Insulin-like growth factor I, growth hormone, and insulin sensitivity: the effects of a one-year cholecalciferol supplementation in middle-aged overweight and obese subjects

1α,25-Dihydroxyvitamin D Downregulates Adipocyte Impact on Breast Cancer Cell Migration and Adipokine Release

BACKGROUND/OBJECTIVES

Excess adiposity is associated with a higher risk of breast cancer metastasis and mortality. Evidence suggests that dietary vitamin D inhibits breast cancer metastasis. However, the mechanistic link between vitamin D's regulation of adipocyte metabolism and metastasis has not been previously investigated. Therefore, the purpose of these experiments was to examine the effect of the active form of vitamin D, 1α,25-dihydroxyvitamin D (1,25(OH)2D), on adipocyte release of bioactive compounds and whether the impact on adipocytes leads to inhibition of breast cancer cell migration, an important step of metastasis.

METHODS

Differentiated 3T3-L1 adipocytes were treated with 1,25(OH)2D for two days, followed by either harvesting the adipocytes or collecting adipocyte-conditioned media without 1,25(OH)2D. A transwell migration assay was conducted with vehicle- or 1,25(OH)2D-conditioned media. In order to explore the mechanism underlying effects on breast cancer metastatic capability, the mRNA expression of leptin, adiponectin, insulin-like growth factor (IGF-1), interleukin-6 (IL-6), and monocyte chemoattractant protein-1 (MCP-1) was measured in adipocytes following either vehicle or 1,25(OH)2D treatment.

RESULTS

Conditioned media from 1,25(OH)2D-treated adipocytes inhibited the migration of metastatic MDA-MB-231 breast cancer cells compared to conditioned media from vehicle-treated adipocytes. Treatment of adipocytes with 1,25(OH)2D decreased mRNA expression of leptin, adiponectin, IGF-1, IL-6, and MCP-1. Consistent with mRNA expression, concentrations of leptin, adiponectin, IGF-1, and IL-6 in adipocyte-conditioned media were decreased with 1,25(OH)2D treatment, although MCP-1 remained unchanged.

CONCLUSIONS

In summary, these results suggest that 1,25(OH)2D alters adipocyte secretions to prevent breast cancer metastasis.

Mediating Effect of Insulin-Like Growth Factor-I Underlying the Link Between Vitamin D and Gestational Diabetes Mellitus

Vitamin D was well-known to be associated with gestational diabetes mellitus (GDM). Insulin-like growth factor-I (IGF-I) has been linked to vitamin D and GDM, respectively. We hypothesize that changes in IGF-I metabolism induced by 25(OH)D3 might contribute to GDM. Therefore, we investigated the independent and combined relationships of serum 25(OH)D3 and IGF-I concentrations with GDM risk, and the mediation effect of IGF-I on 25(OH)D3. A total of 278 pregnant women (including 125 cases and 153 controls) were recruited in our current study. Maternal serum 25(OH)D3 and IGF-I were measured in the second trimester. Logistic regression models were used to estimate the associations of 25(OH)D3 and IGF-I concentrations with the risk of GDM. Mediation analyses were used to explore the mediation effect of IGF-I on the association between 25(OH)D3 and the risk of GDM. After adjusted for the confounded factors, both the third and fourth quartile of 25(OH)D3 decreased the risk of GDM (OR = 0.226; 95% CI, 0.103-0.494; OR = 0.109; 95% CI, 0.045-0.265, respectively) compared to the first quartile of 25(OH)D3. However, the third and fourth quartile of serum IGF-I (OR = 5.174; 95% CI, 2.287-11.705; OR = 12.784; 95% CI, 5.292-30.879, respectively) increased the risk of GDM compared to the first quartile of serum IGF-I. Mediation analyses suggested that 19.62% of the associations between 25(OH)D3 and GDM might be mediated by IGF-I. The lower concentration of serum 25(OH)D3 or higher IGF-I in the second trimester was associated with an increased risk of GDM. The serum IGF-I level might be a potential mediator between 25(OH)D3 and GDM.

Causal associations between insulin-like growth factor 1 and vitamin D levels: a two-sample bidirectional Mendelian randomization study

Background

Insulin-like growth factor 1 (IGF-1) plays a vital role in the attainment and maintenance of bone mass throughout life and is closely related to the stature of children. 25-Hydroxyvitamin D (25-OHD) is an intermediate of vitamin D (Vit D) metabolism and a key indicator of Vit D nutritional status. Multiple studies have revealed that IGF-1 levels undergo a non-significant increase after Vit D supplementation. Here, we analyzed the causal and reverse causal relationships between 25-OHD and IGF-1 levels using Mendelian randomization (MR).

Methods

Two-sample MR was used to estimate an unconfounded bidirectional causal relationship between the level of IGF-1 and those of Vit D and 25-OHD. Single nucleotide polymorphisms (SNPs) were filtered from genome-wide association studies (GWAS) after a comprehensive search of the Integrative Epidemiology Unit GWAS database. Several MR methods were employed, including inverse-variance weighted (IVW) method, and a sensitivity analysis was undertaken to detect whether pleiotropy or heterogeneity biased the MR results.

Results

Genetically predicted IGF-1 was found to have a causal association with Vit D and serum 25-OHD levels, where Vit D and serum 25-OHD levels increased with increasing IGF-1 concentrations (Vit D: IVW β:0.021, 95% CI: 0.005-0.036, p = 7.74 × 10^-3; 25-OHD: IVW β: 0.041, 95% CI: 0.026-0.057, p = 2.50 × 10^-7). A reverse causal effect was also found, indicating Vit D and serum 25-OHD have a positive causal relationship with IGF-1 (Vit D: IVW β:0.182, 95% CI: 0.061-0.305, p = 3.25 × 10^-3; 25-OHD: IVW β: 0.057, 95% CI = 0.017-0.096, p = 4.73 × 10^-3). The sensitivity analysis showed that horizontal pleiotropy was unlikely to bias the causality in this study (MR-Egger: Vit D intercept p = 5.1 × 10^-5, 25-OHD intercept p = 6.4 × 10^-4 in forward analysis; Vit D intercept p = 6.6 × 10^-4, 25-OHD intercept p = 1.9 × 10^-3 in reverse analysis), and a leave-one-out analysis did not identify evidence of bias in the results.

Conclusion

The results of the MR analysis provide evidence that IGF-1 has positive causal and reverse causal relationships with Vit D and serum 25-OHD, respectively, in European populations. Our findings also provide guidance for the prevention and treatment of short stature and other related diseases.

Evaluation of IGF-1, TNF-α, and TGF-β Gene Expression after Oral Vitamin D Supplementation in School-Aged Children with Chronic Bronchial Asthma

BACKGROUND: Airway remodeling in children with bronchial asthma is due to the effect of inflammatory mediators and growth factors on the bronchial epithelium. Vitamin D (VitD) has immunomodulatory effect in many inflammatory diseases as bronchial asthma. The ant-inflammatory and anti-fibrotic role of VitD could prevent or improve air way remodeling in asthmatic patients. AIM: The study investigated the effect of VitD supplementation on the expression of transforming growth factor-beta (TGF-β), tumor necrosis factor-alpha (TNF-α), and insulin growth factor 1(IGF-1) and to correlate them with asthma severity and level of control. METHODS: The serum level of VitD and the mRNA expression of IGF-1, TGF-β, and TNF-α were estimated in 50 patients and 20 healthy controls control subjects using quantitative PCR in real-time. Asthmatic patients with VitD deficiency received VitD supplementation for 2 months followed by remeasurement of serum VitD and the genes expression TGF-β, TNF-α, and IGF-1. RESULT: Pre-intake of VitD and serum level of VitD were lower in all patients than control subjects (p = 0.005). VitD level was directly correlated with IGF-1 mRNA expression, which was indirectly correlated with TGF-β, r = 0.5 and −0.57; p = 0.0001 and 0.002, respectively. After VitD supplementation, the expression of the TGF-β mRNA gene was the only gene that decreased significantly (p = 0.04) together with improved asthma control and spirometric parameters. CONCLUSIONS: VitD supplementation down regulated the gene expression of TGF-β and improved asthma control level, but it did not significantly affect the gene expression of TNF-α and IGF-1.

Overview of Nutraceuticals and Cardiometabolic Diseases following Socio-Economic Analysis

The importance of functional food and nutraceutical products to deal with cardiometabolic diseases (CMDs) and metabolic syndrome (MetS) has gained attention in the past few years. The aim of this narrative review is to highlight the potential and effectiveness of nutraceutical in the improvement of CMDs and MetS biomarkers, alongside their burden of disease and economic health expenditure. A science database search was conducted between May and June 2021. A total of 35 studies were included in this paper. We included male and female subjects, children, and adults, in good health or with cardiovascular or metabolic disease. CMDs and MetS have gradually become worldwide health problems, becoming two of the major causes of morbidity and mortality in western countries. The results indicate a positive link between daily consumption of nutraceutical products and an improvement in cardiometabolic and anthropometric biomarkers. In this paper we included a wide range of nutraceutical products. Most of them showed promising data, indicating that nutraceuticals could provide a new therapeutic treatment to reduce prevalence and pharmaceutical expenditures attributed to CMDs and MetS. Unfortunately, there is a huge vacuum of data on nutraceutical usage, savings, and burden reduction. Therefore, further clinical and pharmaco-economic research in the field is highly required.

Double-counting of effect sizes and inappropriate exclusion of studies in "The influence of vitamin D supplementation on IGF-1 levels in humans: A systematic review and meta-analysis"

We read with interest the review by Kord-Varkaneh et al. which examined the effects of vitamin D supplementation on IGF-1 levels in humans. We believe that the article suffers from severe methodological faults and subsequently the conclusions are likely to be biased. Thus, the authors should address the mentioned limitations and update the analyses to provide robust and trustful estimates. We are concerned that without correction, the analyses may lead to erroneous findings and conclusions.

Vitamin D and cardiovascular health

The principal source of vitamin D in humans is its biosynthesis in the skin through a chemical reaction dependent on sun exposure. In lesser amounts, the vitamin can be obtained from the diet, mostly from fatty fish, fish liver oil and mushrooms. Individuals with vitamin D deficiency, defined as a serum level of 25 hydroxyvitamin D < 20 ng/dl, should be supplemented. Vitamin D deficiency is a prevalent global problem caused mainly by low exposure to sunlight. The main role of 1,25 dihydroxyvitamin D is the maintenance of calcium and phosphorus homeostasis. However, vitamin D receptors are found in most human cells and tissues, indicating many extra-skeletal effects of the vitamin, particularly in the immune and cardiovascular (CV) systems. Vitamin D regulates blood pressure by acting on endothelial cells and smooth muscle cells. Its deficiency has been associated with various CV risk factors and appears to be linked to a higher mortality and incidence of CV disease (CVD). Several mechanisms have been proposed relating vitamin D deficiency to CV risk factors such as renin-angiotensin-aldosterone system activation, abnormal nitric oxide regulation, oxidative stress or altered inflammatory pathways. However, in the latest randomized controlled trials no benefits of vitamin D supplementation for CVD have been confirmed. Although more work is needed to establish the protective role of vitamin D in this setting, according to current evidences vitamin D supplements should not be recommended for CVD prevention.

Patin (Pangasius hypophthalmus) fish protein concentrate alters insulin-like growth factor (IGF)-1 and igf binding protein (IGFBP)-3 level of sprague dawley neonate rats-induced malnutrition

Malnutrition is caused by inadequate protein intake and affects growth factor. High protein from patin (Pangasius hypophthalmus) fish is a well-known protein source. This study aims to investigate the effect of patin fish protein concentrate (PFPC) in the IGF-1 and IGFBP-3 level of Sprague Dawley (SD) neonate rats-induced malnutrition. Thirty male SD neonate rats were divided randomly into five groups, namely normal control (K1), malnutrition control (K2), malnutrition with PFPC 13.26 mg.g-1 body weight (BW)/day (X1), malnutrition with PFPC 19.89 mg.g-1 BW/d (X2), and malnutrition with casein supplement 13.26 mg.g-1 BW/d (X3). K1 received a standard diet, while the others received a low 8% protein diet (L8PD) since those were born until 21 days. The standard diet was refed for all groups during the intervention (14 days). IGF-1 and IGFBP-3 levels were measured by ELISA. Normal data were analyzed by using One-way ANOVA which then was followed by post-hoc Bonferroni. Meanwhile, the others were analyzed by Kruskal Wallis and followed by Mann-Whitney U-test. Spearman test was used for correlation. PFPC contained 81.07% of protein, 4.08% of fat, 7.24% of moisture, 2.77% of ash, and 4.83% of carbohydrate. These contents had affected the growth factor. As a result, in the PFPC intervention, IGF-1, and IGFBP-3 levels (p <0.05) were decreased, while the controls were increased. The decreased values were shown in IGFBP-3 levels (p <0.05) while the increase was shown in both controls. On the other hand, the increase in body weight was shown in all groups, including control ones. A strong correlation was found between IGF-1 and IGFBP-3. PFPC has additional value on repairing malnutrition that is the best dose in effecting IGF-1 dan IGFBP3 levels is 13.26 mg.g-1 BW/d.

Vitamin D and the insulin-like growth factor system: Implications for colorectal neoplasia

Epidemiological studies have strongly associated lower levels of vitamin D and its metabolites with an increased risk of colorectal cancer (CRC). The action of calcitriol, the active metabolite of vitamin D, is mediated by the vitamin D receptor (VDR) that is present in most tissues. In advanced CRC, VDR expression is lowered. Calcitriol has several antineoplastic effects in CRC: it promotes the G1-phase cycle arrest, lowers vascular endothelial growth factor (VEGF) synthesis and acts on tumour stromal fibroblasts to limit cell migration and angiogenesis. Hyperinsulinemia and insulin-like growth factors (IGFs) have been implicated in the pathophysiology of CRC. IGF-1 and IGFBP-3 have been the most studied components of the IGF system. Only 1% of the total serum IGF-1 is free and bioactive, and 80% of it binds to IGFBP-3. IGF-1 and its receptor IGF-1R are known to induce cell proliferation. Both IGF-1 and IGFBP-3 can favour angiogenesis by increasing the transcription of the VEGF gene. A high serum IGF-1/IGFBP-3 ratio is associated with increased risk for CRC. VDR is a transcription factor for the IGFBP-3 gene, and IGF-1 can increase calcitriol synthesis. Studies examining the effect of vitamin D treatment on serum IGF-1 and IGFBP-3 have not been in agreement since different populations, dosages and intervention periods have been used. New vitamin D treatment studies that examine CRC should take in account confounding factors such as obesity or VDR genotypes.

The effect of vitamin D supplementation on insulin-like growth factor-1: A systematic review and meta-analysis of randomized controlled trials

PURPOSE

There is equivocality regarding the interaction between vitamin D and insulin-like growth factor-1 (IGF-1). Thus, the aim of this study was to elucidate the effect of vitamin D supplementation on serum levels of IGF-1 by conducting a systematic review and meta-analysis of randomized controlled trials (RCTs).

METHODS

PubMed, Scopus, and ISI Web of Science databases were searched up to May 2019 for RCTs that evaluated the effect of vitamin D supplementation on IGF-1 levels. Mean and standard deviation changes of IGF-1 in each treatment group were considered for analysis and pooled using random-effect model. Risk of bias for included studies was assessed by the Cochrane scale and the NutriGrade approach was applied to evaluate the quality of evidence.

RESULTS

Six trials (n = 773 participants) were included in the meta-analysis. Compared with control group, vitamin D supplementation yielded no significant effect on serum level of IGF-1 (weighted mean difference [WMD] =4.66 ng/ml, 95 % CIs: -6.72 to 16.03, P = 0.42, I² = 74.8, P_{-heterogeneity} = 0.001). Additionally, no meaningful changes were observed in subgroup analyses.

CONCLUSION

The evidence from the limited number of published trials does not convincingly show that vitamin D supplementation elicits any clinically relevant effects on IGF-1 levels. More high-quality studies are needed to reach a consensual conclusion in this area.

Effects of Dietary or Supplementary Micronutrients on Sex Hormones and IGF-1 in Middle and Older Age: A Systematic Review and Meta-Analysis

Observational research suggests that micronutrients may be protective for sarcopenia, a key health issue during ageing, potentially via effects on hormone synthesis and metabolism. We aimed to carry out a systematic review of RCTs investigating effects of increasing dietary or supplemental micronutrient intake on sex hormones and IGF-1 in individuals aged 45 years or older. We searched MEDLINE, EMBASE and Cochrane databases for RCTs reporting the effects of different micronutrients (vitamins A, C, D, or E; carotenoids; iron; copper; zinc; magnesium; selenium; and potassium) on sex hormones or IGF-1. Of the 26 RCTs identified, nine examined effects of vitamin D, nine of multi-nutrients, four of carotenoids, two of selenium, one of zinc, and one of vitamin E. For IGF-1 increasing vitamin D (MD: -0.53 nmol/L, 95% CI: -1.58, 0.52), multi-nutrients (MD: 0.60 nmol/L, 95% CI -1.12 to 2.33) and carotenoids (MD -1.32 nmol/L; 95% CI -2.76 to 0.11) had no significant effect on circulating concentrations. No significant effects on sex hormones of other micronutrients were found, but data were very limited. All trials had significant methodological limitations making effects of micronutrient supplementation on sex hormones unclear. Further high quality RCTs with physiological doses of micronutrients in people with low baseline intakes or circulating concentrations, using robust methodology, are required to assess effects of supplementation adequately.

Relationship of Vitamin D-Deficient Diet and Irisin, and Their Impact on Energy Homeostasis in Rats

Background and Objective

Previous studies have identified the role of irisin and vitamin D in energy homeostasis. However, the effect of irisin and vitamin D on energy regulation has not been thoroughly investigated. Therefore, in this study, the effects of a vitamin D-deficient diet and irisin on total energy expenditure (TEE), food intake, and blood metabolites were investigated in rats.

Methods

Sixteen healthy weaned male albino rats were randomly divided into two groups: a group fed a normal balanced growth diet (group A: n = 8) and a group fed a normocalcemic diet that is vitamin D deficient with limited ultraviolet (UV) light exposure (group B, n = 8). After 6 weeks, the volumes of respiratory gases were measured by open-circuit indirect calorimetry. Serum irisin, 25-OHVD₃, calcium, insulin, and glucose levels were measured using ELISA. The respiratory quotient (RQ), energy expenditure, and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) were calculated.

Results

Rats with hypovitaminosis D were hypoirisinemic. Food intake, RQ (to the range of using endogenous fat), and glucose levels reduced significantly, while insulin levels increased. Body weight and TEE were non-significant changed. Additionally, irisin was strongly and positively correlated with body weight under normal conditions (r = 0.905, p < 0.01), and a moderate negative correlation in group B (r = −0.429, p < 0.05). TEE and irisin showed no significant correlation.

Conclusion

This study demonstrated that the early changes in energy homeostasis and irisin levels during states of hypovitaminosis D are affected by long-term consumption of a vitamin D-deficient diet with limited UV exposure.

The influence of vitamin D supplementation on IGF-1 levels in humans: A systematic review and meta-analysis

BACKGROUND

Inconsistencies exist with regard to influence of vitamin D supplementation on IGF-1 levels. The inconsistencies could be attributed to several factors, such as dosage and duration of intervention, among others. To address these inconsistencies, this study was conducted to determine the impact of vitamin D supplementation on IGF-1 levels through a systematic review and meta-analysis of randomized controlled trials (RCTs).

METHODS

A comprehensive systematic search was carried out in PubMed/MEDLINE, Web of Science, SCOPUS and Embase for RCTs that investigated the impact of vitamin D intake on circulating IGF-1 levels from inception until June 2019. Weighted mean difference (WMD) with the 95 % CI were applied for estimating combined effect size. Subgroup analysis was performed to specify the source of heterogeneity among studies.

RESULTS

Pooled results from eight studies demonstrated an overall non-significant increase in IGF-1 following vitamin D supplementation (WMD: 4 ng/ml, 95 % CI: -4 to 11). However, a significant degree of heterogeneity among studies was observed (I² = 66 %). The subgroup analyses showed that vitamin D dosage of ≤1000 IU/day (WMD: 10 ng/ml) significantly increased IGF-1 compared to the vitamin D dosage of <1000 IU/day (WMD: -1 ng/ml). Moreover, intervention duration ≤12 weeks (WMD: 11 ng/ml) significantly increased IGF-1 compared to intervention duration <12 weeks (WMD: -3 ng/ml). In the epidemiological cohort study, participants under 60 years of age with a higher dietary vitamin D intake had significantly higher IGF-1 levels when compared to those with lower dietary vitamin D intake in second categories.

CONCLUSION

The main results indicate a non-significant increase in IGF-1 following vitamin D supplementation. Additionally, vitamin D dosages of <1000 IU/day and intervention durations of <12 weeks significantly raised IGF-1 levels.

Vitamin D and growth hormone in children: a review of the current scientific knowledge

Background

Human growth is a complex mechanism that depends on genetic, environmental, nutritional and hormonal factors. The main hormone involved in growth at each stage of development is growth hormone (GH) and its mediator, insulin-like growth factor 1 (IGF-1). In contrast, vitamin D is involved in the processes of bone growth and mineralization through the regulation of calcium and phosphorus metabolism. Nevertheless, no scientific study has yet elucidated how they interact with one another, especially as a dysfunction in which one influences the other, even if numerous biochemical and clinical studies confirm the presence of a close relationship.

Main body

We reviewed and analyzed the clinical studies that have considered the relationship between vitamin D and the GH/IGF-1 axis in pediatric populations. We found two main areas of interest: the vitamin D deficiency status in patients affected by GH deficit (GHD) and the relationship between serum vitamin D metabolites and IGF-1. Although limited by some bias, from the analysis of the studies presented in the scientific literature, it is possible to hypothesize a greater frequency of hypovitaminosis D in the subjects affected by GHD, a reduced possibility of its correction with only substitution treatment with recombinant growth hormone (rGH) and an improvement of IGF-1 levels after supplementation treatment with vitamin D.

Conclusions

These results could be followed by preventive interventions aimed at reducing the vitamin D deficit in pediatric age. In addition, further research is needed to fully understand how vitamin D and growth are intertwined.

Vitamin D supplementation in obesity and during weight loss: A review of randomized controlled trials

Vitamin D deficiency is common in obese individuals and during weight loss. The recommended vitamin D doses in this specific population are higher than for healthy adults. We reviewed vitamin D supplementation trials in obesity, and during medical or surgical weight loss, and report the effects on 25-hydroxyvitamin D [25(OH)D] concentrations and other relevant outcomes. We conducted a systematic search in PubMed, Medline, Embase and the Cochrane library for relevant randomized controlled trials (RCTs) of oral vitamin D supplementation for at least 3 months in obese individuals without weight loss (OB), and those on medical weight loss (MWL) (2010-2018), and following bariatric surgery (Bar S) (without time restriction). Two reviewers screened the identified citations in duplicate and independently and performed full text screening. One reviewer completed data extraction. We identified 13 RCTs in OB, 6 in MWL and 7 in Bar S. Mean baseline 25(OH)D concentrations ranged between 7 and 27 ng/ml in OB, 15-29 ng/ml in MWL and 15-24 ng/ml in Bar S. In OB (Total N 2036 participants), vitamin D doses of 1600-4000 IU/d increased mean 25(OH)D concentrations to ≥30 ng/ml. Based on three trials during MWL (Total N 359 participants), vitamin D doses of 1200-4600 IU/d for 12 months increased 25(OH)D concentration to ≥30 ng/ml. In Bar S (Total N 615 participants), doses ≥2000 IU/d were needed to reach 30 ng/ml. The change in 25(OH)D concentration was inversely proportional to the administered dose, and to BMI and baseline level with doses of 600-3000 IU/day. With these doses, the change in 25(OH)D concentration [Δ25(OH)D] per 100 IU/d was 0.5-1.2 ng/ml. Three trials assessed bone mineral density as a primary outcome, but only one of them showed a protective effect of vitamin D against bone loss at all sites post-Bar S. There was no effect of vitamin D on weight loss. Data on extra-skeletal parameters, namely glycemic and vascular indices were mostly identified in OB, and findings were inconsistent. In conclusion, Vitamin D doses ≥1600-2000 IU/d may be needed to reach a 25(OH)D concentration of 30 ng/ml in obese individuals and following bariatric surgery. The optimal concentration in this population is unknown, and whether the above doses protect against weight loss induced bone loss and fractures still needs to be confirmed. There is no clear evidence for a beneficial effect of vitamin D supplementation on cardio-metabolic parameters in obese individuals, and data on such parameters with weight loss are very scarce. Well-designed long term RCTs assessing the effect of vitamin D supplementation during weight loss on patient important outcomes are needed.

Sex-specific correlation of IGFBP-2 and IGFBP-3 with vitamin D status in adults with obesity: a cross-sectional serum proteomics study

Objective

Subjects with low vitamin D levels are at risk of cardiometabolic disease. The aim of this study was to identify novel serological markers linking vitamin D status with cardiometabolic profile in non-diabetic adults with obesity.

Methods

For the discovery phase, we used quantitative serum proteomics in sex-matched, age-matched and BMI-matched subjects with obesity [BMI: 25–35 kg/m²] and low [25(OH)D < 50 nmol/L] vs. high vitamin D status [25(OH)D > 50 nmol/L] (n = 16). For the validation phase, we performed ELISA in a larger cohort with similar characteristics (n = 179).

Results

We identified 423 and 549 differentially expressed proteins in the high vs. low vitamin D groups of the male and female cohorts, respectively. The small molecule biochemistry protein networks and the glycolysis|gluconeogenesis pathway were significantly enriched in the DEPs of both sexes. As surrogate markers to these processes, the insulin-like growth factor binding protein -2  (IGFBP-2) was upregulated in males, whereas   IGFBP-3 was upregulated in females from the high Vitamin D status. This sex-specific trend  was confirmed using Luminex ELISA to an independent but clinically analogous cohort of males (n = 84, p = 0.002) and females (n = 95, p = 0.03).

Conclusions

The high Vitamin D status correlated with the serological upregulation of IGFBP-2 in males and IGFBP-3 in females with obesity and may constitute surrogate markers of risk reduction of cardiometabolic disease.

Vitamin D Supplementation, Serum 25(OH)D Concentrations and Cardiovascular Disease Risk Factors: A Systematic Review and Meta-Analysis

Background: Cardiovascular disease (CVD) risk factors are associated with low serum 25 hydroxyvitamin D (25(OH)D) concentrations in observational studies; however, clinical trial findings are inconsistent.

Objective: We assessed the effect of vitamin D supplementation and increased serum 25(OH)D concentrations on CVD risk factors in a systemic review and meta-analysis of randomized controlled trials (RCTs).

Design: MEDLINE, CINAHL, EMBASE, and Google Scholar were searched for RCTs that evaluated vitamin D supplementation and cardiovascular outcomes [blood pressure, parathyroid hormone (PTH), serum high-sensitivity C-reactive protein (hs-CRP), total cholesterol, high and low density lipoprotein (HDL and LDL, respectively), triglycerides, peak wave velocity (PWV) and Augmentation Index (AI)] from 1992 through 2017. Meta-analysis was based on a random-effects model and inverse variance method to calculate standardized mean difference (SMD) as effect sizes, followed by a leave-one-out method for sensitivity analysis. Risk of publication bias was assessed using Cochrane checklist and Begg funnel plots. The systematic review is registered as CRD42015025346.

Results: We identified 2341 studies from which 81 met inclusion criteria. The meta-analysis indicated a significant reduction in systolic blood pressure (SMD = −0.102 ± 0.04 mmHg, 95% confidence interval (CI), −0.20 to −0.03), diastolic blood pressure (SMD = −0.07 ± 0.03 mmHg, 95% CI, −0.14 to −0.006), serum PTH (SMD = −0.66 ± 0.08 ng/L, 95% CI, −0.82 to −0.49), hs-CRP (SMD = −0.20 ± 0.07 mg/L, 95% CI, −0.34 to −0.06), total cholesterol (SMD = −0.15 ± 0.06 mmol/L, 95% CI, −0.25 to −0.04), LDL (SMD = −0.10 ± 0.05 mmol/L, 95% CI, −0.20 to −0.003), triglycerides (SMD = −0.12 ± 0.06 mmol/L, 95% CI, −0.23 to −0.003) and a significant increase in HDL (SMD = 0.09 ± 0.04 mmol/L, 95% CI, 0.00 to 0.17) with vitamin D supplementation. These findings remained significant in sensitivity analyses for blood pressure, lipid profile, serum PTH, and serum hs-CRP. There was no significant effect of vitamin D supplementation on PWV (SMD = −0.20 ± 0.13 m/s, 95% CI, −0.46 to 0.06, p = 0.14) and AI (SMD = −0.09 ± 0.14%, 95% CI, −0.37 to 0.19, p = 0.52) for vitamin D supplemented groups.

Conclusion: These findings suggest that vitamin D supplementation may act to protect against CVD through improving risk factors, including high blood pressure, elevated PTH, dyslipidemia, and inflammation.

IGF and IGFBP as an index for discrimination between vitamin D supplementation responders and nonresponders in overweight Saudi subjects

Vitamin D deficiency is common in the Kingdom of Saudi Arabia (KSA). Therefore, it is significant to recognize which biochemical markers modulate serum 25 hydroxyvitamin D (25(OH)D) in response to vitamin D supplementation in such a population. Our aim was to study the correlation of insulin-like growth factor (IGF) and insulin growth factor binding protein (IGFBP) with serum 25(OH)D in response to vitamin D supplementation in a Saudi population. A total of 199 (89 males/110 females) vitamin D deficient subjects (25(OH)D level <50 nmol/L), aged 40.4 ± 11.4 years, were given vitamin D supplements (50,000 IU/mL every week) for the first 2 months, then twice a month for 2 months, followed by daily 1000 IU in the last 2 months. Fasting blood samples were taken at baseline and 6 months after the final dose of vitamin D. Serum 25(OH)D, IGF-1 and IGF-2, and IGFBPs 2-5 were measured. Vitamin D response was computed for all subjects as the difference in levels of serum 25(OH)D concentration at the end of 6 months compared to baseline. After intervention, serum 25(OH)D concentration significantly increased from 35.6 nmol/L (26.6-43.5) to 61.8 nmol/L (54.8-73.3) in responder subjects (P < .01) and from 35.1 nmol/L (21.2-58.2) to 38.3 nmol/L (25.5-48.3) in nonresponders (P = .13). Subjects with lower baseline serum IGF-II, IGFBP-2, and IGF-1/IGFBP-3 ratio are more sensitive to acute vitamin D status changes. IGF1 and IGF-1/IGFBP-3 ratio significantly increased in all subjects after 6 months (P = .01). Changes in 25(OH)D was significantly associated with changes in IGFBP-2 and IGF-1/IGFBP-3 ratio in responders only. This study proposes that changes in circulating IGF-I and IGFBP-3 are modulated by vitamin D supplementation and can be taken into consideration in investigations involving vitamin D correction. Moreover, increase in serum 25(OH)D and IGF-I/IGFBP-3 molar ratio are more sensitive markers for the response to vitamin D supplementation in Saudi population.

An Overview of Novel Dietary Supplements and Food Ingredients in Patients with Metabolic Syndrome and Non-Alcoholic Fatty Liver Disease

Metabolic syndrome (MetS) is characterized by interconnected factors related to metabolic disturbances, and is directly related to the occurrence of some diseases such as cardiovascular diseases and type 2 diabetes. MetS is described as one or both of insulin resistance and visceral adiposity, considered the initial causes of abnormalities that include hyperglycemia, elevated blood pressure, dyslipidemia, elevated inflammatory markers, and prothrombotic state, as well as polycystic ovarian syndrome in women. Other than in MetS, visceral adiposity and the pro-inflammatory state are also key in the development of non-alcoholic fatty liver disease (NAFLD), which is the most prevalent chronic liver disease in modern society. Both MetS and NAFLD are related to diet and lifestyle, and their treatment may be influenced by dietary pattern changes and the use of certain dietary supplements. This study aimed to review the role of food ingredients and supplements in the management of MetS and NAFLD specifically in human clinical trials. Moreover, bioactive compounds and polyunsaturated fatty acids (PUFAs) may be used as strategies for preventing the onset of and treatment of metabolic disorders, such as MetS and NAFLD, improving the inflammatory state and other comorbidities, such as obesity, dyslipidemias, and cardiovascular diseases (CVD).

Associations between bone and energy metabolism in cows fed diets differing in level of dietary cation-anion difference and supplemented with cholecalciferol or calcidiol

Bone-derived hormones play an important role in metabolism. This study examined the hypothesis that interactions between bone and energy metabolism, particularly those involving osteocalcin, are present in dairy cattle and have feedback mechanisms over time. Associations between metabolites in blood were examined in 32 Holstein cows blocked by parity and milk yield and randomly allocated to diets containing either 0.27 mg/kg dry matter (DM) calcidiol or cholecalciferol for an anticipated intake of 3 mg/d (120,000 IU/d) at 11 kg of DM, and positive (+130 mEq/kg DM) or negative (-130 mEq/kg DM) dietary cation-anion difference (DCAD) from 252 d of gestation to calving. Blood was sampled every 3 d, from 9 d prepartum to 30 d postpartum, and plasma concentrations of vitamin D₃, 25-hydroxyvitamin D₃, adiponectin, C-telopeptide of type 1 collagen (CTX1), glucose, insulin-like growth factor 1 (IGF1), insulin, undercarboxylated osteocalcin (uOC), and carboxylated osteocalcin (cOC) were determined. Feeding calcidiol compared with cholecalciferol increased plasma concentrations of 25-hydroxyvitamin D₃ pre- (264.2 ± 8.0 vs. 61.3 ± 8.0 ng/mL) and postpartum (170.8 ± 6.2 vs. 51.3 ± 6.2 ng/mL) but decreased concentrations of vitamin D₃ pre- (1.2 ± 0.6 vs. 14.5 ± 0.6 ng/mL) and postpartum (1.9 ± 0.4 vs. 3.2 ± 0.6 ng/mL). Prepartum, cows fed the negative DCAD diet had reduced concentrations of vitamin D₃ and glucose compared with cows fed a positive DCAD. The combination of negative DCAD and cholecalciferol reduced IGF1 concentrations prepartum. The DCAD treatment had no effect on postpartum concentrations of metabolites. Nulliparous cows had increased concentrations of OC, CTX1, IGF1, glucose, and insulin compared with parous cows. Time series analysis identified associations between metabolites on the same day and over 3-d lags up to ±9 d that suggest feedback between 25-hydroxyvitamin D₃ and vitamin D₃ in the negative lags, indicating that 25-hydroxyvitamin D₃ may exert feedback on vitamin D₃ but not vice versa. We found evidence of a feedback mechanism between vitamin D₃ and IGF1, with positive effect size (ES) on the same day and 3 d later, and negative ES 9 d later, that was more evident in cholecalciferol-fed cows. This suggests an important role of IGF1 in integrating bone metabolism with energy and protein metabolic pathways. Evidence of feedback was found between uOC and particularly cOC with IGF1, with positive ES on the same day but negative ES 6 d before and 6 d after. An association between uOC or cOC and IGF1 has not been previously identified in cattle and suggests that both uOC and cOC may have marked biological activity. Associations between OC and insulin identified in mice were not observed herein, although associations between OC and glucose were similar to those between IGF1 and glucose, supporting associations between glucose, OC, and IGF1. We provide further statistical evidence of crosstalk between vitamin D compounds, bone hormones, and energy metabolism in cattle. In particular, associations between uOC or cOC and IGF1 may provide links between prepartum diets and observations of prolonged increases in milk production and allow better control of peripartum metabolism.

Association of insulin-like growth factor-1 and IGF binding protein-3 with 25-hydroxy vitamin D in pre-pubertal and adolescent Indian girls

BACKGROUND

There is a high prevalence of vitamin D deficiency (VDD) in India. Molecular mechanisms suggest a strong relationship between vitamin D and growth factors. However, there is a paucity of literature with regard to a relationship between insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3) and vitamin D particularly in subjects with VDD. The objective of the study was to assess the relationship between growth factors and serum vitamin D-parathormone (PTH) status in school girls and study the impact of vitamin D supplementation on growth factors in pre-pubertal girls with VDD.

METHODS

Our study subjects were apparently healthy school girls aged 6-18 years. The baseline height, weight, body mass index (BMI), pubertal status, serum 25-hydroxy vitamin D (25OHD), PTH, IGF-1 and IGFBP-3 were assessed in 847 girls aged 6-18 years and in 190 pre-pubertal girls with VDD following supplementation.

RESULTS

The mean age, BMI and serum 25OHD of girls were 11.5±3.2 years, 18.7±4.8 kg/m2 and 9.9±5.6 ng/mL, respectively. VDD was observed in 94.6% of girls. Unadjusted serum IGF-1 levels and IGF-1/IGFBP-3 molar ratio were significantly higher in girls with severe VDD as compared to girls with mild-to-moderate VDD. However, these differences disappeared when adjusted for age, height or sexual maturation. The serum IGF-1 and IGFBP-3 levels increased significantly post supplementation with vitamin D.

CONCLUSIONS

There were no differences in serum IGF-1 levels and the IGF-1/IGFBP-3 molar ratio among VDD categories when adjusted for age, height and sexual maturation in girls. Vitamin D supplementation resulted in a significant increase in serum IGF-1 levels in VDD pre-pubertal girls.

Gender-specific risk factors for androgenetic alopecia in the Korean general population: Associations with medical comorbidities and general health behaviors

BACKGROUND

The relationships between androgenetic alopecia (AGA) and various factors related to metabolic syndrome have been demonstrated in previous studies. However, it remains unclear because of inconsistent results. We investigated the associations between AGA and various risk factors related to metabolic syndrome according to gender.

METHODS

We conducted a population-based cross-sectional survey of 2028 Koreans (1050 men, 978 women). The basic and specific (BASP) classification was used for diagnosis of AGA. We collected information on risk factors though questionnaires and medical records.

RESULTS

AGA was significantly associated with age, family history of AGA, hypertension, diabetes mellitus, and waist circumference in both genders. Female subjects with AGA were more likely to have cerebrovascular disease, dyslipidemia, and obesity; however, these associations were not observed in the male subjects. When multiple regression analysis was applied, there was a significant relationship between hypertension and AGA in male subjects. However, there was no statistically significant association in female subjects.

CONCLUSION

The different results according to gender might arise from different mechanisms of AGA. There was a significant relationship between hypertension and AGA in male subjects. Evaluation of blood pressure in male patients with AGA might facilitate interventions for hypertension.

Frailty and the Quality of Life in Hemodialysis Patients: The Importance of Waist Circumference

OBJECTIVE

Frailty among the end-stage renal disease (ESRD) population is highly prevalent and has been associated with mortality. Little is known about the relation of different aspects of body composition, a modifiable risk factor, with the risk of frailty in ESRD population.

DESIGN AND METHODS

One hundred and fifty-one patients including 85 men and 66 women, aged ≥18 years with ESRD who had been receiving conventional maintenance hemodialysis (HD) for at least 3 months were included. Body fat and muscle mass from both bioimpedance spectroscopy and skin-fold thickness and waist circumference as a surrogate of abdominal obesity were measured. Frailty was defined based on Fried's criteria. Health-related quality of life was collected using the RAND version of the Kidney Disease Quality of Life (KDQOL-36) Survey.

RESULTS

We performed single and multiple predictor logistic regression analyses to determine factors associated with frailty. After adjustment for age, sex, and comorbidities, fat mass (both by bioimpedance spectroscopy and anthropometry) and waist circumference, but not muscle mass remained the main predictors of frailty. The odds ratio of frailty in the third tertile compared with the first was 4.97 (1.70-14.55) and 3.84 (1.39-10.61) for fat mass and waist circumference, respectively (P for trends for both <.05). The scores of physical health and kidney disease effect component of quality of life were lower in frail compared with nonfrail patients (40.7 ± 9.2 vs. 33.7 ± 10.2, P < .01 and 66.8 ± 22.4 vs. 51.6 ± 25.7, P < .05 for physical health and effects of disease, respectively).

CONCLUSIONS

Frailty, which is associated with poor outcomes in chronic HD patients, is common and predicted by fat mass and waist circumference but not by body mass index and muscle mass. Interventions to modify abdominal obesity, reflected by waist circumference, could potentially lower the incidence of frailty and hence improve the quality of life in the HD population.

Vitamin D increases IGF-I and insulin levels in experimental diabetic rats

INTRODUCTION AND OBJECTIVE

Previous studies have found that IGF-I may play an important role in glucose metabolism. The aim of this study is to examine the effect of vitamin D intake on the serum levels of glucose, insulin, and IGF-I in experimental diabetic rats.

MATERIAL AND METHODS

A total of 24 male Sprague-Dawley rats aged six to seven months, with an average weight of 300±30g, were randomly divided into three groups (eight rats per group). The first group served as control and the other two groups received an intraperitoneal injection of 45mg/kg streptozotocin (STZ) to develop diabetes. Then groups were treated for four weeks either with placebo or vitamin D (two injections of 20,000IU/kg).

RESULTS

At the end of the experiment, two injection of vitamin D were found to result in a significant increase in plasma cholecalciferol, which could improve hyperglycaemia and hypoinsulinemia in diabetic rats. HbA1c concentration had a slight and insignificant decrease following vitamin D intake. In addition, a significant decline was observed in the serum IGF-I level of STZ-treated rats in comparison to the controls, which was compensated in the vitamin D group. The serum vitamin D concentration was positively correlated to the changes in IGF-I level by Pearson test.

CONCLUSIONS

These data showed for the first time that vitamin D intake could significantly improve fasting plasma glucose, insulin, and IGF-I in an experimental type 1 diabetes model.

Effects of Vitamin D Supplementation on IGF-1 and Calcitriol: A Randomized-Controlled Trial

Increasing evidence suggests a possible interaction between vitamin D and insulin-like growth factor-1 (IGF-1). We aimed to investigate effects of vitamin D supplementation on IGF-1 (primary outcome) and calcitriol (1,25(OH)₂D) concentrations (secondary outcome). This is a post-hoc analysis of the Styrian Vitamin D Hypertension Trial—a single-center, double-blind, randomized, placebo-controlled trial (RCT) conducted from 2011 to 2014 at the Medical University of Graz, Austria. Two-hundred subjects with arterial hypertension and 25(OH)D concentrations <30 ng/mL were randomized to either receive 2800 IU of vitamin D daily or placebo for eight weeks. A total of 175 participants (mean ± standard deviation age, 60 ± 11 years; 49% women) with available IGF-1 concentrations were included in the present analysis. At baseline, IGF-1 concentrations were significantly correlated with 1,25(OH)₂D (r = 0.21; p = 0.005) but not with 25(OH)D (r = −0.008; p = 0.91). In the RCT, vitamin D had no significant effect on IGF-1 (mean treatment effect 3.1; 95% confidence interval −5.6 to 11.9 ng/mL; p = 0.48), but it increased 1,25(OH)₂D concentrations (mean treatment effect 9.2; 95% confidence interval 4.4 to 13.9 pg/mL; p ≤ 0.001). In this RCT, in hypertensive patients with low 25(OH)D concentrations, there was no significant effect of vitamin D supplementation on IGF-1 concentrations. However, we observed a cross-sectional correlation between 1,25(OH)₂D and IGF-1 and an increase of 1,25(OH)₂D after vitamin D supplementation.

Interactions of the Insulin-Like Growth Factor Axis and Vitamin D in Prostate Cancer Risk in the Prostate Cancer Prevention Trial

Some, but not all, epidemiologic studies report an association between vitamin D and prostate cancer risk. The inconsistent findings might be explained in the context of modification by members of the insulin-like growth factor (IGF) axis. Data and specimens for this nested case-control study (n = 1695 cases and n = 1682 controls) are from the Prostate Cancer Prevention Trial (PCPT). Baseline serum samples were assayed for 25(OH)D, IGF-1, IGF-2, IGFBP-2, IGFBP-3, and the ratio of IGF1:BP3, along with insulin-related markers c-peptide and leptin. The presence of prostate cancer was assessed by prostate biopsy. Multivariate logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CIs) for prostate cancer risk. There were no interactions between serum 25(OH)D and IGF analytes in relation to prostate cancer risk when PCPT treatment arms were combined. In the placebo arm, above median serum 25(OH)D levels were associated with increased risk of prostate cancer among men with higher IGF-2 (OR:1.33, 95% CI: 1.00–1.65), with a significant interaction between 25(OH)D and treatment arm (P_interaction = 0.04). Additionally, there was an interaction between treatment arm and serum IGFBP-3 (P_interaction = 0.03). Higher serum 25(OH)D may increase risk of prostate cancer in the presence of higher circulating IGF-2.

A mouse model of vitamin D insufficiency: is there a relationship between 25(OH) vitamin D levels and obesity?

Background

Vitamin D insufficiency (serum 25-OH vitamin D > 10 ng/ml and < 30 ng/ml) is prevalent in the obese (body mass index (BMI) > 30 kg/m²), yet relationships between the two are poorly understood. Objectives of this study include identification of the impact of obesity on reducing serum 25-OH vitamin D concentration, particularly in response to altered vitamin D₃ supplementation, and to elucidate the longitudinal impact of serum 25-OH vitamin D on body mass index.

Methods

Twenty four-week-old lean and obese male C57BL/6 J mice were fed low, standard, or high levels of cholecalciferol supplementation and followed for 24 weeks. Longitudinal measurements include serum 25-OH and 1,25-(OH)₂ vitamin D, intact PTH, and calcium concentrations, as well as BMI, bone density and body fat/lean mass.

Results

Baseline serum 25-OH concentrations were not different in lean and obese mice (lean 32.8 ± 4.4 ng/ml versus obese 30.9 ± 1.6 ng/ml p = 0.09). Lean mice receiving low supplementation exhibited rapid declines in serum 25-OH vitamin D concentrations, falling from 33.4 ± 5.4 ng/ml to 14.5 ± 3.4 ng/ml after 2 weeks, while obese mice declined at a lower rate, falling from 30.9 ± 1.5 to 19.0 ± 0.9 ng/ml within the same time period. Surprisingly, high vitamin D₃ supplementation did not substantially increase serum vitamin D concentrations above standard supplementation, in either lean or obese mice. No differences in serum 1,25-(OH)₂ vitamin D, intact parathyroid hormone (PTH) or serum calcium were observed between lean and obese mice within the same vitamin D supplementation group. Yet obese mice exhibited lower serum calcitriol, higher serum PTH, and lower bone mineral density (BMD) than did lean mice. Additionally, neither body mass index nor body fat % was significantly correlated with vitamin D concentrations. Interestingly, lean mice with high vitamin D supplementation consumed significantly more food than did lean mice with standard or low supplementation (14.6 ± 1.7 kcal/mouse/day versus 11.8 ± 1.4 and 12.3 ± 1.7 respectively, p < 0.0001 for both).

Conclusions

Low cholecalciferol supplementation in both lean and obese mice significantly and sustainably reduces serum 25-OH vitamin D concentrations. Interestingly, obesity slowed the rate of decline. Over the period of the study, vitamin D insufficiency was not subsequently correlated with greater BMI/body fat, although lean mice with high supplementation consumed greater calories with no apparent BMI increase.

Serum Parathyroid Hormone Responses to Vitamin D Supplementation in Overweight/Obese Adults: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Obesity is often associated with vitamin D deficiency and secondary hyperparathyroidism. Vitamin D supplementation typically leads to the reductions in serum parathyroid hormone (PTH) levels, as shown in normal weight individuals. Meanwhile, the dose of vitamin D supplementation for the suppression of PTH may differ in overweight and obese adults. We conducted a systematic review and meta-analysis of randomized controlled trials to determine the dose of vitamin D supplementation required to suppress PTH levels in overweight/obese individuals. We identified 18 studies that examined overweight or obese healthy adults who were supplemented with varying doses of vitamin D3. The primary outcomes examined were changes in PTH and serum 25-hydroxyvitamin D (25OHD) levels from baseline to post-treatment. The results of the meta-analysis showed that there was a significant treatment effect of vitamin D supplementation on PTH, total standardized mean difference (SMD) (random effects) = -0.38 (95% CI = -0.56 to -0.20), t = -4.08, p < 0.001. A significant treatment effect of vitamin D supplementation was also found on 25OHD, total SMD (random effects) = 2.27 (95% CI = 1.48 to 3.06) t = 5.62, p < 0.001. Data from available clinical trials that supplemented adults with D3 ranging from 400 IU to 5714 IU, showed that 1000 IU of vitamin D supplementation best suppressed serum PTH levels, total SMD = -0.58, while vitamin D supplementation with 4000 IU showed the greatest increase in serum 25OH levels. Vitamin D and calcium supplementation of 700 IU and 500 mg, respectively, also showed a significant treatment effect on the suppression of PTH with a total SMD = -5.30 (95% CI = -9.72 to -0.88). In conclusion, the meta analysis of available clinical trials indicates that 1000 IU vitamin D supplementation can suppress serum PTH levels, while 4000 IU of vitamin D was associated with the largest increase in serum 25OHD levels in the overweight and obese population.

SERUM INSULIN-LIKE GROWTH FACTOR 1 IN LEBANESE SCHOOLCHILDREN AND ITS RELATION TO VITAMIN D AND FERRITIN LEVELS

OBJECTIVE

The aims of our study were to establish reference values for insulin-like growth factor 1 (IGF-1) in Lebanese schoolchildren and to evaluate the relationship between IGF-1 and age, sex, body mass index (BMI), vitamin D, and ferritin.

METHODS

This cross-sectional study included 952 Lebanese schoolchildren (495 boys and 457 girls) aged 8 to 18 years. Blood samples were taken from children attending 10 schools with different socio-economic status (SES). Chemiluminescent immunoassays were used for IGF-1, 25 hydroxyvitamin D (25(OH)D), testosterone, and ferritin measurements.

RESULTS

The mean age was 13.46 ± 2.80 with no significant difference according to sex. IGF-1 was correlated with age in both sexes (P<.0001); it was higher in girls compared to boys (P = .007) and peaked at the ages of 14 and 12 for boys and girls, respectively. For each age group, the median IGF-1 value was higher compared to the values provided by the kit. IGF-1 was significantly correlated with BMI in boys (r = 0.16, P<.0001) but not girls. In both sexes, IGF-1 was inversely correlated with 25(OH)D and ferritin values. After adjustment for age, BMI, and height, the correlation between IGF-1 and 25(OH)D disappeared, whereas the relationship with ferritin persisted (P<.001 for boys, P = .002 for girls). For both sexes, multivariate regression analysis revealed independent associations between IGF-1 and height, Tanner stage, and ferritin. An association was also noted in boys for BMI and testosterone.

CONCLUSION

Our results showed higher and earlier peak IGF-1 values in the pediatric Lebanese population compared to western populations. In addition, an independent inverse relationship was observed between IGF-1 and ferritin. Further studies are needed to identify the reason(s) underlying these results.

ABBREVIATIONS

BMI = body mass index CRP = C-reactive protein CV = coefficient of variation GH = growth hormone IGF-1 = insulin-like growth factor 1 25(OH)D = 25 hydroxyvitamin D SES = socio-economic status TSH = thyroid-stimulating hormone.

Relationship Between 25(OH)D and IGF-I in Children and Adolescents with Growth Hormone Deficiency

Recent studies have shown that vitamin D has an impact on the production and secretion of IGF-I in the liver. The aim of our study was to investigate the relationship between the concentrations of 25-hydroxy vitamin D [25(OH)D] and insulin-like growth factor I (IGF-I) in growth hormone deficient children and adolescents before recombinant human growth hormone (rhGH) treatment. The study was retrospective and included 84 children and adolescents aged 4-17. Prior to initiating rhGH therapy, concentrations of 25(OH)D and IGF-I were measured in all patients. IGF-I concentrations were normalized for bone age. The studied group was divided into two subgroups according to serum 25(OH)D levels. Significant positive correlations between 25(OH)D concentration and IGF-I SDS-normalized for bone age were observed in both studied subgroups. The results of our study suggest that vitamin D deficiency could influence IGF-I concentrations in children and adolescents with growth hormone deficiency, and vitamin D deficiency should be normalized before the measurement of IGF-I concentrations to obtain the reliable and unbiased IGF-I values.

Vitamin D and cardiovascular risk among adults with obesity: a systematic review and meta-analysis

BACKGROUND

Obesity is a risk factor for both vitamin D deficiency and cardiovascular disease. A link between vitamin D status optimisation and improved cardiometabolic profile among adults with obesity could inform public health initiatives.

METHODS

PubMed, Embase and Web of Science were searched for interventional studies examining the effects of vitamin D status improvement on cardiovascular risk factors (anthropometric measures, lipid profile, blood pressure, glucose tolerance) among nondiabetic adults with obesity.

RESULTS

Seventeen publications reporting results from 11 different studies were included. Number of participants ranged from 34 to 1179 subjects. Duration was between 6 weeks and 4 years. Vitamin D was administered as a supplement in ten studies (1000 IU daily to 120 000 IU fortnightly). In one study, participants were advised to increase sunlight exposure and dietary vitamin D intake. The random and fixed-effects meta-analysis showed that vitamin D significantly increased systolic blood pressure and LDL-C levels. The fixed-effects model also indicated a significant decrease in triglyceride levels, which was not evident using the random-effects model. Caution should be given to these results given the small number of studies used and the high heterogeneity between studies for the two latter outcomes. Additionally, a subset of eligible studies with compatible data presentation was included in the meta-analysis.

CONCLUSION

This systematic review highlights a paucity of interventional studies examining the effects of vitamin D status improvement on cardiovascular risk factors among otherwise healthy adults with obesity. Large-scale studies at pharmacologically relevant doses and with sufficient duration are warranted.

Effect of long term vitamin D supplementation on biomarkers of inflammation in Latino and African-American subjects with pre-diabetes and hypovitaminosis D

Low vitamin D levels are associated with minority subjects, the metabolic syndrome, and inflammation. The effect of vitamin D supplementation on markers of inflammation has not been well studied. The aim of the study was to evaluate the effects of high doses of vitamin D supplementation for 1 year on serum biomarkers of inflammation in Latino and African-American subjects with pre-diabetes and hypovitaminosis D. Latino (n=69) and African-American (n=11) subjects who had both pre-diabetes and hypovitaminosis D with a mean age of 52.0 years, a BMI of 32.7 kg/m(2), and 70% of whom were females, were randomized to receive weekly doses (mean±SD) of vitamin D (85 300 IU±16 000) or placebo oil for 1 year. Serum levels of interleukin-6, tumor necrosis factor, highly sensitive C-reactive protein), plasminogen activator inhibitor 1, and insulin-like growth factor-1 were measured at baseline, 6, and 12 months. Serum 25-OH vitamin D levels of 22 ng/ml at baseline quickly rose to nearly 70 ng/ml in subjects receiving vitamin D and did not change in the placebo group. Two-way repeated measures ANOVA showed no differences between the 2 groups in any of the 5 selected parameters. High dose vitamin D supplementation for 1 year in minority subjects with pre-diabetes and hypovitaminosis D failed to affect serum biomarkers of inflammation.Clinical trial reg. no.: NCT00876928, clinicaltrials.gov.

Does vitamin D improve liver enzymes, oxidative stress, and inflammatory biomarkers in adults with non-alcoholic fatty liver disease? A randomized clinical trial

The aim of this study was to investigate the effects of vitamin D supplementation on serum aminotransferases, insulin resistance, oxidative stress, and inflammatory biomarkers in adult patients with non-alcoholic fatty liver disease (NAFLD). Fifty-three patients with NAFLD were enrolled in a parallel, double-blind, placebo-controlled study. The patients were randomly allocated to receive either one oral pearl consisting of 50,000 IU vitamin D3 (n = 27) or a placebo (n = 26), every 14 days for 4 months. Serum aminotransferases, high-sensitive C-reactive protein (hs-CRP), tumor necrosis factor α, malondialdehyde (MDA), total antioxidant capacity, transforming growth factor β1, as well as grade of hepatic steatosis and homeostasis model assessment of insulin resistance were assessed pre- and post-intervention. In patients who received vitamin D supplement compared to the controls, the median of serum 25(OH)D3 significantly increased (16.2 vs. 1.6 ng/ml, P < 0.001). This increase accompanied by significant decrease in serum MDA (-2.09 vs. -1.23 ng/ml, P = 0.03) and near significant changes in serum hs-CRP (-0.25 vs. 0.22 mg/l, P = 0.06). These between-group differences remained significant even after controlling for baseline covariates. Other variables showed no significant changes. Improved vitamin D status led to amelioration in serum hs-CRP and MDA in patients with NAFLD. This might be considered as an adjunctive therapy to attenuate systemic inflammation and lipid peroxidation alongside other treatments for NAFLD patients.

The role of vitamin D in human fracture healing: a systematic review of the literature

INTRODUCTION

Vitamin D is essential for bone mineralization and for the subsequent maintenance of bone quality. Mineralization is part of hard callus formation and bone remodelling, processes, which are part of fracture healing. We provide a comprehensive review of the literature to summarize and clarify if possible, the cellular effects of vitamin D and its clinical involvement in the process of fracture healing in human.

MATERIAL AND METHODS

We conducted a literature search in PubMed, Embase (OVID version), and Web of Science.

RESULTS

A total of 75 in vitro and 30 in vivo studies were found with inconsistent results about the cellular effect of vitamin D on fracture involved inflammatory cells, cytokines, growth factors, osteoblasts, osteoclasts and on the process of mineralization. With only five in vitro studies performed on material derived from a fracture site and one in vivo study in fracture patients, the exact cellular role remains unclear. Seven studies investigated the circulating vitamin D metabolites in fracture healing. Although it appears that 25(OH)D and 24,25(OH)2D3 are not affected by the occurrence of a fracture, this might not be the case with serum concentrations of 1,25(OH)2D3. The potential clinical effect of vitamin D deficiency is only described in one case series and three case controlled studies, where the results tend to show no effect of a vitamin D deficiency. No clinical studies were found investigating solely vitamin D supplementation. Two clinical studies found a positive effect of vitamin D supplementation and calcium, of increased bone mineral density or respectively increased fracture callus area at the fracture site. One study found indirect evidence that vitamin D and calcium promoted fracture healing.

CONCLUSION

Despite these results, and the presumed beneficial effect of vitamin D supplementation in deficient patients, clinical studies that address the effects of vitamin D deficiency or supplementation on fracture healing are scarce and remain inconclusive. We conclude that vitamin D has a role in fracture healing, but the available data are too inconsistent to elucidate how and in what manner.

Higher body mass index is associated with greater severity of alopecia in men with male-pattern androgenetic alopecia in Taiwan: a cross-sectional study

BACKGROUND

Obesity is a risk factor for multiple health problems, but its association with androgenetic alopecia (AGA) remains controversial.

OBJECTIVE

We sought to determine the association between body mass index (BMI) and alopecia severity in men with AGA and early-onset AGA.

METHODS

A cross-sectional study was conducted. The medical charts and photographs of men with a clinical diagnosis of AGA were reviewed.

RESULTS

In all, 189 men were enrolled with a mean age of 30.8 years. In male-pattern AGA (n = 142), men with severe alopecia (grade V-VII) had higher BMI than those with mild to moderate alopecia (grade I-IV) (25.1 vs 22.8 kg/m(2), P = .01). After multivariate adjustments, the risk for severe alopecia was higher in the overweight or obese (BMI ≥24 kg/m(2)) subjects with male-pattern AGA (odds ratio 3.52, P < .01). In early-onset male-pattern AGA (n = 46), the risk for having severe alopecia was also higher in the overweight or obese subjects (odds ratio 4.97, P = .03).

LIMITATIONS

Parameters used to evaluate obesity were limited because of the retrospective nature of the study.

CONCLUSIONS

Higher BMI was significantly associated with greater severity of hair loss in men with male-pattern AGA, especially in those with early-onset AGA.

Obesity in the ageing man

As the population is ageing globally, both ageing and obesity are recognized as major public health challenges. The aim of this narrative review is to present and discuss the current evidence on the changes in body composition, energy balance and endocrine environment that occur in the ageing man. Obesity in the ageing man is related to changes in both body weight and composition due to alterations in energy intake and total energy expenditure. In addition, somatopenia (decreased GH secretion), late-onset hypogonadism (LOH), changes in thyroid and adrenal function, as well as changes in appetite-related peptides (leptin, ghrelin) and, most importantly, insulin action are related to obesity, abnormal energy balance, redistribution of the adipose tissue and sarcopenia (decreased muscle mass). A better understanding of the complex relationship of ageing-related endocrine changes and obesity could lead to more effective interventions for elderly men.

Interactions between vitamin D and IGF-I: from physiology to clinical practice

The interplay between vitamin D and IGF-I is complex and occurs at both endocrine and paracrine/autocrine levels. Vitamin D has been shown to increase circulating IGF-I and IGFBP-3, with the consistent finding of a positive correlation between vitamin D and IGF-I serum values in population-based cohorts of healthy subjects. The modulation of IGF-I and IGFBP-3 concentrations by vitamin D may impact recombinant human (rh) GH dosing for the treatment of GHD. It might also underlie some of the extra-skeletal beneficial effects ascribed to vitamin D. On the other hand, IGF-I stimulates renal production of 1,25-dihydroxyvitamin D, which increases calcium and phosphate availability in the body and suppresses PTH secretion. This effect is responsible for an altered calcium-phosphate balance in uncontrolled acromegaly and might also account for the improvement in bone metabolism associated with rhGH treatment in patients with GHD. Data on the paracrine/autocrine vitamin D-IGF-I interactions are abundant, but mostly not linked to one another. As a result, it is not possible to draw a comprehensive picture of the physiological and/or pathological interrelations between vitamin D, IGF-I and IGF-binding proteins (IGFBP) in different tissues. A potential role of vitamin D action is related to its association with carcinogenesis, a paradigm being breast cancer. Current evidence indicates that, in breast tumours, vitamin D modulates the IGF-I/IGFBP ratio to decrease proliferation and increase apoptosis.

Serum 25-hydroxyvitamin D, parathyroid hormone, and their association with metabolic syndrome in Chinese

Increasing evidence suggests that 25-hydroxyvitamin D [25(OH)D] and parathyroid hormone (PTH) levels are associated with metabolic syndrome (MetS). In 2010, we explored the association of serum 25(OH)D and PTH levels with MetS in 1,390 Chinese participants, aged 20-83 years. Anthropometric phenotypes, blood pressure, and the incidence of MetS were evaluated. In addition, serum lipids, 25(OH)D, and PTH were measured. The median concentration of 25(OH)D and PTH were 55.3 nmol/l and 2.8 pmol/l, respectively. The prevalence of vitamin D deficiency (<50 nmol/l) was 39.9 %, with 34.5 % in men and 47.8 % in women. After accounting for confounding factors and serum PTH, a 10 nmol/l higher serum 25(OH)D level was associated with a 10 % lower risk of MetS (OR = 0.90, 95 % CI 0.84-0.96, P = 0.0007). Furthermore, participants with vitamin D sufficiency had a 35 % lower risk of MetS than those with vitamin D deficiency (OR = 0.65, 95 % CI 0.51-0.84, P = 0.0009). PTH was not associated with the risk of MetS after adjustment for confounding factors. These results were confirmed in both men and women. Thus in this cohort of Chinese individuals, vitamin D deficiency is common and optimal vitamin D level is inversely associated with MetS, independent of several confounders and PTH level. The clinical significance of these findings warrants further study.

The metabolic effects of growth hormone in adipose tissue

There is a general consensus that a reduction in growth hormone (GH) secretion results in obesity. However, the pathophysiologic role of GH in the metabolism of lipids is yet to be fully understood. The major somatic targets of GH are bones and muscles, but GH stimulates lipolysis and seems to regulate lipid deposition in adipose tissue. Patients with isolated GH deficiency (GHD) have enlarged fat depots due to higher fat cell volume, but their fat cell numbers are lower than those of matched controls. The treatment of patients with GH results in a relative loss of body fat and shifts both fat cell number and fat cell volume toward normal, indicating an adipogenic effect of GH. Adults with GHD are characterized by perturbations in body composition, lipid metabolism, cardiovascular risk profile, and bone mineral density. It is well established that GHD is usually accompanied by an increase in fat accumulation; GH replacement in GHD results in the reduction of fat mass, particularly abdominal fat mass. In addition, abdominal obesity results in a secondary reduction in GH secretion that is reversible with weight loss. However, whereas GH replacement in patients with GHD leads to specific depletion of intra-abdominal fat, administering GH to obese individuals does not seem to result in a consistent reduction or redistribution of body fat. Although administering GH to obese non-GHD subjects has only led to equivocal results, more recent studies indicate that GH still remains a plausible metabolic candidate.