Vitamin D and Health: Evolution, Biologic Functions, and Recommended Dietary Intakes for Vitamin D

Unlocking the mystery of the role of Vitamin D in iron deficiency anemia in antenatal women: a case control study in a tertiary care hospital in New Delhi

BACKGROUND

Vitamin D deficiency and anemia are clinical conditions that coexist during pregnancy. A high prevalence of Vitamin D deficiency ranging from 50 to 94% is seen throughout the country. The aim of the study was to discover the association between Vitamin D status and iron deficiency anemia during pregnancy. Improving the vitamin D status of pregnant women is crucial to prevent iron deficiency anemia and can improve maternal and fetal outcomes.

METHODS

A case-control study including 94 primigravida women of age within the age group 18 to 30 years, divided into two groups: a Case Group of 48 patients with already diagnosed iron deficiency anemia (mild to moderate) and a Control Group of 46 antenatal women with normal hemoglobin levels. Data on sociodemographic, clinical characteristics, and the levels of 25(OH) Vitamin D was estimated in both the groups. The association of 25(OH)D levels and anemia was then determined using suitable statistical analysis.

RESULTS

Among pregnant women affected with anemia, 75% of women had serum Vitamin D concentrations < 20 ng/ml compared to 52.2% of women in the controls. Maternal serum vitamin D level was significantly lower in pregnant women affected with anemia (19.61 ± 13.12) as compared to control (29.43 ± 24.05); (p = 0.024). A positive correlation was found between hemoglobin and vitamin D levels in pregnant women (Pearson's r = 0.200, p = 0.05).

CONCLUSIONS

These findings provide evidence suggesting that Vitamin D deficiency or insufficiency during pregnancy may be a risk factor for anemia and correction of Vitamin D levels can improve hemoglobin levels. Educational efforts should be made to include safe vitamin D intake in antenatal care.

Dietary supplementation of 25-hydroxycholecalciferol as an alternative to cholecalciferol in swine diets: A review

25-hydroxycholecalciferol (25-OHD₃ ) formed via hepatic hydroxylation from vitamin D, cholecalciferol, represents the precursor of the biologically active vitamin D hormone, 1,25-dihydroxyvitamin D. Due to a higher absorption rate and the omission of one hydroxylation, dietary supplementation of 25-OHD₃ instead of vitamin D₃ is considered to be more efficient as plasma concentrations of 25-OHD₃ are increased more pronounced. The present review summarises studies investigating potential beneficial effects on mineral homeostasis, bone metabolism, health status and performance in sows, piglets and fattening pigs. Results are inconsistent. While most studies could not demonstrate any or only a slight impact of partial or total replacement of vitamin D₃ by 25-OHD₃ , some experiments indicated that 25-OHD₃ might alter physiological processes when animals are challenged, for example, by a restricted mineral supply.

Vitamin D is associated with body composition and fat intake, but not with cardiometabolic parameters in adults with obesity

Adults with obesity are at higher risk for developing hypovitaminosis D. Some studies suggest that reduced levels of serum 25-hydroxyvitamin D (25(OH)D) may also be related to disorders in cardiometabolic parameters. However, because of the association between 25(OH)D and obesity, we hypothesized that body composition can be a confounding factor in the association of 25(OH)D with cardiometabolic parameters, and that 25(OH)D is inversely associated with body composition and cardiometabolic parameters and directly associated with fat intake. The aim of this study was to analyze the associations between 25(OH)D with body composition, fat intake, and cardiometabolic parameters in adults with obesity. This cross-sectional study consisted of 52 adults with obesity (61.53% female; 37.50 ± 6.88 years; body mass index [BMI]: 33.60 ± 2.89 kg/m²). Cardiometabolic parameters (fasting blood glucose, insulin resistance index, C-reactive protein, blood pressure, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, and cholesterol), body mass, BMI, waist circumference, body fat percentage, and fat intake were evaluated. Body mass was negatively associated with 25(OH)D (β = -0.108; P = .048; and R² = 0.090) and BMI (β = -0.621; P = .031; and R² = 0.103), both adjusted for fat intake. 25(OH)D was positively associated with fat intake (β = 0.129; P = .045 and R² = 0.078) adjusted for sex, age, and skin color. Cardiometabolic parameters were not associated with 25(OH)D, even after adjusted by body composition variables. However, the high prevalence of hypovitaminosis D (75%) and the negative association between 25(OH)D and body composition reinforce the importance of analyzing and monitoring vitamin D status in this population.

Potential roles of vitamin D binding protein in attenuating liver injury in sepsis

BACKGROUND

In sepsis, vitamin D binding protein (VDBP) has been shown to be low-expressed. The current study examined the relationship between serum VDBP level and liver injury in sepsis patients, as well as in a mouse model for sepsis and in cultured liver epithelial cell line exposed to lipopolysaccharide (LPS).

METHODS

The human study included 78 sepsis patients and 50 healthy volunteers. Sepsis patients were categorized into sepsis survivor group (n = 43) and sepsis non-survivor group (n = 35) based on 28-day mortality for data analysis. Adult male C57BL/6 mice were subjected to cecal ligation and puncture (CLP). Serum samples were collected on day 1, 3, 5 and 7 to determine the levels of VDBP, 25-hydroxyvitamin D [25(OH)D₃], 1,25-dihydroxyvitamin D [1,25(OH)₂D₃], interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α). Potential protective effects of VDBP overexpression against LPS-induced liver damage were examined in cultured THLE2 cells.

RESULTS

Serum levels of VDBP, 25(OH)D₃, and 1,25(OH)₂D₃ were significantly lower in sepsis patients vs. the healthy control (P < 0.001), as well as in the sepsis non-survivor group vs. the sepsis survivor group (P < 0.001, P = 0.0338, or P = 0.0013, respectively). Lower serum VDBP level was associated with higher Acute Physiology and Chronic Health Evaluation (APACHE) II score (r = - 0.2565, P = 0.0234) and Sequential Organ Failure Assessment score (r = - 0.3522, P = 0.0016), but lower serum albumin (ALB, r = 0.4628, P < 0.001) and total protein (TP, r = 0.263, P = 0.02). In CLP mice, there was a 5-day period of serum VDBP reduction, followed by return towards the baseline on day 7. VDBP was also decreased in LPS-treated THLE2 cells (P < 0.001). VDBP overexpression reduced LPS-induced THLE2 damage. Reduced damage was associated with decreased oxidative stress and inactivation of the c-Jun N-terminal kinase signaling pathway.

CONCLUSION

VDBP may be protective against sepsis-induced liver injury.

An Approach to Investigate Content-Related Quality of Nutraceuticals Used by Slovenian Consumers: A Case Study with Folate and Vitamin D Supplements

A predisposition for the efficiency of nutraceuticals is that the product contains a sufficient quantity of a vitamin. Several studies have highlighted different quality issues. Our objective was to investigate whether the contents of the vitamins in selected types of food supplements were in accordance with labeling. We focused on two types of food supplements where content-related quality issues could result in public health risks: food supplements for supplementation with (a) folic acid (as 5-methyltetrahydrofolate (5-MTHF)) in pregnancy and (b) with vitamin D in the general population. The study was done on supplements from the global supply that are typically used by Slovenian consumers. We sampled one production batch of 30 different food supplements-six and 24 samples with 5-MTHF and cholecalciferol, respectively. We found samples with vitamin contents outside the 80-150% tolerance interval in both sets. Particularly, 5-MTHF was found to be more problematic, probably due to its lower stability. This study shows the need for better quality control. Quality control is needed during both the manufacturing process and product shelf lifetimes. Content quality should be also subject to external controls by authorities. Voluntarily quality control schemes would also enable consumers to identify products of sufficient quality.

Effects of resistance training on serum 25(OH) D concentrations in young men: a randomized controlled trial

Background

Previous studies indicated that serum 25-hydroxyvitamin D [25(OH)D] concentrations are positively associated with physical activity levels independent of sun exposure. However, the effect of resistance training on serum 25(OH) D concentrations remains unclear. Thus, this study aimed to examine the effect of chronic resistance training on serum 25(OH) D concentrations and determine whether 25(OH) D concentration variations are influenced by body composition changes.

Methods

Eighteen young men aged 19–39 years were randomly divided into a 12-week resistance training group (RT, n = 9) and non-exercise control group (CON, n = 9). The trial was undertaken in Shanghai University of Sport in Shanghai, China. Randomization and allocation to trial group were carried out by a central computer system. Serum 25(OH) D and intact parathyroid hormone concentrations were measured using commercially available enzyme-linked immunosorbent assay kits. Body composition was measured by dual-energy X-ray absorptiometry.

Results

The average serum 25(OH) D concentrations were 26.6 nmol/L at baseline. After the 12-week intervention program, serum 25(OH) D concentrations significantly increased in both groups. Serum 25(OH) D concentrations at midpoint (6-week) increased significantly only in the CON group (P < 0.01). From training midpoint to endpoint, a significantly greater increase in serum 25(OH) D concentrations was noted in the RT group (P-interaction = 0.043); 25(OH) D concentration changes (end-pre) were negatively related to fat-free mass (mid-pre) (r = − 0.565, P = 0.015) and muscle mass (mid-pre) (r = − 0.554, P = 0.017).

Conclusions

There were no beneficial effects of the 12-week resistance training on serum 25(OH) D concentration in vitamin D deficient young men, and an indication that seasonal increase in serum 25(OH) D concentrations during the early phase of resistance training was transiently inhibited, which may partly be attributed to resistance training-induced muscle mass gain.

Trial registration

Chinese Clinical Trial Registry, ChiCTR2000030876. Registered 16 March 2020 - Retrospectively registered, http://www.chictr.org.cn/showproj.aspx?proj=50504.

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

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Nutrihealth Study: Seasonal Variation in Vitamin D Status Among the Slovenian Adult and Elderly Population

Several studies conducted around the world showed substantial vitamin D insufficiency and deficiency among different population groups. Sources of vitamin D in the human body include ultraviolet B (UVB)-light-induced biosynthesis and dietary intake, but people's diets are often poor in vitamin D. Furthermore, in many regions, sun exposure and the intensity of UVB irradiation during wintertime are not sufficient for vitamin D biosynthesis. In Slovenia, epidemiological data about vitamin D status in the population were investigated through a national Nutrihealth study-an extension to the national dietary survey SI.Menu (2017/18). The study was conducted on a representative sample of 125 adult (18-64 years) and 155 elderly (65-74 years old) subjects, enrolled in the study in different seasons. Their vitamin D status was determined by measuring the serum 25-hydroxy-vitamin D (25(OH)D) concentration. Thresholds for vitamin D deficiency and insufficiency were 25(OH)D levels below 30 and 50 nmol/L, respectively. Altogether, 24.9% of the adults and 23.5% of the elderly were found to be vitamin D deficient, while an insufficient status was found in 58.2% and 62.9%, respectively. A particularly concerning situation was observed during extended wintertime (November-April); vitamin D deficiency was found in 40.8% and 34.6%, and insufficient serum 25(OH)D levels were observed in 81.6% and 78.8%, respectively. The results of the study showed high seasonal variation in serum 25(OH)D levels in both the adult and elderly population, with deficiency being especially pronounced during wintertime. The prevalence of this deficiency in Slovenia is among the highest in Europe and poses a possible public health risk that needs to be addressed with appropriate recommendations and/or policy interventions.

Effect of Vitamin D and Magnesium Supplementation on Behavior Problems in Children with Attention-Deficit Hyperactivity Disorder

Background:

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by the three main symptom domains including inattention, hyperactivity, and impulsivity. Recent findings suggested that nutrients might play an important role in the pathology of ADHD. The present study aimed to examine the effects of Vitamin D and magnesium supplementation on behavior problems in children with ADHD.

Methods:

This double-blind, randomized controlled clinical trial study was conducted on 66 children with ADHD in Clinic of Noor and Ali Asghar Hospital in Isfahan, Iran, in 2016. Children were randomly allocated to receive both Vitamin D (50,000 IU/week) and magnesium (6 mg/kg/day) supplements (n = 33) or placebos (n = 33) for 8 weeks. Conners’ Parent Rating Scale was used to evaluate children's behavior at baseline and at the end of the study.

Results:

After 8 weeks of Vitamin D consumption as well as magnesium, the serum levels of 25-hydroxy-Vitamin D3 and magnesium increased significantly in the intervention group compared with placebo group. Supplementation with Vitamin D and magnesium caused a significant decrease in conduct problems, social problems, and anxiety/shy scores; but it had no significant effect on psychosomatic problems score.

Conclusions:

Vitamin D and magnesium supplementation in children with ADHD was effective on conduct problems, social problems, and anxiety/shy scores compared with placebo intake, but it did not affect psychosomatic problem scores, significantly.

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.

Vitamin D in Wild and Farmed Atlantic Salmon (Salmo Salar)-What Do We Know?

Salmon have been widely publicized as a good dietary source of vitamin D, but recent data points to large variation in vitamin D content and differences between wild and farmed salmon. We aimed to: (1) investigate the content of vitamin D in Atlantic salmon (Salmo salar) in wild species caught in two different waters, (2) perform a 12-week feeding trial in farmed Salmo salar with 270-1440 µg vitamin D3/kg feed (4-20 times maximum level in the EU) and (3) conduct a review for the published data on the content of vitamin D in salmonids. Content of vitamin D3 in the fillet from wild salmon caught in the Baltic Sea and the North Sea was significantly different (p < 0.05), being 18.5 ± 4.6 µg/100 g and 9.4 ± 1.9 µg/100 g, respectively. In the farmed salmon the content ranged from 2.9 ± 0.7 µg vitamin D3/100 g to 9.5 ± 0.7 µg vitamin D3/100 g. Data from 2018 shows that farmed salmon contained 2.3-7.3 µg vitamin D3/100 g. Information on the content of vitamin D in wild and farmed salmonids is very limited, which calls for further research to ensure a sustainable production of salmon with adequate vitamin D.

Vitamin D-supplemented yogurt drink reduces Candida infections in a paediatric intensive care unit: a randomised, placebo-controlled clinical trial

BACKGROUND

The prevalence of Candida infections in paediatric intensive care units (PICUs) has dramatically increased as a result of resistance to conventional anti-fungal treatments. Because vitamin D has been shown to exhibit fungicidal activity against Candida infection in an in vitro antimicrobial screening, we aimed to investigate the effect of vitamin D on Candida infections in the PICU.

METHODS

Four hundred sixteen eligible children aged between 12 months to 5 years old admitted to the PICU, who were on broad-spectrum antibiotic therapy, participated in the study. Patients were randomly assigned to two study groups, receiving a plain yogurt drink (placebo group) or supplemented with 300 IU day^-1 vitamin D (VD group). Primary outcome was defined as the incidences of Candida colonisation (Candida isolated from rectal swab) 14 days after enrollment. Secondary outcome measures were Candida growth in blood (candidaemia) and urine (candiduria).

RESULTS

The prevalence of candiduria as well as candidaemia was significantly lower in the VD-treated group (26 cases) than in the placebo group (62 cases). The mean (SD) length of PICU stay was obviously lowered in the VD group [11.8 (1.2) days] compared to the placebo group [15.2 (2.3 days)], whereas cases of patient death were similar between the two groups.

CONCLUSIONS

Supplementation of vitamin D effectively reduces infections of Candida in children who were critically ill and on broad-spectrum antibiotic treatment.

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

INTRODUCTION

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Vitamin D Receptor Expression in Dogs

Background

There is growing evidence linking low blood vitamin D concentration to numerous diseases in people and in dogs. Vitamin D influences cellular function by signaling through the vitamin D receptor (VDR). Little is known about which non‐skeletal tissues express the VDR or how inflammation influences its expression in the dog.

Objectives

To define which non‐skeletal canine tissues express the VDR and to investigate expression in inflamed small intestine.

Animals

Thirteen non‐skeletal tissues were collected prospectively from 6 control dogs. Thirty‐five dogs diagnosed with a chronic enteropathy (CE) and 24 control dogs were prospectively enrolled and duodenal biopsies were evaluated for VDR expression.

Methods

Prospective; blinded assessment of canine intestinal VDR. Dogs with CE were included once other identifiable causes of intestinal disease were excluded. Age matched controls were included with no intestinal clinical signs. VDR expression was assessed immunohistochemically in all samples, using a Rat IgG VDR monoclonal antibody. Quantitative real‐time polymerase chain reaction (qPCR) was also used for duodenal biopsies.

Results

VDR expression as assessed by immunohistochemistry (IHC) was highest in the kidney, duodenum, skin, ileum and spleen, and weak in the colon, heart, lymph node, liver, lung, and ovary. Gastric and testicular tissue did not express the VDR. There was no statistical difference in duodenal VDR expression between the 24 healthy dogs and 34 dogs with CE when quantified by either qPCR (P = 0.87) or IHC (P = 0.099).

Conclusions and Clinical Importance

The lack of down regulation of VDR expression in inflamed intestine contrasts with previous studies in humans. Our findings support future studies to investigate whether vitamin D and its analogues can be used to modulate intestinal inflammation in the dog.

Effects of chronic endurance exercise training on serum 25(OH)D concentrations in elderly Japanese men

BACKGROUND

Higher levels of physical activity and cardiorespiratory fitness are positively related to serum 25-hydroxyvitamin D [25(OH)D] concentrations; however, the response of 25(OH)D concentrations to chronic endurance exercise training is unclear. Therefore, the purpose of this study was to elucidate whether serum 25(OH)D concentrations were directly increased by 5 weeks of endurance exercise training and influenced by changes in body fat in elderly men.

METHODS

Twenty elderly Japanese men were randomized to either the 5-week endurance exercise training group (ET group; N = 10) or the sedentary control group (SC group; N = 10). Fasting blood samples were collected to determine serum 25(OH)D and other blood parameters. The visceral fat area and hepatic fat content were assessed by magnetic resonance imaging and proton magnetic resonance spectroscopy, respectively.

RESULTS

After 5 weeks of endurance exercise training, the levels of maximal oxygen uptake (VO₂ max) were significantly increased from 23.3 at baseline to 28.1 mL/kg/min at the endpoint for the ET group; levels were unchanged for the SC group. A significant seasonal reduction in serum 25(OH)D concentrations was observed in the SC group (P < 0.05), while no change was found in the ET group. The results may be partly attributed to the slight decrease in intrahepatic fat in the ET group. No changes were observed in percent body fat or visceral fat area.

CONCLUSIONS

The results of our study suggest that 5 weeks of endurance training could inhibit the seasonal reduction in serum 25(OH)D concentrations without changes in body fat.

Effect of an Acute Bout of Endurance Exercise on Serum 25(OH)D Concentrations in Young Adults

CONTEXT

Regular exercise or high physical activity levels are associated with higher serum 25-hydroxyvitamin D [25(OH)D] concentrations; however, the effect of acute exercise on serum 25(OH)D concentrations remains unclear.

OBJECTIVE

We aimed to clarify whether acute endurance exercise has a direct effect on the circulating 25(OH)D concentrations in young adults.

DESIGN AND SETTING

Exercise intervention trial in an institutional practice.

PATIENTS

Twenty young, active adults (males, n = 10; females, n = 10).

INTERVENTIONS

Participants were asked to perform a cycling exercise for 30 minutes at 70% maximal oxygen uptake.

MAIN OUTCOME MEASURES

The serum concentrations of 25(OH)D and other blood parameters were assessed before exercise and at 0, 0.5, 1, 3, and 24 hours after exercise.

RESULTS

The serum 25(OH)D concentrations were significantly increased not only at 0 (P < 0.01), 1 (P < 0.05), and 3 hours (P < 0.01) after exercise, but they were also increased at 24 hours (P < 0.05) after acute endurance exercise in young adults. A significant sex × time interaction effect was observed (P < 0.05), and the incremental areas under the curve for the 25(OH)D concentrations were significantly higher in men than in the women (P < 0.01).

CONCLUSIONS

There is a direct effect of endurance exercise on serum 25(OH)D concentrations. In addition, sex disparity was observed in the serum 25(OH)D response to acute endurance exercise, and the increase in 25(OH)D concentrations was greater in men than in women.

Model-based meta-analysis for comparing Vitamin D2 and D3 parent-metabolite pharmacokinetics

Association of Vitamin D (D3 & D2) and its 25OHD metabolite (25OHD3 & 25OHD2) exposures with various diseases is an active research area. D3 and D2 dose-equivalency and each form's ability to raise 25OHD concentrations are not well-defined. The current work describes a population pharmacokinetic (PK) model for D2 and 25OHD2 and the use of a previously developed D3-25OHD3 PK model [1] for comparing D3 and D2-related exposures. Public-source D2 and 25OHD2 PK data in healthy or osteoporotic populations, including 17 studies representing 278 individuals (15 individual-level and 18 arm-level units), were selected using search criteria in PUBMED. Data included oral, single and multiple D2 doses (400-100,000 IU/d). Nonlinear mixed effects models were developed simultaneously for D2 and 25OHD2 PK (NONMEM v7.2) by considering 1- and 2-compartment models with linear or nonlinear clearance. Unit-level random effects and residual errors were weighted by arm sample size. Model simulations compared 25OHD exposures, following repeated D2 and D3 oral administration across typical dosing and baseline ranges. D2 parent and metabolite were each described by 2-compartment models with numerous parameter estimates shared with the D3-25OHD3 model [1]. Notably, parent D2 was eliminated (converted to 25OHD) through a first-order clearance whereas the previously published D3 model [1] included a saturable non-linear clearance. Similar to 25OHD3 PK model results [1], 25OHD2 was eliminated by a first-order clearance, which was almost twice as fast as the former. Simulations at lower baselines, following lower equivalent doses, indicated that D3 was more effective than D2 at raising 25OHD concentrations. Due to saturation of D3 clearance, however, at higher doses or baselines, the probability of D2 surpassing D3's ability to raise 25OHD concentrations increased substantially. Since 25OHD concentrations generally surpassed 75 nmol/L at these higher baselines by 3 months, there would be no expected clinical difference in the two forms.

Model-based meta-analysis for development of a population-pharmacokinetic (PPK) model for Vitamin D3 and its 25OHD3 metabolite using both individual and arm-level data

Clinical studies investigating relationships between D3 and 25OHD3 vary in dosing regimen, assays, demographics, and control of exogenous D3. This leads to uncertain and conflicting exposure-related associations with D3 and 25OHD3. To elucidate this parent-metabolite system, a PPK model was developed to predict mean D3 and 25OHD3 exposure from varied doses and administration routes. Sources of exposure variability related to metabolite baseline, weight, and assay type were explored. Specific search criteria were used in PUBMED to identify public source PK data pertaining to D3 and 25OHD3 in healthy or osteoporotic populations. Overall 57 studies representing 5395 individuals were selected, including 25 individual-level profiles and treatment-arm data. IV, oral, single and multiple dose data were used, with D3 and 25OHD3 dosing. A nonlinear mixed effects model was developed to simultaneously model PK dispositions of D3 and 25OHD3 (NONMEM v7.2), which were described by 2-compartment models with nonlinear and linear clearances, respectively. Proportional and additive assay variances were included on the 25OHD3 prediction. Unit-level random effects were weighted by treatment-arm size. D3 model estimates, relative to bioavailability were: maximum rate of metabolism ([Formula: see text], 1.62 nmol/h), Michaelis-Menten constant ([Formula: see text], 6.39 nmol/L), central volume of distribution ([Formula: see text], 15.5 L), intercompartmental clearance ([Formula: see text], 0.185 L/h), peripheral volume of distribution ([Formula: see text], 2333 L/h), and baseline concentration ([Formula: see text], 3.75 nmol/L). For 25OHD3 ([Formula: see text] = metabolite): [Formula: see text] = 0.0153 L/h, [Formula: see text] = 4.35 L, [Formula: see text] = 6.87 L, [Formula: see text] = 0.0507 L/h. Simulations of 25OHD3 concentration indicated an inverse relationship between 25OHD3 baseline and response, as well as a less than proportional 25OHD3 response. Estimation of assay bias parameters suggested that HPLC-MS and RIA produced similar measurement results, whereas CPBA and CHEMI are over-predictive of 25OHD3 concentration, relative to HPLC-MS.

Oral Manifestations of Chronic Kidney Disease and Renal Secondary Hyperparathyroidism: A Comparative Review

Recent epidemiological studies have demonstrated that significant associations exist between oral disease and diseases involving non-oral tissues. Occasionally, the roles may be reversed and the oral cavity can be severely affected by systemic disease originating in another part of the body. Renal secondary hyperparathyroidism is a common endocrinopathy that occurs as a consequence of chronic azotemic kidney disease. Renal osteodystrophy, the most dramatic clinical consequence of renal secondary hyperparathyroidism is uncommon, but can result in demineralization of maxillofacial bones, loosening of teeth, and pathological jaw fractures. The purpose of this report is to update the current understanding of the pathophysiology of this endocrine disease and to compare the oral manifestations of renal secondary hyperparathyroidism in humans and companion animals. A 50-year review of the veterinary literature was undertaken to examine the clinical presentation of renal osteodystrophy in dogs, and to determine what clinical consequences of renal secondary hyperparathyroidism have been reported in domestic cats.

A Semi-Experimental Study to Assess Whether the Current Recommended Protocol for Treating Vitamin D Deficiency is Enough?

Background:

Urbanization and diet change have increased the prevalence of Vitamin D deficiency. Unfortunately, none of the suggested treatments is widely accepted.

Objectives:

Therefore, we evaluated the most used and suggested protocol for treating Vitamin D deficiency in Percutaneous coronary intervention (PCI) candidate patients referred to our hospital in a short-term clinical trial.

Patients and Methods:

All patients with coronary artery disease, referred to our hospital and candidates for PCI (drug eluted stents) were included. Deficient patients were randomly assigned to treatment (Vitamin D3 pearls of 50,000 IU; one per week for 10 weeks then one pearl every month for maintenance) and non-treatment groups. Vitamin D was measured after nine months.

Results:

After initial evaluation, 116 cases were found to be deficient, and were divided into two equal groups of 58. No significant difference was found between the normal, treated and non-treated groups regarding age and gender. Thirty-two out of 58 (55.1%) subjects were vitamin D deficient and reached normal levels by taking supplements and seven out of 58 (12%) were deficient and reached normal levels without taking supplements, with the difference being significant (P < 0.001).

Conclusions:

The used protocol is not enough for treating Vitamin D deficiency. Furthermore, the protocol should be revised according to baseline Vitamin D classification.

Patients with Active Acromegaly are at High Risk of 25(OH)D Deficiency

Acromegaly is a chronic disease characterized by hypersecretion of growth hormone (GH) and insulin-like growth factor 1 (IGF-1). Electrolyte disturbances such as hypercalcemia and hyperphosphatemia are reported in patients with this disorder. There is limited data on vitamin D status in subjects with acromegaly. The aim of the study was to determine calcium, inorganic phosphate, magnesium, alkaline phosphatase, and 25(OH)D levels with regard to the activity of the disease. We also studied correlations of 25(OH)D and IGF-1, GH, body mass, body mass index, and age. A study group consisted of 55 acromegalic patients, and was divided into three subgroups: active acromegaly (AA), well-controlled acromegaly (WCA), cured acromegaly (CA). We enrolled 29 healthy subjects to a control group (CG). Vitamin D deficiency was recorded in all AA patients, 13 WCA patients (92.86%), 10 CA patients (62.5%), and 13 controls (54.17%). The highest 25(OH)D levels were found in the CG group and the lowest in the AA group (p = 0.012). The dose of octreotide did not influence serum 25(OH)D levels. A significant positive correlation between IGF-1 and 25(OH)D levels was observed in the AA group (r = 0.58, p = 0.024). Inorganic phosphate levels were the highest in the AA group. In conclusion, active acromegalic patients have lower 25(OH)D levels in comparison with the CG and are at higher risk of vitamin D deficiency.

Enhanced antioxidant capacity and anti-ageing biomarkers after diet micronutrient supplementation

A growing number of studies confirm an important effect of diet, lifestyle and physical activity on health status, the ageing process and many metabolic disorders. This study focuses on the influence of a diet supplement, NucleVital^®Q10 Complex, on parameters related to redox homeostasis and ageing. An experimental group of 66 healthy volunteer women aged 35–55 supplemented their diet for 12 weeks with the complex, which contained omega-3 acids (1350 mg/day), ubiquinone (300 mg/day), astaxanthin (15 mg/day), lycopene (45 mg/day), lutein palmitate (30 mg/day), zeaxanthine palmitate (6 mg/day), L-selenomethionine (330 mg/day), cholecalciferol (30 µg/day) and α-tocopherol (45 mg/day). We found that NucleVital^®Q10 Complex supplementation significantly increased total antioxidant capacity of plasma and activity of erythrocyte superoxide dismutase, with slight effects on oxidative stress biomarkers in erythrocytes; MDA and 4-hydroxyalkene levels. Apart from the observed antioxidative effects, the tested supplement also showed anti-ageing activity. Analysis of expression of SIRT1 and 2 in PBMCs showed significant changes for both genes on a mRNA level. The level of telomerase was also increased by more than 25%, although the length of lymphocyte telomeres, determined by RT-PCR, remained unchanged. Our results demonstrate beneficial effects concerning the antioxidant potential of plasma as well as biomarkers related to ageing even after short term supplementation of diet with NucleVital^®Q10 Complex.

Vitamin D: can fish food-based solutions be used for reduction of vitamin D deficiency in Poland?

OBJECTIVE

The multitude of diseases promoted by vitamin D deficiency makes providing the human organism with a constant and sufficiently high supply of this compound a high priority. The aim of this study was to verify the extent to which fish present in the Polish diet can satisfy the body's requirement for this compound. The obtained data would help to evaluate whether a diet rich in fish may be a solution for vitamin D deficiency.

METHODS

Cholecalciferol and ergocalciferol in muscle tissues of fish species popular in the Polish market were determined by means of high-performance liquid chromatography. Based on these updated data, and on data regarding fish consumption, it was possible to assess the level of vitamin D intake provided by fish consumption.

RESULTS

This study proved that some of the investigated species of fish are a good source of vitamin D3. Among wild fish, Baltic salmon and herring contained the highest amount of cholecalciferol. Surprisingly, the highest content of this compound was observed in lean tilapia, farmed in China. Ergocalciferol also was found in the studied fish samples.

CONCLUSION

Analysis of vitamin D content in various fish species indicated that the disproportion between requirement and supply seems too vast to enable eradication of vitamin D deficiency by fish food-based solutions. Still, increasing fish consumption or changing consumption patterns could be beneficial and result in noticeable improvements in vitamin D status.

Vitamin D improves inflammatory bowel disease outcomes: Basic science and clinical review

Vitamin D deficiency is commonly diagnosed among patients with inflammatory bowel disease (IBD). Patients with IBD are at risk of low bone density and increased fractures due to low vitamin D levels, long standing disease, and frequent steroid exposures; as a result, it is well established that vitamin D supplementation in this population is important. There is increasing support for the role of vitamin D in strengthening the innate immune system by acting as an immunomodulator and reducing inflammation in experimental and human IBD. The active form of vitamin D, 1,25(OH)D3, acts on T cells to promote T helper (Th)2/regulatory T responses over Th1/Th17 responses; suppresses dendritic cell inflammatory activity; induces antibacterial activity; and regulates cytokine production in favor of an anti-inflammatory response. Murine and human IBD studies support a therapeutic role of vitamin D in IBD. Risk factors for vitamin D deficiency in this population include decreased sunlight exposure, disease duration, smoking, and genetics. Vitamin D normalization is associated with reduced risk of relapse, reduced risk of IBD-related surgeries, and improvement in quality of life. Vitamin D is an inexpensive supplement which has been shown to improve IBD outcomes. However, further research is required to determine optimal serum vitamin D levels which will achieve beneficial immune effects, and stronger evidence is needed to support the role of vitamin D in inducing disease response and remission, as well as maintaining this improvement in patients’ disease states.

Association between serum 25-hydroxyvitamin D and inflammatory cytokines in healthy adults

Here, we aimed to examine the associations between levels of serum 25-hydroxyvitamin D [25(OH)D] and inflammatory cytokines in healthy Japanese adults. A total of 95 healthy adults (61 women; age range 21–69 years) participated in our study. Fasting blood samples were analyzed for 25(OH)D, 1,25-dihydroxyvitamin D [1,25(OH)₂D], interferon-γ (IFN-γ), interleukin-6 (IL-6), and interleukin-17 (IL-17) levels using enzyme-linked immunosorbent assays kits. Total percent body fat was determined by dual energy X-ray absorptiometry (DXA). Moderate to vigorous physical activity (MVPA) was assessed objectively using an activity monitor for 7 days. The mean 25(OH)D concentration was 34.7 nmol/L, and 83 subjects had 25(OH)D concentrations less than 50 nmol/L. Multiple linear regression analysis revealed that serum 25(OH)D level was positively related to plasma IL-17 level (β = 0.26, p = 0.025), after adjustment for gender, age, vitamin D intake, alcohol consumption, smoking status, and percent body fat. This relationship remained statistically significant (β = 0.28, p = 0.019) even after additional adjustment for MVPA. However, no significant association was found between serum 25(OH)D level and plasma IFN-γ or IL-6 levels. In conclusion, this study identified a high prevalence of vitamin D deficiency in healthy Japanese adults. Serum 25(OH)D level was positively related to IL-17 level, independent of physical activity.

Vitamin D and the athlete: risks, recommendations, and benefits

Vitamin D is well known for its role in calcium regulation and bone health, but emerging literature tells of vitamin D's central role in other vital body processes, such as: signaling gene response, protein synthesis, hormone synthesis, immune response, plus, cell turnover and regeneration. The discovery of the vitamin D receptor within the muscle suggested a significant role for vitamin D in muscle tissue function. This discovery led researchers to question the impact that vitamin D deficiency could have on athletic performance and injury. With over 77% of the general population considered vitamin D insufficient, it's likely that many athletes fall into the same category. Research has suggested vitamin D to have a significant effect on muscle weakness, pain, balance, and fractures in the aging population; still, the athletic population is yet to be fully examined. There are few studies to date that have examined the relationship between vitamin D status and performance, therefore, this review will focus on the bodily roles of vitamin D, recommended 25(OH)D levels, vitamin D intake guidelines and risk factors for vitamin D insufficiency in athletes. In addition, the preliminary findings regarding vitamin D's impact on athletic performance will be examined.

Vitamin D - effects on skeletal and extraskeletal health and the need for supplementation

Vitamin D, the sunshine vitamin, has received a lot of attention recently as a result of a meteoric rise in the number of publications showing that vitamin D plays a crucial role in a plethora of physiological functions and associating vitamin D deficiency with many acute and chronic illnesses including disorders of calcium metabolism, autoimmune diseases, some cancers, type 2 diabetes mellitus, cardiovascular disease and infectious diseases. Vitamin D deficiency is now recognized as a global pandemic. The major cause for vitamin D deficiency is the lack of appreciation that sun exposure has been and continues to be the major source of vitamin D for children and adults of all ages. Vitamin D plays a crucial role in the development and maintenance of a healthy skeleton throughout life. There remains some controversy regarding what blood level of 25-hydroxyvitamin D should be attained for both bone health and reducing risk for vitamin D deficiency associated acute and chronic diseases and how much vitamin D should be supplemented.

Sunlight and Vitamin D: A global perspective for health

Vitamin D is the sunshine vitamin that has been produced on this earth for more than 500 million years. During exposure to sunlight 7-dehydrocholesterol in the skin absorbs UV B radiation and is converted to previtamin D3 which in turn isomerizes into vitamin D3. Previtamin D3 and vitamin D3 also absorb UV B radiation and are converted into a variety of photoproducts some of which have unique biologic properties. Sun induced vitamin D synthesis is greatly influenced by season, time of day, latitude, altitude, air pollution, skin pigmentation, sunscreen use, passing through glass and plastic, and aging. Vitamin D is metabolized sequentially in the liver and kidneys into 25-hydroxyvitamin D which is a major circulating form and 1,25-dihydroxyvitamin D which is the biologically active form respectively. 1,25-dihydroxyvitamin D plays an important role in regulating calcium and phosphate metabolism for maintenance of metabolic functions and for skeletal health. Most cells and organs in the body have a vitamin D receptor and many cells and organs are able to produce 1,25-dihydroxyvitamin D. As a result 1,25-dihydroxyvitamin D influences a large number of biologic pathways which may help explain association studies relating vitamin D deficiency and living at higher latitudes with increased risk for many chronic diseases including autoimmune diseases, some cancers, cardiovascular disease, infectious disease, schizophrenia and type 2 diabetes. A three-part strategy of increasing food fortification programs with vitamin D, sensible sun exposure recommendations and encouraging ingestion of a vitamin D supplement when needed should be implemented to prevent global vitamin D deficiency and its negative health consequences.

Serum 25-hydroxyvitamin D and markers of insulin resistance in a Japanese working population

BACKGROUND/OBJECTIVES

The association between vitamin D status and insulin resistance (IR) has been less studied among Asians, and it remains elusive whether calcium could modify such an association. We examined the association of serum 25-hydroxyvitamin D (25(OH)D) concentrations with IR markers and the potential effect modification by calcium intake among a Japanese population.

SUBJECTS/METHODS

The authors analyzed data (n=494) from a cross-sectional survey conducted in 2009 among a Japanese working population aged 20-68 years. Fasting serum 25(OH)D and insulin, as well as fasting plasma glucose were determined, and homeostatic model assessment of IR (HOMA-IR) was calculated. Calcium intake was assessed using a validated diet history questionnaire. Multiple linear regression was done with adjustment of potential confounding variables.

RESULTS

Fasting insulin and HOMA-IR were significantly inversely associated with 25(OH)D concentration across quartiles of 25(OH)D after fully adjusting for covariates (P(trend)=0.04 and 0.02, respectively). Across clinically relevant categories of 25(OH)D, compared with participants in the vitamin D sufficiency group, those in the vitamin D insufficiency group had a 5% higher HOMA-IR score, and those in the hypovitaminosis D group had an 18% higher HOMA-IR score (P(trend)=0.01). In an analysis by calcium intake, the HOMA-IR score was highest among participants with both a low calcium intake and lowest 25(OH)D concentrations, with significant inverse trend being observed in the group with lower calcium intake (P(trend)=0.02).

CONCLUSIONS

Our findings suggest that low vitamin D status is associated with IR among Japanese adults.

The Vitamin D Receptor, Inflammatory Bowel Diseases, and Colon Cancer

The nuclear receptor is an emerging therapeutic target in various human diseases. Vitamin D receptor (VDR), a nuclear receptor, mediates the biological functions of vitamin D. Classically, vitamin D is recognized as an essential contributor to mineral and bone homeostasis. Increasing evidence demonstrates that vitamin D is involved in inflammatory responses. Persistent intestinal inflammation is associated with colon cancer. This review focuses on vitamin D and VDR in inflammatory bowel diseases and colon cancer. We place emphasis on the regulatory roles of vitamin D/VDR on in inflammation, enteric bacteria, and tumorigenesis. We summarize the signaling pathways regulated by VDR in intestinal homeostasis. Finally, we discuss the potential application of the insights gleaned from these findings to personalized therapies in chronic inflammation and colon cancer.

The D-lightful vitamin D for child health

Vitamin D deficiency and insufficiency is common in children. Vitamin D deficiency is defined as a 25-hydroxyvitamin D <20 ng/mL and insufficiency as 21-29 ng/mL. The major sources of vitamin D are sun exposure, diet, and supplements. In young children, vitamin D deficiency causes a mineralization defect of the skeleton, resulting in rickets. Vitamin D deficiency has been linked to many chronic diseases, including multiple sclerosis, type 1 diabetes, infectious diseases, heart disease, and type 2 diabetes. In utero vitamin D deficiency increases risk for preeclampsia and the need for a cesarean section. Children living at higher latitudes and who are presumed to be at increased risk for vitamin D deficiency are at higher risk for developing type 1 diabetes and multiple sclerosis later in life. The Institute of Medicine recommends that children 0-1 year and 1-18 years need 400 and 600 IU/d, respectively, of vitamin D for maximal skeletal health. The Endocrine Society's Clinical Guidelines recommended that to prevent and treat vitamin D deficiency, children 0-1 year and 1-18 years need 400-1000 and 600-1000 IU/d, respectively.

Daily consumption of vitamin D- or vitamin D + calcium-fortified yogurt drink improved glycemic control in patients with type 2 diabetes: a randomized clinical trial

BACKGROUND

Low serum concentrations of 25-hydroxyvitamin D [25(OH)D] have been associated with impaired glucose tolerance and diabetes.

OBJECTIVE

This study aimed to compare the effects of daily intake of vitamin D- or vitamin D(3) + calcium-fortified yogurt drink on glycemic status in subjects with type 2 diabetes (T2D).

DESIGN

Ninety diabetic subjects were randomly allocated to 3 groups to consume plain yogurt drink (PY; containing no vitamin D and 150 mg Ca/250 mL), vitamin D-fortified yogurt drink (DY; containing 500 IU vitamin D(3) and 150 mg Ca/250 mL), or vitamin D + calcium-fortified yogurt drink (DCY; containing 500 IU vitamin D(3) and 250 mg Ca/250 mL) twice per day for 12 wk. Fasting serum glucose (FSG), glycated hemoglobin (Hb A(1c)), homeostasis model assessment of insulin resistance (HOMA-IR), serum lipid profile, and percentage fat mass (FM) were assessed before (baseline) and after the intervention.

RESULTS

In both the DY and DCY groups, mean serum 25(OH)D(3) improved (+32.8 ± 28.4 and +28.8 ± 16.1 nmol/L, respectively; P < 0.001 for both), but FSG [-12.9 ± 33.7 mg/dL (P = 0.015) and -9.6 ± 46.9 mg/dL (P = 0.035)], Hb A(1c) [-0.4 ± 1.2% (P < 0.001) and -0.4 ± 1.9% (P < 0.001)], HOMA-IR [-0.6 ± 1.4 (P = 0.001) and -0.6 ± 3.2 (P < 0.001)], waist circumference (-3.6 ± 2.7 and -2.9 ± 3.3; P < 0.001 for both), and body mass index [in kg/m(2); -0.9 ± 0.6 (P < 0.001) and -0.4 ± 0.7 (P = 0.005)] decreased significantly more than in the PY group. An inverse correlation was observed between changes in serum 25(OH)D(3) and FSG (r = -0.208, P = 0.049), FM (r = -0.219, P = 0.038), and HOMA-IR (r = -0.219, P = 0.005).

CONCLUSION

Daily intake of a vitamin D-fortified yogurt drink, either with or without added calcium, improved glycemic status in T2D patients. This trial was registered at clinicaltrials.gov as NCT01229891.

Cytochromes P450 are essential players in the vitamin D signaling system

From earliest development on, the vitamin D receptor (VDR) is expressed in most cells of the mammalian body. The VDR is a nuclear, ligand-induced transcription factor that regulates in complex with hormonally active vitamin D the expression of more than 900 genes involved in a wide array of physiological functions (e.g. calcium homeostasis, growth control, differentiation, cognition, immune response, etc.). Accordingly, severe health problems are associated to vitamin deficiencies. Synthesis of the major active form 1α,25(OH)₂D₃ from vitamin D and subsequent metabolism are exclusively controlled by specific P450-forms. Synthesis, a two-step process, starts with a 25-hydroxylation primarily by CYP2R1 (CYP27A1, CYP2J2, and CYP3A4 may also contribute) and a subsequent 1α-hydroxylation via CYP27B1. Circulating in the bloodstream, 1α,25(OH)₂D₃ acts at sites of VDR expression (target sites) in an endocrine way. However, it is also capable of autocrine/paracrine functions since various target tissues are fully competent in 1α,25(OH)₂D₃ synthesis, as illustrated by three examples. 1α,25(OH)₂D₃ levels are short-lived: the hormone upregulates its rapid metabolism by CYP24A1 that attacks repeatedly the vitamin D C₂₀₋₂₇ side chain, thereby producing a complex cascade of transient metabolites with increasing polarity. Most of these metabolites still retain 1α,25(OH)₂D₃-like activities on the VDR, contributing to the overall effect that is commonly attributed to 1α,25(OH)₂D₃. As selective inhibitors of CYP24A1 increase the lifetime and thereby the function of vitamin D metabolites, they will help exploring whether and which intrinsic activities distinct metabolites possess. It appears likely that this strategy may unmask important regulators of new functions.