Low serum vitamin D is associated with high risk of diabetes in Korean adults

Hepatocyte vitamin D receptor functions as a nutrient sensor that regulates energy storage and tissue growth in zebrafish

Vitamin D receptor (VDR) has been implicated in fatty liver pathogenesis, but its role in the regulation of organismal energy usage remains unclear. Here, we illuminate the evolutionary function of VDR by demonstrating that zebrafish Vdr coordinates hepatic and organismal energy homeostasis through antagonistic regulation of nutrient storage and tissue growth. Hepatocyte-specific Vdr impairment increases hepatic lipid storage, partially through acsl4a induction, while simultaneously diminishing fatty acid oxidation and liver growth. Importantly, Vdr impairment exacerbates the starvation-induced hepatic storage of systemic fatty acids, indicating that loss of Vdr signaling elicits hepatocellular energy deficiency. Strikingly, hepatocyte Vdr impairment diminishes diet-induced systemic growth while increasing hepatic and visceral fat in adult fish, revealing that hepatic Vdr signaling is required for complete adaptation to food availability. These data establish hepatocyte Vdr as a regulator of organismal energy expenditure and define an evolutionary function for VDR as a transcriptional effector of environmental nutrient supply.

Association of serum 25-hydroxyvitamin D with metabolic disturbances in adolescents

OBJECTIVES

Data concerning the association of vitamin D with metabolic disturbances in adolescents are contradictory. The aim of this study was to identify metabolic abnormalities in adolescents with 25-hydroxyvitamin D (25[OH]D) deficiency and to determine informative indices for the early detection of these metabolic disturbances.

METHODS

A cross-sectional observational study including 90 adolescents aged 13-15 years was carried out during the winter. Anthropometric measures were collected. Fasting blood samples were assessed for the following parameters: serum 25(OH)D, lipids, and glucose.

RESULTS

The majority of the study adolescents had low 25(OH)D concentration. The prevalence of 25(OH)D deficiency (<12 ng/ml) and insufficiency (12-20 ng/ml) in adolescents was 34.4% and 55.6%, respectively. Among the metabolic disturbance, hypo-high-density lipoprotein cholesterolemia prevailed in the adolescents, while hypercholesterolemia, hypertriglyceridemia, and hyperglycemia were rare. 25(OH)D status showed an association with the metabolic score for insulin resistance (METS-IR, r = -0.40; p < .001), high-density lipoprotein cholesterol level (r = 0.31; p = .003), atherogenic index of plasma (r = -0.30; p = .004) and body mass index (r = -0.23, p = .032). There were no significant correlations between 25(OH)D level and other lipid or glucose levels. The degree of hypovitaminosis D affects METS-IR values.

CONCLUSIONS

25(OH)D deficiency in the studied adolescents had not yet manifested serious metabolic diseases. Of all the analyzed parameters, METS-IR was most strongly associated with 25(OH)D level and can be considered a useful marker of early metabolic disturbances in adolescents with 25(OH)D deficiency.

The critical issue linking lipids and inflammation: Clinical utility of stopping oxidative stress

The formation of an atheroma begins when lipoproteins become trapped in the intima. Entrapped lipoproteins become oxidized and activate the innate immune system. This immunity represents the primary association between lipids and inflammation. When the trapping continues, the link between lipids and inflammation becomes chronic and detrimental, resulting in atherosclerosis. When entrapment ceases, the association between lipids and inflammation is temporary and healthy, and the atherogenic process halts. Therefore, the link between lipids and inflammation depends upon lipoprotein retention in the intima. The entrapment is due to electrostatic forces uniting apolipoprotein B to polysaccharide chains on intimal proteoglycans. The genetic transformation of contractile smooth muscle cells in the media into migratory secretory smooth muscle cells produces the intimal proteoglycans. The protein, platelet-derived growth factor produced by activated platelets, is the primary stimulus for this genetic change. Oxidative stress is the main stimulus to activate platelets. Therefore, minimizing oxidative stress would significantly reduce the retention of lipoproteins. Less entrapment decreases the association between lipids and inflammation. More importantly, it would halt atherogenesis. This review will analyze oxidative stress as the critical link between lipids, inflammation, and the pathogenesis of atherosclerosis. Through this perspective, we will discuss stopping oxidative stress to disrupt a harmful association between lipids and inflammation. Numerous therapeutic options will be discussed to mitigate oxidative stress. This paper will add a new meaning to the Morse code distress signal SOS-stopping oxidative stress.

Association of Fasting Glucose and Glycated Hemoglobin with Vitamin D Level According to Diabetes Mellitus Status in Korean Adults

Objectives

Previous studies have suggested that vitamin D deficiency might increase the risk of type 2 diabetes mellitus(DM). However, few studies have examined whether vitamin D continues to affect glucose control after DM diagnosis. Therefore, we examined the association between vitamin D and glucose in nondiabetics and DM patients.

Methods

We analyzed data for 32,943 adults aged 19 years and older from the 2008 to 2014 Korea National Health and Nutrition Examination Survey. Vitamin D levels were determined using the 25-hydroxyvitamin D concentration, and patients were grouped into one of three categories according to those results DM was defined as a fasting glucose level ≥ 126 mg/dL, current use of DM medications or insulin injections, or a self-reported diagnosis of DM by a doctor.

Results

In male DM patients, hemoglobin A1c(HbA1c) level increased significantly as vitamin D levels became severely deficient. Among the abnormal HbA1c subgroups of males and postmenopausal females, HbA1c levels were significantly higher in the severe vitamin D deficiency subgroup (p for trend = 0.0044 and 0.0219 for males and postmenopausal females, respectively). There were significant differences between abnormal HbA1c subgroups and normal HbA1c subgroups in both males and females. Regardless of sex or menopause status, however, there was no significant association between vitamin D and fasting glucose in fasting glucose subgroups.

Conclusion

Males and females in the abnormal HbA1c subgroups showed markedly elevated blood glucose when they also had vitamin D deficiency. Furthermore, there was a more distinct difference in the HbA1c subgroups than in the fasting glucose subgroups.

Sex-Dependent Association of Vitamin D With Insulin Resistance in Humans

BACKGROUND

Animal studies suggested that vitamin D might decrease insulin resistance. Estrogen increased insulin sensitivity and glucose tolerance in rodents. However, sex-specific association of vitamin D with insulin resistance in humans remains unclear.

OBJECTIVES

To investigate the sex-dependency of the association of insulin resistance and 25-hydroxyvitamin D [25(OH)D] in a large Caucasian population.

METHODS

Cross-sectional study from out-patients' blood samples with measurements of 25(OH)D and homeostatic model assessment of insulin resistance (HOMA-IR) drawn at exactly the same day (n = 1887). This cohort was divided into 3 groups: (1) group with vitamin D deficiency (n = 1190), (2) group with vitamin D sufficiency (n = 686), and (3) vitamin D excess groups (n = 11); the vitamin D excess group was excluded from further analysis due to the small size.

RESULTS

Analysis of the entire study population showed that serum 25(OH)D was inversely associated with HOMA-IR [Spearman correlation coefficient (rs) = -0.19, P < 0.0001]. When considering the vitamin D status, this association was only seen in the vitamin D deficiency group but not in the vitamin D sufficient group. The correlation was sex-dependent: HOMA-IR was inversely correlated with vitamin D in women with vitamin D deficiency (rs = -0.26, P < 0.0001) but not in men with vitamin D deficiency (rs = 0.01, P = 0.714). After multivariate linear regression analysis considering confounding factors, this relationship was again only seen in women.

CONCLUSION

Vitamin D was inversely and independently associated with insulin resistance only in women with vitamin D deficiency. Based on our data, we suggest that in particular vitamin D deficient women might benefit from vitamin D substitution by improving insulin resistance. This, however, needs to be proven in adequately designed double-blind placebo-controlled clinical studies.

Effect of vitamin D on experimental model of polycystic ovary syndrome in female rats

AIMS

Vitamin D plays an important role in the regulation of ovulatory dysfunction. We aimed to study the effect of vitamin D on letrozole-induced PCOS in female rats.

MATERIAL & METHODS

40 non-pregnant Wistar rats were divided into four groups: group I control (received 1 ml of 1% aqueous solution of (CMC)/d orally), group II letrozole-induced PCOS group (received letrozole 200 μg/d orally), group III vitamin D-treated group (received vitamin D 1000 IU/kg/d), group IV letrozole and vitamin D treated group (received letrozole and vitamin D as group II and group III for 90 days. BMI, ovarian weight, serum vitamin D, biochemical metabolic and oxidative stress markers were evaluated, ovarian tissues glutathione, malondialdehyde levels and caspase-3 activity were measured. Histopathological examination of the ovary and coronary artery were done.

KEY FINDINGS

Letrozole-induced typical PCOS with significant decrease in vitamin D and coronary vasculopathy. Group II shows insignificant change in all parameters but there is significant increase in vitamin D and decrease in triglyceride and glutathione. In group VI all parameters were significantly improved but coronary vasculopathy was partly improved. Vitamin D was significantly negatively correlated with all parameters but significantly positively correlated with estradiol, insulin sensitivity, and HDL and insignificantly correlated with glutathione. Both Insulin resistance and testosterone were significantly positively correlated with all parameters but significantly negatively correlated with estradiol, insulin sensitivity, HDL and glutathione.

SIGNIFICANCE

These results holding the promise of beneficial impact of vitamin D administration to PCOS and its associated cardiovascular disorders.

Low Serum 25-Hydroxyvitamin D Level as a Potential Risk Factor of Erectile Dysfunction in Elderly Men with Moderate to Severe Lower Urinary Tract Symptoms

Purpose

To evaluate the correlation between vitamin D level and erectile dysfunction (ED) in male lower urinary tract symptoms (LUTS) patients.

Materials and Methods

We analyzed data from 534 male patients who were tested for LUTS from 2014 to 2017. LUTS severity was classified into mild (≤7) or moderate to severe (≥8) based on total IPSS scores. Vitamin D deficiency was defined as a serum 25-hydroxyvitamin D [25(OH)D] level of less than 20 ng/mL. The severity of ED was dichotomized into mild (≥17 points) or moderate to severe (≤16 points) depending on total IIEF-5 scores. The association of the serum 25(OH)D level with moderate to severe ED was assessed using logistic regression analysis.

Results

In the entire cohort, moderate to severe ED was significantly associated with age ≥60 years (odds ratio [OR], 1.762; 95% confidence interval [CI], 1.011–3.073) and moderate to severe LUTS (OR, 2.075; 95% CI, 1.134–3.789), but not with serum 25(OH)D level (OR, 1.001; 95% CI, 0.979–1.023). Whereas, in the subgroup consisting of moderate to severe LUTS patients over 60 years (n=223), either low serum 25(OH)D level (OR, 0.944; 95% CI, 0.903–0.986) or vitamin D deficiency (OR, 2.949; 95% CI, 1.118–7.782) was the independent risk factor of moderate to severe ED as a result of each multivariate analysis.

Conclusions

Low vitamin D status closely correlated with moderate to severe ED in elderly men with moderate to severe LUTS.

A multicenter case control study of association of vitamin D with breast cancer among women in Karachi, Pakistan

Background

The prevalence of vitamin D inadequacy and breast cancer are both high among women living in Karachi, Pakistan.

Methods

A matched case control study was conducted in two hospitals of Karachi, Pakistan to evaluate the association of vitamin D (serum 25-hydroxyvitamin D) concentrations, vitamin D supplementation and sun exposure with breast cancer among Pakistani women. A total of 411 newly diagnosed histologically confirmed primary breast cancer cases were enrolled and 784 controls, free of breast and any other cancers, were matched by age (year of birth ± 5 years), residence in the same geographic area and study site. Information was collected on sociodemographic history, history of vitamin D supplementation, past medical and obstetrical history, family history of breast cancer, sun exposure history, histopathology reports and anthropometric measurement and venous blood was collected to measure serum 25-hydroxyvitamin D (25(OH)D) concentration.

Results

Compared to patients with sufficient serum vitamin D (>30 ng/ml), women with serum vitamin D deficiency (<20ng/ml), had a higher risk of breast cancer (OR = 1.65, 95%CI: 1.10, 2.50). Women with history of vitamin D supplementation one year prior to enrollment, had significant protective effect against breast cancer (OR = 0.32, 95% CI: 0.24, 0.43).

Conclusions and recommendation

Serum vitamin D deficiency was associated with increased risk of breast cancer, while vitamin D supplementation was associated with decreased risk of breast cancer. In Pakistani women, where vitamin D deficiency is common, raising and maintaining serum vitamin D at population level is a safe and affordable strategy. It may play a role in reducing the incidence of both vitamin D deficiency and breast cancer, particularly among poor women where the breast cancer mortality is highest due to limited resources for early detection, diagnosis, and treatment. The effects of vitamin D with regard to breast cancer risk in Karachi Pakistan should be further evaluated.

Vitamin D deficiency in the aetiology of obesity-related insulin resistance

The obese insulin-resistant state is often associated with low circulating concentration of vitamin D 25-hydroxyvitamin D₃ [25(OH)D₃ ]. Fat sequestration of vitamin D in the expanded obese adipose tissue mass has been pointed out as a plausible explanation for this circulating vitamin D deficiency. However, the putative mechanisms behind this hypovitaminosis D remain to be elucidated. The presence of vitamin D receptor and vitamin D-metabolizing enzymes in insulin-sensitive organs suggests that vitamin D may be involved in glucose and lipid metabolism and may be related to insulin sensitivity. Indeed, mainly in vitro studies support a role of vitamin D in regulating glucose and lipid metabolism in several insulin-sensitive tissues including adipose tissue, skeletal muscle, liver, as well as pancreatic insulin secretion. A potential role of vitamin D in gut barrier function and metabolism has also been suggested. This review summarizes recent knowledge on vitamin D deficiency in the aetiology of obesity-related insulin resistance and discusses potential underlying mechanisms. Finally, the role of vitamin D supplementation on insulin sensitivity and glycaemic control is discussed.

Comprehensive Review on Diabetes Associated Cardiovascular Complications - The Vitamin D Perspective

Vitamin D, a steroid hormone is primarily known for its role in calcium and bone mineral homeostasis. Over the years, vitamin D has been implicated in various non-skeletal diseases. The extraskeletal phenomenon can be attributed to the presence of vitamin D receptors (VDRs) in almost all cells and identification of 1-α hydroxylase in extrarenal tissues. The vitamin D deficiency (VDD) pandemic was globally reported with increasing evidence and paralleled the prevalence of diabetes, obesity and cardiovascular diseases (CVDs). A dependent link was proposed between hypovitaminosis D glycemic status, insulin resistance and also the other major factors associated with type 2 diabetes leading to CVDs. Insulin resistance plays a central role in both type 2 diabetes and insulin resistance syndrome. These 2 disorders are associated with distinct etiologies including hypertension, atherogenic dyslipidemia, and significant vascular abnormalities that could lead to endothelial dysfunction. Evidence from randomised clinical trials and meta-analysis, however, yielded conflicting results. This review summarizes the role of vitamin D in the regulation of glucose homeostasis with an emphasis on insulin resistance, blood pressure, dyslipidaemia, endothelial dysfunction and related cardiovascular diseases and also underline the plausible mechanisms for all the documented effects.

The association of VDR polymorphisms and type 2 diabetes in older people living in community in Santiago de Chile

INTRODUCTION

Several polymorphisms have been associated with obesity and type 2 diabetes in different populations.

OBJECTIVE

To investigate the frequencies of a genetic polymorphism of vitamin D receptor (FokI and BsmI) in patients with T2D.

METHODS

The case-control study was conducted in 138 patients with T2D and 172 control subjects, men and women (60-79 years old). The genotype and allele frequency determination of VDR polymorphisms were determined in these subjects.

RESULTS

The frequency of the C allele of the FokI polymorphism was significantly higher in the T2D group than in healthy subjects (p = 0.025). The frequencies of the BsmI variant were similar in subjects with and without T2D (p = 0.747). Consistent with these data, there was an association of the C allele with T2D (OR = 1.74, 95% CI = 1.003-3.084, p = 0.036), but not the AG + GG variants for BsmI (OR = 1.02, 95% CI = 0.635-1.649, p = 0.916). We can observe a significant association between carrier of the T > C variant of FokI and type 2 diabetes, adjusted for vitamin D, age, obesity (overweight and obesity), seasonality, sex and Homa-IR. Here, we show a significant association between the FokI polymorphisms (TC + CC) and T2D with an odds ratio of 1.9001 (95% CI (1.0970-3.6838), p = 0.041).

CONCLUSION

Our study suggests that the C allele (TC + CC) of the VDR-FokI gene is a possible risk factor for T2D in older people living in a community in Santiago de Chile.

Sexual Dimorphism for the Association between Vitamin D and Insulin Resistance in Chinese People

BACKGROUND

The relationship between vitamin D and insulin resistance is still controversial. Many factors could influence this relationship. In addition, this relationship in different genders was still unclear.

METHODS

A total of 6597 subjects, including 2813 males and 3784 females, were analyzed. The serum levels of 25(OH)D, fasting blood glucose (FBG), fasting insulin, HbA1c, and other metabolic parameters were tested. The waist circumference (WC), weight, and height were also measured. Questionnaires regarding smoking and drinking were collected from these subjects.

RESULTS

Serum 25(OH)D was categorized into quartiles. Increasing 25(OH)D levels were associated with reduced trend of homeostasis model assessment of insulin resistance (HOMA-IR) in both males and females. Pearson's correlation indicated 25(OH)D level was inversely associated with the HOMA-IR for male subjects (r = -0.055, P = 0.028) but not for female subjects (r = -0.005, P = 0.798). Age, triglyceride (TG), and low-density lipoprotein (LDL) were associated with the vitamin D levels in males and females. In regression analysis, serum 25(OH)D concentration was significantly associated with HOMA-IR only in overweight males.

CONCLUSION

We found an inverse association between 25(OH)D and HOMA-IR in Chinese overweight males. Vitamin D supplementation might be beneficial in this population. However, further clinical trials are needed to confirm this association.

Associations of vitamin D with insulin resistance, obesity, type 2 diabetes, and metabolic syndrome

The aim of this study is to determine the relationships of vitamin D with diabetes, insulin resistance obesity, and metabolic syndrome. Intra cellular vitamin D receptors and the 1-α hydroxylase enzyme are distributed ubiquitously in all tissues suggesting a multitude of functions of vitamin D. It plays an indirect but an important role in carbohydrate and lipid metabolism as reflected by its association with type 2 diabetes (T2D), metabolic syndrome, insulin secretion, insulin resistance, polycystic ovarian syndrome, and obesity. Peer-reviewed papers, related to the topic were extracted using key words, from PubMed, Medline, and other research databases. Correlations of vitamin D with diabetes, insulin resistance and metabolic syndrome were examined for this evidence-based review. In addition to the well-studied musculoskeletal effects, vitamin D decreases the insulin resistance, severity of T2D, prediabetes, metabolic syndrome, inflammation, and autoimmunity. Vitamin D exerts autocrine and paracrine effects such as direct intra-cellular effects via its receptors and the local production of 1,25(OH)₂D₃, especially in muscle and pancreatic β-cells. It also regulates calcium homeostasis and calcium flux through cell membranes, and activation of a cascade of key enzymes and cofactors associated with metabolic pathways. Cross-sectional, observational, and ecological studies reported inverse correlations between vitamin D status with hyperglycemia and glycemic control in patients with T2D, decrease the rate of conversion of prediabetes to diabetes, and obesity. However, no firm conclusions can be drawn from current studies, because (A) studies were underpowered; (B) few were designed for glycemic outcomes, (C) the minimum (or median) serum 25(OH) D levels achieved are not measured or reported; (D) most did not report the use of diabetes medications; (E) some trials used too little (F) others used too large, unphysiological and infrequent doses of vitamin D; and (G) relative paucity of rigorous clinical data on the effects of vitamin D sufficiency on non-calcium endpoints. Although a large number of observational studies support improving T2D, insulin resistance, obesity, and metabolic syndrome with vitamin D adequacy, there is a lack of conclusive evidence from randomized control clinical trials that, these disorders are prevented following optimization of serum levels of 25(OH)D. However, none of the currently conducted clinical studies would resolve these issues. Thus, specifically designed, new clinical studies are needed to be conducted in well-defined populations, following normalizing the serum vitamin D levels in vitamin D deficient prediabetes subjects, to test the hypothesis that hypovitaminosis D worsens these disorders and correction would alleviate it.

Non-musculoskeletal benefits of vitamin D

The aim of this study is to determine and critically evaluate the plausible relationships of vitamin D with extra-skeletal tissues in humans. Severe vitamin D deficiency results in rickets in children and osteomalacia in adults; these beneficial effects in the musculoskeletal system and certain physiological functions are well understood. Nevertheless, mounting reports support additional beneficial effects of vitamin D, outside the musculoskeletal system. This review explores the recent advances in knowledge about the non-skeletal effects of vitamin D. Peer-reviewed papers were extracted from research databases using key words, to assess correlations between vitamin D and extra-skeletal diseases and conditions. As per the guidelines of the Preferred Reporting Items for Systematic Reviews (PRISMA); general interpretations of results are included; taking into consideration the broader evidence and implications. This review summarizes current knowledge of the effects of vitamin D status on extra-skeletal tissues with special attention given to relationships between vitamin D status and various diseases commonly affecting adults; the effects of intervention with vitamin D and exposure to sunlight. Evidence suggests that vitamin D facilitates the regulation of blood pressure; and cardiac; endothelial; and smooth muscle cell functions; playing an important role in cardiovascular protection. In addition; 1,25(OH)₂D improves immunity; subdues inflammation; and reduces the incidence and severity of common cancers; autoimmune diseases and infectious diseases. Almost all adequately powered; epidemiological and biological studies that use; adequate doses of vitamin D supplementation in D-deficient populations have reported favorable outcomes. These studies have concluded that optimizing 25(OH)D status improves the functionality of bodily systems; reduces comorbidities; improves the quality of life; and increases survival. Although accumulating evidence supports biological associations of vitamin D sufficiency with improved physical and mental functions; no definitive evidence exists from well-designed; statistically powered; randomized controlled clinical trials. Nevertheless, most studies point to significant protective effects of vitamin D in humans when the minimum 25(OH)D serum level exceeds 30ng/mL and is maintained throughout the year.

Effects of Single Vitamin D₃ Injection (200,000 Units) on Serum Fibroblast Growth Factor 23 and Sclerostin Levels in Subjects with Vitamin D Deficiency

BACKGROUND

Vitamin D deficiency remains common in all age groups and affects skeletal and non-skeletal health. Fibroblast growth factor 23 is a bone-derived hormone that regulates phosphate and 1,25-dihydroxyvitamin D homeostasis as a counter regulatory factor. 1,25-Dihydroxyvitamin D stimulates fibroblast growth factor 23 synthesis in bone, while fibroblast growth factor 23 suppresses 1,25-dihydroxyvitamin D production in the kidney. The aim of this study was to evaluate the effects of vitamin D₃ intramuscular injection therapy on serum fibroblast growth factor 23 concentrations, and several other parameters associated with bone metabolism such as sclerostin, dickkopf-1, and parathyroid hormone.

METHODS

A total of 34 subjects with vitamin D deficiency (defined by serum 25-hydroxyvitamin D levels below 20 ng/mL) were randomly assigned to either the vitamin D injection group (200,000 units) or placebo treatment group. Serum calcium, phosphate, urine calcium/creatinine, serum 25-hydroxyvitamin D, fibroblast growth factor 23, sclerostin, parathyroid hormone, and dickkopf-1 levels were serially measured after treatment.

RESULTS

Comparing the vitamin D injection group with the placebo group, no significant changes were observed in serum fibroblast growth factor 23, parathyroid hormone, or dickkopf-1 levels. Serum sclerostin concentrations transiently increased at week 4 in the vitamin D group. However, these elevated levels declined later and there were no statistically significant differences as compared with baseline levels.

CONCLUSION

Serum fibroblast factor 23, sclerostin, parathyroid hormone, and dickkopf-1 levels were not affected significantly by single intramuscular injection of vitamin D₃.

Relationship between Serum 25-hydroxy-vitamin D Concentration and Risk of Metabolic Syndrome in Patients with Fatty Liver

Background

The vitamin D deficiency rate in Koreans is still high and dietary intake is insufficient. The purpose of this study was to provide basic data for the management of metabolic syndrome (MetS) by analyzing the effect of vitamin D levels on the MetS in patients with fatty liver.

Methods

We analyzed the MetS ratio and serum 25-hydroxy-vitamin D (25[OH]D) concentration in 151 adults diagnosed with fatty liver by using obesity index and blood profiles. We collected data on demographic factors, nutrient intake, and lifestyle habits.

Results

The mean 25(OH)D concentration of all subjects was 14 ng/mL and the insufficiency and deficiency rates were 40.4% and 29.8%. The proportion of MetS was 38.4% and the mean 25(OH)D level of MetS group was 12.1 ng/mL. Low-density lipoprotein cholesterol, triglyceride, and blood glucose were higher in the MetS group than in the normal group, and the waist circumference of the male was significantly higher than that of the normal group. The results showed that the lower the vitamin D concentration, the higher the risk of MetS (odds ratio, 1.47, 95% confidence interval, 0.98–2.81; P=0.043).

Conclusions

These results suggest that serum 25(OH)D levels may be a risk factor for MetS in patients with fatty liver.

The relationship between vitamin D and estimated glomerular filtration rate and urine microalbumin/creatinine ratio in Korean adults

The present study was conducted to assess the association between 25-hydroxyvitamin D [25(OH)D], estimated glomerular filtration rate (eGFR) and urine microalbumin/creatinine ratio (uACR) in Korean adults. Data on 4,948 adults aged ≥20 years from the Korean National Health and Nutrition Examination Survey V-3 (2012) were analyzed. After adjusting for the related variables (except age), the odds ratios (ORs) of vitamin D deficiency with the normal group as a reference were significantly higher in the decreased eGFR plus elevated uACR group [3.089 (95% CI, 1.722–5.544)], but not in the elevated uACR [1.247 (95% CI, 0.986–1.577)] and decreased eGFR group [1.303 (95% CI, 0.789–2.152)]. However, when further adjusting for age, the ORs of vitamin D deficiency with the normal group as a reference were significantly higher in the elevated uACR group [1.312 (95% CI, 1.035–1.662)], decreased eGFR group [1.761 (95% CI, 1.062–2.919)] and the decreased eGFR plus elevated uACR group [3.549 (95% CI, 1.975–6.365)]. In conclusion, vitamin D deficiency was positively associated with the elevated uACR and decreased eGFR. In addition, vitamin D level decreased greatly when decreased eGFR and elevated uACR appeared simultaneously.

Seasonal variations of vitamin D and its relation to lipid profile in Iranian children and adults

BACKGROUND

Vitamin D has a multitude of functional properties and acts like a hormone in the body. Its effect on the lipid profile is one of the proposed mechanisms for its relationship with many disorders during its deficiency. But, this relationship is still conflicting and debatable, so this study was conducted to determine the association between serum level of vitamin D and lipid profiles, including serum concentrations of cholesterol, triglyceride (TG), HDL, and LDL in healthy subjects.

METHODS

In this cross-sectional study, 541 volunteers with age of 5-60 years from normal and healthy subjects were selected via random sampling. Demographics and history of daily or weekly sunlight exposures were recorded. Measuring vitamin D was done in two consecutive seasons: winter and summer. Ten milliliters of peripheral venous blood sample was withdrawn after an overnight fasting. Serum levels of 25(OH) D (25, hydroxy vitamin D3) were measured using the enzyme-linked immunosorbent assay (ELISA), and the Confirmatory test was done by high-performance liquid chromatography (HPLC).

RESULTS

Mean age in the total mixed population was 30.83 ± 14.02 years. Subjects were 50.5% male and 49.5% female. Mean 25(OH) D in the total population for winter and summer were 45.8 ± 24.26 ng/ml and 55.24 ± 37.47 ng/ml respectively. In the total population, 38.08% were vitamin D deficient. Comparing serum lipid levels in the summer and winter showed a significant difference for cholesterol, LDL, and HDL, but no significant effect was found for TG. Analysis for the comparison of lipid profiles between the two genders in winter showed that there were significant differences in all lipid profiles except for LDL, while such analysis for summer revealed significant difference just for TG. In multivariate analysis, there was a significant mean difference only for LDL in subgroups with vitamin D insufficiency and deficiency. There was no correlation between Vitamin D and lipid profiles.

CONCLUSIONS

Vitamin D is different between the two seasons regardless of gender variations. Its status showed some significant relationship with some lipid profiles (cholesterol, LDL, and HDL) during the two seasons. There were different results among winter and summer based on the gender.

Investigation of vitamin D status and its correlation with insulin resistance in a Chinese population

Objective

Although many studies worldwide have focused on the relationship between vitamin D and insulin resistance, results remain controversial. Furthermore, concentrations of serum 25-hydroxyvitamin D (25(OH)D) in the Chinese population are unclear. We aimed to investigate vitamin D status and its correlation with insulin resistance among a Chinese adult population.

Design

Serum 25(OH)D, fasting blood glucose, fasting insulin, glycated Hb (HbA1c) and other metabolic parameters were assessed. Neck circumference, waist circumference, hip circumference, weight and height were also measured. Lifestyle factors including smoking and drinking status were obtained. Diabetes mellitus was diagnosed by HbA1c according to the 2010 American Diabetes Association criteria.

Setting

Eastern China.

Subjects

Of 7200 residents included, 6597 individuals were ultimately analysed.

Results

We enrolled 2813 males (mean age 52·7 (sd 13·5) years) and 3784 females (52·3 (sd 13·5) years); mean serum 25(OH)D concentration was 43·1 (sd 11·6) and 39·6 (sd 9·8) nmol/l, respectively. Additionally, 83·3 % of participants were 25(OH)D deficient. A significant difference in 25(OH)D was observed between males and females in winter and spring (P<0·001). Furthermore, 25(OH)D concentrations were inversely associated with the homeostasis model assessment of insulin resistance (HOMA-IR) in the overweight and pre-diabetic populations. After adjusting for several variables, 25(OH)D was significantly associated with HOMA-IR in winter. When 25(OH)D values were categorized into quartiles, HOMA-IR was significantly associated with decreasing 25(OH)D.

Conclusions

The majority of the Chinese population was vitamin D deficient and this deficiency was negatively associated with insulin resistance, particularly in the overweight and pre-diabetic populations. Moreover, these associations might be more evident in the winter.

Efficacy and safety of vitamin D3 B.O.N intramuscular injection in Korean adults with vitamin D deficiency

Objective

There has been no prospective study that examined intramuscular injection of high-dose vitamin D in Korean adults. The aim of this study was to assess the efficacy and safety of high-dose vitamin D₃ after intramuscular injection in Korean adults with vitamin D deficiency.

Method

This study was a 24-week, prospective, multicenter, randomized, double-blind, placebo-controlled trial. A total of 84 subjects ≥19 and <65 years of age were randomly allocated to either the vitamin D₃ or placebo group in a 2:1 ratio. After randomization, a single injection of plain vitamin D₃ 200,000 IU or placebo was intramuscularly administered. If serum 25-hydroxyvitamin D (25[OH]D) concentrations were <30 ng/mL on week 12 or thereafter, a repeat injection was administered.

Results

After a single intramuscular injection of vitamin D₃ to adults with vitamin D deficiency, the proportion of subjects with serum 25(OH)D concentrations ≥30 ng/mL within 12 weeks was 46.4% in the vitamin D₃ group and 3.6% in the placebo group (p < 0.0001). The proportion of subjects with serum 25(OH)D concentrations ≥30 ng/mL within 24 weeks was 73.2% in the vitamin D₃ group and 3.6% in the placebo group (p < 0.0001). Mean change in serum 25(OH)D concentrations at weeks 12 and 24 after vitamin D₃ injection was 12.8 ± 8.1 and 21.5 ± 8.1 ng/mL, respectively, in the vitamin D₃ group, with no significant changes in the placebo group. Serum parathyroid hormone concentrations showed a significant decrease in the vitamin D₃ group but no change in the placebo group.

Conclusion

Intramuscular injection of vitamin D₃ 200,000 IU was superior to placebo in terms of its impact on serum 25(OH)D concentrations, and is considered to be safe and effective in Korean adults with vitamin D deficiency.

Relationship between homeostasis model assessment of insulin resistance and beta cell function and serum 25-hydroxyvitamin D in non-diabetic Korean adults

The purpose of this study is to look at these relationships in non-diabetic Korean adults. This study was based on data from the KNHANES V-1, which is representative of the population of Korea. A total of 5,492 participants (≥20 years in age) without type 1 or type 2 diabetes, assessed for serum 25-hydroxyvitamin D [25(OH)D], fasting blood glucose and insulin, as well as anthropometric variables, were included in the analyses. The key study results were as follows: First, vitamin D status [vitamin D deficient, 25(OH)D <25 nM; vitamin D insufficient, 25(OH)D ≥25, <50 nM; vitamin D sufficient, 25(OH)D ≥50 nM] was inversely associated with homeostasis model assessment of insulin resistance (HOMA-IR) and beta cell function (HOMA-B) in model 2 (adjusted for age and gender) and 3 (further adjusted for smoking, alcohol drinking, regular exercise, systolic and diastolic blood pressure, waist circumference, and body mass index). Second, in model 4, when further adjusted for total cholesterol, triglycerides, and HDL-C, vitamin D status was inversely associated with HOMA-B. However, association of vitamin D status and HOMA-IR was no longer significant. In conclusion, vitamin D was inversely associated with beta cell function in non-diabetic Korean adults but was not associated with insulin resistance.

Impact of adolescent pregnancy on hypertension in postmenopausal women

OBJECTIVE

Several studies have reported the detrimental effects on maternal health due to pregnancy during adolescence, but no studies have reported the influence of adolescent pregnancy on blood pressure in women's later life.

METHOD

We investigated whether there was an association between adolescent pregnancy and the risk of hypertension in Korean postmenopausal women. This study used the data of 2538 postmenopausal women from the Korean National Health and Nutrition Examination Survey in 2010-2011. Multivariate logistic regression analyses were used to evaluate the independent association between adolescent pregnancy and hypertension by adjusting for potential confounding factors.

RESULTS

Postmenopausal women with a history of adolescent pregnancy had a higher prevalence of hypertension than those without a history of adolescent pregnancy. After fully adjusting for potential confounding factors such as age, lifestyle, sociodemographic factors, known hypertension risk factors, and reproductive factors, a history of adolescent pregnancy was significantly associated with hypertension (odds ratio, 1.702; 95% confidence interval, 1.125-2.574).

CONCLUSION

This study showed that a history of adolescent pregnancy is significantly and independently associated with a higher risk of hypertension in postmenopausal women.

Relationship between homeostasis model assessment of insulin resistance and beta cell function and serum 25-hydroxyvitamin D in non-diabetic Korean adults

The purpose of this study is to look at these relationships in non-diabetic Korean adults. This study was based on data from the KNHANES V-1, which is representative of the population of Korea. A total of 5,492 participants (≥20 years in age) without type 1 or type 2 diabetes, assessed for serum 25-hydroxyvitamin D [25(OH)D], fasting blood glucose and insulin, as well as anthropometric variables, were included in the analyses. The key study results were as follows: First, vitamin D status [vitamin D deficient, 25(OH)D <25 nM; vitamin D insufficient, 25(OH)D ≥25, <50 nM; vitamin D sufficient, 25(OH)D ≥50 nM] was inversely associated with homeostasis model assessment of insulin resistance (HOMA-IR) and beta cell function (HOMA-B) in model 2 (adjusted for age and gender) and 3 (further adjusted for smoking, alcohol drinking, regular exercise, systolic and diastolic blood pressure, waist circumference, and body mass index). Second, in model 4, when further adjusted for total cholesterol, triglycerides, and HDL-C, vitamin D status was inversely associated with HOMA-B. However, association of vitamin D status and HOMA-IR was no longer significant. In conclusion, vitamin D was inversely associated with beta cell function in non-diabetic Korean adults but was not associated with insulin resistance.

Prevalence of Vitamin D Deficiency in Singapore: Its Implications to Cardiovascular Risk Factors

Objective

Vitamin D deficiency is a global health challenge and has been linked to type 2 diabetes and other chronic diseases. However, the relationship between vitamin D status, body composition, and cardiovascular risks has not been well characterized in Asian populations. The objectives of this study were to examine the factors associated with the low vitamin D levels in a sunny tropical region and to assess the role of vitamin D status in cardiovascular risk factors.

Design and Methods

This was a cross-sectional study. One hundred and fourteen healthy participants (59 males and 55 females) residing in Singapore took part in this study. Plasma 25OH-D₃ concentration was measured by using LC-MS/MS. Body fat (%) was measured by using three different techniques including bioelectrical impedance analysis (BIA), BOD POD, and dual-energy X-ray absorptiometry (DEXA). Basic anthropometric measurements, fasting blood glucose (FBG), fasting serum insulin (FSI), and lipid profiles were obtained using standard protocols.

Results

Approximately 42% of the participants were vitamin D deficient (< 20 ng/mL). Vitamin D status was inversely associated with body fat (%), homeostasis model assessment of insulin resistance (HOMA-IR), and total cholesterol/high density lipoprotein (TC/HDL) ratio, while positively associated with lean body mass (LBM) and hand grip strength (HGS).

Conclusions

The high prevalence of vitamin D deficiency in a sunny tropical region reinforces the need to recognize that sunlight alone is not the precursor for optimal vitamin D status. This raises the need to investigate public health measures that will encourage exposure to sunlight without overexposure that is harmful to skin. More importantly, vitamin D deficiency is associated with increased cardiovascular risks, i.e. HOMA-IR, TC/HDL, and LDL/HDL. Future studies should attempt to elucidate the potential mechanisms.

Calcium and Vitamin D Supplementations: 2015 Position Statement of the Korean Society for Bone and Mineral Research

Calcium and vitamin D are essential components for bone health, thus calcium and vitamin D supplementation is an important strategy in the management of osteoporosis. However, the benefit of calcium and vitamin D supplementation on bone health is still controversial. Moreover, potentially harmful effects of excessive calcium supplementation on cardiovascular health are recently suggested. Too high a level of vitamin D has been also reported to have several, possibly related, harmful events. Korea is well known for low dietary calcium intake and vitamin D deficiency in its population. This position statement developed the following recommendation for adequate levels of calcium and vitamin D intake in Korean, postmenopausal women and men older than 50 years: Adequate calcium intake and optimal vitamin D level are essential for preventing and treating osteoporosis in postmenopausal women and men older than 50 years. We recommend a daily calcium intake of 800 to 1,000 mg/day. Food remains the best source of calcium; however calcium supplements should be considered when dietary intake of calcium is inadequate. We recommend dietary vitamin D intake of more than 800 IU per day, a level which appears to reduce the risk of fractures. When vitamin D deficiency is suspected, serum 25-hydroxy-vitamin D (25-[OH]D) level should be tested. We suggest that a serum 25-(OH)D level greater than 20 ng/mL is generally appropriate for prevention of osteoporosis. However, a serum 25-(OH)D level greater than 30 ng/mL is probably helpful for management of osteoporosis and prevention of fractures.

Parathyroid hormone, calcium, and sodium bridging between osteoporosis and hypertension in postmenopausal Korean women

The coexistence of osteoporosis and hypertension, which are considered distinct diseases, has been widely reported. In addition, daily intake of calcium and sodium, as well as parathyroid hormone levels (PTH), is known to be associated with osteoporosis and hypertension. This study aimed to determine the association of low calcium intake, high sodium intake, and PTH levels with osteoporosis and hypertension in postmenopausal Korean women. Data for postmenopausal Korean women aged 50 years or older were obtained from the Korea National Health and Nutrition Examination Survey 2008-2011. Osteoporosis was diagnosed using dual energy X-ray absorptiometry, while hypertension was diagnosed using blood pressure data. The odds ratios for osteoporosis and hypertension were calculated using logistic regression analysis for quartiles of the daily calcium intake, daily sodium intake, and PTH levels. Women with hypertension had a high coexistence of osteoporosis (43.6 vs. 36.5 %; P = 0.022), and vice versa (21.1 vs. 16.6 %; P = 0.022). PTH was significantly associated with osteoporosis and hypertension, and a high intake of calcium was strongly correlated with a low incidence of osteoporosis. This is the first study to report the characteristics of postmenopausal Korean women who have high dietary sodium intake and low dietary calcium intake, in association with the incidence of osteoporosis and hypertension. Osteoporosis and hypertension were strongly associated with each other, and PTH appears to be a key mediator of both diseases, suggesting a possible pathogenic link.

Nutrients other than carbohydrates: their effects on glucose homeostasis in humans

Besides carbohydrates, other nutrients, such as dietary protein and amino acids; the supply of fat, vitamin D, and vitamin K; and sodium intake seem to affect glucose homeostasis. Although their effect is less pronounced than that of the amount and composition of carbohydrates, it seems reasonable to consider how nutrient intake habits may be modified to support an improved glucose homeostasis. For instance, taking into account the effect of some nutrients to lower blood glucose concentration on a day-by-day basis might support improvement of glucose homeostasis in the long run. On the other hand, lowering sodium intake too much, as recommended to avoid the development of hypertension, particularly in sodium-sensitive people, might lead to insulin resistance and thereby might risk increasing fasting as well as postprandial blood glucose concentrations. This review summarizes the state of our knowledge of how several nutrients other than carbohydrates, such as protein, fatty acids, vitamin D, vitamin K, magnesium, zinc, chromium, and sodium, affect blood glucose concentrations. Sufficient evidence exists to show that, in prospective studies based on randomized controlled trials, these selected nutrients affect blood glucose regulation. The review describes potential mechanisms leading to the observed effect. As much as is possible from the available data, the extent of the effect, is considered.

Urban-rural differences explain the association between serum 25-hydroxyvitamin D level and insulin resistance in Korea

An increasing number of studies report associations between low serum 25-hydroxyvitamin D [25(OH)D] level and insulin resistance; however, whether low vitamin D levels directly contribute to increased insulin resistance is unclear. We investigated the impact of residential area on the association between 25(OH)D and insulin resistance in elderly Koreans. Using data from the Korean Urban Rural Elderly study, we conducted cross-sectional analyses in 1628 participants (505 men and 1123 women). Serum 25(OH)D was analyzed as both continuous and categorized variables. Homeostasis model assessment for insulin resistance (HOMA-IR) was calculated using fasting blood glucose and insulin levels. In men, 25(OH)D level was inversely associated with HOMA-IR (standardized β = −0.133, p < 0.001) after adjustment for age, body mass index, waist circumference, smoking, alcohol intake, exercise, and study year. However, we noted significant urban-rural differences in 25(OH)D level (43.4 versus 65.6 nmol/L; p < 0.001) and HOMA-IR (1.2 versus 0.8 mmol·pmol/L²; p < 0.001). When we additionally adjusted for residential area, the association between 25(OH)D and HOMA-IR was attenuated (standardized β = −0.063, p = 0.115). In women, the association between 25(OH)D and HOMA-IR was not significant before or after adjustment for residential area. Environmental or lifestyle differences in urban and rural areas may largely explain the inverse association between serum 25(OH)D and insulin resistance.

Status of vitamin D, antimicrobial peptide cathelicidin and T helper-associated cytokines in patients with diabetes mellitus and pulmonary tuberculosis

Pulmonary tuberculosis (PTB) is a high burden infectious disease in China. The immune function is damaged in patients with diabetes mellitus (DM) who are easy to infect with Mycobacterium tuberculosis (Mtb). The growth of Mtb has been shown to be restrained following the administration of vitamin D and antimicrobial peptide cathelicidin (LL-37); however, the effect in patients with DM and PTB remains unclear. Vitamin D can regulate the immune system through Vitamin D receptors expressed in T helper (Th) cells. The aim of the present study was to analyze the status and correlations of vitamin D, LL-37 and Th-associated cytokines in patients with PTB or PTB with DM (DMPTB). Serum 25-hydroxyvitamin D₃ [25(OH)D₃] levels were measured by liquid chromatography-tandem mass spectrometry, while plasma LL-37 levels were analyzed using a solid-phase enzyme-linked immunosorbent assay. Flow cytometry was used to analyze the levels of Th cytokines, including Th1-associated IFN-γ, Th2-associated IL-4 and Th17-associated IL-17. The results revealed that patients with PTB and DMPTB were vitamin D deficient or had insufficient vitamin D levels. Furthermore, the levels of LL-37, IFN-γ, IL-4 and IL-17 were higher in the PTB and DMPTB groups when compared with the normal controls. These results indicated that vitamin D supplementation is necessary for PTB and DMPTB patients. In addition, LL-37, IFN-γ and IL-17 may be diagnostic indexes that become elevated in the compensatory response caused by Mtb infection. Vitamin D can regulate the immune status in patients suffering from PTB.

Interactions between dietary calcium intake and bone mineral density or bone geometry in a low calcium intake population (KNHANES IV 2008-2010)

CONTEXT

Little is known about the interactions between dietary calcium intake and bone strength parameters in populations or areas with low calcium intake.

OBJECTIVE

The objective of the study was to investigate the relationship between dietary calcium intake and bone mineral density (BMD) or bone geometry in an Asian population with low calcium intake.

DESIGN AND SETTING

This was a cross-sectional study of data from the Korea National Health and Nutrition Examination Survey, 2008-2010.

PARTICIPANTS

A total of 3448 men and 3812 women older than 50 years were stratified by daily dietary calcium intake: less than 400 mg/d, 400-799 mg/d, 800-1199 mg/d, and 1200 mg/d or greater.

MAIN OUTCOME MEASURES

BMD was measured by dual-energy X-ray absorptiometry and the geometric index was calculated.

RESULTS

Mean daily calcium intake was 470 mg/d in this population. BMD in the lumbar spine (both sexes) and femoral neck (women) was significantly lower only when calcium intake was less than 400 mg/d. In men, femoral neck and total hip BMD was positively related to calcium intake up to 1200 mg/d. Calcium intake less than 400 mg/d was negatively related to femoral cortical thickness and buckling ratio. These interactions disappeared when the 25-hydroxyvitamin D level was 30 ng/mL or greater in men and 20 ng/mL or greater in women.

CONCLUSIONS

Low calcium intake was significantly related with low BMD and increased risk of osteoporosis. However, the association between calcium and BMD was not consistently linear, and a sufficient vitamin D level appears to compensate for the negative influences of low calcium intake on bone.

Association between serum 25-hydroxyvitamin D level and insulin resistance in a rural population

PURPOSE

A low serum 25-hydroxyvitamin D [25(OH)D] level in the blood has been correlated with an increased risk of diabetes mellitus; however, the association between serum 25(OH)D level and insulin resistance has not been established in a Korean rural population. The aim of this study was to investigate the independent association between serum 25(OH)D level and insulin resistance in rural Korean adults.

MATERIALS AND METHODS

This study used data from the Korean Genome Epidemiology Study-Kangwha Study. In the 2011 study, 1200 adults completed health examinations. In an ancillary study, serum 25(OH)D level was measured in a subsample (n=813). After excluding those taking vitamin D supplements, a cross-sectional analysis was carried out on 807 participants (324 men and 483 women) aged 40 to 89 years old. Measured from overnight fasting blood samples, glucose and insulin levels were used to calculate the homeostasis model assessment for insulin resistance (HOMA-IR). Measures of glucose, insulin, and HOMA-IR were log-transformed for parametric tests.

RESULTS

Serum 25(OH)D level was inversely associated with HOMA-IR (β=-0.003, p=0.039) in a univariate analysis. However, the association was not significant after adjustment for sex and age (β=-0.002, p=0.123) or after adjustment for sex, age, body mass index, smoking status, alcohol intake, and regular exercise (β=-0.003, p=0.247).

CONCLUSION

Our findings suggest that vitamin D is not independently associated with insulin resistance in Korean men and women.

Inverse relationship between vitamin D status and insulin resistance and the risk of impaired fasting glucose in Korean children and adolescents: the Korean National Health and Nutrition Examination Survey (KNHANES) 2009-2010

OBJECTIVE

To investigate whether low vitamin D status was related to insulin resistance (IR) or impaired fasting glucose (IFG) in Korean adolescents, after adjusting for total body fat mass (FM).

DESIGN

A cross-sectional study.

SETTING

Korea National Health and Nutrition Examination Survey (KNAHNES) 2009-2010.

SUBJECTS

In total, 1466 participants (769 males) aged 10-19 years were assessed for serum 25-hydroxyvitamin D (25(OH)D) levels, for FM by whole-body dual-energy X-ray absorptiometry and for IR by homeostasis model assessment (HOMA-IR) after an 8 h fast.

RESULTS

Age-, sex-, season- and physical-activity-adjusted regression models showed that serum 25(OH)D levels were significantly related to markers of adiposity (P = 0.016 for FM (g), P = 0.023 for FM (%) and P = 0.035 for fat mass index). When the participants were stratified into three 25(OH)D categories (<37.5 nmol/l (n 553), 37.5 to < 50 nmol/l (n 543) and ≥ 50 nmol/l (n 370)), significantly decreasing trends were observed for fasting insulin (all P < 0.001), HOMA-IR (all P < 0.001) and the odds ratios for IFG (all P for trend < 0.05) from the lowest to the highest 25(OH)D category, after adjustments for age, sex, physical activity and all markers of adiposity. In the multivariate logistic regression analysis, the likelihood of participants in the lowest serum 25(OH)D category having IFG was 2.96-3.15 compared with those in the highest 25(OH)D category (all P < 0.05).

CONCLUSIONS

There was a significant inverse relationship between vitamin D status and IR and the risk of IFG, independent of adiposity, in Korean adolescents.

25-Hydroxyvitamin D insufficiency is associated with cardiometabolic risk in Korean adolescents: the 2008-2009 Korea National Health and Nutrition Examination Survey (KNHANES)

OBJECTIVE

Vitamin D insufficiency is known to be related to cardiometabolic disorders; however, the associations among serum 25-hydroxyvitamin D (25(OH)D) concentration and metabolic syndrome and cardiometabolic risk factors in children and adolescents have not yet been clearly delineated. For this reason, we investigated the relationship among serum 25(OH)D concentration and metabolic syndrome and cardiometabolic risk factors among Korean adolescents.

DESIGN

We performed a cross-sectional analysis and used hierarchical multivariate logistic regression analysis models to adjust for confounding variables.

SETTING

We used the data gathered during the 2008-2009 Korea National Health and Nutrition Examination Survey (KNHANES).

SUBJECTS

Our subjects included 1504 Korean adolescents aged 12-18 years who participated in the KNHANES.

RESULTS

Vitamin D insufficiency, defined as 25(OH)D concentration <50 nmol/l, was found in 75·3% of Korean adolescents and was associated with an increased risk of the prevalence of metabolic syndrome. Waist circumference and BMI were the most closely correlated cardiometabolic components of metabolic syndrome according to serum 25(OH)D status, but no significant relationship was found between serum 25(OH)D concentration and insulin resistance or for the risks for high blood pressure, hyperglycaemia, reduced HDL-cholesterol or hypertriacylglycerolaemia, with or without adjustment for confounding variables.

CONCLUSIONS

Low serum 25(OH)D concentration appears to be associated with several cardiometabolic risk factors and an increased risk of the prevalence of metabolic syndrome in Korean adolescents.

The Association of vitamin D status and fasting glucose according to body fat mass in young healthy Thais

BACKGROUND

Existing inconclusive data on the relationship between vitamin D status and human glucose homeostasis suggests that other factors, such as adiposity, might influence this relationship. The present study aimed to investigate the association between 25-hydroxyvitamin D [25(OH)D] and fasting plasma glucose (FPG) in the context of different amounts of total body fat in a healthy community-based population in Bangkok, Thailand.

METHODS

This cross-sectional study was a part of health survey of employees of the Electricity Generating Authority of Thailand. There were 1,990 healthy subjects (72.8% male) in this study. Total body fat was measured by bioelectrical impedance analysis. Total serum 25(OH)D, 25(OH)D3 and 25(OH)D2 were measured by LC-MS/MS.

RESULTS

Age (r = 0.134, p < 0.001) and FPG (r = 0.089, p < 0.001) were positively correlated with 25(OH)D levels, while total body fat mass (r = -0.049, p = 0.03) were negatively correlated with 25(OH)D levels. 25(OH)D levels were higher in males than in females (65.0 ± 0.5 vs. 53.5 ± 0.5 nmol/L, p < 0.001). After controlling for age, gender and total fat mass, FPG was no longer correlated with 25(OH)D. However, when subjects were stratified according to fat-free mass tertiles and controlled for age and gender, there was a positive, although weak association between 25(OH)D levels and FPG (p = 0.01) in the lowest tertile.

CONCLUSIONS

We therefore speculate that adiposity might influence the relationship of vitamin D status and FPG.

Deficiency of 25-hydroxyvitamin d and dyslipidemia in Indian subjects

Background. Vitamin D deficiency is widespread throughout the world. Several reports have incriminated vitamin D deficiency as the cause of rickets, osteomalacia, and other chronic diseases. Recent studies have suggested a possible link between deficiency of 25-hydroxyvitamin D and dyslipidemia. Aim. To investigate the association between 25-hydroxyvitamin D deficiency and dyslipidemia in Indian subjects. Methodology. We recruited 150 asymptomatic consecutive subjects from patients' attendees at the Departments of Neurology and Medicine in Yashoda Hospital, Hyderabad, India. Study period was from October 2011 to March 2012. All subjects underwent 25-hydroxyvitamin D assay by chemiluminescent microparticle immunoassay, fasting blood sugar and lipid profile, calcium, phosphorus, alkaline phosphatase, and C-reactive protein (CRP). Results. Out of 150 subjects, men were 82 (54.6%), and mean age was 49.4 (±15.6) years. Among risk factors, hypertension was noted in 63/150 (42%), 25-hydroxyvitamin D deficiency in 59/150 (39.3%), diabetes in 45/150 (30%), dyslipidemia in 60 (40%), smoking in 35/150 (23.3%), and alcoholism in 27/150 (18%). Deficiency of 25-hydroxyvitamin D was significantly associated with dyslipidemia (P = 0.0001), mean serum glucose (P = 0.0002) mean CRP (P = 0.04), and mean alkaline phosphatase (P = 0.01). Multivariate analysis showed that 25-hydroxyvitamin D deficiency was independently associated with dyslipidemia (odds ratio: 1.9; 95% CI : 1.1–3.5). Conclusions. We found that deficiency of 25-hydroxyvitamin D was independently associated with dyslipidemia in Indian subjects.

Low serum vitamin D level is associated with high risk of metabolic syndrome in post-menopausal women

BACKGROUND

Serum vitamin D status, as indicated by 25-(OH)D, is inversely associated with glucose homeostasis, lipid profiles, and blood pressure. Evidence on the association of serum vitamin D with metabolic syndrome (MS) however, is very limited in post-menopausal women.

AIM

To investigate the association between serum vitamin D and MS.

MATERIALS AND METHODS

This study was a crosssectional study including 778 Korean adults who visited a health promotion center in a university hospital from January 2010 to May 2011. MS was defined according to the American Heart Association/National Heart, Lung, and Blood Institute criteria and the Korean Society for the Study of Obesity. MS and its individual components were assessed, as well as serum 25-(OH)D levels with a multiple logistic regression analysis.

RESULTS

The overall prevalence of the MS in participants of this study was 147 (18.9%). After multiple adjustments, compared with the highest quartile serum 25- (OH)D level group (19.9-55.9 ng/ml), the odds ratio for MS in the lowest level group (4.2-9.7 ng/ml) was 2.44 [95% confidence interval (CI)=1.32-4.48], in the lower level group (9.8- 14.1 ng/ml) was 2.20 (95% CI=1.24-3.90), and in the intermediate level group (14.3-19.8 ng/ml) was 1.81 (95% CI=1.02-3.20). Among the components of MS, the adjusted odds ratios for having an elevated blood pressure, and high triglyceride level in the lowest level group were 1.81 (95% CI, 1.15-2.85), 2.74 (95% CI, 1.64-4.57), respectively.

CONCLUSIONS

We found that a low serum 25-(OH)D level is significantly associated with the presence of MS and some metabolic components, especially the high triglyceride level and blood pressure in post-menopausal women.

Low vitamin D status is associated with nonalcoholic Fatty liver disease independent of visceral obesity in Korean adults

Objective

To investigate the association between serum 25-hydroxyvitamin D [25(OH)D] levels and nonalcoholic fatty liver disease (NAFLD) independent of visceral obesity in Koreans and to examine whether the associations differ according to the presence of diabetes or insulin resistance.

Research Design and Methods

A total of 1081 adults were enrolled from a population-based cohort in Ansan city. Serum 25(OH)D concentrations were measured in all subjects. Insulin resistance was measured by homeostasis model assessment of insulin resistance (HOMA-IR). Using computed tomography, NAFLD was diagnosed if the liver attenuation index (LAI, the difference between the mean hepatic and splenic attenuation) was <5 Hounsfield Units.

Results

In subjects with diabetes (n = 282), 25(OH)D levels were negatively associated with waist circumference, fasting insulin, HOMA-IR, triglyceride levels, and visceral abdominal fat, and were positively associated with LAI after adjusting for age, sex, season, exercise, and vitamin supplementation. In subjects without diabetes, only triglyceride level was negatively associated with 25(OH)D. The adjusted odds ratio (OR) for NAFLD increased sequentially across decreasing quartiles of 25(OH)D in subjects with diabetes even after adjusting for visceral fat [Q1 vs. Q4; OR for NAFLD 2.5 (95% CI:1.0–6.2)]. In contrast, no significant difference in OR was observed in subjects without diabetes. When we classified non-diabetic subjects by HOMA-IR, an increase in the OR for NAFLD across decreasing quartiles of 25(OH)D was observed in the high HOMA-IR (≥2.5) group [n = 207, Q1 vs. Q4; OR 3.8(1.4–10.3)], but not in the low HOMA-IR (<2.5) group [n = 592, OR 0.8 (0.3–1.9)].

Conclusions

Low vitamin D status is closely associated with NAFLD, independent of visceral obesity in subjects with diabetes or insulin resistance.

Association between serum vitamin d and metabolic risk factors in korean schoolgirls

Objectives

Vitamin D, a key regulator of bone metabolism, has been recently been linked with energy homeostasis and metabolic disorders in western countries. However, few studies have focused on the association of vitamin D with metabolic risk factors among Asian children. We studied the prevalence of vitamin D insufficiency and the association of 25-hydroxyvitamin D [25(OH)D] with metabolic risk factors in Korean schoolgirls.

Methods

The sample consisted of 320 13-year-old girls recruited from two middle schools in the city of Gwacheon, Korea (latitude 37°N), in July 2011. Anthropometric and blood biochemistry data were obtained for this cross-sectional observational study. We also obtained lifestyle data from questionnaires and dietary data from 3-day food diaries.

Results

Vitamin D deficiency [25(OH)D < 20 ng/mL] was noted in 63.8% of participants. The mean 25(OH)D level was not significantly lower in the overweight group. Level of physical activity and vitamin D intake did not significantly affect 25(OH)D. However, 25(OH)D levels were positively correlated with milk intake and negatively correlated with soft drink intake. Serum 25(OH)D had a negative relationship with fasting glucose and insulin resistance index (homeostasis model assessment-insulin resistance; HOMA-IR) after adjustment for physical activity and body mass index z score (r = −0.144, p = 0.015), and with metabolic risk score similarly (r = −0.141, p = 0.012). Levels of insulin, HOMA-IR, and systolic blood pressure were higher in girls with deficient 25(OH)D levels than in those with sufficient levels.

Conclusion

We found that low 25(OH)D levels were associated with higher blood glucose and insulin resistance. Korean girls with low 25(OH)D levels could be at increased risk for metabolic disorders.

Association of diabetes mellitus with a combination of vitamin d deficiency and arsenic exposure in the korean general population: analysis of 2008-2009 korean national health and nutrition examination survey data

Objectives

We present data from the Korean National Health and Nutritional Examination Survey (KNHANES) 2008–2009 on the combination of vitamin D deficiency and arsenic exposure on diabetes mellitus (DM) in a representative sample of the adult Korean population.

Methods

This study was based on data obtained from the KNHANES 2008–2009, which was conducted for 3 years (2007–2009) using a rolling sampling design that involved a complex, stratified, multistage, probability-cluster survey of a representative sample of the non-institutionalized civilian population in South Korea.

Results

Data analysis revealed that subjects who showed both vitamin D levels in the 1^st quartile (Q) and urinary arsenic levels in the 4^th Q, had a 302% increased risk of having DM, as compared with those whose vitamin D and urinary arsenic levels were in the 4^th Q and 1^st Q, respectively.

Conclusion

The present study reconfirmed an association of DM with low vitamin D levels and arsenic exposure, and further showed a combination of vitamin D deficiency and arsenic exposure on DM in the general Korean population. To the best of our knowledge, this is the first report describing a combination of vitamin D deficiency and arsenic exposure on DM. The present findings have important public health implications.

Serum 25-hydroxy vitamin D levels in relation to body mass index: a systematic review and meta-analysis

BACKGROUND

Although several cross-sectional studies have investigated serum vitamin D levels in relation to body mass index (BMI), findings are inconsistent.

OBJECTIVE

This systematic review and meta-analysis of published cross-sectional data was conducted to summarize the evidence on the link between serum vitamin D levels and BMI in adults.

METHODS

PubMed, ISI Web of Science, Scopus and Google scholar database were searched to May 2012 for all relevant published papers. We found 34 articles that reported the correlation coefficients between serum 25-hydroxy vitamin D (25(OH)D) levels and BMI in apparently healthy adults (>18 years). The primary analysis was done on these 34 papers that reported 37 correlation coefficients. To find the source of between-study heterogeneity, our secondary analysis was confined to eight studies that had used random sampling method and reported the correlations for the whole population.

RESULTS

Our meta-analysis on 34 relevant papers revealed an overall significant inverse, but weak, association between serum 25(OH)D levels and BMI (Fisher's Z = -0.15, 95% CI: -0.19, -0.11) with a significant heterogeneity between studies. In the subgroup analysis based on gender and study location (East vs. West), the inverse associations were significant in both genders (male: Fisher's Z = -0.11, 95% CI: -0.14, -0.08 and female: -0.14, 95% CI: -0.21, -0.08) and both study locations (East: -0.09, 95% CI: -0.14, -0.04 and West: -0.23, 95% CI: -0.31, -0.17). In the subgroup analysis based on developmental status of countries, the weak inverse association remained significant in developed countries (-0.17, 95% CI: -0.21, -0.14), but not in developing nations (-0.10, 95% CI: -0.20, 0.01). Using meta-regression, we found that latitude (P = 0.91) or longitude (P = 0.2) of cities did not significantly contribute to the computed effect sizes. When we restricted our analysis to eight selected studies that used random sampling method, we reached the same findings. In this analysis, gender and developmental status of countries explained the between-study heterogeneity.

CONCLUSION

There is a significant inverse weak correlation between serum 25(OH)D levels and BMI in adult population, except for women living in developing countries. Further research particularly in developing countries and populations living near the equator is needed.

The association between vitamin D status and type 2 diabetes in a Thai population, a cross-sectional study

OBJECTIVE

To explore vitamin D status in relation to diabetes, based on data from a national health examination survey in Thailand.

DESIGN AND METHODS

A total of 2641 adults, aged 15-98 years, were randomly selected according to geographical region from the Thai 4th National Health Examination Survey sample. Logistic regressions were used to examine the cross-sectional association between diabetes status and level of 25(OH)D separately by age groups and areas of residence.

RESULTS

Fifty per cent of the subjects were men and 5·8% had diabetes. The mean level of 25(OH)D was 79·3 ± 0·8 nm. Based on cut-off values of 50 and 75 nm, six per cent and 45% had vitamin D insufficiency, respectively. In a regression model, it was found that 25(OH)D3 and total 25(OH)D were positively associated with diabetes. In addition, logistic regression analysis showed that low circulating 25(OH)D3, but not 25(OH)D2, levels was significantly associated with an increased odds of diabetes in older persons (aged ≥70 years) in urban areas. However, for subjects residing in rural areas, no association between serum 25(OH)D3 or total 25(OH)D and diabetes was found. Furthermore, vitamin D insufficiency was associated with a higher risk of diabetes (OR, 1·56; 95% CI, 1·10-1·12) only in the urban elderly.

CONCLUSION

Low vitamin D status is modestly associated with a small increase in the risk of diabetes in the urban Thai elderly. The observation that higher vitamin D status is associated with increased diabetic risk in young adults needs to be further explored and confirmed.

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

BACKGROUND/OBJECTIVES

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

SUBJECTS/METHODS

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

RESULTS

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

CONCLUSIONS

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

High prevalence of vitamin D insufficiency or deficiency in young adolescents in Korea

Recent studies suggest that vitamin D insufficiency or deficiency is not only a problem of older generations anymore but also an important health concern among younger generations. However, comprehensive data are lacking in Korean adolescents. We investigated the vitamin D (25-hydroxy vitamin D [25(OH)D]) status, the prevalence of vitamin D insufficiency or deficiency, and the association between vitamin D levels and insulin resistance and lipid profiles in a sample of 188 Korean adolescents aged 12-13 years who participated in a general health check-up at a tertiary hospital. Vitamin D deficiency was considered as serum concentrations <20 ng/mL (50 nmol/L); a level of 21-29 ng/mL (52-72 nmol/L) was considered to indicate vitamin D insufficiency, whereas a level of 30 ng/mL or greater (>75 nmol/L) was considered sufficient or optimum. In this cross-sectional study, vitamin D insufficiency or deficiency was found in 98.9 % of boys and 100 % of girls, whereas only 1.1 % of boys and 0 % of girls had a serum 25(OH)D level of greater than 30 ng/mL. In multivariate linear regression analysis, HOMA-IR, triglyceride, and LDL cholesterol were inversely associated with 25(OH)D concentrations. We found that vitamin D insufficiency or deficiency is a very common health problem in Korean adolescents, particularly in girls, and that serum 25(OH)D levels are inversely associated with insulin resistance and lipid profiles. These results suggest that more time spent in outdoor activity for sunlight exposure and higher vitamin D intake may be needed in younger adolescents in South Korea.

Vitamin D in the new millennium

The incidence of vitamin D deficiency is rising worldwide, yet in the vast majority of patients, the condition remains undiagnosed and untreated. Current evidence overwhelmingly indicates that supplemental doses greater than 800 IU/day have beneficial effects on the musculoskeletal system, improving skeletal homeostasis, thus leading to fewer falls and fractures. Evidence is also accumulating on the beneficial effects of vitamin D on extraskeletal systems, such as improving immune health, autoimmune disorders, cancer, neuromodulation, diabetes, and metabolic syndrome. The cause-effect relationship of vitamin D deficiency with increasing incidences of nonskeletal disorders is being investigated. Published reports support the definition of sufficiency, serum levels of 25-hydroxyvitamin D [25(OH)D] greater than 30 ng/mL (75 nmol/L). To achieve this, most people need vitamin D supplementation ranging from 600 to 2000 IU/day; consumption up to of 5000 international units (IU) per day of vitamin D is reported as safe. Although light-skinned individuals need 1000 IU/day of vitamin D, elderly and dark-skinned individuals are likely to need approximately 2000 IU/day to maintain serum 25(OH)D levels greater than 30 ng/mL. Other vulnerable patients, such as the obese, those who have undergone bariatric surgery, and those with gastrointestinal malabsorption syndromes, may require higher doses of vitamin D to maintain normal serum levels and be healthy.