Vitamin D dose response is underestimated by Endocrine Society's Clinical Practice Guideline

Meta-Analysis of European Clinical Trials Characterizing the Healthy-Adult Serum 25-hydroxyvitamin D Response to Vitamin D Supplementation

To obtain reliable data that allow health authorities to re-evaluate recommendations for oral vitamin D uptake, we conducted a meta-analysis to investigate the impact of supplementation on serum 25-hydroxyvitamin D (25(OH)D) levels in healthy adults in Europe. Of the publications identified (n = 4005) in our literature search (PUBMED, through 2 January 2022), 49 primary studies (7320 subjects, 73 study arms) were eligible for inclusion in our meta-analysis. The risk of bias was assessed using the Cochrane RoB tool based on seven categories, according to which each study is rated using three grades, and overall was rated as rather low. The median duration of intervention was 136.78 days (range, 1088 days); the mean weighted baseline 25(OH)D concentration and mean age were 33.01 vs. 33.84 nmol/L and 46.8 vs. 44.8 years in the vitamin D and placebo groups, respectively. Using random-effects models, 25(OH)D levels were increased by 36.28 nmol/L (95% CI 31.97-40.59) in the vitamin D group compared to the placebo, with a relative serum increment of 1.77 nmol/L per 2.5 μg of vitamin D daily. Notably, the relative serum 25(OH)D increment was affected by various factors, including the dosage and baseline serum 25(OH)D concentration, decreasing with increasing vitamin D doses and with increasing baseline serum levels. We estimate that supplementation in all healthy adults in Europe with appr. 25 μg of vitamin D (1000 IU) daily would raise serum 25(OH)D levels in 95% of the population to ≥50 nmol/L. Our work provides health authorities with reliable data that can help to re-evaluate recommendations for oral vitamin D supplementation.

Clarifying the Heterogeneity in Response to Vitamin D in the Development, Prevention, and Treatment of Type 2 Diabetes Mellitus: A Narrative Review

In this review, we explore the potential drivers of heterogeneity in response to Vitamin D (VitD) therapy, such as bioavailability, sex-specific response, and autoimmune pathology, in those at risk for and diagnosed with T2DM. In addition, we propose distinct populations for future interventions with VitD. The literature concerning VitD supplementation in the prevention, treatment, and remission of type 2 diabetes mellitus (T2DM) spans decades, is complex, and is often contradictory with mixed findings upon intervention. By association, VitD status is powerfully predictive with deficient subjects reporting greater risk for T2DM, conversion to T2DM from prediabetes, and enhanced response to VitD therapy. Preclinical models strongly favor intervention with VitD owing to the pleiotropic influence of VitD on multiple systems. Additional research is crucial as there remain many questions unanswered that are related to VitD status and conditions such as T2DM. Future research must be conducted to better understand the potentially spurious relationships between VitD status, supplementation, sun exposure, health behaviors, and the diagnosis and management of T2DM. Public health practice can greatly benefit from a better understanding of the mechanisms by which we can reliably increase VitD status and how this can be used to develop education and improve health behaviors.

Daily vs. monthly oral vitamin D3 for treatment of symptomatic vitamin D deficiency in infants: a randomized controlled trial

OBJECTIVES

Compare the efficacy and safety of daily vs. monthly oral vitamin D₃ in treating symptomatic vitamin D deficiency in infants.

METHODS

90 infants with symptomatic vitamin D deficiency were randomized into Daily (D) [46 infants] and Bolus (B) [44 infants] groups to receive oral vitamin D₃, daily (2000 IU/day) and bolus (60,000 IU/month) for three months respectively. Both groups received daily oral calcium @50 mg/kg/day. Serum calcium (Ca), phosphate (P), alkaline phosphatase (ALP), 25-hydroxy cholecalciferol [25(OH)D], parathyroid hormone (PTH) levels, urine calcium: creatinine ratio and radiological score were assessed at baseline, 4 and 12 weeks. At the end of 12 weeks, 78 infants were available for evaluation of efficacy and safety of both regimens.

RESULTS

Both regimens led to a statistically significant increase in Ca and P levels and fall in ALP and PTH levels from baseline to 4 and 12 weeks of therapy, with no inter-group difference. Infants in group D had statistically significant higher mean 25(OH)D levels as compared to group B at 4 weeks (group D 130.89 ± 43.43 nmol/L, group B - 108.25 ± 32.40 nmol/L; p - 0.012) and 12 weeks (group D - 193.69 ± 32.47 nmol/L, group B - 153.85 ± 33.60 nmol/L; p<0.001). Eight infants [group D - 6/41 (14.6 %); group B - 2/37 (5.4 %), p=0.268] developed mild asymptomatic hypercalcemia without hypercalciuria at 12 weeks that corrected spontaneously within a week.

CONCLUSIONS

Both daily and monthly oral vitamin D₃ in equivalent doses are efficacious and safe for treating symptomatic vitamin D deficiency in infants.

Efficacy and safety of various oral regimens (three oral doses) and schedules (daily v. monthly) of cholecalciferol in North Indian adults with low vitamin D status: evidence from a randomised controlled trial

Vitamin D (VD) deficiency (serum 25 hydroxy vitamin D (25(OH)D) concentration of < 20 ng/ml), in endemic proportions, demands a supplementation strategy with optimal dosing regimens. A randomised parallel-group, active-controlled trial was conducted among apparently healthy, VD-deficient subjects, aged 18-60 years who received 600 μg/d (Group A), 1000 μg/d (Group B), 2000 μg/d (Group C) and 60 000 μg/month (Group D) of oral cholecalciferol. The intervention was carried in two phases (I and II) of 12 weeks each, with same dose, separated by a washout phase of 12 weeks. Serum 25(OH)D, intact parathyroid hormones (iPTH), Ca, phosphorous (PO4), alkaline phosphatase (ALP) and spot urine Ca/Cr were measured at baseline, 12, 24 and 36 weeks following the intervention, and adverse events were recorded at each occurrence and at 12, 24 and 36 weeks. A statistically significant time-group interaction was found in serum 25(OH)D concentration (P < 0·05). Serum 25(OH)D concentration increased significantly from baseline to 12 weeks (P < 0·05) in all the groups with no change at 24 weeks but further increase at 36 weeks (P < 0·05). At the end of the study, Group C had maximum increment in serum 25(OH)D concentration, while as Groups C and D (95 %, and 90 %) had higher proportion of subjects VD sufficient than Groups A and B (65 % and 78 %) (P < 0·05). No significant time-dose interactions were observed in serum iPTH, Ca, PO4 and ALP or urine Ca/Cr ratio. Three subjects (two in Group C and one in Group D) developed transient hypercalciuria. Supplementation with daily 2000 μg or monthly 60 000 μg of oral cholecalciferol among adults seems optimal and safe.

The effects of vitamin D-fortified foods on circulating 25(OH)D concentrations in adults: a systematic review and meta-analysis

Improvement of vitamin D status of the general population has been a challenge for policymakers. We conducted a meta-analysis to evaluate whether vitamin D-fortified products can be a suitable solution for tackling vitamin D deficiency. Our secondary objective was to determine the effect of some variables including age, latitude and BMI on efficacy of this strategy. MEDLINE, PubMed, Embase, Cochrane Library and Google Scholar were searched and 231 studies were found in a preliminary search. After screening of titles and abstracts, 23 studies were selected. Pooled data comparing fortification with vitamin D +/- Ca with control showed statistically significant effect on total 25(OH)D concentrations (2002 participants, mean difference (MD): 25·4 nmol/l, (95 % CI 19·5, 31·3)). The subgroup analysis by duration of intervention (less than 12 weeks v. more than 12 weeks) and type of vehicle (dairy product, juice, grain product, oil and combination of dairy and grain products), isoform of the vitamin (D₃v. D₂) and dose of the fortificant (≥ 1000 IU/d v. < 1000 IU/d) also indicated significant effect of fortification with vitamin D on serum 25(OH)D concentrations. In conclusion, the circulating 25(OH)D response to vitamin D-fortified food consumption is influenced by age, BMI and the baseline 25(OH)D concentrations. Notwithstanding, an average of 2 nmol/l increase in circulating 25(OH)D concentration for each 100 IU vitamin D intake per d is expected for general adult population. These findings can be informative for policymakers to tackle vitamin D deficiency through food fortification strategy.

The Role of Vitamin D Intake on the Prognosis and Incidence of Lung Cancer: A Systematic Review and Meta-Analysis

The correlation between vitamin D intake and lung cancer development is controversial. This meta-analysis aims to evaluate the relationship between vitamin D and the prognosis and incidence of lung cancer. A comprehensive database search on PubMed, Web of Science, EBSCO, and Cochrane Library was carried out from the beginning to November 2020. Long-term survival and the incidence rate of patients with lung cancer were the primary outcomes of the study. Ten eligible studies were selected for the meta-analysis following specific inclusion and exclusion criteria. Four included studies, covering 5,007 patients, compared the overall survival (OS) and relapse-free survival (RFS) of lung cancer patients among total vitamin D users with non-users. Significantly, the estimated pooled hazard ratio (HR) revealed that vitamin D could improve OS and RFS of lung cancer patients [HR=0.83, 95% CI (0.72-0.95); HR=0.79, 95% CI (0.61-0.97), respectively]. Vitamin D intake was inversely associated with lung cancer incidence in six studies [OR=0.90, 95% CI (0.83-0.97)]. The present meta-analysis shows vitamin D not only improves the long-term survival of lung cancer patients but has a beneficial effect on the incidence of lung cancer. Notwithstanding, more studies are needed to confirm the study results.

Vitamin D3 Dose Requirement That Raises 25-Hydroxyvitamin D to Desirable Level in Overweight and Obese Elderly

CONTEXT

Guidelines for the dosage of vitamin D supplementation vary widely globally.

OBJECTIVE

To investigate the impact of 2 vitamin D doses, bracketed between the IOM recommended dietary allowance (RDA) and the upper tolerable limit, on vitamin D nutritional status in elderly individuals.

METHODS

This post hoc analysis of data collected from a 12-month, double-blind, randomized control trial included 221 ambulatory participants (≥ 65 years) with a mean BMI of 30.2 kg/m2 and a mean baseline serum 25-hydroxyvitamin D [25(OH)D] level of 20.4 ± 7.4 ng/mL, who were recruited from 3 outpatient centers in Lebanon. All participants received 1000 mg of elemental calcium daily from calcium citrate plus the daily equivalent of either 600 IU or 3750 IU of vitamin D3.

RESULTS

Mean 25(OH)D level at 12 months was 26.0 ng/mL with low dose and 36.0 ng/mL with high dose vitamin D3. The proportion of participants reaching a value ≥ 20 ng/mL was 86% in the low dose, and 99% in the high dose arms, with no gender differences. The increment of 25(OH)D per 100 IU/day was 1 ng/mL with the low dose, and 0.41 ng/mL with the high dose. Serum 25(OH)D levels at 1 year were highly variable in both treatment arms. Baseline 25(OH)D level and vitamin D dose-but not age, BMI, gender, or season-were significant predictors of serum 25(OH)D level post-intervention.

CONCLUSION

The IOM Recommended Dietary Allowance (RDA) of 600 IU/day does not bring 97.5% of ambulatory elderly individuals above the desirable threshold of 20 ng/mL. Country-specific RDAs are best derived taking into account the observed variability and predictors of achieved 25(OH)D levels.

Vitamin D retesting by general practitioners: a factor and cost analysis

OBJECTIVES

Vitamin D testing by Primary Care doctors is increasing, placing greater workloads on healthcare systems. There is little data though on vitamin D retesting in Ireland. This study aims to investigate the factors associated with vitamin D retesting by Irish General Practitioners (GPs) and examine the resulting costs.

METHODS

This is a retrospective analysis over 5 years (2014-2018) of GP requested 25-hydroxyvitamin D (25(OH)D) results in 36,458 patients at a major city hospital in Dublin, Ireland. Those with one test were compared with individuals who were retested and samples categorised to determine changes in status between tests.

RESULTS

Nearly one in four patients (n=8,305) were retested. Positive predictors of retesting were female (p<0.001), age (60-69 years, p<0.001), location (Co. Kildare, p<0.001) and initial deficiency (<30 nmol/L, p<0.001) or insufficiency (30-49.9 nmol/L, p<0.001). Vitamin D status improved on retesting, with deficiency halving on first retest (9 vs. 18%, p<0.001) and dropping to 6% on further retests. About 12.2% of retests were done within 3 months and 29% had ≥2 retests within 1 year. 57% of retests were in those initially vitamin D replete (>50 nmol/L). The annual cost of inappropriate testing was €61,976.

CONCLUSIONS

One in four patients were retested and this varied by age, gender and patient location. Over 10% of retests were inappropriately early (<3 months), a third too frequent and over half were in replete individuals incurring significant costs. Clear guidance for GPs on minimum retesting intervals is needed, as well as laboratory ordering systems to limit requests using pre-defined criteria.

The Role of Vitamin D in the Management of Chronic Pain in Fibromyalgia: A Narrative Review

INTRODUCTION

Fibromyalgia (FM) is a complex disorder characterized primarily by chronic, widespread musculoskeletal pain. Currently, the Food and Drug Administration (FDA) has approved the use of three medications to treat FM: pregabalin, duloxetine, and milnacipran. The pharmaceutical intervention has lacked consistent pain relief among all patients. Therefore, the investigation into alternative treatment options has grown in interest. This narrative review aims to evaluate the evidence regarding vitamin D for the treatment of FM.

METHODS

Narrative review.

RESULTS

Low serum vitamin D has been linked to various chronic pain states. An association between vitamin D deficiency and FM has been reported but is controversial in the literature. Some studies have documented the beneficial effects of vitamin D supplementation on reducing pain symptoms and improving the overall quality of life in those with FM. Despite these positive findings, many of the studies regarding this topic lack adequate power to make substantial conclusions about the effects of vitamin D on FM.

CONCLUSION

Existing studies provide promising results. However, additional high-quality data on vitamin D supplementation is needed before recommendations for pain management can be made. Vitamin D supplementation is inexpensive, has minimal side effects, and can benefit FM patients regardless of its efficacy in pain control. Additionally, high-quality studies are warranted to fully elucidate the potential of vitamin D to manage chronic pain in FM.

Vitamin D and Allergy Susceptibility during Gestation and Early Life

Worldwide, the prevalence of allergies in young children, but also vitamin D deficiency during pregnancy and in newborns is rising. Vitamin D modulates the development and activity of the immune system and a low vitamin D status during pregnancy and in early life might be associated with an increased risk to develop an allergy during early childhood. This review studies the effects of vitamin D during gestation and early life, on allergy susceptibility in infants. The bioactive form of vitamin D, 1,25(OH)2D, inhibits maturation and results in immature dendritic cells that cause a decreased differentiation of naive T cells into effector T cells. Nevertheless, the development of regulatory T cells and the production of interleukin-10 was increased. Consequently, a more tolerogenic immune response developed against antigens. Secondly, binding of 1,25(OH)2D to epithelial cells induces the expression of tight junction proteins resulting in enhanced epithelial barrier function. Thirdly, 1,25(OH)2D increased the expression of anti-microbial peptides by epithelial cells that also promoted the defense mechanism against pathogens, by preventing an invasive penetration of pathogens. Immune intervention by vitamin D supplementation can mitigate the disease burden from asthma and allergy. In conclusion, our review indicates that a sufficient vitamin D status during gestation and early life can lower the susceptibility to develop an allergy in infants although there remains a need for more causal evidence.

Vitamin D levels and risk of type 1 diabetes: A Mendelian randomization study

BACKGROUND

Vitamin D deficiency has been associated with type 1 diabetes in observational studies, but evidence from randomized controlled trials (RCTs) is lacking. The aim of this study was to test whether genetically decreased vitamin D levels are causally associated with type 1 diabetes using Mendelian randomization (MR).

METHODS AND FINDINGS

For our two-sample MR study, we selected as instruments single nucleotide polymorphisms (SNPs) that are strongly associated with 25-hydroxyvitamin D (25OHD) levels in a large vitamin D genome-wide association study (GWAS) on 443,734 Europeans and obtained their corresponding effect estimates on type 1 diabetes risk from a large meta-analysis of 12 type 1 diabetes GWAS studies (Ntot = 24,063, 9,358 cases, and 15,705 controls). In addition to the main analysis using inverse variance weighted MR, we applied 3 additional methods to control for pleiotropy (MR-Egger, weighted median, and mode-based estimate) and compared the respective MR estimates. We also undertook sensitivity analyses excluding SNPs with potential pleiotropic effects. We identified 69 lead independent common SNPs to be genome-wide significant for 25OHD, explaining 3.1% of the variance in 25OHD levels. MR analyses suggested that a 1 standard deviation (SD) decrease in standardized natural log-transformed 25OHD (corresponding to a 29-nmol/l change in 25OHD levels in vitamin D-insufficient individuals) was not associated with an increase in type 1 diabetes risk (inverse-variance weighted (IVW) MR odds ratio (OR) = 1.09, 95% CI: 0.86 to 1.40, p = 0.48). We obtained similar results using the 3 pleiotropy robust MR methods and in sensitivity analyses excluding SNPs associated with serum lipid levels, body composition, blood traits, and type 2 diabetes. Our findings indicate that decreased vitamin D levels did not have a substantial impact on risk of type 1 diabetes in the populations studied. Study limitations include an inability to exclude the existence of smaller associations and a lack of evidence from non-European populations.

CONCLUSIONS

Our findings suggest that 25OHD levels are unlikely to have a large effect on risk of type 1 diabetes, but larger MR studies or RCTs are needed to investigate small effects.

Vitamin D Metabolism and Guidelines for Vitamin D Supplementation

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

Genome-wide Association Study for Vitamin D Levels Reveals 69 Independent Loci

We aimed to increase our understanding of the genetic determinants of vitamin D levels by undertaking a large-scale genome-wide association study (GWAS) of serum 25 hydroxyvitamin D (25OHD). To do so, we used imputed genotypes from 401,460 white British UK Biobank participants with available 25OHD levels, retaining single-nucleotide polymorphisms (SNPs) with minor allele frequency (MAF) > 0.1% and imputation quality score > 0.3. We performed a linear mixed model GWAS on standardized log-transformed 25OHD, adjusting for age, sex, season of measurement, and vitamin D supplementation. These results were combined with those from a previous GWAS including 42,274 Europeans. In silico functional follow-up of the GWAS results was undertaken to identify enrichment in gene sets, pathways, and expression in tissues, and to investigate the partitioned heritability of 25OHD and its shared heritability with other traits. Using this approach, the SNP heritability of 25OHD was estimated to 16.1%. 138 conditionally independent SNPs were detected (p value < 6.6 × 10-9) among which 53 had MAF < 5%. Single variant association signals mapped to 69 distinct loci, among which 63 were previously unreported. We identified enrichment in hepatic and lipid metabolism gene pathways and enriched expression of the 25OHD genes in liver, skin, and gastrointestinal tissues. We observed partially shared heritability between 25OHD and socio-economic traits, a feature which may be mediated through time spent outdoors. Therefore, through a large 25OHD GWAS, we identified 63 loci that underline the contribution of genes outside the vitamin D canonical metabolic pathway to the genetic architecture of 25OHD.

Challenges to Quantify Total Vitamin Activity: How to Combine the Contribution of Diverse Vitamers?

This state-of-the-art review aims to highlight the challenges in quantifying vitamin activity in foods that contain several vitamers of a group, using as examples the fat-soluble vitamins A and D as well as the water-soluble folate. The absorption, metabolism, and physiology of these examples are described along with the current analytical methodology, with an emphasis on approaches to standardization. Moreover, the major food sources for the vitamins are numerated. The article focuses particularly on outlining the so-called SLAMENGHI factors influencing a vitamer's' ability to act as a vitamin, that is, molecular species, linkage, amount, matrix, effectors of absorption, nutrition status, genetics, host-related factors, and the interaction of these. After summarizing the current approaches to estimating the total content of each vitamin group, the review concludes by outlining the research gaps and future perspectives in vitamin analysis. There are no standardized methods for the quantification of the vitamers of vitamin A, vitamin D, and folate in foods. For folate and β-carotene, a difference in vitamer activity between foods and supplements has been confirmed, whereas no difference has been observed for vitamin D. For differences in vitamer activity between provitamin A carotenoids and retinol, and between 25-hydroxyvitamin D and vitamin D, international consensus is lacking. The challenges facing each of the specific vitamin communities are the gaps in knowledge about bioaccessibility and bioavailability for each of the various vitamers. The differences between the vitamins make it difficult to formulate a common strategy for assessing the quantitative differences between the vitamers. In the future, optimized stationary digestive models and the more advanced dynamic digestive models combined with in vitro models for bioavailability could more closely resemble in vivo results. New knowledge will enable us to transfer nutrient recommendations into improved dietary advice to increase public health throughout the human life cycle.

Laboratory trend in vitamin D status in Ireland: Dual concerns about low and high 25OHD

Serum 25-hydroxyvitamin D (25OHD) is the pre-eminent estimate of vitamin D status that we have been measuring in a hospital laboratory setting since the 1970s. We previously evaluated the trend in 25OHD results in our laboratory from 1993 to 2013. Using a time series analysis of monthly average 25OHD results the trend was modelled, and this was used to forecast monthly average 25OHD from 2014 to 2016. In this study, all 25OHD results from 2014 to 2016 were retrieved (n = 67,922) and trimmed to 40,307 results after duplicates were excluded. The average monthly actual 25OHD was almost identical to the average monthly forecast 25OHD (p = 0.028) with a strong correlation between the actual 25OHD and forecast 25OHD (r = 0.69, p < 0.001). This upward trend is attributed to higher oral intake of vitamin D. We have a dual concern: policies to prevent hypovitaminosis D must be offset by strategies to avert hypervitaminosis D.

Evolution of Serum 25OHD in Response to Vitamin D3-Fortified Yogurts Consumed by Healthy Menopausal Women: A 6-Month Randomized Controlled Trial Assessing the Interactions between Doses, Baseline Vitamin D Status, and Seasonality

BACKGROUND

Adequate vitamin D status contributes to bone fragility risk reduction and possibly other pathological conditions that occur with aging. In response to pharmaceutical vitamin D3 supplements, several studies have documented the influence of doses, baseline status, and seasonality on serum 25-hydroyvitamin D (s25OHD).

OBJECTIVE

Using fortified yogurt, we investigated in one randomized controlled trial how both baseline status, as assessed by measuring s25OHD prior the onset of the trial, and the season of enrollment quantitatively influenced the response to the supplemented (Suppl.) of vitamin D3 (VitD3) in healthy community-dwelling women.

METHODS

A 24-week controlled trial was conducted in menopausal women (mean age: 61.5). Participants were randomized into 3 groups (Gr): Gr.Suppl.0, time controls maintaining dietary habits; Gr.Suppl.5 and Gr.Suppl.10 consuming one and two 125-g servings of VitD3-fortified yogurts with 5- and 10-µg daily doses, respectively. The 16 intervention weeks lasted from early January to mid-August, the 8 follow-up weeks, without product, from late August to mid-October. Before enrollment, subjects were randomized into 2 s25OHD strata: low stratum (LoStr): 25-50 nmol/L; high stratum (HiStr): >50-75 nmol/L.

RESULTS

All enrolled participants adhered to the protocol throughout the 24-week study: Gr.Suppl.0 (n = 45), Gr.Suppl.5 (n = 44), and Gr.Suppl.10 (n = 44). Over the 16 intervention and 8 follow-up weeks, s25OHD increased in both supplemented groups, more in Gr.Suppl.10 than in Gr.Suppl.5. At the end of the intervention, the subject proportion with s25OHD ≥ 50 nmol/L was 37.8, 54.5, and 63.6% in Gr.Suppl.0, Gr.Suppl.5, and Gr.Suppl.10, respectively. The constant rate of s25OHD per supplemental VitD3 microgram was greater in LoStr than HiStr. The s25OHD increase was greater with late (mid-March) than early (mid-January) inclusion.

CONCLUSION

This randomized trial demonstrates (1) a dose-dependent s25OHD improvement related to fortified yogurt consumption; (2) an inversely baseline-dependent increase in s25OHD; and (3) a seasonal effect that highlights the importance of VitD3-fortified foods during winter, even at 5 µg/d, in healthy menopausal women.

Vitamin D Vitamers Affect Vitamin D Status Differently in Young Healthy Males

Dietary intake of vitamin D includes vitamin D3 (vitD3), 25-hydroxyvitamin D3 (25OH-D3), and vitamin D2 (vitD2). However, the bioactivity of the different species has not been scientifically established. The hypothesis in this study was that vitD3, 25OH-D3, and vitD2 have an equal effect on 25-hydroxyvitamin D in serum (vitamin D status). To test our hypothesis, we performed a randomized, crossover study. Twelve young males consumed 10 µg/day vitD3 during a four-week run-in period, followed by 3 × 6 weeks of 10 µg/day vitD3, 10 µg/day 25OH-D3, and 10 µg/day vitD2. The content of vitD3, vitD2, 25OH-D3, and 25-hydroxyvitamin D2 (25OH-D2) in serum was quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The hypothesis that the three sources of vitamin D affect vitamin D status equally was rejected. Based on the assumption that 1 µg vitD3/day will show an increase in vitamin D status of 1.96 nmol/L, the results showed that 23 µg vitD2 and 6.8 µg 25OH-D3 was similar to 10 µg vitD3. These results demonstrate that further investigations are necessary to determine how to quantify the total vitamin D activity based on chemical quantification of the individual vitamin D metabolites to replace the total vitamin D activity assessed in biological rat models.

Patients with Nonalcoholic Fatty Liver Disease Have a Low Response Rate to Vitamin D Supplementation

Background: Hypovitaminosis D is associated with an increased severity of nonalcoholic fatty liver disease (NAFLD), but reports on the response to cholecalciferol (vitamin D₃) supplementation are conflicting.Objective: The objective of this study was to determine if standard vitamin D₃ supplementation is effective in NAFLD with hypovitaminosis D.Methods: Sixty-five well-characterized adults [age (mean ± SD): 51.6 ± 12.3 y] with biopsy-proven NAFLD were screened. Forty-two patients (the ratio of men to women was 13:29) had hypovitaminosis D (plasma 25-hydroxyvitamin D [25(OH)D] <30 ng/mL). An observational study was performed in NAFLD patients with hypovitaminosis D treated with 2000 IU cholecalciferol (vitamin D₃) daily for 6 mo per clinical practice. Plasma 25(OH)D, hepatic and metabolic panels, and metabolic syndrome components were assessed before and after cholecalciferol supplementation. Body composition was measured by using bioelectrical impedance analysis. The primary outcome measure was plasma 25(OH)D ≥30 ng/mL at the end of the study. Secondary outcomes included change in serum transaminases, fasting plasma glucose, and insulin and homeostasis model assessment of insulin resistance (HOMA-IR). Chi-square, Student's t tests, correlation coefficient, and multivariate analysis were performed.Results: Twenty-six (61.9%) patients had nonalcoholic steatohepatitis (NASH), and 16 (38.1%) had hepatic steatosis. After 6 mo of cholecalciferol supplementation, plasma 25(OH)D ≥30 ng/mL was observed in 16 subjects (38.1%; responders) whereas the remaining 26 patients (61.9%) were nonresponders with plasma 25(OH)D <30 ng/mL. Significantly fewer (P < 0.01) patients with NASH were responders (4 of 26, 15.4%) than those with hepatic steatosis (12 of 16, 75%). Baseline fasting serum alanine aminotransferase, plasma glucose, and HOMA-IR were similar in the responders and nonresponders, but the NASH score on the liver biopsy was lower (16.5%) in the responders (P < 0.001). Nonresponders had a higher fat mass (10.5%) and lower fat-free mass (10.4%) than responders did. End-of-treatment alanine aminotransferase and HOMA-IR improved only in responders. The baseline HOMA-IR and histological NASH score were independent predictors of nonresponse to cholecalciferol supplementation.Conclusions: Daily supplementation with 2000 IU cholecalciferol for 6 mo did not correct hypovitaminosis D in the majority of patients with NASH. Further studies are needed to determine if higher doses are effective. This trial was registered at clinicaltrials.gov as 13-00153.

Elevated PTH with normal serum calcium level: a structured approach

Normocalcaemic hyperparathyroidism is a common biochemical finding, usually identified during an assessment of bone or renal health. Hypercalcaemia must be considered by calculation of adjusted calcium, and a careful history taken to assess dietary calcium intake and for the possibility of a malabsorption syndrome. 25-hydroxyvitamin D (25OHD) should be measured and replaced if indicated. The management plan for the patient is influenced by the context in which calcium and PTH were measured. In this brief review we describe the assessment of a patient with normocalcaemic hyperparathyroidism.

Rising trend in vitamin D status from 1993 to 2013: dual concerns for the future

BACKGROUND

The Institute of Medicine 2011 Report on Dietary Reference Intakes for Calcium and Vitamin D specified higher intakes for all age groups compared to the 1997 report, but also cautioned against spurious claims about an epidemic of vitamin D deficiency and against advocates of higher intake requirements. Over 40 years, we have noted marked improvement in vitamin D status but we are concerned about hypervitaminosis D.

OBJECTIVE

We sought to evaluate the 25-hydroxyvitamin D (25OHD) trend over 20 years.

DESIGN

We retrieved all results of serum 25OHD from 1993 to 2013 (n=69 012) that was trimmed to one sample per person (n=43 782). We conducted a time series analysis of the monthly averages for 25OHD using a simple sequence chart and a running median smoothing function. We modelled the data using univariate auto-regressive integrated moving average (ARIMA) and forecast 25OHD levels up to 2016.

RESULTS

The time series sequence chart and smoother function demonstrated a steady upward trend with seasonality. The yearly average 25OHD increased from 36.1 nmol/l in 1993 to 57.3 nmol/l in 2013. The ARIMA model was a good fit for the 25OHD time series; it forecasted monthly average 25OHD up to the end of 2016 with a positive stationary R(2) of 0.377.

CONCLUSIONS

Vitamin D status improved over the past 40 years, but there remains a dual problem: there are groups at risk of vitamin D deficiency who need public health preventative measures; on the other hand, random members of the population are taking unnecessarily high vitamin D intakes for unsubstantiated claims.

A Randomized, Double-Blind, Parallel Study to Evaluate the Dose-Response of Three Different Vitamin D Treatment Schemes on the 25-Hydroxyvitamin D Serum Concentration in Patients with Vitamin D Deficiency

Many people worldwide are vitamin D (VTD) deficient or insufficient, and there is still no consensus on the dose of VTD that should be administered to achieve a 25(OH)D concentration of 20 or 30 ng/mL. In this study, we aimed to determine an adapted supplementation of VTD able to quickly and safely increase the vitamin D status of healthy adults with low 25(OH)D. One hundred and fifty (150) subjects were randomized into three groups, each to receive, orally, a loading dose of 50,000, 100,000 or 200,000 IU of VTD3 at Week 0, followed by 25,000, 50,000 or 100,000 IU at Week 4 and Week 8. Whereas 25(OH)D baseline values were not different between groups (p = 0.42), a significant increase was observed at Week 12 (p < 0.0001) with a mean change from baseline of 7.72 ± 5.08, 13.3 ± 5.88 and 20.12 ± 7.79 ng/mL. A plateau was reached after eight weeks. No related adverse event was recorded. This study demonstrated a linear dose-response relationship with an increase in 25(OH)D levels proportional to the dose administered. In conclusion, a loading dose of 200,000 IU VTD3 followed by a monthly dose of 100,000 IU is the best dosing schedule to quickly and safely correct the VTD status.

Moderate amounts of vitamin D3 in supplements are effective in raising serum 25-hydroxyvitamin D from low baseline levels in adults: a systematic review

There is controversy surrounding the designation of vitamin D adequacy as defined by circulating levels of the metabolite 25-hydroxyvitamin D (25(OH)D). Depending on the cutoff level chosen, dietary intakes of vitamin D may or may not provide sufficient impact upon vitamin D status measured as improvement in serum levels of 25(OH)D. We sought to examine whether modest daily doses (5-20 μg) as found in fortified foods or multivitamin supplements had a measureable impact on vitamin D status, defined as moving from below to above 50 nmol/L, or from less than 30 nmol/L to above 30 nmol/L. Published literature was searched for relevant articles describing randomized controlled trials. Exclusion criteria were: studies not involving humans; review articles; studies lacking blood level data pre- and post-treatment; no control group; bolus treatments (weekly, monthly, yearly); vitamin D < 5 μg or > 20 μg; baseline 25(OH)D ≥ 75 nmol/L; subjects not defined as healthy; studies < 8 weeks; and age < 19 years. Of the 127 studies retrieved, 18 publications with 25 separate comparisons met criteria. The mean rate constant, defined as change in 25(OH)D in nmol/L per μg vitamin D administered, was calculated as 2.19 ± 0.97 nmol/L per μg. There was a significant negative correlation (r = -0.65, p = 0.0004) between rate constant and administered dose. To determine impact of the dose reflecting the Estimated Average Requirement (EAR) of 10 μg administered in nine studies (10 comparisons), in every case mean 25(OH)D status rose either from "insufficient" (30-50 nmol/L) to "sufficient" (> 50 nmol/L) or from "deficient" (< 30 nmol/L) to "insufficient" (> 30 but < 50 nmol/L). Our study shows that when baseline levels of groups were < 75 nmol/L, for every microgram of vitamin D provided, 25(OH)D levels can be raised by 2 nmol/L; and further, when groups were deficient or insufficient in vitamin D, there was significant value in providing additional 10 μg per day of vitamin D.

Live longer with vitamin D?

The global burden of vitamin D deficiency or insufficiency is of great concern for public health. According to recent studies, vitamin D deficiency is an important etiological factor in the pathogenesis of many chronic diseases. Whether or not there is a connection between 25-hydoxyvitamin D (25(OH)D) status and overall mortality is a matter of considerable debate. A new meta-analysis confirmed that low 25(OH)D levels were associated with a significant increased risk for all-cause mortality. Individuals with severe vitamin D deficiency have almost twice the mortality rate as those with 25(OH)D level ≥ 30 ng/mL, (≥75 nmol/L). Unlike previous meta-analyses which suggested that serum 25(OH)D > 50 ng/mL was associated with increased mortality, this new analysis found that there was no increased risk even when 25(OH)D levels were ≥70 ng/mL. In general, closer attention should be paid to vitamin D deficiency in medical and pharmaceutical practice than has been the case hitherto. The results of these studies are consistent with the recommendation to improve the general vitamin D status in children and adults by means of a healthy approach to sunlight exposure, consumption of foods containing vitamin D and supplementation with vitamin D preparations.

An association between abnormal bone turnover, systemic inflammation, and osteoporosis in patients with chronic pancreatitis: a case-matched study

INTRODUCTION

Because of deteriorating exocrine function, malabsorption renders chronic pancreatitis (CP) patients at risk of osteoporosis and fracture. However, the pathogenesis of low bone mineral density (BMD) has not been characterized. We hypothesized that bone turnover is elevated in CP, and we sought to investigate an association between bone metabolism and systemic inflammation.

METHODS

Twenty-nine CP patients and twenty-nine matched controls were recruited. Bone-turnover markers procollagen 1 amino-terminal propeptide (P1NP), OC (osteocalcin; bone formation markers), and carboxy-terminal telopeptide of type I collagen (CTX-I; bone resorption marker) were measured along with vitamin D (25-hydroxyvitamin D, 25OHD), parathyroid hormone (PTH), interleukin 6 (IL-6), high-sensitivity (hs) C-reactive protein (CRP), and sex/thyroid hormones. BMD was measured by dual-energy X-ray absorptiometry. Smoking status was noted.

RESULTS

Of the CP patients, 31% had osteoporosis and 44.8% osteopenia (controls: 6.9 and 51.7%, respectively; P=0.019). BMD was lower for patients at the lumbar spine (P=0.014) and femoral neck (P=0.029). Patients had elevated bone formation (P1NP (P=0.0068), OC (P=0.033)) and bone resportion (CTX-I (P=0.016)) compared with controls. Patients had lower 25OHD compared with controls (P=0.0126) and higher inflammatory markers (hsCRP, P=0.0013). Sex and thyroid hormone levels were similar. Patients with lowest 25OHD levels had highest P1NP. In a multivariable model, age, PTH, and smoking were predictive of 25OHD. Patients with osteoporosis had higher P1NP, PTH, and IL-6 and lower 25OHD. Using analysis of variance, inflammation (hsCRP) was highest in those with lowest 25OHD and lowest BMD.

CONCLUSIONS

For the first time, bone turnover was shown to be abnormal in CP, and importantly, an association between low 25-OHD, smoking, and systematic inflammation was identified. Moreover, those with osteoporosis had the highest systemic inflammation. Together these factors provide an avenue for potential modification of risk factors, which may ultimately reduce bone loss and avert fractures in this group.

Estimated intake of vitamin D and its interaction with vitamin A on lung cancer risk among smokers

Data are very limited on vitamin D and lung cancer prevention in high-risk populations. The authors investigated whether estimated vitamin D intake was associated with lung cancer risk and whether effect modification by vitamin A existed among current/former heavy smokers and workers with occupational exposure to asbestos. A case-cohort study selected 749 incident lung cancers and 679 noncases from the Carotene and Retinol Efficacy Trial (CARET), 1988-2005. The active intervention was supplementation of 30 mg β-carotene + 25,000 IU retinyl palmitate/day. Baseline total intake including both diet (from food frequency questionnaire) and personal supplements (from brand names linked to the labeled potencies) was assessed. Hazard ratios (HRs) were estimated by Cox proportional hazard models. No significant association of total vitamin D intake with lung cancer was observed overall. However, total vitamin D intake ≥600 versus <200 IU/day was associated with a lower risk of non-small cell lung cancer among former smokers [HR = 0.36, 95% confidence interval (CI) = 0.13-0.96]. Total vitamin D intake ≥400 versus <400 IU/day was associated with a lower risk of total lung cancer among participants who received the CARET active intervention (HR = 0.56, 95% CI = 0.32-0.99) and among those who had total vitamin A intake ≥1,500 µg/day retinol activity equivalent (RAE; HR = 0.46, 95% CI = 0.23-0.91). The beneficial associations were attenuated among those who did not receive the CARET active intervention or who had total vitamin A intake <1,500 µg/day RAE (p-interaction = 0.02 for current smokers). Our observation suggests that vitamin A may assist vitamin D in preventing lung cancer among smokers.

Predictors of serum 25(Oh)D increase following bimonthly supplementation with 100,000IU vitamin D in healthy, men aged 25-65 years

Vitamin D replenishment therapy typically entails standard dosages, but related increases in serum 25(OH)D levels vary between individuals. This study was aimed to identify factors that affect the efficacy of vitamin D supplementation.

SUBJECTS AND METHODS

79 healthy men aged 25-65 with 25(OH)D<20ng/ml participated in a vitamin D supplementation study. All participants received 100,000IU vitamin D bimonthly, e.g., 1666IU/day. Personal and demographic information, physical activity and sun-exposure questionnaires were completed by the participants. Weight, height, and waist circumference were recorded. Serum calcium, creatinine, 25(OH)D, PTH, lipid profile, and liver-enzyme levels were assessed. All measurements were repeated after 6 and 12 months. The difference between baseline serum 25(OH)D and 12-month measurements was calculated (delta). Linear regression was performed to identify predictors for increases in 25(OH)D levels.

RESULTS

Mean serum 25(OH)D level increases according to BMI were 12.6±5.29ng/ml for BMI≤25, 10.12±4.95ng/ml for 25<BMI<30, and only 6.39± 5.33ng/ml for BMI>30, which differed significantly from the other BMI categories (p=0.003). In a regression model to predict 25(OH)D increase, BMI was the main predictor (p<0.001), explaining 21.6% of the variance in serum 25(OH)D (inverse association). Age, sun-exposure, serum cholesterol, physical-activity, baseline 25(OH)D levels and seasonality were insignificant. The full model explained 27.9% of the variance in serum 25(OH)D.

CONCLUSION

This study's main findings are that BMI affect vitamin D response in healthy men. Quantitative supplementation adjustments may be warranted in obese men, for whom the dose may need to be doubled. This article is part of a special issue entitled '16th Vitamin D Workshop'.

Abiraterone inhibits 1α,25-dihydroxyvitamin D3 metabolism by CYP3A4 in human liver and intestine in vitro

The chemopreventive and therapeutic effects of vitamin D3 are exerted through its dihydroxylated metabolite, 1α,25-dihydroxyvitamin D3 [1α,25(OH)2D3]. Inactivation of 1α,25(OH)2D3 by cytochrome P450 3A4 (CYP3A4) may be an important determinant of its serum and tissue levels. Abiraterone, a steroidogenesis inhibitor used in late stage prostate cancer treatment, is a CYP17A1 inhibitor. The purpose of this study was to assess the potential of abiraterone to block hepatic and intestinal inactivation of biologically active vitamin D3in vitro and to evaluate if abiraterone can alter CYP3A4 marker substrate activities. Biotransformation reactions were initiated with NADPH regenerating solutions following initial preincubation of pooled human hepatic or intestinal microsomal protein or human recombinant CYP3A4 supersomes with 1α,25(OH)2D3, midazolam or triazolam for 10min at 37°C. Formation of hydroxylated metabolites of 1α,25(OH)2D3, midazolam or triazolam was analyzed by liquid chromatography-mass spectrometry method. Co-incubation of 1α,25(OH)2D3 with abiraterone at varying concentrations (0.2-100μM) led to up to ∼85% inhibition of formation of hydroxylated metabolites of 1α,25(OH)2D3 thus preventing inactivation of active vitamin D3. The IC50 values for individual metabolites of 1α,25(OH)2D3 ranged from 0.4 to 2.2μM in human liver microsomes or human intestinal microsomes. The mechanism of CYP3A4-mediated inhibition of 1α,25(OH)2D3 by abiraterone was competitive (apparent Ki 2.8-4.3μM). Similar inhibitory effects were also observed upon inclusion of abiraterone into midazolam or triazolam hydroxylation assays. In summary, our results suggest that abiraterone inhibits the CYP3A4-mediated inactivation of active vitamin D3 in human liver and intestine, potentially providing additional anti-cancer benefits to prostate cancer patients. This article is part of a Special Issue entitled '16th Vitamin D Workshop'.

Limited utility of tartrate-resistant acid phosphatase isoform 5b in assessing response to therapy in osteoporosis

BACKGROUND

Tartrate-resistant acid phosphatase isoform 5b (TRACP5b) is a serum bone resorption marker. Our aim was to investigate its utility in monitoring metabolic bone disease.

METHODS

Serum TRACP5b, C-terminal cross-linking telopeptide of type I collagen, urine N-terminal cross-linking telopeptide of type I collagen and free deoxypyridinoline were measured pre- and post-treatment with a parathyroid hormone analogue [PTH (1-34)] (n = 14) or a bisphosphonate (N-BP) (n = 8). TRACP5b, bone alkaline phosphatase (bone ALP), 25-hydroxyvitamin D (25OHD) and parathyroid hormone (PTH) were measured in 100 osteoporosis patients on prolonged bisphosphonate therapy.

RESULTS

Changes in TRACP5b were smaller in magnitude but mimicked those of other bone resorption markers. Absolute changes in TRACP5b and the other resorption markers correlated significantly (p < 0.001). In patients on long-term bisphosphonates, TRACP5b and bone ALP levels were not suppressed. Vitamin D status was consistent with the level of supplementation.

CONCLUSION

TRACP5b has limited utility as a single marker of metabolic bone disease treatment.