Vitamin D research and clinical practice: at a crossroads

Developmental exposure to vitamin D deficiency and subsequent risk of schizophrenia

Over the last half century, a body of convergent evidence has accumulated linking disruption of early brain development with an increased risk of mental disorders, including schizophrenia. The orderly cascade of brain development may be disrupted by exposure to suboptimal concentrations of a range of biological substrates and micronutrients. We hypothesized that those exposed to vitamin D deficiency during early life, have an increased risk of neurodevelopmental disorders, including schizophrenia. The hypothesis was based on the link between an increased risk of schizophrenia in (a) those born in winter and spring, when vitamin D deficiency is more prevalent, and (b) the offspring of dark-skinned migrants living in cold climates, who have a markedly increased risk of vitamin D deficiency. In this review, we summarize evidence from analytic epidemiology related to this hypothesis. Two case-control studies based on Danish neonatal dried blood spots have found that neonatal vitamin deficiency is associated with an increased risk of schizophrenia. However, recent genetic analyses have also suggested that common variants linked to schizophrenia may lead to lower vitamin D concentrations (possibly mediated via reduced outdoor activity). We summarize limitations of the current evidence and outline suggestions that can guide future research. Based on currently available data, there is insufficient evidence to support public health recommendations related to this topic. However, we cannot reject the hypothesis that the provision of vitamin D supplementation to pregnant women and/or offspring in groups vulnerable to vitamin D deficiency may subsequently reduce the incidence of schizophrenia in the offspring.

Single oral dose of vitamin D3 supplementation prior to in vitro fertilization and embryo transfer in normal weight women: the SUNDRO randomized controlled trial

BACKGROUND

Improving in vitro fertilization success is an unmet need. Observational studies have suggested that women with deficient or insufficient vitamin D have lower chances of in vitro fertilization success, but whether supplementation improves clinical pregnancy rate remains unclear.

OBJECTIVE

This study aimed to determine whether oral vitamin D₃ supplementation improves clinical pregnancy in women undergoing an in vitro fertilization cycle.

STUDY DESIGN

The "supplementation of vitamin D and reproductive outcome" trial is a 2-center randomized superiority double-blind placebo-controlled trial. Subjects were recruited between October 2016 and January 2019. Participants were women aged 18 to 39 years with low vitamin D (peripheral 25-hydroxyvitamin D of <30 ng/mL), serum calcium of ≥10.6 mg/dL, body mass index of 18 to 25 kg/m², and antimüllerian hormone levels of >0.5 ng/mL and starting their first, second, or third treatment cycle of conventional in vitro fertilization or intracytoplasmic sperm injection. The primary outcome was the cumulative clinical pregnancy rate per cycle. Pregnancies obtained with both fresh or frozen embryo transfers were included. Clinical pregnancy was defined as an intrauterine gestational sac with a viable fetus. The primary analysis was performed according to the intention-to-treat principle and could also include natural conceptions. Secondary outcomes included total dose of gonadotropins used, embryologic variables (number of oocytes retrieved, number of suitable oocytes retrieved, fertilization rate, and rate of top-quality embryos), and clinical outcomes (miscarriage rate and live birth rate).

RESULTS

Overall, 630 women were randomized 2 to 12 weeks before the initiation of the in vitro fertilization cycle to receive either a single dose of 600,000 IU of vitamin D₃ (n=308) or placebo (n=322). Interestingly, 113 (37%) and 130 (40%) women achieved a clinical pregnancy in the treatment and placebo groups, respectively (P=.37). The risk ratio of clinical pregnancy in women receiving vitamin D₃ was 0.91 (95% confidence interval, 0.75-1.11). Compared with the placebo, vitamin D₃ supplementation did not improve the rate of clinical pregnancy. Exploratory subgroup analyses for body mass index, age, indication to in vitro fertilization, ovarian reserve, interval between drug administration and initiation of the cycle, and basal levels of 25-hydroxyvitamin D failed to highlight any clinical situation that could benefit from the supplementation.

CONCLUSION

In women with normal weight with preserved ovarian reserve and low vitamin D levels undergoing in vitro fertilization cycles, a single oral dose of 600,000 IU of vitamin D₃ did not improve the rate of clinical pregnancy. Although the findings do not support the use of vitamin D₃ supplementation to improve in vitro fertilization success rates, further studies are required to rule out milder but potentially interesting benefits and explore the effectiveness of alternative modalities of supplementation.

The VITamin D and OmegA-3 TriaL (VITAL): Do Results Differ by Sex or Race/Ethnicity?

Whether vitamin D or marine omega-3 (n-3) fatty acid supplementation reduces risk of cancer or cardiovascular disease (CVD) in general populations at usual risk for these outcomes is relatively unexplored in randomized trials. The primary goal of the VITamin D and OmegA-3 TriaL (VITAL), a nationwide, randomized, placebo-controlled, 2 × 2 factorial trial of vitamin D₃ (2000 IU/day) and marine n-3 fatty acids (1 g/day) in the primary prevention of cancer and CVD among 25 871 US men aged ≥50 years and women aged ≥55 years, was to fill these knowledge gaps. Studying the influence of sex and race/ethnicity on treatment-related outcomes was a prespecified goal; such analyses help ensure that important effects are not missed and contribute to the foundation for developing targeted recommendations for supplement use. To enable investigation of potential sex- and race-specific treatment effects, trial investigators enrolled an even balance of men (n = 12 786) and women (n = 13 085) and oversampled African Americans (n = 5106). Significant or suggestive variation in intervention effects according to sex, race/ethnicity, and other participant characteristics was observed for some, though not all, outcomes. Additional research is needed to determine which individuals may be most likely to derive a net benefit from vitamin D or n-3 fatty acid supplementation. (VITAL clinicaltrials.gov identifier: NCT01169259).

Relationship Between Vitamin D Level and Mortality in Adults With Psoriasis: A Retrospective Cohort Study of NHANES Data

PURPOSE

Studies have shown an increased risk for mortality in patients with psoriasis. Furthermore, research has demonstrated an inverse relationship between 25-hydroxyvitamin D (25[OH]D) level and all-cause mortality. This study investigated the association between 25(OH)D level and all-cause mortality in US adults with psoriasis.

METHODS

Data from NHANES (1999-2014 and mortality data through December 31, 2015) were analyzed. Quartiles of 25(OH)D level were created based on 25(OH)D levels among patients. Cox proportional hazards models were used for estimating hazard ratios (95% CI) for all-cause mortality.

FINDINGS

A total of 82,091 participants were enrolled in the NHANES study from 1999 to 2014. Overall, 610 patients with psoriasis were identified in NHANES. The mean (SD) duration of follow-up was 5.61 (3.38) years (3427.92 person-years). The hazard ratio for mortality in the fully adjusted model was 0.12 (95% CI, 0.02-0.60; P_trend = 0.01) in patients with a high 25(OH)D concentration compared to those with 25(OH)D deficiency.

IMPLICATIONS

The 25(OH)D concentration was significantly inversely associated with all-cause mortality among these patients with psoriasis. Studies have shown an increased risk for mortality in patients with psoriasis compared to the general population. Vitamin D is not regularly metabolized in patients with psoriasis due to their skin abnormality. Vitamin D supplementation has been associated with a reduced mortality in patients with psoriasis. In practice, attention to vitamin D level is crucial, as is the use of vitamin D supplementation, for improving the health of these patients.

Novel predictive risk factor of erectile dysfunction: Serum 25-hydroxy vitamin D

The present study aimed to investigate the association between the severity of erectile dysfunction (ED) and serum 25-hydroxy vitamin D. It also sought to determine the cut-off level of serum 25-hydroxy vitamin D for ED. This study included 130 men who had ED between 2018 and 2019. Patients were divided into three groups according to their scores on the international index of erectile function-5 (IIEF-5) Turkish validated short form questionnaire. The serum 25-hydroxy vitamin D results were compared between the groups. The mean age of the patients was 49.28 ± 13.62 years. Groups 1, 2 and 3 included 44 (33.8%) patients with severe ED, 56 (43.1%) patients with moderate ED and 30 (23.1%) patients with mild ED, respectively. Statistical significance was observed between the groups and serum 25-hydroxy vitamin D levels. A positive correlation was detected between the IIEF-5 scores, serum testosterone and serum 25-hydroxy vitamin D levels. A cut-off level for serum 25-hydroxy vitamin D was calculated as 27.32 ng/ml. During multivariate analysis, we found that serum 25-hydroxy vitamin D levels were independent prognostic risk factors for decreased IIEF-5 scores. Decreased serum 25-hydroxy vitamin D levels were associated with decreased IIEF-5 scores. Therefore, vitamin D replacement therapy may improve symptoms.

Vitamin D and Its Potential Interplay With Pain Signaling Pathways

About 50 million of the U.S. adult population suffer from chronic pain. It is a complex disease in its own right for which currently available analgesics have been deemed woefully inadequate since ~20% of the sufferers derive no benefit. Vitamin D, known for its role in calcium homeostasis and bone metabolism, is thought to be of clinical benefit in treating chronic pain without the side-effects of currently available analgesics. A strong correlation between hypovitaminosis D and incidence of bone pain is known. However, the potential underlying mechanisms by which vitamin D might exert its analgesic effects are poorly understood. In this review, we discuss pathways involved in pain sensing and processing primarily at the level of dorsal root ganglion (DRG) neurons and the potential interplay between vitamin D, its receptor (VDR) and known specific pain signaling pathways including nerve growth factor (NGF), glial-derived neurotrophic factor (GDNF), epidermal growth factor receptor (EGFR), and opioid receptors. We also discuss how vitamin D/VDR might influence immune cells and pain sensitization as well as review the increasingly important topic of vitamin D toxicity. Further in vitro and in vivo experimental studies will be required to study these potential interactions specifically in pain models. Such studies could highlight the potential usefulness of vitamin D either alone or in combination with existing analgesics to better treat chronic pain.

Principal results of the VITamin D and OmegA-3 TriaL (VITAL) and updated meta-analyses of relevant vitamin D trials

Whether supplemental vitamin D reduces risk of cancer or cardiovascular disease (CVD) is relatively unexplored in randomized trial settings. The VITamin D and OmegA-3 TriaL (VITAL) was a nationwide, randomized, placebo-controlled, 2 × 2 factorial trial of daily vitamin D₃ (2000 IU) and marine omega-3 fatty acids (1 g) in the primary prevention of cancer and CVD among 25,871 U.S. men aged ≥50 and women aged ≥55, including 5106 African Americans. Median treatment duration was 5.3 years. Vitamin D did not significantly reduce the primary endpoint of total invasive cancer incidence (hazard ratio [HR] = 0.96 [95% confidence interval 0.88-1.06]) but showed a promising signal for reduction in total cancer mortality (HR = 0.83 [0.67-1.02]), especially in analyses that accounted for latency by excluding the first year (HR = 0.79 [0.63-0.99]) or first 2 years (HR = 0.75 [0.59-0.96]) of follow-up. Vitamin D did not significantly reduce the co-primary endpoint of major CVD events (HR = 0.97 [0.85-1.12]), other cardiovascular endpoints, or all-cause mortality (HR = 0.99 [0.87-1.12]). Updated meta-analyses that include VITAL and other recent vitamin D trials indicate a significant reduction in cancer mortality but not in cancer incidence or CVD endpoints. Additional research is needed to determine which individuals may be most likely to derive a net benefit from vitamin D supplementation. (VITAL clinicaltrials.gov identifier: NCT01169259).

Fitting Marginal Structural and G-Estimation Models Under Complex Treatment Patterns: Investigating the Association Between De Novo Vitamin D Supplement Use After Breast Cancer Diagnosis and All-Cause Mortality Using Linked Pharmacy Claim and Registry Data

Studies have shown that accounting for time-varying confounding through time-dependent Cox proportional hazards models may provide biased estimates of the causal effect of treatment when the confounder is also a mediator. We explore 2 alternative approaches to addressing this problem while examining the association between vitamin D supplementation initiated after breast cancer diagnosis and all-cause mortality. Women aged 50-80 years were identified in the National Cancer Registry Ireland (n = 5,417) between 2001 and 2011. Vitamin D use was identified from linked prescription data (n = 2,570). We sought to account for the time-varying nature of vitamin D use and time-varying confounding by bisphosphonate use using 1) marginal structural models (MSMs) and 2) G-estimation of structural nested accelerated failure-time models (SNAFTMs). Using standard adjusted Cox proportional hazards models, we found a reduction in all-cause mortality in de novo vitamin D users compared with nonusers (hazard ratio (HR) = 0.84, 95% confidence interval (CI): 0.73, 0.99). Additional adjustment for vitamin D and bisphosphonate use in the previous month reduced the hazard ratio (HR = 0.45, 95% CI: 0.33, 0.63). Results derived from MSMs (HR = 0.44, 95% CI: 0.32, 0.61) and SNAFTMs (HR = 0.45, 95% CI: 0.34, 0.52) were similar. Utilizing MSMs and SNAFTMs to account for time-varying bisphosphonate use did not alter conclusions in this example.

Vitamin D, Marine n-3 Fatty Acids, and Primary Prevention of Cardiovascular Disease Current Evidence

Whether marine omega-3 fatty acid (n-3 FA) or vitamin D supplementation can prevent cardiovascular disease (CVD) in general populations at usual risk for this outcome is unknown. A major goal of VITAL (Vitamin D and Omega-3 Trial) was to fill this knowledge gap. In this article, we review the results of VITAL, discuss relevant mechanistic studies regarding n-3 FAs, vitamin D, and vascular disease, and summarize recent meta-analyses of the randomized trial evidence on these agents. VITAL was a nationwide, randomized, placebo-controlled, 2×2 factorial trial of marine n-3 FAs (1 g/d) and vitamin D₃ (2000 IU/d) in the primary prevention of CVD and cancer among 25 871 US men aged ≥50 and women aged ≥55 years, including 5106 blacks. Median treatment duration was 5.3 years. Supplemental n-3 FAs did not significantly reduce the primary cardiovascular end point of major CVD events (composite of myocardial infarction, stroke, and CVD mortality; hazard ratio [HR], 0.92 [95% CI, 0.80-1.06]) but were associated with significant reductions in total myocardial infarction (HR, 0.72 [95% CI, 0.59-0.90]), percutaneous coronary intervention (HR, 0.78 [95% CI, 0.63-0.95]), and fatal myocardial infarction (HR, 0.50 [95% CI, 0.26-0.97]) but not stroke or other cardiovascular end points. For major CVD events, a treatment benefit was seen in those with dietary fish intake below the cohort median of 1.5 servings/wk (HR, 0.81 [95% CI, 0.67-0.98]) but not in those above (P interaction=0.045). For myocardial infarction, the greatest risk reductions were in blacks (HR, 0.23 [95% CI, 0.11-0.47]; P interaction by race, 0.001). Vitamin D supplementation did not reduce major CVD events (HR, 0.97 [95% CI, 0.85-1.12]) or other cardiovascular end points. Updated meta-analyses that include VITAL and other recent trials document coronary risk reduction from supplemental marine n-3 FAs but no clear CVD risk reduction from supplemental vitamin D. Additional research is needed to determine which individuals may be most likely to derive net benefit from supplementation. Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01169259.

Current vitamin D status in European and Middle East countries and strategies to prevent vitamin D deficiency: a position statement of the European Calcified Tissue Society

Vitamin D deficiency (serum 25-hydroxyvitamin D (25(OH)D) <50 nmol/L or 20 ng/mL) is common in Europe and the Middle East. It occurs in <20% of the population in Northern Europe, in 30-60% in Western, Southern and Eastern Europe and up to 80% in Middle East countries. Severe deficiency (serum 25(OH)D <30 nmol/L or 12 ng/mL) is found in >10% of Europeans. The European Calcified Tissue Society (ECTS) advises that the measurement of serum 25(OH)D be standardized, for example, by the Vitamin D Standardization Program. Risk groups include young children, adolescents, pregnant women, older people (especially the institutionalized) and non-Western immigrants. Consequences of vitamin D deficiency include mineralization defects and lower bone mineral density causing fractures. Extra-skeletal consequences may be muscle weakness, falls and acute respiratory infection, and are the subject of large ongoing clinical trials. The ECTS advises to improve vitamin D status by food fortification and the use of vitamin D supplements in risk groups. Fortification of foods by adding vitamin D to dairy products, bread and cereals can improve the vitamin D status of the whole population, but quality assurance monitoring is needed to prevent intoxication. Specific risk groups such as infants and children up to 3 years, pregnant women, older persons and non-Western immigrants should routinely receive vitamin D supplements. Future research should include genetic studies to better define individual vulnerability for vitamin D deficiency, and Mendelian randomization studies to address the effect of vitamin D deficiency on long-term non-skeletal outcomes such as cancer.

The Role of Vitamin D in Pediatric Orthopedics

Understanding the role of vitamin D is an important component of the proper care of the pediatric orthopedic patient. Vitamin D is an essential component of bone metabolism in the growth and development of the pediatric skeleton, which can be acutely affected by changes to the body's vitamin D, calcium, and phosphate levels, resulting in pathologic conditions such as rickets or fractures. This article reviews the main areas in which vitamin D relates to pediatric orthopedics and highlights some of the areas where future research is being directed.

Vitamin D and Public Health

Since the early 2000's, interest in vitamin D has grown significantly among the research, clinical and lay communities [...].

Circulating Vitamin D and Colorectal Cancer Risk: An International Pooling Project of 17 Cohorts

BACKGROUND

Experimental and epidemiological studies suggest a protective role for vitamin D in colorectal carcinogenesis, but evidence is inconclusive. Circulating 25-hydroxyvitamin D (25(OH)D) concentrations that minimize risk are unknown. Current Institute of Medicine (IOM) vitamin D guidance is based solely on bone health.

METHODS

We pooled participant-level data from 17 cohorts, comprising 5706 colorectal cancer case participants and 7107 control participants with a wide range of circulating 25(OH)D concentrations. For 30.1% of participants, 25(OH)D was newly measured. Previously measured 25(OH)D was calibrated to the same assay to permit estimating risk by absolute concentrations. Study-specific relative risks (RRs) for prediagnostic season-standardized 25(OH)D concentrations were calculated using conditional logistic regression and pooled using random effects models.

RESULTS

Compared with the lower range of sufficiency for bone health (50-<62.5 nmol/L), deficient 25(OH)D (<30 nmol/L) was associated with 31% higher colorectal cancer risk (RR = 1.31, 95% confidence interval [CI] = 1.05 to 1.62); 25(OH)D above sufficiency (75-<87.5 and 87.5-<100 nmol/L) was associated with 19% (RR = 0.81, 95% CI = 0.67 to 0.99) and 27% (RR = 0.73, 95% CI = 0.59 to 0.91) lower risk, respectively. At 25(OH)D of 100 nmol/L or greater, risk did not continue to decline and was not statistically significantly reduced (RR = 0.91, 95% CI = 0.67 to 1.24, 3.5% of control participants). Associations were minimally affected when adjusting for body mass index, physical activity, or other risk factors. For each 25 nmol/L increment in circulating 25(OH)D, colorectal cancer risk was 19% lower in women (RR = 0.81, 95% CI = 0.75 to 0.87) and 7% lower in men (RR = 0.93, 95% CI = 0.86 to 1.00) (two-sided Pheterogeneity by sex = .008). Associations were inverse in all subgroups, including colorectal subsite, geographic region, and season of blood collection.

CONCLUSIONS

Higher circulating 25(OH)D was related to a statistically significant, substantially lower colorectal cancer risk in women and non-statistically significant lower risk in men. Optimal 25(OH)D concentrations for colorectal cancer risk reduction, 75-100 nmol/L, appear higher than current IOM recommendations.

Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease

BACKGROUND

It is unclear whether supplementation with vitamin D reduces the risk of cancer or cardiovascular disease, and data from randomized trials are limited.

METHODS

We conducted a nationwide, randomized, placebo-controlled trial, with a two-by-two factorial design, of vitamin D₃ (cholecalciferol) at a dose of 2000 IU per day and marine n-3 (also called omega-3) fatty acids at a dose of 1 g per day for the prevention of cancer and cardiovascular disease among men 50 years of age or older and women 55 years of age or older in the United States. Primary end points were invasive cancer of any type and major cardiovascular events (a composite of myocardial infarction, stroke, or death from cardiovascular causes). Secondary end points included site-specific cancers, death from cancer, and additional cardiovascular events. This article reports the results of the comparison of vitamin D with placebo.

RESULTS

A total of 25,871 participants, including 5106 black participants, underwent randomization. Supplementation with vitamin D was not associated with a lower risk of either of the primary end points. During a median follow-up of 5.3 years, cancer was diagnosed in 1617 participants (793 in the vitamin D group and 824 in the placebo group; hazard ratio, 0.96; 95% confidence interval [CI], 0.88 to 1.06; P=0.47). A major cardiovascular event occurred in 805 participants (396 in the vitamin D group and 409 in the placebo group; hazard ratio, 0.97; 95% CI, 0.85 to 1.12; P=0.69). In the analyses of secondary end points, the hazard ratios were as follows: for death from cancer (341 deaths), 0.83 (95% CI, 0.67 to 1.02); for breast cancer, 1.02 (95% CI, 0.79 to 1.31); for prostate cancer, 0.88 (95% CI, 0.72 to 1.07); for colorectal cancer, 1.09 (95% CI, 0.73 to 1.62); for the expanded composite end point of major cardiovascular events plus coronary revascularization, 0.96 (95% CI, 0.86 to 1.08); for myocardial infarction, 0.96 (95% CI, 0.78 to 1.19); for stroke, 0.95 (95% CI, 0.76 to 1.20); and for death from cardiovascular causes, 1.11 (95% CI, 0.88 to 1.40). In the analysis of death from any cause (978 deaths), the hazard ratio was 0.99 (95% CI, 0.87 to 1.12). No excess risks of hypercalcemia or other adverse events were identified.

CONCLUSIONS

Supplementation with vitamin D did not result in a lower incidence of invasive cancer or cardiovascular events than placebo. (Funded by the National Institutes of Health and others; VITAL ClinicalTrials.gov number, NCT01169259 .).

Trends in vitamin D supplement use in a general female and breast cancer population in Ireland: A repeated cross-sectional study

Background

Vitamin D has been linked with improved survival after breast cancer diagnosis but little is known about prescribing rates. This study investigates trends in vitamin D supplement use in both a general female and breast cancer population.

Methods

Women with a breast cancer diagnosis were identified from the National Cancer Registry of Ireland (n = 19870). Women who had any vitamin D claim between 2005 and 2011 were identified from pharmacy claims data (n = 8556). Prevalence rates were calculated as a proportion of all eligible women and by age (< 55 years, ≥ 55 years). Poisson regression was used to compare rates of vitamin D prescribing across years (risk ratio (RR), 95% CI).

Results

There was a statistically significant increase in women with a claim for vitamin D between 2005–2011, with the largest increase among breast cancer patients aged ≥ 55 years (RR = 2.26; 95% CI, 2.11–2.42).

Conclusion

This may have significant public health implications if associations between vitamin D and improved breast cancer survival prove to be causal.

Circulating Serum 25-Hydroxyvitamin D Levels and Bone Mineral Density: Mendelian Randomization Study

There is considerable discussion of the importance for increased serum 25-hydroxyvitamin D (S-25OHD) concentration associated with adequacy for bone health. Accordingly, whether long-term high S-25OHD concentration in general positively affects bone mineral density (BMD) is uncertain. We used a Mendelian randomization design to determine the association between genetically increased S-25OHD concentrations and BMD. Five single-nucleotide polymorphisms (SNPs) in or near genes encoding enzymes and carrier proteins involved in vitamin D synthesis or metabolism were used as instrumental variables to genetically predict 1 standard deviation increase in S-25OHD concentration. Summary statistics data for the associations of the S-25OHD-associated SNPs with dual-energy X-ray absorptiometry (DXA)-derived femoral neck and lumbar spine BMD were obtained from the Genetic Factors for Osteoporosis (GEFOS) Consortium (32,965 individuals) and ultrasound-derived heel estimated BMD from the UK Biobank (142,487 individuals). None of the SNPs were associated with BMD at Bonferroni-corrected significance level, but there was a suggestive association between rs6013897 near CYP24A1 and femoral neck BMD (p = 0.01). In Mendelian randomization analysis, genetically predicted 1 standard deviation increment of S-25OHD was not associated with higher femoral neck BMD (SD change in BMD 0.02; 95% confidence interval [CI] -0.03 to 0.07; p = 0.37), lumbar spine BMD (SD change in BMD 0.02; 95% CI -0.04 to 0.08; p = 0.49), or estimated BMD (g/cm² change in BMD -0.03; 95% CI -0.05 to -0.01; p = 0.02). This study does not support a causal association between long-term elevated S-25OHD concentrations and higher BMD in generally healthy populations. These results suggest that more emphasis should be placed on the development of evidence-based cut-off points for vitamin D inadequacy rather than a general recommendation to increase S-25OHD. © 2018 American Society for Bone and Mineral Research.

Is there a role or target value for nutritional vitamin D in chronic kidney disease?

Vitamin D is important for bone health in the general population but the value of vitamin D supplementation, and the role of 25-hydroxyvitamin D independently of 1,25-dihydroxyvitmain D, in individuals with chronic kidney disease (CKD), particularly in those who require dialysis, remains uncertain. Supplementation may improve some biochemical parameters, such as reducing PTH levels in patients to CKD-stage 4 who have vitamin D deficiency; but it remains to be established whether the role of nutritional vitamin D in maintaining bone health in the general population can be extrapolated to the CKD population. There is currently insufficient evidence to recommend conclusively that nutritional vitamin D supplementation should be prescribed to individuals with CKD who have 25-hydroxyvitamin D deficiency, either for skeletal or non-skeletal health outcomes.

Large-scale randomized clinical trials of bioactives and nutrients in relation to human health and disease prevention - Lessons from the VITAL and COSMOS trials

Several bioactive compounds and nutrients in foods have physiological properties that are beneficial for human health. While nutrients typically have clear definitions with established levels of recommended intakes, bioactive compounds often lack such a definition. Although a food-based approach is often the optimal approach to ensure adequate intake of bioactives and nutrients, these components are also often produced as dietary supplements. However, many of these supplements are not sufficiently studied and have an unclear role in chronic disease prevention. Randomized trials are considered the gold standard of study designs, but have not been fully applied to understand the effects of bioactives and nutrients. We review the specific role of large-scale trials to test whether bioactives and nutrients have an effect on health outcomes through several crucial components of trial design, including selection of intervention, recruitment, compliance, outcome selection, and interpretation and generalizability of study findings. We will discuss these components in the context of two randomized clinical trials, the VITamin D and OmegA-3 TriaL (VITAL) and the COcoa Supplement and Multivitamin Outcomes Study (COSMOS). We will mainly focus on dietary supplements of bioactives and nutrients while also emphasizing the need for translation and integration with food-based trials that are of vital importance within nutritional research.

Effects of Vitamin D on Blood Pressure, Arterial Stiffness, and Cardiac Function in Older People After 1 Year: BEST-D (Biochemical Efficacy and Safety Trial of Vitamin D)

Background

The relevance of vitamin D for prevention of cardiovascular disease is uncertain. The BEST‐D (Biochemical Efficacy and Safety Trial of vitamin D) trial previously reported effects of vitamin D on plasma markers of vitamin D status, and the present report describes the effects on blood pressure, heart rate, arterial stiffness, and cardiac function.

Methods and Results

This was a randomized, double‐blind, placebo‐controlled trial of 305 older people living in United Kingdom, who were allocated vitamin D 4000 IU (100 μg), vitamin D 2000 IU (50 μg), or placebo daily. Primary outcomes were plasma concentrations of 25‐hydroxy‐vitamin D and secondary outcomes were blood pressure, heart rate, and arterial stiffness in all participants at 6 and 12 months, plasma N‐terminal prohormone of brain natriuretic peptide levels in all participants at 12 months, and echocardiographic measures of cardiac function in a randomly selected subset (n=177) at 12 months. Mean (SE) plasma 25‐hydroxy‐vitamin D concentrations were 50 (SE 2) nmol/L at baseline and increased to 137 (2.4), 102 (2.4), and 53 (2.4) nmol/L after 12 months in those allocated 4000 IU/d, 2000 IU/d of vitamin D, or placebo, respectively. Allocation to vitamin D had no significant effect on mean levels of blood pressure, heart rate, or arterial stiffness at either 6 or 12 months, nor on any echocardiographic measures of cardiac function, or plasma N‐terminal prohormone of brain natriuretic peptide concentration at 12 months.

Conclusions

The absence of any significant effect of vitamin D on blood pressure, arterial stiffness, or cardiac function suggests that any beneficial effects of vitamin D on cardiovascular disease are unlikely to be mediated through these mechanisms.

Clinical Trial Registration

URL: https://www.clinicaltrialsregister.eu/ctr-search/search. Unique identifier: EudraCT number: 2011–005763‐24a

Increase of vitamin D assays prescriptions and associated factors: a population-based cohort study

A worldwide increase in the frequency of testing for serum 25-hydroxyvitamin D (25OHD) levels has been observed over the last years. Our aim was to measure the evolution in the number of vitamin D assays performed in France from 2008 to 2013 and to investigate some of the drivers that may explain this increase. Patients within the representative 1/97th sample of the French health insurance system reimbursement database (EGBS database) who had at least one 25OHD or 1-25(OH)₂D assay between 2008 and 2013 were included. Trends over time in number of vitamin D assays were analysed globally and per year in a multivariable Poisson regression model with GEE. Among the 639,163 patients of the EGBS database, 118,509 (18.5%) had at least one vitamin D assay over the 6-year study period. Among the individuals tested, 52.1% had only one test. The number of vitamin D assays (25OHD or 1-25(OH)₂D) increased 7.5-fold from 9,620 in 2008 to 81,641 in 2013. This study confirms the rapid and dramatic increase in vitamin D assays prescriptions and shows that this is mostly due to a global increase of the proportion of patients tested rather than an increase in repetition of tests in some individual patients.

Vitamin D Receptor Genotype, Vitamin D3 Supplementation, and Risk of Colorectal Adenomas: A Randomized Clinical Trial

Importance

Despite epidemiological and preclinical evidence suggesting that vitamin D and calcium inhibit colorectal carcinogenesis, daily supplementation with these nutrients for 3 to 5 years was not found to significantly reduce the risk of recurrent colorectal adenomas in a recent randomized clinical trial.

Objective

To investigate whether common variants in 7 vitamin D and calcium pathway genes (VDR, GC, DHCR7, CYP2R1, CYP27B1, CYP24A1, and CASR) modify the effects of vitamin D3 or calcium supplementation on colorectal adenoma recurrence.

Design, Setting, and Participants

We examined 41 candidate single-nucleotide polymorphisms (SNPs) in 2259 participants in a randomized, double-blind, placebo-controlled trial conducted at 11 clinical centers in the United States. Eligibility criteria included a recently diagnosed adenoma and no remaining colorectal polyps after complete colonoscopy. The study's treatment phase ended on August 31, 2013, and the analysis for the present study took place from July 28, 2014, to October 19, 2016.

Interventions

Daily oral supplementation with vitamin D3 (1000 IU) or calcium carbonate (1200 mg elemental calcium) or both or neither.

Main Outcomes and Measures

The outcomes assessed were the occurrence of 1 or more adenomas or advanced adenomas (estimated diameter, ≥1 cm; or with villous histologic findings, high-grade dysplasia, or cancer) during follow-up. Treatment effects and genotype associations and interactions were estimated as adjusted risk ratios (RRs) and 95% confidence intervals (CIs). The effective number of independent SNPs was calculated to correct for multiple testing.

Results

Among the 2259 participants randomized, 1702 were non-Hispanic whites who completed the trial and had genotype data for analysis (1101 men; mean [SD] age 58.1 [6.8] years). The effect of vitamin D3 supplementation on advanced adenomas, but not on adenoma risk overall, significantly varied according to genotype at 2 VDR SNPs (rs7968585 and rs731236) in linkage disequilibrium (D' = 0.98; r2 = 0.6). For rs7968585, among individuals with the AA genotype (26%), vitamin D3 supplementation reduced risk by 64% (RR, 0.36; 95% CI, 0.19-0.69; P = .002; absolute risk decreased from 14.4% to 5.1%). Among individuals with 1 or 2 G alleles (74%), vitamin D3 supplementation increased risk by 41% (RR, 1.41; 95% CI, 0.99-2.00; P = .05; absolute risk increased from 7.7% to 11.1%; P < .001 for interaction). There were no significant interactions of genotypes with calcium supplementation.

Conclusions and Relevance

Our findings suggest that benefits from vitamin D3 supplementation for the prevention of advanced colorectal adenomas may vary according to vitamin D receptor genotype.

Trial Registration

clinicaltrials.gov Identifier: NCT00153816.

The relevance of serum vitamin D in psoriasis: a review

Observational research has identified low serum levels of 25-hydroxyvitamin D (25[OH]D) in many non-skeletal diseases. Whether this is causal or due to underlying illness is unknown. Low serum 25[OH]D levels are also reported in the general population. Observational and experimental studies identify that vitamin D supplementation may be beneficial in reducing all-cause mortality in elderly women, as well as cancer mortality. Our aim was to review the literature to identify the relevance of serum 25[OH]D levels in psoriasis. Forty-five studies were included in our analysis. Most of these studies identified low serum 25[OH]D levels in psoriasis patients. Evidence of causality is lacking. Treatment with phototherapy leads to an increase in serum 25[OH]D. There is little evidence that the increase in 25[OH]D after phototherapy correlates with improved disease severity. Multiple studies report an improvement in psoriasis with vitamin D supplementation. These data are predominantly from small observational or non-randomised interventional studies. Randomised controlled trials to date have had small numbers and short follow-up periods. The optimal dose of supplementation is unknown and dosing is not standardised across different studies. The definition of vitamin D insufficiency varies across studies. Low serum 25[OH]D levels may be associated with comorbidities in psoriasis patients, including metabolic syndrome and cardiovascular risk. Evidence of causation is absent. Until further high-quality evidence is available, the relevance of low serum 25[OH]D levels in psoriasis patients is unknown, as is the benefit of supplementation on disease control. Supplementation in patients with low 25[OH]D is of benefit to those at risk of impaired bone health.

Can Stoss Therapy Be Used in Children with Vitamin D Deficiency or Insufficiency without Rickets?

OBJECTIVE

Stoss vitamin D treatment has been recommended for its non-skeletal benefits in adults, but there is a lack of data on the optimal dose of vitamin D stoss therapy in children with vitamin D deficiency/insufficiency without rickets. This study aimed to compare efficiency/side effects of two different stoss therapy regimens (10 000 IU/kg and 300 000 IU vitamin D3) administered in children with vitamin D deficiency/insufficiency without rickets.

METHODS

Sixty-four children who had vitamin D deficiency/insufficiency were studied. A serum 25-hydroxyvitamin-D (25-OH-D) level of 15-20 ng/mL was considered as vitamin D insufficient and <15 ng/mL was considered as vitamin D deficient. The patients were divided into two groups according to the stoss therapy doses they received. Serum calcium, phosphate, alkaline phosphatase, 25-OH-D, parathyroid hormone levels, and spot urine calcium/creatinine ratios before/after treatment were recorded. Wrist radiography and renal ultrasonography were performed.

RESULTS

The mean age of the subjects was 10.6±4.4 years. Thirty-two children were treated with a single vitamin D3 dose of 10 000 IU/kg and 32 patients received 300 000 IU. No difference was found in 25-OH-D levels between the two groups at presentation. The mean level of 25-OH-D was higher in the 10 000 IU/kg group at the second week of therapy. There was no difference between the groups at post-treatment weeks 4 and 12. The 25-OH-D was found to be below optimal levels (≥30 ng/mL) in 66.5% and <20 ng/mL in 21.8% of patients at the third month in both groups. None developed hypercalcemia and/or hypercalciuria. Nephrolithiasis was not detected in any patient.

CONCLUSION

This study showed that both doses of stoss therapy used in the treatment of vitamin D insufficiency/deficiency are effective and safe. However, an optimal level of 25-OH-D cannot be maintained for more than three months.

Vitamin D deficiency and non-lipid biomarkers of cardiovascular risk

INTRODUCTION

Deficient 25-hydroxyvitamin D (25(OH)D) levels have been associated with dyslipidemia and cardiovascular diseases, though the underlying mechanism of these associations is uncertain. We analyzed associations between vitamin D and other non-lipid biomarkers of cardiovascular risk to better elucidate possible relationships between deficient 25(OH)D and cardiovascular disease.

MATERIAL AND METHODS

We performed a cross-sectional analysis of 4,591 adults included in a clinical laboratory database from 2009 to 2011 with available measurements for 25(OH)D and the following biomarkers: homocysteine (Hcy), high-sensitivity C-reactive protein (hs-CRP), cystatin-C, creatinine, γ-glutamyltransferase (GGT), uric acid, and hemoglobin A_1c (HbA_1c). We calculated odds ratios (OR) of having high levels of each biomarker associated with 25(OH)D deficiency (< 20 ng/ml) compared to optimal levels (≥ 30 ng/ml) using logistic regression adjusted for age, sex, and lipids.

RESULTS

The mean ± SD age was 60 ±14 years and 46% of patients were women. In multivariable-adjusted models, adults with deficient 25(OH)D compared to those with optimal levels had increased odds of elevated biomarkers as follows: Hcy (OR = 2.53, 95% CI: 1.92-3.34), hs-CRP (1.62, 1.36-1.93), cystatin-C (2.02, 1.52-2.68), creatinine (2.06, 1.35-3.14), GGT (1.39, 1.07-1.80), uric acid (1.60, 1.31-1.95), and HbA_1c (2.47, 1.95-3.13). In analyses evaluating women and men separately, 25(OH)D deficient women but not men had increased odds of elevated levels of all biomarkers studied. There were significant interactions based on sex between 25(OH)D and Hcy (p = 0.003), creatinine (p = 0.004), uric acid (p = 0.040), and HbA_1c (p = 0.037).

CONCLUSIONS

Deficient 25(OH)D is associated with elevated levels of many biomarkers of cardiovascular risk, particularly among women, in a United States population.

Vitamin D deficiency in an inpatient forensic intellectual disability service

No research has examined vitamin D deficiency among inpatients within forensic intellectual disability services, despite their potentially increased risk. Tests of serum 25(OHD) concentration in blood are routinely offered to patients within the service as part of the admission and annual physical health check. Results were classified as deficient <25, insufficient <50, sufficient 50-75 or optimal >75. Deficient or insufficient patients were offered supplement treatment and retested within 6 months. Levels were compared between groups: level of security and gender. At baseline, 87% of patients were deficient or insufficient, whilst 13% were sufficient or optimal. At follow-up, 53% had sufficient or optimal levels. However, some patients remained deficient (13%) or insufficient (34%) due to non-compliance with treatment. Women appeared more likely to be deficient. High levels of vitamin D deficiency were found among this population. Vitamin D screening and treatment is a simple and effective way of improving the physical health of this population.

Vitamin D and colorectal cancer: molecular, epidemiological and clinical evidence

In many cells throughout the body, vitamin D is converted into its active form calcitriol and binds to the vitamin D receptor (VDR), which functions as a transcription factor to regulate various biological processes including cellular differentiation and immune response. Vitamin D-metabolising enzymes (including CYP24A1 and CYP27B1) and VDR play major roles in exerting and regulating the effects of vitamin D. Preclinical and epidemiological studies have provided evidence for anti-cancer effects of vitamin D (particularly against colorectal cancer), although clinical trials have yet to prove its benefit. In addition, molecular pathological epidemiology research can provide insights into the interaction of vitamin D with tumour molecular and immunity status. Other future research directions include genome-wide research on VDR transcriptional targets, gene-environment interaction analyses and clinical trials on vitamin D efficacy in colorectal cancer patients. In this study, we review the literature on vitamin D and colorectal cancer from both mechanistic and population studies and discuss the links and controversies within and between the two parts of evidence.

Association Between Vitamin D Status and Schizophrenia: A First Psychotic Episode Study

Vitamin D deficiency has been linked with schizophrenia. We aimed to determine whether patients with a first episode of psychosis (FEP) had lower vitamin D levels compared with controls considering their final diagnosis. We conducted a cross-sectional study determining 25-hydroxyvitamin D blood levels. 25-Hydroxyvitamin D levels were considered optimum at 20 ng/mL or greater. A group of 45 adult patients with FEP and a group of 22 healthy controls matched for age were recruited. The patient group was subdivided in two final diagnosis groups (schizophrenia versus other psychoses) after a 6-month follow-up. Average vitamin D values were deficient for FEP patients, especially those 22 with a final diagnosis of schizophrenia. These results relating vitamin D and schizophrenia generate interest to further examine this association.

Evaluation of vitamin D3 intakes up to 15,000 international units/day and serum 25-hydroxyvitamin D concentrations up to 300 nmol/L on calcium metabolism in a community setting

Supplementation by the general public with vitamin D at doses above the Tolerable Upper Level of Intake (UL) is becoming quite common. The objective of the current analysis was to characterize the effect of vitamin D supplementation at doses up to 15,000 IU/d in a community-based program on vitamin D status, calcium homeostasis as well as on kidney, liver and immune function. We evaluated data collected for 3,882 participants in a community program for whom there were blood measurements at program entry and at follow-up within 6-18 months between 2013 and 2015. Participants were supplemented with a wide range of vitamin D doses (1,000 - 15,000 IU/d) aimed at achieving serum 25-hydroxyvitamin D [25(OH)D] levels of at least 100 nmol/L. Serum 25(OH)D concentrations up to 300 nmol/L were achieved without perturbation of calcium homeostasis or incidence of toxicity. Hypercalcemia and hypercalciuria were not related to an increase in 25(OH)D concentrations nor vitamin D dose. To achieve serum 25(OH)D levels >100 nmol/L on average, required vitamin D intakes of 6,000 IU/d for normal Body Mass Index (BMI), 7,000 IU/d for overweight and 8,000 IU/d for obese. Doses of vitamin D in excess of 6,000 IU/d were required to achieve serum 25(OH)D concentrations above 100 nmol/L, especially in individuals who were overweight or obese without any evidence of toxicity. Serum 25(OH)D concentrations up to 300 nmol/L were found to be safe.

The role of vitamin D and VDR in carcinogenesis: Through epidemiology and basic sciences

In the last two decades vitamin D (VD) research has demonstrated new extraskeletal actions of this pre-hormone, suggesting a protective role of this secosteroid in the onset, progression and prognosis of several chronic noncommunicable diseases, such as cardiovascular disease, diabetes mellitus or cancer. Regarding carcinogenesis, both preclinical and epidemiological evidence available show oncoprotective actions of VD and its receptor, the VDR. However, in late neoplastic stages the VD system (VDS) seems to be less functional, which appears to be due to an epigenetic silencing of the system. In preclinical experimental studies, VD presents oncoprotective actions through modulation of inflammation, cell proliferation, cell differentiation, angiogenesis, invasive and metastatic potential, apoptosis, miRNA expression regulation and modulation of the Hedgehog signalling pathway. Moreover, epidemiological evidence points towards an oncoprotective role of vitamin D and VDR in colorectal cancer. This association is more controversial with breast, ovarian and prostate cancers, although with a few adverse effects. Nonetheless, we should consider other factors to determine the benefit of increased serum concentration of VD. Much of the epidemiological evidence is still inconclusive, and we will have to wait for new, better-designed ongoing RCTs and their results to discern the real effect of vitamin D in cancer risk reduction and therapy. The objective of this literature review is to offer an up-to-date analysis of the role of the VD and VDR, in the onset, progression and prognosis of all types of cancer. We further discuss the available literature and suggest new hypotheses and future challenges in the field of VD research.

Serum vitamin D and change in lipid levels over 5 y: The Atherosclerosis Risk in Communities study

OBJECTIVES

Deficiency of 25-hydroxyvitamin D (25[OH]D) is associated with increased risk for cardiovascular disease, perhaps mediated through dyslipidemia. Deficient 25(OH)D is cross-sectionally associated with dyslipidemia, but little is known about longitudinal lipid changes. The aim of this study was to determine the relationship of 25(OH)D deficiency to longitudinal lipid changes and risk for incident dyslipidemia.

METHODS

This was a longitudinal community-based study of 13 039 participants from the ARIC (Atherosclerosis Risk in Communities) study who had 25(OH)D and lipids measured at baseline (1990-1992) and lipids remeasured in 1993 to 1994 and 1996 to 1998. Mixed-effect models were used to assess the association of 25(OH)D and lipid trends after adjusting for clinical characteristics and for baseline or incident use of lipid-lowering therapy. Risk for incident dyslipidemia was determined for those without baseline dyslipidemia.

RESULTS

Baseline mean ± SD age was 57 ± 6 y and 25(OH)D was 24 ± 9 ng/mL. Participants were 57% women, 24% black. Over a mean follow-up of 5.2 y, the fully adjusted average differences (95% confidence interval [CI]) comparing deficient (<20 ng/mL) to optimal (≥30 ng/mL) 25(OH)D were: total cholesterol (TC) -2.40 mg/dL (-4.21 to -0.60), high-density lipoprotein cholesterol (HDL-C) -3.02 mg/dL (-3.73 to -2.32) and the ratio of TC to HDL-C 0.18 (0.11-0.26). Those with deficient compared with optimal 25(OH)D had modestly increased risk for incident dyslipidemia in demographic-adjusted models (relative risk [RR], 1.19; 95% CI, 1.02-1.39), which was attenuated in fully adjusted models (RR, 1.12; 95% CI, 0.95-1.32).

CONCLUSIONS

Deficient 25(OH)D was prospectively associated with lower TC and HDL-C and a greater ratio of TC to HDL-C after considering factors such as diabetes and adiposity. Further work including randomized controlled trials is needed to better assess how 25(OH)D may affect lipids and cardiovascular risk.

Vitamin D and Cardiovascular Disease: Can Novel Measures of Vitamin D Status Improve Risk Prediction and Address the Vitamin D Racial Paradox?

PURPOSE OF REVIEW

To provide a state-of-the-art update on some emerging measures of vitamin D status and discuss how assessment of these key vitamin D metabolites might improve prognostication of risk for cardiovascular disease (CVD) outcomes.

RECENT FINDINGS

Vitamin D deficiency is a highly prevalent condition and relatively easy to treat with supplementation and/or modest sunlight exposure. A substantial body of experimental and epidemiological evidence suggest that vitamin D deficiency is a risk factor for CVD. Most epidemiologic studies to date have focused on total 25-hydroxyvitamin D [25(OH)D] concentrations, which is the established marker of vitamin D stores. However, there is emerging evidence that other novel markers of vitamin D metabolism may better characterize 'true' vitamin D status. Some key novel measures include bioavailable 25(OH)D, free 25(OH)D, 1-25 dihydroxyvitamin D, 24,25-dihydroxyvitamin D3 [24,25(OH)₂D3], and ratio of 24,25(OH)₂D3 to 25(OH)D [the vitamin D metabolic ratio]. Utilization of these biomarkers may enhance understanding of the association between vitamin D and CVD risk, and may provide explanation for the observation that 25(OH)D is a stronger CVD risk factor in whites than blacks.

SUMMARY

Novel measures of vitamin D status could potentially change clinical practice regarding how patients are currently screened for vitamin D status and defined as vitamin D deficient or not. However, whether measuring any of these alternate markers of vitamin D status can provide further insight regarding CVD risk beyond the traditionally measured 25(OH)D concentrations is uncertain at this time. This is an area where further research is strongly needed.

Vitamin D Insufficiency and Cognitive Function Trajectories in Older Adults: The Rancho Bernardo Study

BACKGROUND

Evidence of a role for vitamin D (VitD) in cognitive aging is mixed and based primarily on extreme VitD deficiency. We evaluated the association of VitD insufficiency with cognitive function in older, community-dwelling adults living in a temperate climate with year-round sunshine.

METHODS

A population-based longitudinal study of 1,058 adults (median age 75; 62% women) who had cognitive function assessed and serum levels of 25-hydroxyvitaminD (25OHD) measured in 1997-99 and were followed for up to three additional cognitive function assessments over a 12-year period.

RESULTS

Overall, 14% (n = 145) of participants had VitD insufficiency defined as 25OHD <30 ng/ml. Adjusting for age, sex, education, and season, VitD insufficiency was associated with poorer baseline performance on the Mini-Mental Status Exam (MMSE) (p = 0.013), Trails Making Test B (Trails B) (p = 0.015), Category Fluency (p = 0.006), and Long Term Retrieval (p = 0.019); differences were equivalent to 5 years of age. For those with VitD insufficiency, the odds of mildly impaired performance at baseline were 38% higher for MMSE (p = 0.08), 78% higher for Trails B (p = 0.017), and 2-fold higher for Category Fluency and Long Term Retrieval (both p = 0.001). VitD insufficiency was not related to the rate of cognitive decline on any test or the risk of developing impaired performance during follow-up.

CONCLUSION

In this population with little VitD deficiency, even moderately low VitD was associated with poorer performance on multiple domains of cognitive function. Low VitD did not predict 12-year cognitive decline. Clinical trials are essential to establish a causal link between VitD and cognitive well-being.

Effectiveness of Vitamin D Supplementation for Cardiovascular Health Outcomes

There is a plausible physiological theory, supported by many observational studies, that vitamin D supplementation should be effective for improving cardiovascular end points, such as blood pressure (BP), large artery stiffness, atherosclerosis, endothelial function and clinical events. However, results from randomised controlled trials (RCTs) have been inconsistent. In this review, we evaluated the evidence regarding the effectiveness of vitamin D supplementation for cardiovascular surrogate and hard clinical end points. RCTs were assessed in terms of sample size, duration of supplementation, baseline vitamin D level inclusion criteria (i.e., absence of vitamin D deficiency), dosage of vitamin D and population under investigation. Forty-five RCTs were identified. Eight RCTs with BP and 6 RCTs with large artery stiffness as the end points were found to comply with guidelines for the optimal design of clinical trials evaluating nutrient effects. Only 2 of the RCTs with an optimal design were effective in decreasing BP with vitamin D supplementation, although these were of moderate sample size (<150) and very short duration (8 weeks for both), whilst no RCT was effective in reducing large artery stiffness. Similar results were observed for atherosclerotic and endothelial function markers as end points. Only 1 RCT reported cardiovascular events as an end point and found neither increased nor decreased incident cardiovascular events over 7 years of follow-up. In conclusion, results from published RCTs indicate that vitamin D supplementation is ineffective in improving cardiovascular health among various patient populations, including in the presence or absence of vitamin D deficiency.

Blood levels of vitamin D and health-functional status in asymptomatic individuals: a cross sectional study

BACKGROUND

Recently issued guidelines do not recommend screening for vitamin D deficiency in asymptomatic adults. The large range of health effects that have been associated with vitamin D deficiency raises the possibility that vitamin D levels may be a marker of poor health status rather than a cause of it. We investigated an association between vitamin D level and health-functional status.

METHODS

This cross-sectional study comprised 205 individuals who had taken a first plasma vitamin D test and were not symptomatic for vitamin D deficiency. During an interview, participants responded to questions regarding demographic information and their exposure to the sun, as well as a health-functional status questionnaire - World Organization of Family Doctors/COOP charts. Correlations between study variables and vitamin D levels were calculated. A stepwise linear regression was performed to estimate variables that independently predict vitamin D levels.

RESULTS

The participants were 51 men and 154 women, mean age 41 years. Vitamin D level was positively correlated with weekend sun exposure and negatively correlated with body mass index (BMI). A reported positive change in health over the previous 2 weeks correlated with a higher vitamin D level. Individuals with higher vitamin D levels were more likely to report participation in physical activity and to report capability of performing daily activities. A total of 176 (86%) of the study population was deficient in vitamin D, according to a level <30 ng mL^-1 . Vitamin D deficiency was associated with older age, higher BMI, Arab compared with Jewish ethnicity (darker skin), and religious identification (more body covering). In the multivariate analysis older age, female gender, religious identification, Arab ethnicity, higher BMI, sunscreen use and low exposure to sun during the weekdays all associated with lower vitamin D levels.

CONCLUSION

No parameter of functional health demonstrated capability of distinguishing vitamin D deficiency among healthy young to middle-aged adults.

Long-term adherence and effects on grip strength and upper leg performance of prescribed supplemental vitamin D in pregnant and recently pregnant women of Somali and Swedish birth with 25-hydroxyvitamin D deficiency: a before-and-after treatment study

Background

Muscular weakness and severe vitamin D deficiency is prevalent in Somali (veiled) pregnant women, Sweden. The study aims here were to explore adherence to prescribed supplemental vitamin D in new mothers with vitamin D deficiency and its effects on grip strength and upper leg performance in Somali (target group TG) and Swedish women (reference group RG) from spring through winter.

Methods

A before- and after study was designed. A cross-sectional sample of women in antenatal care with serum 25-OHD ≤50 nmol/L were prescribed one or two tablets daily (800 or 1600 IU vitamin D3 with calcium) for 10 months. Reminders were made by Somali nurses (TG) or Swedish doctors (RG). Baseline and 10 month measurements of plasma nmol/L 25-OHD, maximal grip strength held for 10 s (Newton, N) and ability to squat (yes;no) were done. Total tablet intake (n) was calculated. Outcome variables were changes from baseline in grip strength and ability to squat. Predicting variables for change in grip strength and ability to squat were calculated using linear and binary regression in final models. Undetectable 25-OHD values (<10 nmol/L) were replaced with ‘9’ in statistic calculations.

Results

Seventy-one women (46 TG, 1/3 with undetectable baseline 25-OHD; 25 RG) participated. At the 10-month follow up, 17% TG and 8% RG women reported having refrained from supplement. Mean 25-OHD increased 16 to 49 nmol/L (TG) and 39 nmol/L to 67 nmol/L (RG), (both p < 0.001). Grip strength had improved from 153 to 188 N (TG) (p < 0.001) and from 257 to 297 N (RG) (p = 0.003) and inability to squat had decreased in TG (35 to 9, p < 0.001). Intake of number of tablets predicted increased grip strength (B 0.067, 95%CI 0.008–0.127, p = 0.027). One tablet daily (>300 in total) predicted improved ability to squat (OR 16; 95% CI 1.8–144.6).

Conclusions

Adherence to supplemental vitamin D and calcium should be encouraged as an even moderate intake was associated to improved grip strength and upper leg performance, which was particularly useful for the women with severe 25-OHD deficiency and poor physical performance at baseline.

Trial registration

ClinicalTrials.gov Identifier: NCT02922803. Date of registration: September 28, 2016.

25-Hydroxyvitamin D Levels and Markers of Subclinical Myocardial Damage and Wall Stress: The Atherosclerosis Risk in Communities Study

BACKGROUND

Low 25-hydroxyvitamin D (25[OH]D) is associated with increased cardiovascular disease risk. Less known is whether 25(OH)D deficiency contributes to subclinical myocardial damage and wall stress (high-sensitivity cardiac troponin T [hs-cTnT] and N-terminal pro-brain natriuretic peptide [NT-proBNP]) or whether associations vary among subgroups.

METHODS AND RESULTS

Overall, 11 311 Atherosclerosis Risk in Communities participants without prevalent cardiovascular disease had 25(OH)D, hs-cTnT, and NT-proBNP measured at baseline (1990-1992), and 8990 had measurements of hs-cTnT and NT-proBNP repeated 6 years later. We examined associations of deficient 25(OH)D (<20 ng/mL) with prevalent elevated hs-cTnT (≥14 ng/L) and NT-proBNP (≥100 pg/mL), change in hs-cTnT and NT-proBNP, and incident elevated hs-cTnT and NT-proBNP. We tested for interactions by age (<56 and ≥56 years), sex, and race. In fully adjusted models, 25(OH)D was not associated with prevalent elevated hs-cTnT and NT-proBNP. Deficient 25(OH)D, however, was associated with increased 6-year change in hs-cTnT (β=0.54 ng/L [95% CI 0.08-1.01]) but not change in NT-proBNP. Deficiency in 25(OH)D was not associated with incident elevated hs-cTnT in the overall cohort but was associated with incident elevated hs-cTnT in younger but not older adults (relative risk 2.18 [95% CI 1.21-3.94] versus 0.78 [95% CI 0.56-1.08], respectively; P=0.01 for interaction by age). Deficient 25(OH)D was also associated with incident elevated NT-proBNP in men but not women (P=0.01 for interaction by sex).

CONCLUSIONS

Vitamin D deficiency was associated with increased 6-year change in hs-cTnT levels. Hypothesis-generating differences in associations by age and sex, but not race, were observed. If these associations are causal, further research is needed to understand mechanisms by which low 25(OH)D confers increased risk in these subgroups and whether treating deficient 25(OH)D can prevent myocardial damage and wall stress.

Short-term Variability of Vitamin D-Related Biomarkers

BACKGROUND

Quantifying the variability of biomarkers is important, as high within-person variability can lead to misclassification of individuals. Short-term variability of important markers of vitamin D metabolism is relatively unknown.

METHODS

A repeatability study was conducted in 160 Atherosclerosis Risk in Communities study participants (60% female, 28% black, mean age 76 years). Fasting serum was drawn at 2 time points, a median of 6 (range 3-13) weeks apart. Vitamin D binding protein (VDBP) and 25-hydroxyvitamin D [25(OH)D] were measured by LC-MS, fibroblast growth factor (FGF23) and parathyroid hormone (PTH) by enzyme-linked immunoassay, and calcium and phosphorus by Roche Cobas 6000. Free and bioavailable 25(OH)D were calculated. We calculated the within-person CV (CV_W), intraclass correlation coefficient (ICC), Spearman rank correlation coefficient (r), and percent reclassified.

RESULTS

The CV_W was lowest for calcium (2.0%), albumin (3.6%), 25(OH)D (6.9%), VDBP (7.0%) and phosphorus (7.6%); intermediate for free 25(OH)D (9.0%) and bioavailable 25(OH)D (9.9%); and highest for PTH (16.7%) and FGF23 (17.8%). Reclassification was highest for PTH, VDBP, and phosphorus (all 7.5%). The ICC and r were highest (≥0.80) for 25(OH)D, free 25(OH)D, bioavailable 25(OH)D and PTH, but somewhat lower (approximately 0.60-0.75) for the other biomarkers.

CONCLUSIONS

Six-week short-term variability, as assessed by CV_W, was quite low for VDBP, calcium and phosphorus, but fairly high for FGF23 and PTH. As such, multiple measurements of FGF23 and PTH may be needed to minimize misclassification. These results provide insight into the extent of potential misclassification of vitamin D markers in research and clinical settings.

The Effect of Serum 25-Hydroxyvitamin D on Elevated Homocysteine Concentrations in Participants of a Preventive Health Program

Both lower serum 25-hydroxyvitamin D [25(OH)D] and elevated homocysteine concentrations are potential risk factors for cardiovascular disease (CVD). A recent analysis of the National Health and Nutrition Examination Survey reported an inverse association of serum 25(OH)D with homocysteine, however, the longitudinal relationship has yet to be investigated. We hypothesized and examined whether a temporal increase in 25(OH)D concentrations is paralleled by a reduction in the risk for elevated homocysteine. We analyzed data of 4475 participants with repeated assessments of serum 25(OH)D and homocysteine concentrations who enrolled in a preventive health program that encourages vitamin D supplementation and monitors serum 25(OH)D and homocysteine concentrations. We defined elevated homocysteine as concentrations greater than 13 micromoles per liter. Logistic regression was applied to assess the association of temporal changes in serum 25(OH)D with the risk of elevated homocysteine. We observed an inverse gradient whereby greater increases in 25(OH)D concentrations were associated with a lower prevalence of elevated homocysteine. Relative to those without temporal increases in 25(OH)D, participants who showed improvements in their serum 25(OH)D concentrations of “<25”, “25–50”, “50–75”, and “≥75” nanomoles per liter at follow up were 0.92 (95% confidence interval: 0.62–1.37), 0.52 (0.33–0.80), 0.34 (0.20–0.58), and 0.32 (0.19–0.54) times as likely to have elevated homocysteine, respectively. These observations suggest that temporal improvements in vitamin D status reduce serum homocysteine concentrations, and therefore may potentially contribute to the primary prevention of CVD.

The vitamin D status of the US population from 1988 to 2010 using standardized serum concentrations of 25-hydroxyvitamin D shows recent modest increases

BACKGROUND

Temporal trends in the US population's vitamin D status have been uncertain because of nonstandardized serum 25-hydroxyvitamin D [25(OH)D] measurements.

OBJECTIVE

To accurately assess vitamin D status trends among those aged ≥12 y, we used data from the cross-sectional NHANESs.

DESIGN

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for measuring 25(OH)D (sum of 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3), calibrated to standard reference materials, was used to predict LC-MS/MS-equivalent concentrations from radioimmunoassay data (1988-2006 surveys; n = 38,700) and to measure LC-MS/MS concentrations (2007-2010 surveys; n = 12,446). Weighted arithmetic means and the prevalence of 25(OH)D above or below cutoff concentrations were calculated to evaluate long-term trends.

RESULTS

Overall, mean predicted 25(OH)D showed no time trend from 1988 to 2006, but during 2007-2010 the mean measured 25(OH)D was 5-6 nmol/L higher. Those groups who showed the largest 25(OH)D increases (7-11 nmol/L) were older, female, non-Hispanic white, and vitamin D supplement users. During 1988-2010, the proportions of persons with 25(OH)D <40 nmol/L were 14-18% (overall), 46-60% (non-Hispanic blacks), 21-28% (Mexican Americans), and 6-10% (non-Hispanic whites).

CONCLUSIONS

An accurate method for measuring 25(OH)D showed stable mean concentrations in the US population (1988-2006) and recent modest increases (2007-2010). Although it is unclear to what extent supplement usage compared with different laboratory methods explain the increases in 25(OH)D, the use of higher vitamin D supplement dosages coincided with the increase. Marked race-ethnic differences in 25(OH)D concentrations were apparent. These data provide the first standardized information about temporal trends in the vitamin D status of the US population.

Natural Products for Cancer Prevention: Clinical Update 2016

OBJECTIVES

To present a clinical update of natural products for cancer prevention and provide oncology nurses with an evidence-based review of natural products for patient counseling and education.

DATA SOURCES

Clinical trials published in PubMed.

CONCLUSION

In the past 4 years since the publication of the original review there have been minimal changes in the conclusions of the published literature on the use of natural products for cancer prevention. To date, clinical trials have not demonstrated conclusive benefit of using natural products for cancer prevention, and current guidelines do not recommend their use. This review provides an update on published and ongoing trials and can serve as an updated resource for nurses. Evidence-based natural products databases can help nurses stay current with the scientific literature and be effective educators and health coaches for their patients, who can be influenced by marketing of unregulated products.

IMPLICATIONS FOR NURSING PRACTICE

Patients often discuss the use of natural products with nurses. Nurses have an opportunity to educate and coach patients in effective preventive lifestyle practices.