Maintenance of wintertime vitamin D status with cholecalciferol supplementation is not associated with alterations in serum cytokine concentrations among apparently healthy younger or older adults

Development and In Vivo Evaluation of a Novel Vitamin D3 Oral Spray Delivery System

Developing drugs that are highly selective to host tissues but are the least toxic remains one of the most difficult challenges in cancer treatment. Recent studies have shown that tumor cells from a variety of sources can express vitamin D3 receptors and that the response to vitamin D3 and its analogs is prone to growth arrest and cell death. However, conventional vitamin D3 drug formulations lack dose control and cannot target specific cells or tissues. The aim of this study was to prepare vitamin D3 nanospray for inhalation delivery route. This study evaluated the physical properties of the formulation (particle size distribution and biological stability), the total number of sprays per bottle, the spray volume per spray, and the loading variance of the spray. The optimized vitamin D3 spray formula is easy to spray, has fewer drips, and has a fast drying time. It can be stored for 3 months at 37 ± 2 °C temperature, 75 ± 5% relative humidity, and away from light, and can maintain biological stability. This study showed that compared with traditional nasal sprays, the spray has a larger fan angle (82.1 degrees) and beam width (104.88 mm), more symmetrical spray on both sides of the spray column, a faster coverage of the administration site, and a wider range, which is suitable for inhalation delivery routes.

Associations Between 25-Hydroxyvitamin D and Total and γ' Fibrinogen and Plasma Clot Properties and Gene Interactions in a Group of Healthy Black South African Women

The role of 25-hydroxyvitamin D [25(OH)D] in reducing the risk of cardiovascular disease (CVD) has been recognized, but the mechanisms involved are unclear. Researchers have discovered a link between vitamin D and fibrinogen. Until now, data on the relationship between vitamin D and the γ' splice variant of fibrinogen and fibrin clot characteristics remain unexplored. In this study, 25(OH)D, total and γ' fibrinogen, as well as turbidimetrically determined plasma clot properties, were quantified, and fibrinogen and FXIII SNPs were genotyped in 660 Black, apparently healthy South African women. Alarmingly, 16 and 45% of the women presented with deficient and insufficient 25(OH)D, respectively. Total fibrinogen and maximum absorbance (as a measure of clot density) correlated inversely, whereas γ' fibrinogen correlated positively with 25(OH)D. γ' fibrinogen increased whereas maximum absorbance decreased over the deficient, insufficient, and sufficient 25(OH)D categories before and after adjustment for confounders. 25(OH)D modulated the association of the SNPs regarding fibrinogen concentration and clot structure/properties, but did not stand after correction for false discovery rate. Because only weak relationships were detected, the clinical significance of the findings are questionable and remain to be determined. However, we recommend vitamin D fortification and supplementation to reduce the high prevalence of this micronutrient deficiency and possibly to improve fibrinogen and plasma clot structure if the relationships are indeed clinically significant. There is a need for large cohort studies to demonstrate the relationship between vitamin D and cardiovascular and inflammatory risk factors as well as to uncover the molecular mechanisms responsible.

Low-Dose Vitamin D3 Supplementation Does Not Affect Natural Regulatory T Cell Population but Attenuates Seasonal Changes in T Cell-Produced IFN-γ: Results From the D-SIRe2 Randomized Controlled Trial

Background

Seasonal variations have been reported for immune markers. However, the relative contributions of sunlight and vitamin D variability on such seasonal changes are unknown.

Objective

This double-blind, randomized, placebo-controlled trial tested whether daily 400 IU vitamin D₃ supplementation affected short-term (12 weeks) and long-term (43 weeks) natural regulatory T cell (nTreg) populations in healthy participants.

Design

62 subjects were randomized equally to vitamin D versus placebo in March and assessed at baseline, April (4w), June (12w), September (25w) and January (43w). Circulating nTregs, ex vivo proliferation, IL-10 and IFN-γ productions were measured. Vitamin D metabolites and sunlight exposure were also assessed.

Results

Mean serum 25-hydroxyvitamin D (25(OH)D) increased from 35.8(SD 3.0) to 65.3(2.6) nmol/L in April and remained above 75 nmol/L with vitamin D supplementation, whereas it increased from 36.4(3.2) to 49.8(3.5) nmol/L in June to fall back to 39.6(3.5) nmol/L in January with placebo. Immune markers varied similarly between groups according to the season, but independently of 25(OH)D. For nTregs, the mean (%CD3⁺CD4⁺CD127^lo cells (SEM)) nadir observed in March (2.9(0.1)%) peaked in September at 4.0(0.2)%. Mean T cell proliferation peaked in June (33156(1813) CPM) returning to the nadir in January (17965(978) CPM), while IL-10 peaked in June and reached its nadir in September (median (IQR) of 262(283) to (121(194) pg/ml, respectively). Vitamin D attenuated the seasonal increase in IFN-γ by ~28% with mean ng/ml (SEM) for placebo vs vitamin D, respectively, for April 12.5(1.4) vs 10.0(1.2) (p=0.02); June 13.9(1.3) vs 10.2(1.7) (p=0.02) and January 7.4(1.1) vs 6.0(1.1) (p=0.04).

Conclusions

Daily low dose Vitamin D intake did not affect the nTregs population. There were seasonal variation in nTregs, proliferative response and cytokines, suggesting that environmental changes influence immune response, but the mechanism seems independent of vitamin D status. Vitamin D attenuated the seasonal change in T cell-produced IFN-γ, suggesting a decrease in effector response which could be associated with inflammation.

Clinical Trial Registration

https://www.isrctn.com, identifier (ISRCTN 73114576).

Vitamin D supplementation and inflammatory and metabolic biomarkers in patients with knee osteoarthritis: post hoc analysis of a randomised controlled trial

The aim of this study was to determine whether vitamin D supplementation and maintaining vitamin D sufficiency are associated with changes in inflammatory and metabolic biomarkers in patients with knee osteoarthritis (OA) and vitamin D deficiency. A total of 413 participants with symptomatic knee OA and vitamin D deficiency were enrolled in a randomised, placebo-controlled trial and received 1·25 mg vitamin D3 or placebo monthly for 24 months across two sites. In this post hoc analysis, 200 participants from one site (ninety-four from the placebo group and 106 from the vitamin D group; mean age 63·1 (sd 7·3) years, 53·3 % women) were randomly selected for measurement of serum levels of inflammatory and metabolic biomarkers at baseline and 24 months using immunoassays. In addition, participants were classified into two groups according to serum 25-hydroxyvitamin D (25(OH)D) levels at months 3 and 24: (1) not consistently sufficient (25(OH)D≤50 nmol/l at either month 3 or 24, n 61), and (2) consistently sufficient (25(OH)D>50 nmol/l at both months 3 and 24, n 139). Compared with placebo, vitamin D supplementation had no significant effect on change in serum high-sensitive C-reactive protein, IL-6, IL-8, IL-10, leptin, adiponectin, resistin, adipsin and apelin. Being consistently vitamin D sufficient over 2 years was also not associated with changes in these biomarkers compared with not being consistently sufficient. Vitamin D supplementation and maintaining vitamin D sufficiency did not alter serum levels of inflammatory and metabolic biomarkers over 2 years in knee OA patients who were vitamin D insufficient, suggesting that they may not affect systemic inflammation in knee OA patients.

Thirteen weeks of supplementation of vitamin D and leucine-enriched whey protein nutritional supplement attenuates chronic low-grade inflammation in sarcopenic older adults: the PROVIDE study

Background

A chronic low-grade inflammatory profile (CLIP) is associated with sarcopenia in older adults. Protein and Vitamin (Vit)D have immune-modulatory potential, but evidence for effects of nutritional supplementation on CLIP is limited.

Aim

To investigate whether 13 weeks of nutritional supplementation of VitD and leucine-enriched whey protein affected CLIP in subjects enrolled in the PROVIDE-study, as a secondary analysis.

Methods

Sarcopenic adults (low skeletal muscle mass) aged ≥ 65 years with mobility limitations (Short Physical Performance Battery 4–9) and a body mass index of 20–30 kg/m² were randomly allocated to two daily servings of active (n = 137, including 20 g of whey protein, 3 g of leucine and 800 IU VitD) or isocaloric control product (n = 151) for a double-blind period of 13 weeks. At baseline and after 13 weeks, circulating interleukin (IL)-8, IL-1 receptor antagonist (RA), soluble tumor-necrosis-factor receptor (sTNFR)1, IL-6, high-sensitivity C-reactive protein, pre-albumin and 25-hydroxyvitamin(OH)D were measured. Data-analysis included repeated measures analysis of covariance (corrected for dietary VitD intake) and linear regression.

Results

IL-6 and IL-1Ra serum levels showed overall increases after 13 weeks (p = 0.006 and p < 0.001, respectively). For IL-6 a significant time × treatment interaction (p = 0.046) was observed, with no significant change over time in the active group (p = 0.155) compared to control (significant increase p = 0.012). IL-8 showed an overall significant decrease (p = 0.03). The change in pre-albumin was a significant predictor for changes in IL-6 after 13 weeks.

Conclusions

We conclude that 13 weeks of nutritional supplementation with VitD and leucine-enriched whey protein may attenuate the progression of CLIP in older sarcopenic persons with mobility limitations.

Electronic supplementary material

The online version of this article (10.1007/s40520-019-01208-4) contains supplementary material, which is available to authorized users.

Effect of Cholecalciferol Supplementation on Treatment Response and IL-10 Level in Vitamin D Deficient Parthenium Dermatitis Patients: A Randomized Double-Blind Placebo-Controlled Trial

Allergic contact dermatitis following exposure to Parthenium is a chronic disease associated with frequent relapses and significant disturbance in the quality of life. The affected patients have lower circulating levels and decreased expression of IL-10. Hence, measures to increase its level may enhance the therapeutic outcome. The clinical trial was undertaken to evaluate the effect of cholecalciferol supplementation on treatment response and IL-10 level in Parthenium dermatitis patients with vitamin D deficiency. A total of 72 patients were recruited and randomized to receive either cholecalciferol tablet 60,000 IU per week or matching placebo for 8 weeks with standard background treatment. Eczema Area Severity Index (EASI) and Dermatology Life Quality Index (DLQI) were assessed at baseline, 4 weeks, and 8 weeks while IL-10 and serum 25-hydroxyvitamin D levels were measured at baseline and 8 weeks. Levels of 25-hydroxyvitamin D and IL-10 showed a significant rise in both placebo and vitamin D groups following the intervention. The relatively higher increase in IL-10 level observed in the vitamin D group was statistically insignificant compared to placebo group. Significant reduction in EASI, as well as DLQI scores, was noted after 1 and 2 months, but the reduction in these scales was not significantly different between the groups. Cholecalciferol supplementation for 2 months did not reduce the disease severity in clinically diagnosed Parthenium dermatitis patients. However, treatment initiation significantly improved plasma IL-10 levels after 2 months in both placebo and cholecalciferol groups.

Decreased Serum 25-Hydroxyvitamin D in Aging Male Mice Is Associated With Reduced Hepatic Cyp2r1 Abundance

The prevalence of vitamin D deficiency, as determined by circulating levels of 25-hydroxycalciferol [25(OH)D], is greater in older individuals compared with the young. To examine the hypothesis that altered production or inactivation of 25(OH)D contributes to lower circulating levels of 25(OH)D, we measured the serum levels of parent vitamin D3 (cholecalciferol) and 25(OH)D. We also determined the relative abundance of transcripts encoding hepatic CYP2R1 and CYP27B1, the principal 25-hydroxylases, transcripts encoding enzymes that degrade 25(OH)D in the liver (Cyp3A11) and kidney (Cyp24A1) and transcripts encoding megalin and cubilin, proteins critical to vitamin D resorption in the kidney in mice at three different ages. We observed a significant decline in the relative abundance of Cyp2R1 in the liver with aging (one-way ANOVA, P = 0.0077). Concurrent with the decrease in mRNA, a significant decline in hepatic CYP2R1 protein (one-way ANOVA for trend, P = 0.007) and 25(OH)D (one-way ANOVA for trend, P = 0.002) and in the ratio of 25(OH)D3 to cholecalciferol (one-way ANOVA, P = 0.0003). By contrast, levels of the transcripts encoding Cyp3a11, Cyp24a1, and Cyp27b1 megalin and cubilin were unchanged with aging. A significant positive correlation was found between Cyp2r1 mRNA and 25(OH)D, and a stronger correlation was found between Cyp2r1 mRNA and the ratio of 25(OH)D3 to cholecalciferol. These results indicate that decreased expression of CYP2R1 contributes to the reduced serum levels of 25(OH)D in aging.

Impact of vitamin D supplementation on endothelial and inflammatory markers in adults: A systematic review

This systematic review aims to evaluate randomised controlled trials (RCTs) investigating the effect of vitamin D supplementation on endothelial function and inflammation in adults. An electronic search of published randomised controlled trials, using Cochrane, Pubmed and Medline databases was conducted, with the search terms related to vitamin D and endothelial function. Inclusion criteria were RCTs in adult humans with a measure of vitamin D status using serum/plasma 25(OH)D and studies which administered the intervention through the oral route. Among the 1107 studies retrieved, 29 studies met the full inclusion criteria for this systematic review. Overall, 8 studies reported significant improvements in the endothelial/inflammatory biomarkers/parameters measured. However, in 2 out of the 8 studies, improvements were reported at interim time points, but improvements were absent post-intervention. The remaining 21 trial studies did not show significant improvements in the markers of interest measured. Evidence from the studies included in this systematic review did not demonstrate that vitamin D supplementation in adults, results in an improvement in circulating inflammatory and endothelial function biomarkers/parameters. This systematic review does not therefore support the use of vitamin D supplementation as a therapeutic or preventative measure for CVD in this respect.

The impact of cholecalciferol supplementation on the systemic inflammatory profile: a systematic review and meta-analysis of high-quality randomized controlled trials

Causal links between vitamin D status [25(OH)D] and systemic inflammation were examined through a systematic review of randomized controlled trials (RCTs). Selected RCTs were ⩾12 weeks, conducted in adults free of acute inflammatory disease, and of high-quality (Jadad score ⩾3). Of 14 studies that met our criteria, 9 studies (15 study arms) permitted extraction of data. There was no effect on the weighted mean difference (WMD) of IL-6 (WMD (95% confidence interval)=0.1, (-0.166, 0.366) pg/ml, P=0.462) or C-reactive protein (CRP) (WMD=-0.324, (-1.007, 0.359) mg/l, P=0.352). Subgroup analyses of trials achieving ⩾80 nmol/l indicated a trend for lower CRP (WMD=-0.834, (-1.726, 0.058) mg/l, P=0.067), however heterogeneity was significant (I²=66.7%, P=0.017). Studies employing a low dose (<1000 IU/d) showed increased CRP (WMD=0.615, (0.132, 1.098), P=0.013). In contrast, ⩾1000 IU/d had a favourable effect on CRP (WMD=-0.939, (-1.805, -0.073), P=0.034) but heterogeneity was significant (I²=61.3%, P=0.017). Meta-regression indicated that older age predicted a significant decrease in IL-6 (β=-0.02, (-0.034, -0.006) pg/ml, P=0.013) and CRP (β=-0.06, (-0.103, -0.017), P=0.01), whereas a greater percentage of females (β=0.027, (0.011, 0.044), P=0.004) and longer study duration independently predicted a higher WMD for CRP (β=0.049, (0.018, 0.079), P=0.005). Available high-quality RCTs did not support a beneficial effect of cholecalciferol on systemic IL-6 and CRP. Future studies should consider the confounding effects of age, gender and study duration, while possibly targeting an achieved 25(OH)D ⩾80 nmol/l.

Vitamin D and Weight Cycling: Impact on Injury, Illness, and Inflammation in Collegiate Wrestlers

This study explored the link between vitamin D status and frequency of skin infections, inflammation, and injury in college wrestlers during an academic year. Methods: Serum 25-hydroxyvitamin D (25(OH)D) (n = 19), plasma cytokine (TNF-α, IL-6, IL-10) (n = 18) concentrations, and body weight/composition were measured and injury/illness/skin infection data were collected in fall, winter, and spring. Results: In the fall, 74% of wrestlers had vitamin D concentrations <32 ng/mL which increased to 94% in winter and spring. Wrestlers lost an average of 3.4 ± 3.9 kg (p < 0.001) during the season with corresponding decreases in fat mass and increases in lean mass (p < 0.01). An inverse association between 25(OH)D concentrations and total body mass and body fat percentage was observed at all-time points (p < 0.01). Concentrations of cytokines were highly variable among individuals and did not change across time (p > 0.05). Correlations between vitamin D status, cytokines, or frequency of illness, injury, or skin infections were not observed. Conclusions: A high prevalence of vitamin D insufficiency (<32 ng/mL) and deficiency (<20 ng/mL) was observed in wrestlers and was associated with higher adiposity. It remains unclear if higher vitamin D status would reduce injury, illness, and skin infection risk.

Impact of micronutrients supplementation on bone repair around implants: microCT and counter-torque analysis in rats

The use of natural substances and micronutritional approaches has been suggested as a therapeutic alternative to benefit the bone healing associated with no side effects. Nevertheless, the influence of micronutritional interventions with therapeutic proprieties on the bone repair has yet to be intensely evaluated, and no evidence is available exploring the impact of micronutrient supplementation on the peri-implant bone healing.

OBJECTIVE

This study investigated the effect of micronutrients supplementation on the bone repair around implants.

MATERIAL AND METHODS

One screw-shaped titanium implant was inserted in each tibia of each rat, which were assigned to: daily administration, for 30 d, of the placebo solution (Placebo group-n:18) or micronutrients supplementation (Micronutrients group-n:18), based on calcium, magnesium, zinc, and vitamin D3 intake. After, the animals were sacrificed. One of the implants was removed by applying a counter-torque force to evaluate the force to rupture the bone-implant interface. The other implant was evaluated by microcomputed tomography (CT) examination to determine the bone-to-implant contact (BIC) and the bone volume (BV/TV).

RESULTS

No statistically significant differences were observed between the groups for both counter-torque values and microCT parameters (p>0.05).

CONCLUSION

Within the limits of this study, micronutrients supplementation did not provide additional benefits to the bone healing around dental implants.

Vitamin D3 supplementation in healthy adults: a comparison between capsule and oral spray solution as a method of delivery in a wintertime, randomised, open-label, cross-over study

Vitamin D is typically supplied in capsule form, both in trials and in clinical practice. However, little is known regarding the efficacy of vitamin D administered via oral sprays - a method that primarily bypasses the gastrointestinal absorption route. This study aimed to compare the efficacy of vitamin D3 liquid capsules and oral spray solution in increasing wintertime total 25-hydroxyvitamin D (25(OH)D) concentrations. In this randomised, open-label, cross-over trial, healthy adults (n 22) received 3000 IU (75 µg) vitamin D3 daily for 4 weeks in either capsule or oral spray form. Following a 10-week washout phase, participants received the opposite treatment for a final 4 weeks. Anthropometrics and fasted blood samples were obtained before and after supplementation, with samples analysed for total 25(OH)D, creatinine, intact parathyroid hormone and adjusted Ca concentrations. At baseline, vitamin D sufficiency (total 25(OH)D>50 nmol/l), insufficiency (31-49 nmol/l) and clinical deficiency (<30 nmol/l) were evident in 59, 23 and 18 % of the participants, respectively. Overall, baseline total mean 25(OH)D concentration averaged 59·76 (sd 29·88) nmol/l, representing clinical sufficiency. ANCOVA revealed no significant difference in the mean and standard deviation change from baseline in total 25(OH)D concentrations between oral spray and capsule supplementation methods (26·15 (sd 17·85) v. 30·38 (sd 17·91) nmol/l, respectively; F=1·044, adjusted r 2 0·493, P=0·313). Oral spray vitamin D3 is an equally effective alternative to capsule supplementation in healthy adults.

Oral spray wintertime vitamin D3 supplementation has no impact on inflammation in Gaelic footballers

Vitamin D inadequacy [total 25(OH)D <50 nmol/L] is widespread in athletes. The biologically active metabolite, 1,25-dihydroxyvitamin D, may be involved in regulating inflammation although in vitro findings have not been consistently replicated in human intervention trials. This study, conducted at a latitude of 55°N, aimed to assess inflammatory biomarkers in Gaelic footballers before and after a wintertime vitamin D₃ intervention. Samples from a 12-week double-blind, randomized, placebo-controlled trial, in which 42 Gaelic footballers received 3000 IU (75 μg) vitamin D₃ daily or placebo via oral spray solutions, were analysed for a range of inflammatory biomarkers. Cytokines (interleukin-8 and tumor necrosis factor-α), cathelicidin and high sensitivity C-reactive protein were quantified by multiplex assay, enzyme-linked immunosorbent assay and clinical biochemistry, respectively. White blood cell, lymphocyte, and neutrophil concentrations were determined by full blood profile. Data on total 25-hydroxyvitamin D, measured by LC-MS/MS, were available from the previous study. Vitamin D₃ supplementation significantly increased mean total 25-hydroxyvitamin D concentrations from 47 to 84 nmol/L (P = 0.006); yet this had no effect on white blood cell count (P = 0.699), lymphocyte (P = 0.694), neutrophil (P = 0.594), interleukin-8 (P = 0.334), tumor necrosis factor-α (P = 0.587), cathelicidin (P = 0.745) or high sensitivity C-reactive protein concentration (P = 0.621) compared to placebo. 12-weeks vitamin D₃ supplementation did not impact the immune profile of Gaelic footballers. This is likely because biomarkers were within their respective normal range or at a concentration similar to that of the general population at baseline. Future studies are encouraged to use inflammation as their primary outcome measure and recruit athletes at risk of compromised immunity.

Aging, low-grade systemic inflammation and vitamin D: a mini-review

We conducted a mini-review of the literature, focusing on aging-related systemic inflammation and its association with vitamin D (VitD). As main findings, data indicate that inflammation in aging seems to have multiple origins, including immunosenescence, and from intestinal and adipose tissue, where VitD may modulate these three factors, through mechanisms not totally known. From the selected studies, three randomized clinical trials of VitD supplementation showed improvements in inflammatory status, whereas two studies did not. Ten epidemiological studies showed associations between VitD and inflammation, whereas two studies did not. One case study reinforced this association. As such, we can assume a reasonable association between VitD and inflammation in the elderly, and a promising role of supplementation in some situations. However, most studies did not take into account environmental and individual factors such as the season of the year, latitude, skin color or even the use of some medicines; in addition, the doses, time of intervention and the sample sizes differed between the studies. In conclusion, although more controlled VitD studies, both clinical and epidemiological, are necessary, it is important to remember the network of factors involved in systemic inflammation in the elderly; an understanding of the dietetic and non-dietetic factors is needed to offer a realistic approach.

Calcium and 1,25-dihydroxyvitamin D3 modulate genes of immune and inflammatory pathways in the human colon: a human crossover trial

BACKGROUND

A high dietary calcium intake with adequate vitamin D status has been linked to lower colorectal cancer risk, but the mechanisms of these effects are poorly understood.

OBJECTIVE

The objective of this study was to elucidate the effects of a Western-style diet (WD) and supplemental calcium and/or 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on the colorectal mucosa.

DESIGN

We conducted 2 crossover trials to define molecular pathways in the human colorectum altered by 1) a 4-wk WD supplemented with and without 2 g calcium carbonate/d and 2) a 4-wk WD supplemented with 1,25(OH)2D3 (0.5 μg/d) with or without 2 g calcium carbonate/d. The primary study endpoint was genome-wide gene expression in biopsy specimens of the rectosigmoid colonic mucosa. Serum and urinary calcium concentrations were also measured.

RESULTS

Changes in urinary calcium accurately reflected calcium consumption. The WD induced modest upregulation of genes involved in inflammatory pathways, including interferon signaling, and calcium supplementation reversed these toward baseline. In contrast, supplementation of the WD with 1,25(OH)2D3 induced striking upregulation of genes involved in inflammation, immune response, extracellular matrix, and cell adhesion. Calcium supplementation largely abrogated these changes.

CONCLUSIONS

Supplementing 1,25(OH)2D3 to a WD markedly upregulated genes in immune response and inflammation pathways, which were largely reversed by calcium supplementation. This study provides clinical trial evidence of global gene expression changes occurring in the human colorectum in response to calcium and 1,25(OH)2D3 intervention. One action of 1,25(OH)2D3 is to upregulate adaptive immunity. Calcium appears to modulate this effect, pointing to its biological interaction in the mucosa. This trial was registered at clinicaltrials.gov as NCT00298545 Trial protocol is available at http://clinicalstudies.rucares.org (protocol numbers PHO475 and PHO554).

Vitamin D and Immune Response: Implications for Prostate Cancer in African Americans

Prostate cancer (PCa) is the most common cancer among men in the U.S. African American (AA) men have a higher incidence and mortality rate compared to European American (EA) men, but the cause of PCa disparities is still unclear. Epidemiologic studies have shown that vitamin D deficiency is associated with advanced stage and higher tumor grade and mortality, while its association with overall PCa risk is inconsistent. Vitamin D deficiency is also more common in AAs than EAs, and the difference in serum vitamin D levels may help explain the PCa disparities. However, the role of vitamin D in aggressive PCa in AAs is not well explored. Studies demonstrated that the active form of vitamin D, 1,25-dihydroxyvitamin D, has anti-inflammatory effects by mediating immune-related gene expression in prostate tissue. Inflammation also plays an important role in PCa pathogenesis and progression, and expression of immune-related genes in PCa tissues differs significantly between AAs and EAs. Unfortunately, the evidence linking vitamin D and immune response in relation to PCa is still scarce. This relationship should be further explored at a genomic level in AA populations that are at high risk for vitamin D deficiency and fatal PCa.

Effect of vitamin D supplementation on selected inflammatory biomarkers in older adults: a secondary analysis of data from a randomised, placebo-controlled trial

Observational studies have suggested that 25-hydroxyvitamin D (25(OH)D) levels are associated with inflammatory markers. Most trials reporting significant associations between vitamin D intake and inflammatory markers used specific patient groups. Thus, we aimed to determine the effect of supplementary vitamin D using secondary data from a population-based, randomised, placebo-controlled, double-blind trial (Pilot D-Health trial 2010/0423). Participants were 60- to 84-year-old residents of one of the four eastern states of Australia. They were randomly selected from the electoral roll and were randomised to one of three trial arms: placebo (n 214), 750 μg (n 215) or 1500 μg (n 215) vitamin D3, each taken once per month for 12 months. Post-intervention blood samples for the analysis of C-reactive protein (CRP), IL-6, IL-10, leptin and adiponectin levels were available for 613 participants. Associations between intervention group and biomarker levels were evaluated using quantile regression. There were no statistically significant differences in distributions of CRP, leptin, adiponectin, leptin:adiponectin ratio or IL-10 levels between the placebo group and either supplemented group. The 75th percentile IL-6 level was 2·8 pg/ml higher (95 % CI 0·4, 5·8 pg/ml) in the 1500 μg group than in the placebo group (75th percentiles:11·0 v. 8·2 pg/ml), with a somewhat smaller, non-significant difference in 75th percentiles between the 750 μg and placebo groups. Despite large differences in serum 25(OH)D levels between the three groups after 12 months of supplementation, we found little evidence of an effect of vitamin D supplementation on cytokine or adipokine levels, with the possible exception of IL-6.

Indices of adiposity as predictors of cardiometabolic risk and inflammation in young adults

BACKGROUND

Studies investigating obesity and cardiometabolic risk have focused on 'at-risk' populations and methodological inconsistencies have produced equivocal findings. The present cross-sectional study investigated indices of body composition as predictors of cardiometabolic risk and their relationship with inflammation in apparently healthy young adults.

METHODS

A fasting blood sample was taken from consenting adults (160 males, 32 females, aged 18-40 years) for assessment of cardiometabolic risk markers (blood pressure, lipid profiles and insulin resistance) and inflammatory markers (C-reactive protein, tumour necrosis factor-α, interleukin-6, interleukin-10 and adiponectin). Together with anthropometry, fat mass (FM) and fat-free mass (FFM) were determined by dual-energy X-ray absorptiometry. FM was expressed in absolute terms (kg), as well as relative to total body weight (%), height [FM index (FMI, kg m(-2) )] and FFM (FM : FFM,%).

RESULTS

Although anthropometric indices were associated with most cardiometabolic risk markers, the strongest relationship was observed with FMI. Relative to having a low cardiometabolic risk (≤2 markers above clinically relevant cut-offs), each kg m(-2) increase in FMI, increased the likelihood of having an increased cardiometabolic risk by 29% (odds ratio = 1.29; 95% confidence interval = 1.12-1.49). Inflammatory markers were not associated with body composition or cardiometabolic risk.

CONCLUSIONS

FMI was the strongest predictor of overall cardiometabolic risk but not inflammation per se. However, anthropometric indices, such as body mass index and waist-to-height ratio, remain valuable surrogate measures of adiposity in this group, particularly when risk markers are considered independently.

Vitamin D and inflammation

Several studies found an inverse relationship between 25-hydroxyvitamin D [25(OH)D] and markers of inflammation. A controversy exists as to whether vitamin D lowers inflammation or whether inflammation lowers 25(OH)D concentrations. Certainly 25(OH)D concentrations fall after major surgery. However, is this due to inflammation lowering 25(OH)D or is 25(OH)D being metabolically cleared by the body to quell inflammation. We searched the literature and found 39 randomized controlled trials (RCT) of vitamin D and markers of inflammation. Seventeen found significantly reduced inflammatory markers, 19 did not, one was mixed and one showed adverse results. With few exceptions, studies in normal subjects, obesity, type 2 diabetics, and stable cardiovascular disease did not find significant beneficial effects. However, we found that 6 out of 7 RCTS of vitamin D3 in highly inflammatory conditions (acute infantile congestive heart failure, multiple sclerosis, inflammatory bowel disease, cystic fibrosis, SLE, active TB and evolving myocardial infarction) found significant reductions. We found baseline and final 25(OH)D predicted RCTs with significant reduction in inflammatory markers. Vitamin D tends to modestly lower markers of inflammation in highly inflammatory conditions, when baseline 25(OH)D levels were low and when achieved 25(OH)D levels were higher. Future inquiries should: recruit subjects with low baseline 25(OH)D levels, subjects with elevated markers of inflammation, subjects with inflammatory conditions, achieve adequate final 25(OH)D levels, and use physiological doses of vitamin D. We attempted to identify all extant randomized controlled trials (RCTs) of vitamin D that used inflammatory markers as primary or secondary endpoints.

Association between serum vitamin D concentrations and inflammatory markers in the general adult population

OBJECTIVE

In recent years links among vitamin D deficiency, inflammation and cardio-metabolic disease were proposed. As information regarding the associations between vitamin D and inflammatory markers in the general population is sparse, we investigated the associations of 25-hydroxy vitamin D [25(OH)D] with high-sensitivity C-reactive protein (hs-CRP), fibrinogen and white blood cell count (WBC).

MATERIALS/METHODS

The study population comprised 2723 men and women aged 25-88 years from the first follow-up of the Study of Health in Pomerania. Analyses of variance, linear and logistic regressions were performed to assess the associations between 25(OH)D and the three inflammatory markers. The models were adjusted for age, sex, waist circumference, diabetes mellitus, dyslipidemia, anti-inflammatory medication and month of blood sampling. The association between 25(OH)D and WBC was assessed separately in smokers (n = 718) and non-smokers (n = 2005) as effect modification was observed.

RESULTS

We detected a U-shaped association between 25(OH)D and hs-CRP with a nadir of 21-25 ng/ml in fully-adjusted linear regression models with restricted cubic splines (p < 0.01; p' < 0.01). We further detected an inverse association between 25(OH)D and fibrinogen (p < 0.01). In addition, there was an inverse association between 25(OH)D and WBC in smokers (p = 0.02) but no association in non-smokers (p = 0.73).

CONCLUSION

Our study confirms a potential role of 25(OH)D in chronic inflammation. Yet, different inflammatory biomarkers are differently associated with 25(OH)D. Beneficial effects of increasing 25(OH)D were observed for fibrinogen and WBC (in smokers only). In contrast, the U-shaped association between 25(OH)D and hs-CRP indicates that ever-increasing 25(OH)D concentrations may also be related to proinflammatory states.

Vitamin D deficiency is associated with inflammation in older Irish adults

CONTEXT

Inadequate vitamin D status is common within elderly populations and may be implicated in the etiology of autoimmune disease and inflammation. Few studies have investigated the relationship between vitamin D status and age-related immune dysfunction in humans.

OBJECTIVE

The aim of this study was to investigate the association between vitamin D status and immune markers of inflammation in a large sample of older adults.

DESIGN, SETTING, AND PARTICIPANTS

An observational investigation of 957 Irish adults (>60 years of age) recruited in Northern Ireland (55°N latitude) as part of the Trinity Ulster Department of Agriculture aging cohort study.

MAIN OUTCOME MEASURE

We measured serum 25-hydroxyvitamin D (25(OH)D) by liquid chromatography tandem mass spectrometry and serum cytokines IL-6, TNF-α, IL-10, and C-reactive protein (CRP) by ELISA.

RESULTS

Concentrations of IL-6, CRP, and the ratios of IL-6 to IL-10 and CRP to IL-10 were significantly higher in individuals with deficient (<25 nmol/L) serum 25(OH)D compared with those with sufficient (>75 nmol/L) status after adjustment for age, sex, and body mass index (P < .05). Vitamin D status was a significant predictor of the IL-6 to IL-10 cytokine ratio, and those participants defined as deficient were significantly more likely to have an IL-6 to IL-10 ratio >2:1 compared with those defined as sufficient.

CONCLUSIONS

This study demonstrated significant associations between low vitamin D status and markers of inflammation (including the ratio of IL-6 to IL-10) within elderly adults. These findings suggest that an adequate vitamin D status may be required for optimal immune function, particularly within the older adult population.

Vitamin D supplementation for prevention of mortality in adults

BACKGROUND

Available evidence on the effects of vitamin D on mortality has been inconclusive. In a recent systematic review, we found evidence that vitamin D3 may decrease mortality in mostly elderly women. The present systematic review updates and reassesses the benefits and harms of vitamin D supplementation used in primary and secondary prophylaxis of mortality.

OBJECTIVES

To assess the beneficial and harmful effects of vitamin D supplementation for prevention of mortality in healthy adults and adults in a stable phase of disease.

SEARCH METHODS

We searched The Cochrane Library, MEDLINE, EMBASE, LILACS, the Science Citation Index-Expanded and Conference Proceedings Citation Index-Science (all up to February 2012). We checked references of included trials and pharmaceutical companies for unidentified relevant trials.

SELECTION CRITERIA

Randomised trials that compared any type of vitamin D in any dose with any duration and route of administration versus placebo or no intervention in adult participants. Participants could have been recruited from the general population or from patients diagnosed with a disease in a stable phase. Vitamin D could have been administered as supplemental vitamin D (vitamin D3 (cholecalciferol) or vitamin D2 (ergocalciferol)) or as an active form of vitamin D (1α-hydroxyvitamin D (alfacalcidol) or 1,25-dihydroxyvitamin D (calcitriol)).

DATA COLLECTION AND ANALYSIS

Six review authors extracted data independently. Random-effects and fixed-effect meta-analyses were conducted. For dichotomous outcomes, we calculated the risk ratios (RRs). To account for trials with zero events, we performed meta-analyses of dichotomous data using risk differences (RDs) and empirical continuity corrections. We used published data and data obtained by contacting trial authors.To minimise the risk of systematic error, we assessed the risk of bias of the included trials. Trial sequential analyses controlled the risk of random errors possibly caused by cumulative meta-analyses.

MAIN RESULTS

We identified 159 randomised clinical trials. Ninety-four trials reported no mortality, and nine trials reported mortality but did not report in which intervention group the mortality occurred. Accordingly, 56 randomised trials with 95,286 participants provided usable data on mortality. The age of participants ranged from 18 to 107 years. Most trials included women older than 70 years. The mean proportion of women was 77%. Forty-eight of the trials randomly assigned 94,491 healthy participants. Of these, four trials included healthy volunteers, nine trials included postmenopausal women and 35 trials included older people living on their own or in institutional care. The remaining eight trials randomly assigned 795 participants with neurological, cardiovascular, respiratory or rheumatoid diseases. Vitamin D was administered for a weighted mean of 4.4 years. More than half of the trials had a low risk of bias. All trials were conducted in high-income countries. Forty-five trials (80%) reported the baseline vitamin D status of participants based on serum 25-hydroxyvitamin D levels. Participants in 19 trials had vitamin D adequacy (at or above 20 ng/mL). Participants in the remaining 26 trials had vitamin D insufficiency (less than 20 ng/mL).Vitamin D decreased mortality in all 56 trials analysed together (5,920/47,472 (12.5%) vs 6,077/47,814 (12.7%); RR 0.97 (95% confidence interval (CI) 0.94 to 0.99); P = 0.02; I(2) = 0%). More than 8% of participants dropped out. 'Worst-best case' and 'best-worst case' scenario analyses demonstrated that vitamin D could be associated with a dramatic increase or decrease in mortality. When different forms of vitamin D were assessed in separate analyses, only vitamin D3 decreased mortality (4,153/37,817 (11.0%) vs 4,340/38,110 (11.4%); RR 0.94 (95% CI 0.91 to 0.98); P = 0.002; I(2) = 0%; 75,927 participants; 38 trials). Vitamin D2, alfacalcidol and calcitriol did not significantly affect mortality. A subgroup analysis of trials at high risk of bias suggested that vitamin D2 may even increase mortality, but this finding could be due to random errors. Trial sequential analysis supported our finding regarding vitamin D3, with the cumulative Z-score breaking the trial sequential monitoring boundary for benefit, corresponding to 150 people treated over five years to prevent one additional death. We did not observe any statistically significant differences in the effect of vitamin D on mortality in subgroup analyses of trials at low risk of bias compared with trials at high risk of bias; of trials using placebo compared with trials using no intervention in the control group; of trials with no risk of industry bias compared with trials with risk of industry bias; of trials assessing primary prevention compared with trials assessing secondary prevention; of trials including participants with vitamin D level below 20 ng/mL at entry compared with trials including participants with vitamin D levels equal to or greater than 20 ng/mL at entry; of trials including ambulatory participants compared with trials including institutionalised participants; of trials using concomitant calcium supplementation compared with trials without calcium; of trials using a dose below 800 IU per day compared with trials using doses above 800 IU per day; and of trials including only women compared with trials including both sexes or only men. Vitamin D3 statistically significantly decreased cancer mortality (RR 0.88 (95% CI 0.78 to 0.98); P = 0.02; I(2) = 0%; 44,492 participants; 4 trials). Vitamin D3 combined with calcium increased the risk of nephrolithiasis (RR 1.17 (95% CI 1.02 to 1.34); P = 0.02; I(2) = 0%; 42,876 participants; 4 trials). Alfacalcidol and calcitriol increased the risk of hypercalcaemia (RR 3.18 (95% CI 1.17 to 8.68); P = 0.02; I(2) = 17%; 710 participants; 3 trials).

AUTHORS' CONCLUSIONS

Vitamin D3 seemed to decrease mortality in elderly people living independently or in institutional care. Vitamin D2, alfacalcidol and calcitriol had no statistically significant beneficial effects on mortality. Vitamin D3 combined with calcium increased nephrolithiasis. Both alfacalcidol and calcitriol increased hypercalcaemia. Because of risks of attrition bias originating from substantial dropout of participants and of outcome reporting bias due to a number of trials not reporting on mortality, as well as a number of other weaknesses in our evidence, further placebo-controlled randomised trials seem warranted.

Ability of vitamin D to reduce inflammation in adults without acute illness

In vitro studies and some clinical studies suggest that vitamin D plays an important role in reducing inflammation. The objective of this review was to examine recent evidence that vitamin D status influences the level of inflammation in adults without acute illness or injury. Five large cross-sectional studies and two randomized controlled trials are the focus of this review. Associations between 25-hydroxyvitamin D (25OHD) and inflammation markers are significant and inverse in study populations with low 25OHD levels (<21 ng/mL). They are also inverse in adults with relatively high inflammation levels. These associations in the few available randomized controlled vitamin D intervention trials have been null; this may be because they were not examined in populations with sufficiently low levels of 25OHD or high levels of inflammation.

Effect of supplementation with vitamin D2-enhanced mushrooms on vitamin D status in healthy adults

Vitamin D deficiency is emerging worldwide and many studies now suggest its role in the development of several chronic diseases. Due to the low level of vitamin D naturally occurring in food there is a need for supplementation and use of vitamin D-enhanced products. The aim of the present study was to determine if daily consumption of vitamin D2-enhanced mushrooms increased vitamin D status in free-living healthy adults or affected markers of the metabolic syndrome. A total of ninety volunteers (aged 40-65 years) were randomly assigned to one of two 4-week studies: mushroom study (15 µg vitamin D2 or placebo mushroom powder) and capsule study (15 µg vitamin D3 or placebo capsules). Consumption of vitamin D2-enhanced mushrooms increased serum 25-hydroxyvitamin D2 (25(OH)D2) by 128 % from baseline (3·9 (sd 1·9) nmol/l; P < 0·05). Serum 25(OH)D3 increased significantly in the vitamin D3 capsule group (a 55 % increase from a baseline of 44.0 (sd 17·1) nmol/l; P < 0·05). Vitamin D status (25(OH)D) was affected only in the vitamin D3 group. Plasminogen activator inhibitor-1 was lowered by vitamin D2 intake. Vitamin D2 from enhanced mushrooms was bioavailable and increased serum 25(OH)D2 concentration with no significant effect on 25(OH)D3 or total 25(OH)D.

Relationship between 25-hydoxyvitamin D, muscle strength, and incidence of injury in healthy adults: a systematic review

The purpose of this systematic review is to answer the following clinical questions in healthy adults: is vitamin D status related to (1) muscle strength? (2) or incidence of injury? A literature search was performed using Pubmed, SPORTDiscus, and Web of Science to capture relevant articles that have examined these outcomes. Inclusion criteria required studies to address at least one of the 2 questions stated above, enroll healthy human subjects with a mean age of 18 to 65 years of age, and include serum 25-hydoxyvitamin D measures. Study characteristics such as vitamin D status, study design, and study population were documented. Measured assessors and outcomes from all studies were extracted to answer at least one of the two questions. When applicable, data were used to compute effect sizes at a 95% confidence interval for comparisons across studies to answer the 2 questions. The results of these studies indicate a weak to moderate effect of higher 25-hydoxyvitamin D levels on greater muscle strength and reduced incidence of injury. Randomized controlled clinical trials examining these questions are scarce when compared with the popularity of vitamin D testing; therefore, future trials are necessary to advance our understanding and to clarify the effect vitamin D has on extraskeletal outcomes in healthy adults.

Seasonal patterns of abdominal pain consultations among adults and children

BACKGROUND AND AIM

Consultations for chronic abdominal pain are frequent in adults and children. A seasonal pattern of abdominal pain consultations with winter predominance was shown in previous pediatric studies; however, no studies have investigated whether such a pattern exists in adult patients. Understanding the differences in seasonal patterns of abdominal pain consultations among adults and children may indicate that either different mechanisms exist for common chronic pain conditions or triggering factors may vary by age. The aim of the study was to investigate whether a seasonal variation in abdominal pain consultation patterns exists among adults and children.

METHODS

The number of outpatient consultations among children (5-17 years) and adults (18 years or older) with a diagnosis of abdominal pain of nonspecified origin (International Classification of Diseases-9 code 789.0) from May 2000 to December 2008 was identified in an administrative claims database. The primary outcome measure was the rate of abdominal pain consultations (total number of abdominal pain consultations/total number of distinct patients by month×1000) by season in children and adults. Seasons were defined as follows: winter (December-February), spring (March-May), summer (June-August), and fall (September-November). A trend test was conducted to determine the degree of linearity in the patterns between the 2 groups. Among children, subanalyses by age 5 to 11 years and 12 to 17 years and sex were conducted.

RESULTS

A total of 172.4 million distinct patients (13.4% children, 87.6% adults) were identified in the database between May 2000 and December 2008. During the same time period, 15.6 million patient consultations for abdominal pain were identified (10.1% children, 89.9% adults). Children demonstrated a seasonal pattern in abdominal pain consultations, which best fit a quadratic regression curve, with consultations less common during the summer months. Abdominal pain consultations in adults were linear with no seasonal predominance. The trend in seasonal variation of abdominal pain consultations among children stratified by age and sex remained consistent with the overall child population.

CONCLUSIONS

Abdominal pain consultations in children are less common during summer months, whereas no evidence of seasonal pattern of consultation was found in adults. Factors involved in the pathogenesis of abdominal pain in adults and children may differ.

Circulating pro-inflammatory cytokines are elevated and peak power output correlates with 25-hydroxyvitamin D in vitamin D insufficient adults

The purpose of this study was to identify circulating cytokines, skeletal muscle strength, and peak power output in young adults with contrasting serum 25-hydroxyvitamin D (25(OH)D) concentrations. Serum 25(OH)D, inflammatory cytokines, muscle strength, and peak power output were, therefore, measured in young adults (25-42 years). Data were collected during the winter to avoid the seasonal influence on serum 25(OH)D. After serum 25(OH)D concentration measurements, subjects were separated into one of two groups: (1) vitamin D insufficient [serum 25(OH)D ≤32 ng/mL, n = 14], or (2) vitamin D sufficient [serum 25(OH)D >32 ng/mL, n = 14]. Following group allocation, serum 25(OH)D concentrations were significantly (p < 0.05) lower and pro-inflammatory cytokines [interleukin (IL)-2, IL-1β, tumor necrosis factor-α, and interferon-γ] were significantly (all p < 0.05) greater in vitamin D insufficient adults. An anti-inflammatory cytokine (i.e., IL-10; p > 0.05), peak isometric forces (p > 0.05), and peak power outputs (p > 0.05) were not significantly different between vitamin D groups. However, peak power outputs correlated with serum 25(OH)D concentrations in vitamin D insufficient (r = 0.55, p < 0.05) but not in vitamin D sufficient adults (r = -0.27, p = 0.36). Based on these data, we conclude that vitamin D insufficiency, in part, could result in pro-inflammatory stress without altering muscular strength or function in young adults. Future research investigating the causality of the correlation between low-serum 25(OH)D and peak power output in young adults is required.

Improvement of vitamin D status resulted in amelioration of biomarkers of systemic inflammation in the subjects with type 2 diabetes

BACKGROUND

Both vitamin D deficiency and inflammation have been linked to cardiovascular disease, the major cause of death in diabetes. In this study, the effects of daily intake of vitamin D-fortified yoghourt drink (doogh) on systemic inflammatory biomarkers in subjects with type 2 diabetes (T2D) were investigated.

SUBJECTS AND METHODS

In this 12-week randomized controlled trial, T2D subjects received either plain doogh (PD; containing 170 mg calcium and no detectable vitamin D/250 mL, n(1) = 50) or vitamin D3-fortified doogh (FD; containing 170 mg calcium and 500 IU/250 mL, n(2) = 50) twice a day. Glycemic status, body fat mass and systemic inflammatory biomarkers including serum highly sensitive C-reactive protein (hsCRP), serum amyloid A (SAA), interleukin(IL)-2, IL-6, IL-10 and tumour necrosis factor (TNF)-α were evaluated at the beginning and after the intervention. Data were expressed as either mean ± SD or median (interquartile range) whenever they had either normal or non-normal distribution, respectively.

RESULTS

In the patients receiving the vitamin D fortified drink, compared with those receiving the unfortified drink, a significant increase in serum 25(OH)D was accompanied by significant changes in TNF-α (-57.9 (-264.6) versus +106.3 (683.2), p = 0.044), IL-6 (-6.3 (-69.2), p = 0.002), hsCRP (-0.39 (-1.50) versus +0.8 (1.52), p < 0.001), SAA (-14.2 ± 44.5 versus +5.6 ± 37.5 mg/L, p = 0.022) and IL-10 (+38.7 ± 157.0 versus -51.9 ± 165.2 ng/L, p = 0.013). The between-group differences of hsCRP, SAA and IL-6 changes remained significant even after controlling for changes quantitative insulin check index (p < 0.001, p < 0.001 and p = 0.009, respectively).

CONCLUSIONS

Improvement of vitamin D status of T2D subjects resulted in amelioration of the systemic inflammatory markers. This may have preventive implications against cardiovascular disease and other diabetic complications.

Effects of ultraviolet light on human serum 25-hydroxyvitamin D and systemic immune function

BACKGROUND

Many immune-mediated diseases are associated with low levels of vitamin D and sunlight. UV light or supplementation with vitamin D can increase regulatory T-cell activity and prevent animal models of autoimmune disease. Increasing population vitamin D levels may therefore alleviate the burden of human immune-mediated disease.

OBJECTIVE

To determine the responses of circulating 25-hydroxyvitamin D [25(OH)D] levels, regulatory T-cell numbers, and immune function to UV light exposure in patients being treated for skin disease.

METHODS

Twenty-four subjects with skin disease from the North of Scotland were recruited between December and March. At baseline, and after 2 and 4 weeks of narrowband UV light exposure, we measured peripheral blood 25(OH)D level, numbers of regulatory T cells (CD4(+)CD25(hi)FoxP3(+)), and T-cell proliferative and cytokine responses to anti-CD3/CD28 stimulation.

RESULTS

Median (interquartile range) narrowband UV-B received during the study was 39.1 (30.9) as standard erythema dose, comparable to a quarter of the median summer sunlight exposure received locally. This increased the 25(OH)D level from a mean ± SD of 34 ± 17 nmol/L to 58 ± 16 nmol/L after 2 weeks and 78 ± 19 nmol/L after 4 weeks. The mean proportion of circulating regulatory T cells increased from 0.5% to 1.6% CD3(+) cells, which significantly correlated with the increased 25(OH)D level. UV treatment was also followed by reduced proliferative and IL-10 responses to anti-CD3/CD28 independent of the 25(OH)D level.

CONCLUSION

Narrowband UV light reduces systemic immune responsiveness via the induction of regulatory T cells. Light and 25(OH)D levels may affect particular immune functions independently. The levels of serum 25(OH)D over which these effects are apparent should guide future interventions.

Different doses of supplemental vitamin D maintain interleukin-5 without altering skeletal muscle strength: a randomized, double-blind, placebo-controlled study in vitamin D sufficient adults

BACKGROUND

Supplemental vitamin D modulates inflammatory cytokines and skeletal muscle function, but results are inconsistent. It is unknown if these inconsistencies are dependent on the supplemental dose of vitamin D. Therefore, the purpose of this study was to identify the influence of different doses of supplemental vitamin D on inflammatory cytokines and muscular strength in young adults.

METHODS

Men (n = 15) and women (n = 15) received a daily placebo or vitamin D supplement (200 or 4000 IU) for 28-d during the winter. Serum 25-hydroxyvitamin D (25(OH)D), cytokine concentrations and muscular (leg) strength measurements were performed prior to and during supplementation. Statistical significance of data were assessed with a two-way (time, treatment) analysis of variance (ANOVA) with repeated measures, followed by a Tukey's Honestly Significant Difference to test multiple pairwise comparisons.

RESULTS

Upon enrollment, 63% of the subjects were vitamin D sufficient (serum 25(OH)D ≥ 30 ng/ml). Serum 25(OH)D and interleukin (IL)-5 decreased (P < 0.05) across time in the placebo group. Supplemental vitamin D at 200 IU maintained serum 25(OH)D concentrations and increased IL-5 (P < 0.05). Supplemental vitamin D at 4000 IU increased (P < 0.05) serum 25(OH)D without altering IL-5 concentrations. Although serum 25(OH)D concentrations correlated (P < 0.05) with muscle strength, muscle strength was not changed by supplemental vitamin D.

CONCLUSION

In young adults who were vitamin D sufficient prior to supplementation, we conclude that a low-daily dose of supplemental vitamin D prevents serum 25(OH)D and IL-5 concentration decreases, and that muscular strength does not parallel the 25(OH)D increase induced by a high-daily dose of supplemental vitamin D. Considering that IL-5 protects against viruses and bacterial infections, these findings could have a broad physiological importance regarding the ability of vitamin D sufficiency to mediate the immune systems protection against infection.