy and lactation on maternal vitamin D status and mature milk antirachitic activity

Pregnant and lactating women and breastfed infants are at risk of vitamin D deficiency. The supplemental vitamin D dose that optimises maternal vitamin D status and breast milk antirachitic activity (ARA) is unclear. Healthy pregnant women were randomised to 10 (n 10), 35 (n 11), 60 (n 11) and 85 (n 11) µg vitamin D3/d from 20 gestational weeks (GW) to 4 weeks postpartum (PP). The participants also received increasing dosages of fish oil supplements and a multivitamin. Treatment allocation was not blinded. Parent vitamin D and 25-hydroxyvitamin D (25(OH)D) were measured in maternal plasma at 20 GW, 36 GW and 4 weeks PP, and in milk at 4 weeks PP. Median 25(OH)D and parent vitamin D at 20 GW were 85 (range 25-131) nmol/l and 'not detectable (nd)' (range nd-40) nmol/l. Both increased, seemingly dose dependent, from 20 to 36 GW and decreased from 36 GW to 4 weeks PP. In all, 35 µg vitamin D/d was needed to increase 25(OH)D to adequacy (80-249 nmol/l) in &gt;97·5 % of participants at 36 GW, while &gt;85 µg/d was needed to reach this criterion at 4 weeks PP. The 25(OH)D increments from 20 to 36 GW and from 20 GW to 4 weeks PP diminished with supplemental dose and related inversely to 25(OH)D at 20 GW. Milk ARA related to vitamin D3 dose, but the infant adequate intake of 513 IU/l was not reached. Vitamin D3 dosages of 35 and &gt;85 µg/d were needed to reach adequate maternal vitamin D status at 36 GW and 4 weeks PP, respectively.

Changes in Vitamin D Status in Overweight Middle-Aged Adults with or without Impaired Glucose Metabolism in Two Consecutive Nordic Summers

Background

Sun exposure is the main driver of vitamin D synthesis. High latitude, obesity, and type 2 diabetes mellitus (T2DM) are all risk factors for vitamin D deficiency. However, the seasonal variation in vitamin D concentrations (25[OH]D) in such populations before and after sun exposure during the summer is unknown. Therefore, we investigated 25[OH]D status before and after two consecutive summers in high latitude and its associations with body fat, sex, and glucose metabolism.

Methods

158 participants from Sweden (87 women, 71 men; mean age, 60 ± 5 y; body mass index ≥ 25 kg/m²) and 25[OH]D were measured and evaluated in relation to normal or impaired glucose tolerance, body composition, and dietary habits during summer season.

Results

Eighty-four percent of the participants were categorized with low to deficient 25[OH]D values before summer (55.1 ± 21.7 nmol·L⁻¹), with a significant increase after the summer season (66.3 ± 21.0 nmol·L⁻¹; P < 0.001). However, the values remained below the recommended range (76–250 nmol·L⁻¹) in 66% of the participants. These findings were verified in a subgroup of the study population during the subsequent summer. Participants who reported use of vitamin D supplements had higher initial concentrations (64.2 ± 20.1 nmol·L⁻¹) compared to nonusers (53.7 ± 21.7 nmol·L⁻¹; P=0.04). Further, 25[OH]D values correlated negatively with fat mass (kg) prior to summer only in the female population (r=−0.29,  P=0.008).

Conclusions

In the present study, sun exposure had a beneficial but insufficient effect on 25[OH]D levels, and the same levels were documented in two consecutive summer seasons, confirming that vitamin D supplementation in both summer and winter should be considered in this population.

Influence of daily 10–85 μg vitamin D supplements during pregnancy and lactation on maternal vitamin D status and mature milk antirachitic activity

Pregnant and lactating women and breastfed infants are at risk of vitamin D deficiency. The supplemental vitamin D dose that optimises maternal vitamin D status and breast milk antirachitic activity (ARA) is unclear. Healthy pregnant women were randomised to 10 (n 10), 35 (n 11), 60 (n 11) and 85 (n 11) µg vitamin D3/d from 20 gestational weeks (GW) to 4 weeks postpartum (PP). The participants also received increasing dosages of fish oil supplements and a multivitamin. Treatment allocation was not blinded. Parent vitamin D and 25-hydroxyvitamin D (25(OH)D) were measured in maternal plasma at 20 GW, 36 GW and 4 weeks PP, and in milk at 4 weeks PP. Median 25(OH)D and parent vitamin D at 20 GW were 85 (range 25–131) nmol/l and ‘not detectable (nd)’ (range nd–40) nmol/l. Both increased, seemingly dose dependent, from 20 to 36 GW and decreased from 36 GW to 4 weeks PP. In all, 35 µg vitamin D/d was needed to increase 25(OH)D to adequacy (80–249 nmol/l) in >97·5 % of participants at 36 GW, while >85 µg/d was needed to reach this criterion at 4 weeks PP. The 25(OH)D increments from 20 to 36 GW and from 20 GW to 4 weeks PP diminished with supplemental dose and related inversely to 25(OH)D at 20 GW. Milk ARA related to vitamin D3 dose, but the infant adequate intake of 513 IU/l was not reached. Vitamin D3 dosages of 35 and >85 µg/d were needed to reach adequate maternal vitamin D status at 36 GW and 4 weeks PP, respectively.

Determinants of vitamin D status in physically active elderly in the Netherlands

Purpose

Vitamin D deficiencies are common in elderly, which increases the risk for, e.g., bone fractures. Identification of determinants of vitamin D status may provide leads for specific deficiency prevention strategies. Although determinants of vitamin D status have been studied in various populations, this has not been examined in elderly that have a physically active lifestyle.

Methods

Vitamin D status of 450 physically active elderly who do not use vitamin D supplements was determined and information on possible determinants (demographic, dietary intake and physical activity) was collected around a prolonged four day walking event in July and analyzed in linear regression models.

Results

The average summertime serum 25(OH)D concentration was 88.8 ± 22.4 nmol/L. Only 2% of the participants had a 25(OH)D concentration below 50 nmol/L. Dietary intake of vitamin D was 4.0 ± 1.9 µg/day, and the participants spent 12.4 ± 8.6 h/week on outdoor activities. In the multivariate model, lower age (= − 0.48, 95% CI − 0.80 to − 0.16), lower BMI (= − 0.86, 95% CI − 1.62 to − 0.10), being a moderate to high drinker versus a non-drinker (= 7.97, 95% CI 0.43–15.51) and more outdoor physical activity (= 0.25, 95% CI 0.01–0.50) were significantly associated with higher 25(OH)D concentrations.

Conclusions

In physically active elderly, vitamin D status was very high in summertime, with few deficiencies, suggesting that elderly with a physical active lifestyle might not necessarily need supplements during the summer period. Lower age, lower BMI, higher alcohol intake and more outdoor physical activity had a significant association with vitamin D status.

Exercise and Diabetes: A Narrative Review

Persons with diabetes might experience significant benefits through regular exercise. Not unlike the general population, those with diabetes could also lack motivation to participate in an exercise program. Often, those treating persons with diabetes lack training and/or interest in exercise prescription and are therefore unable to provide the needed information and encouragement. In many cases, reluctance to exercise could result from an inability to find an enjoyable exercise activity. Attempts to find activities that, not only provide effective aerobic challenges, but are also enjoyable to participate in are fraught with difficulty. Three electronic databases were searched in January 2017. Evidence for the merits of exercise for those with diabetes was robust. Numerous reports have addressed the degree of noncompliance to exercise recommendations and the barriers reported for this nonadherence. Additional studies concluded that most medical providers are deficient in formal training in the prescription of an exercise program. Newer studies are evaluating the effects of exercise and vitamin D supplementation and their interplay with diabetic peripheral neuropathy and ulceration. Exercise confers remarkable benefits to those with diabetes; however, the challenges to compelling patients with diabetes to exercise are formidable. An improved focus on exercise prescription and related motivation during provider training must be undertaken.

Predictors of 25-hydroxyvitamin D status among individuals with metabolic syndrome: a cross-sectional study

BACKGROUND

The risk of metabolic syndrome can be influenced by inadequate vitamin D levels, and exposure to sunlight is the main external source of vitamin D. The present study assessed the influence of environmental, biological, and nutritional factors in relation to seasonal 25-hydroxyvitamin D (25OHD) concentration in individuals with metabolic syndrome.

METHODS

This cross-sectional study enrolled 180 individuals with metabolic syndrome aged between 18 and 80 years. The 25OHD concentration was considered the dependent variable; independent variables included age, sex, skin color, use of sunscreen, skin type, sun exposure score, ultraviolet radiation index, geographic location, season, body mass index, waist:hip ratio, waist circumference, parathyroid hormone level, total serum calcium level, and calcium and vitamin D intake.

RESULTS

The average vitamin D in individuals evaluated in summer 32 ± 10 ng/mL was greater than in the winter 26 ± 8 ng/mL (p < 0.017). HDL-cholesterol was the only component of the MetS that differed significantly between the seasons (p < 0.001), showing higher concentrations in autumn 45 ± 8 mg/dL than in summer 35 ± 8 mg/dL. In the multiple regression model, gender, WHR, sun exposure score, and winter vs. summer explained 10% of the variation in 25OHD concentration (p = 0.004).

CONCLUSIONS

Sex, waist:hip ratio, sun exposure, and summer season were predictors of 25OHD status among individuals with metabolic syndrome. HDL-cholesterol was the only component of metabolic syndrome that differed significantly between the seasons.

Effects of Maternal Vitamin D Supplementation on the Maternal and Infant Epigenome

INTRODUCTION

Mothers and infants are at high risk for inadequate vitamin D status. Mechanisms by which vitamin D may affect maternal and infant DNA methylation are poorly understood.

OBJECTIVE

This study quantified the effects of vitamin D₃ supplementation on DNA methylation in pregnant and lactating women and their breastfed infants.

MATERIALS AND METHODS

In this randomized controlled pilot study, pregnant women received vitamin D₃ 400 international units (IU) (n = 6; control) or 3,800 IU (n = 7; intervention) daily from late second trimester through 4-6 weeks postpartum. Epigenome-wide DNA methylation was quantified in leukocytes collected from mothers at birth and mother-infant dyads at 4-6 weeks postpartum.

RESULTS

At birth, intervention group mothers showed DNA methylation gain and loss at 76 and 89 cytosine-guanine (CpG) dinucleotides, respectively, compared to controls. Postpartum, methylation gain was noted at 200 and loss at 102 CpGs. Associated gene clusters showed strongest biologic relevance for cell migration/motility and cellular membrane function at birth and cadherin signaling and immune function at postpartum. Breastfed 4-6-week-old infants of intervention mothers showed DNA methylation gain and loss in 217 and 213 CpGs, respectively, compared to controls. Genes showing differential methylation mapped most strongly to collagen metabolic processes and regulation of apoptosis.

CONCLUSIONS

Maternal vitamin D supplementation during pregnancy and lactation alters DNA methylation in mothers and breastfed infants. Additional work is needed to fully elucidate the short- and long-term biologic effects of vitamin D supplementation at varying doses, which could hold important implications for establishing clinical recommendations for prenatal and offspring health promotion.

Contribution of sun exposure to the vitamin D dose received by various groups of the Spanish population

Although the harmful effects of excessive exposure to solar ultraviolet (UV) radiation are well known, the recommended dose of UV radiation is beneficial for the synthesis of vitamin D by the skin, in addition to being useful in the treatment of various illnesses and mental problems. Numerous studies have shown that vitamin D performs important functions in the human organism, such as absorbing calcium and phosphorous and contributing to the immune system, among others. Several studies have found that a high percentage of various groups of the Spanish population suffer from vitamin D deficiency, and since very few natural foods contain vitamin D, it was considered important to determine whether groups such as schoolchildren, outdoor workers and athletes, receive enough solar radiation to produce adequate levels of vitamin D in their daily activities. It was found that the amount of vitamin D (in IU) produced by personal effective solar UV doses could exceed the recommended dose of 1000IU/day in spring and summer, while the winter estimate (about 220IU/day) is only one quarter of the recommended dose. These results suggest that most people would not receive the recommended daily vitamin D dose in winter from exposure to solar UV radiation, the main source of vitamin D.

Determinants of Vitamin D Status in Indian School-children

INTRODUCTION

Due to the high prevalence of Vitamin D deficiency in spite of abundant sunshine and scarcity of studies investigating Vitamin D status in Indian children from rural and semirural areas, the objectives of this cross-sectional study were to: (1) assess the Vitamin D status of school-children in a semi-rural setting and (2) identify the determinants of Vitamin D status in these children.

MATERIALS AND METHODS

Data collected included anthropometric measurements (height and weight), body composition, three-one-day dietary recall method, demographic data, and sunlight exposure. Serum 25-hydroxyVitamin D (25(OH)D) was estimated by enzyme-linked immunosorbent assay (ELISA) technique. SPSS software was used for statistical analysis.

RESULTS

Anthropometric characteristics of the children were similar and mean serum 25(OH)D concentration was 58.5 ± 10.3 nmol/L with no significant differences between genders. Around 80% children reported sunlight exposure of 2 h or more. A majority (71%) of children were Vitamin D insufficient with serum 25(OH)D concentrations between 50 and 74.9 nmol/L. Determinants of Vitamin D identified were duration of sunlight exposure and body fat percent. Significant (P < 0.05) positive association of duration of sunlight exposure was observed with serum 25(OH)D concentrations, while BF% showed a negative association with serum 25(OH)D (β = -0.307; standard error = 0.1388; P < 0.05).

DISCUSSION

We have reported a high prevalence of Vitamin D insufficiency in school-children aged 6-12 years, from a semirural setting, in spite of a majority (80%) reporting >2 h of sunlight exposure. We have also demonstrated that duration of sunlight exposure and body fat percentage are the two important determinants of serum 25(OH)D concentrations in these children.

Milk vitamin D in relation to the 'adequate intake' for 0-6-month-old infants: a study in lactating women with different cultural backgrounds, living at different latitudes

Breast-fed infants are susceptible to vitamin D deficiency rickets. The current vitamin D 'adequate intake' (AI) for 0-6-month-old infants is 10 µg/d, corresponding with a human milk antirachitic activity (ARA) of 513 IU/l. We were particularly interested to see whether milk ARA of mothers with lifetime abundant sunlight exposure reaches the AI. We measured milk ARA of lactating mothers with different cultural backgrounds, living at different latitudes. Mature milk was derived from 181 lactating women in the Netherlands, Curaçao, Vietnam, Malaysia and Tanzania. Milk ARA and plasma 25-hydroxyvitamin D (25(OH)D) were analysed by liquid-chromatography-MS/MS; milk fatty acids were analysed by GC-flame ionisation detector (FID). None of the mothers reached the milk vitamin D AI. Milk ARA (n; median; range) were as follows: Netherlands (n 9; 46 IU/l; 3-51), Curaçao (n 10; 31 IU/l; 5-113), Vietnam: Halong Bay (n 20; 58 IU/l; 23-110), Phu Tho (n 22; 28 IU/l; 1-62), Tien Giang (n 20; 63 IU/l; 26-247), Ho-Chi-Minh-City (n 18; 49 IU/l; 24-116), Hanoi (n 21; 37 IU/l; 11-118), Malaysia-Kuala Lumpur (n 20; 14 IU/l; 1-46) and Tanzania-Ukerewe (n 21; 77 IU/l; 12-232) and Maasai (n 20; 88 IU/l; 43-189). We collected blood samples of these lactating women in Curaçao, Vietnam and from Tanzania-Ukerewe, and found that 33·3 % had plasma 25(OH)D levels between 80 and 249·9 nmol/l, 47·3 % between 50 and 79·9 nmol/l and 19·4 % between 25 and 49·9 nmol/l. Milk ARA correlated positively with maternal plasma 25(OH)D (range 27-132 nmol/l, r 0·40) and milk EPA+DHA (0·1-3·1 g%, r 0·20), and negatively with latitude (2°S-53°N, r -0·21). Milk ARA of mothers with lifetime abundant sunlight exposure is not even close to the vitamin D AI for 0-6-month-old infants. Our data may point at the importance of adequate fetal vitamin D stores.

The half-life of 25(OH)D after UVB exposure depends on gender and vitamin D receptor polymorphism but mainly on the start level

The 25(OH)D decrease over time in a group (N= 22) with high 25(OH)D start levels was exponential. The half-life (T_1/2) was 89 days and prolonged in materials with lower 25(OH)D start levels.