The metabolic syndrome and carotid intima-media thickness in relation to the parathyroid hormone to 25-OH-D(3) ratio in a general population

Current Overview on Therapeutic Potential of Vitamin D in Inflammatory Lung Diseases

Inflammatory lung disorders (ILDs) are one of the world's major reasons for fatalities and sickness, impacting millions of individuals of all ages and constituting a severe and pervasive health hazard. Asthma, lung cancer, bronchiectasis, pulmonary fibrosis acute respiratory distress syndrome, and COPD all include inflammation as a significant component. Microbe invasions, as well as the damage and even death of host cells, can cause and sustain inflammation. To counteract the negative consequences of irritants, the airways are equipped with cellular and host defense immunological systems that block the cellular entrance of these irritants or eliminate them from airway regions by triggering the immune system. Failure to activate the host defense system will trigger chronic inflammatory cataracts, leading to permanent lung damage. This damage makes the lungs more susceptible to various respiratory diseases. There are certain restrictions of the available therapy for lung illnesses. Vitamins are nutritional molecules that are required for optimal health but are not produced by the human body. Cholecalciferol (Vitamin D) is classified as a vitamin, although it is a hormone. Vitamin D is thought to perform a function in bone and calcium homeostasis. Recent research has found that vitamin D can perform a variety of cellular processes, including cellular proliferation; differentiation; wound repair; healing; and regulatory systems, such as the immune response, immunological, and inflammation. The actions of vitamin D on inflammatory cells are dissected in this review, as well as their clinical significance in respiratory illnesses.

Association of Low Vitamin D with Complications of HIV and AIDS: A literature Review

With the advent of combination antiretroviral therapy (cART), the survival of HIV patients has improved dramatically, but the complications of the disease and treatment have become an important issue in the management of HIV patients. Vitamin-D deficiency is common in HIV patients. Low vitamin-D is associated with different comorbidities in the HIV uninfected general population. In this review, we first briefly describe vitamin D synthesis and mechanism of action and we focus on the epidemiological and clinical data dealing with the relationship between vitamin D deficiency in HIV infection with several comorbidities which has been found to be increasingly common in patients living with HIV infection. We searched the PubMed database using the keywords "HIV," "vitamin D" and other common disorders or conditions that are relatively common in HIV infection. The other conditions included in the search were osteoporosis and fracture, cardiovascular disease, diabetes and insulin resistance, active tuberculosis, hepatitis-C co-infection, and HIV disease progression. Articles presenting original data as well as systematic reviews and met analysis related to HIV population were included in our analysis. Vitamin-D deficiency seems to be associated with several adverse outcomes in HIV patients but a definite cause and effect relationship with vitamin-D is yet to be confirmed in most of the cases. However, the literature supporting the efficacy of vitamin-D supplementation is lacking.

Association of circulating 25-hydroxyvitamin D and parathyroid hormone with carotid intima media thickness in children and adolescents with excess weight

Evidence on the association of vitamin D and parathyroid hormone (PTH) with cardiovascular risk factors in the young is limited. We therefore assessed the relationships of circulating vitamin D and PTH concentrations and subclinical atherosclerosis in overweight or obese children and adolescents. This was a cross-sectional study, investigated the association of 25-hydroxyvitamin D (25(OH)D), intact PTH (iPTH), and iPTH/25(OH)D ratio with carotid intima-media thickness (cIMT) in 368 Iranian children and adolescents with a body mass index (BMI) ≥1 z-score based on WHO criteria. Ultrasound measurement of cIMT was performed. Multivariable linear and logistic regressions were used to test associations between 25(OH)D, iPTH, and iPTH/25(OH)D ratio using one-ln-unit increment with cIMT. Median (25-75 interquartile range) 25(OH)D and iPTH concentrations were 11.8 (8.2-18.6) ng/ml and 38.2 (25.0-61.4) pg/ml, respectively. Among boys, each one-ln-unit increase of iPTH and iPTH/25(OH)D ratio was significantly associated with 0.194 mm and 0.147 mm increase, respectively, in cIMT, after adjustment for confounders. A similar pattern of association was observed between iPTH (β = 0.143, p = 0.037) and iPTH/25(OH)D ratio (β=0.172, p = 0.007) with cIMT among obese participants. Furthermore, among obese participants in the fully adjusted model, each one-ln-unit increase of iPTH and 25(OH)D/iPTH ratio was significantly associated with 53% and 39% increased odds of having high cIMT, respectively. Girls and those who were overweight did not show any significant association of 25(OH)D, iPTH, and iPTH/25(OH)D ratio with cIMT. High iPTH and iPTH/25(OH)D ratio were associated with increased cIMT in boys and those who are obese.

Role of vitamin D deficiency in type 2 diabetes mellitus and diabetic neuropathy development

Type 2 diabetes mellitus (DM) is a global epidemic associated with severe vascular complications development. Diabetic neuropathy is the most common chronic complication of DM that worsens patients life quality and prognosis. Therefore, studies dealing with DM and diabetic neuropathy underlying mechanisms are extremely relevant. The review discusses current views on vitamin D role in glucose metabolism and inflammatory processes. It is reported that vitamin D deficiency can contribute to insulin resistance development, and change in vitamin D receptor activity or extra- and intracellular calcium concentration due to vitamin D deficiency can affect pancreatic -cells function and lead to decrease in insulin production. Key pathogenic mechanisms of diabetic neuropathy as well as possible relationship between vitamin D deficiency and neuropathy development are in focus of this review. Results of recent clinical trials regarding vitamin D supplementation in patients with DM are also discussed. The presented data suggest that vitamin D deficiency can be considered as a non-classical risk factor for the development of not only DM but its complications as well.

Prevalence and association of metabolic syndrome and vitamin D deficiency among postmenopausal women in a rural block of West Bengal, India

Background

Prevalence of metabolic syndrome (MS) and vitamin D deficiency was reported among postmenopausal women (PMW) in India. However, no report is available regarding the association of MS and 25-hydroxyvitamin D [25(OH)D] among PMW in India. This study aimed to find out the prevalence of MS and 25(OH)D status as well as their association among rural PMW of West Bengal, India.

Materials and methods

This cross-sectional study was conducted among 222 randomly selected rural PMW in Singur Block, West Bengal, India. Serum 25(OH)D, Blood pressure (BP), waist circumference (WC), fasting blood glucose (FBG), triglycerides (TG) and high density lipoprotein cholesterol (HDL-C) were measured using standard procedures. MS was defined as per International Diabetes Federation, 2005 (for Asian-Indians) criteria. Statistical tests were done using SPSS software.

Results

Prevalence of metabolic syndrome was 46%. 51% and 19% PMW were vitamin D insufficient and deficient, respectively. 22% and 53% women having MS were vitamin D insufficient and deficient, respectively. Among the PMW, 21% and 47% with WC≥80cm; 22% and 62% with FBG≥110mg/dl; 21% and 54% with TG≥150mg/dl; 23% and 51% with HDL-C<50mg/dl, 15% and 55% with BP≥130/85mm of Hg were vitamin D insufficient and deficient, respectively. Significant statistical association between FBG and 25(OH)D status existed (p = 0.01). Significant positive correlation between WC and 25(OH)D level (p = 0.004) and significant negative correlation between FBG and 25(OH)D level observed (p = 0.02). WC was the only statistically significant predictor of the dependent variable. Odds of non-sufficient 25(OH)D level increased with decrease in WC.

Conclusion

High prevalence of MS as well as vitamin D insufficiency and deficiency existed among PMW of Singur block, West Bengal, India. 25(OH)D had significant inverse and direct relationship with FBG and WC. Low 25(OH)D may be one of the potential risk factors for developing MS in PMW or vice-versa.

Nutrient-Derived Dietary Patterns and Their Association With Metabolic Syndrome in a Japanese Population

Background

Nutrients have been proposed to be related to metabolic syndrome (MetS). The aims of this study were to identify dietary patterns that correlated with several nutrients using reduced rank regression (RRR) and to examine the association between extracted dietary patterns and prevalence of MetS in a Japanese population.

Methods

The study population comprised 1,092 Japanese men and women (35–69 years old) who had participated in the baseline survey of the Japan Multi-Institutional Collaborative Cohort Study in Tokushima Prefecture. Dietary patterns were derived with RRR using 46 food items as predictors and six established nutrients (potassium, calcium, vitamin D, vitamin C, insoluble dietary fiber, and carotene) as response variables. Associations between extracted dietary patterns and MetS were then examined with logistic regression models.

Results

Among the six dietary patterns, dietary pattern 1 (DP1) explained the largest proportion (60.1%) of variance in the six nutrients. Therefore, only DP1 was selected for further analysis. DP1 was characterized by high intake frequency of vegetables, fruits, fish and small fish, natto (fermented soybeans), and deep-fried tofu. After adjustment for potential confounders, significant inverse associations were found between DP1 score and MetS (odds ratio [OR] for each quartile: 1.00, 0.58, 0.60, 0.52; P_trend = 0.02); DP1 and high blood pressure (P_trend = 0.0002); and DP1 and high blood glucose (P_trend = 0.02).

Conclusion

A dietary pattern characterized by high intake of vegetables, fruits, fish and small fish, natto, and deep-fried tofu was associated with reduced prevalence of MetS in a Japanese population.

Association of Serum 25-hydroxyvitamin D in Carotid Intima-media Thickness: A Study from South India

Background:

Abnormal carotid intima-media thickness (IMT) is a marker of carotid atherosclerosis which is a risk factor for cerebrovascular and cardiovascular diseases. Recent studies have found an association of 25-hydroxyvitamin D deficiency with abnormal carotid IMT.

Purpose:

The purpose of the study was to investigate the association of serum 25-hydroxyvitamin D levels with carotid IMT in Indian participants.

Materials and Methods:

We prospectively recruited 300 participants at Yashoda Hospital, Hyderabad, during the study period between January 2012 and December 2014. All participants were assessed for fasting blood sugar, lipid profile, C-reactive protein (CRP), serum alkaline phosphatase, serum calcium, serum phosphorous, serum 25-hydroxyvitamin D levels, and carotid Doppler examination.

Results:

Among the 300 participants, men were 190 (63.3%) and mean age was 51.9 ± 7.7 years with a range from 35 to 64 years. On risk factors evaluation, 105 (35%) were hypertensive, 79 (26.3%) diabetics, 63 (21%) smokers, and 56 (18.6%) were alcoholics. On evaluation of biochemical parameters, 81 (27%) had dyslipidemia, 120 (40%) had elevated CRP levels, 119 (39.6%) had 25-hydroxyvitamin D deficiency, mean alkaline phosphatase was 93.9 ± 14.9 IU/L, serum calcium (mg/dL) was 9.2 ± 2.3, and serum phosphorous 4.4 ± 1.2 mg/dL. On carotid imaging, 121 (40.3%) had abnormal IMT. After multivariate analysis, 25-hydroxyvitamin D deficiency (odds ratio [OR]: 2.14; 95% confidence interval [CI]: 1.29–3.55), dyslipidemia (OR: 2.53; 95% CI: 1.46–4.40), elevated CRP (OR: 2.27; 95% CI: 1.37–3.76), smoking (OR: 2.09; 95% CI: 1.16–3.77), and diabetes (OR: 1.84; 95% CI: 1.05–3.21) were independently associated with abnormal IMT.

Conclusion:

In our study, we established 25-hydroxyvitamin D deficiency as an independently associated with abnormal IMT in Indian participants.

Better Body Composition and Lipid Profile Can Be Associated with Vitamin D Status in Spanish Elderly? The PHYSMED Study

Studies have shown that vitamin D deficiency increases the risk for lipid metabolism disorders, but this relationship has provided inconsistent results in elderly. Thus the aim was to assess the association between body composition and blood lipid profile levels on serum 25-hydrovitamin D [25(OH)D] concentration in Spanish elderly. A cross-sectional multicentre study was carried out in 383 participants (58.2% females) aged of 55-88 years. Fasting blood samples analyzed serum concentrations of 25(OH)D, low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides (TG) and total cholesterol (TC). Body composition parameters (fat mass, fat free mass) were obtained by bioimpedance, waist circumference (WC), physical activity and vitamin D intake were also evaluated. BMI, fat mass and total fat mass were lower in vitamin D sufficient subjects than vitamin D insufficient and deficient subjects, but this difference was not significant (p>0,05). Those with vitamin D adequate levels also showed lower TC/HDL ratio than those who had inadequate (insufficient or deficient) vitamin D levels (p=0.04). Significant association between 25(OH)D and BMI, waist circumference, total muscle mass, TC/HDL-c ratio, HDL and TG (for all p≤ 0.05) was found after controlling for some confounders. Subjects with inadequate HDL levels (<40mg/dL) showed 1.7 times higher odds than vitamin D deficiency than those with adequate HDL levels (>60mg/dL) (95% CI= 1.10 to 2.85 p= 0.017) and WC was negatively associated with vitamin D status odds ratio of 0.98 (0.96 to 1.00; p= 0.04). Vitamin D concentration was positively correlated with HDL-c and total muscle mass, as well as negatively correlated with WC, LDL-c/HDL-c and TC/HDL-c independently of age, gender and some confounders.

A vitamin D pathway gene-gene interaction affects low-density lipoprotein cholesterol levels

Much evidence suggests an association between vitamin D deficiency and chronic diseases such as obesity and dyslipidemia. Although genetic factors play an important role in the etiology of these diseases, only a few studies have investigated the relationship between vitamin D-related genes and anthropometric and lipid profiles. The aim of this study was to investigate the association of three vitamin D-related genes with anthropometric and lipid parameters in 542 adult individuals. We analyzed the rs2228570 polymorphism in the vitamin D receptor gene (VDR), rs2134095 in the retinoid X receptor gamma gene (RXRG) and rs7041 in the vitamin D-binding protein gene (GC). Polymorphisms were genotyped by TaqMan allelic discrimination. Gene-gene interactions were evaluated by the general linear model. The functionality of the polymorphisms was investigated using the following predictors and databases: SIFT (Sorting Intolerant from Tolerant), PolyPhen-2 (Polymorphism Phenotyping v2) and Human Splicing Finder 3. We identified a significant effect of the interaction between RXRG (rs2134095) and GC (rs7041) on low-density lipoprotein cholesterol (LDL-c) levels (P=.005). Furthermore, our in silico analysis suggested a functional role for both variants in the regulation of the gene products. Our results suggest that the vitamin D-related genes RXRG and GC affect LDL-c levels. These findings are in agreement with other studies that consistently associate vitamin D and lipid profile. Together, our results corroborate the idea that analyzing gene-gene interaction would be helpful to clarify the genetic component of lipid profile.

Vitamin D as a risk factor for premature atherosclerosis in patients with type 2 diabetes

BACKGROUND

Several cardiovascular risk factors have been recognized in patients with diabetes and vitamin D deficiency is emerging as a new risk. The aim of this study was to determine the effect of vitamin D deficiency on the incidence of premature atherosclerosis in patients with type 2 diabetes.

METHODS

A total of 78 patients with type 2 diabetes were subjected to history taking, physical examination, fasting glucose level, homeostasis model assessment of insulin resistance, lipid profile, 25(OH) vitamin D measurement, and carotid Doppler.

RESULTS

Patients with normal carotid intima-media thickness (CIMT) had sufficient vitamin D. Of those with increased CIMT 23.1% had insufficient vitamin D while 76.9% had sufficient vitamin D (six patients had plaques, one of them had vitamin D insufficiency, and the other five patients had sufficient vitamin D). There was a statistically significant difference in the serum level of vitamin D between patients with increased CIMT, and those with normal intima, with a decreased level in the first group. There was a significant negative correlation between vitamin D and fasting blood glucose. There was a statistically significant correlation in left CIMT between the vitamin D sufficiency group and the vitamin D insufficiency group, with higher values in the second group. There was no statistically significant difference in serum cholesterol, triglycerides, HDL cholesterol, and LDL cholesterol in patients with increased CIMT and those with normal intima.

CONCLUSIONS

Decreased vitamin D levels in patients with diabetes lead to increased CIMT. The absence of a statistically significance difference in lipid profile between increased and normal CIMT groups raises the possibility of underlying causes for atherosclerosis in patients with diabetes other than dyslipidemia.

Vitamin D deficiency is common among adults in Wallonia (Belgium, 51°30' North): findings from the Nutrition, Environment and Cardio-Vascular Health study

Data on the vitamin D status of the population of Wallonia (Belgium, 51°30' North) are scarce. This study was carried out to estimate vitamin D deficiency, identify potential determinants, and analyze their relationship with vitamin D supplementation. We tested the hypothesis that vitamin D deficiency is common in the general population, particularly among subjects without supplementation. Vitamin D deficiency was defined as a serum level of 25-hydroxyvitamin D (25(OH)D) concentration less than 50nmol/L. Data were analyzed from 915 participants of the Nutrition, Environment and Cardio-Vascular Health cross-sectional survey. The median (interquartile range) 25(OH)D level was 53.1 (37.8-69.9) nmol/L, and 44.7% of the subjects were vitamin D deficient. Subjects without vitamin D supplementation were more concerned by vitamin D deficiency than those with supplementation (odds ratio [OR], 3.35; P < .0001). From a multivariate standpoint, the potential determinants of vitamin D deficiency among subjects without vitamin D supplementation were season, specifically spring and winter (OR, 7.36 and 6.44, respectively), obesity (OR, 2.19), low household income (OR, 1.73), and lack of solarium use (OR, 1.79). For subjects with supplementation, the only determinant observed for vitamin D deficiency was obesity (OR, 5.00). This work evidenced the high prevalence of 25(OH)D deficiency in the general population, especially among nonsupplemented subjects with obesity, low household income, and/or lack of light. Vitamin D supplementation looks effective in our population, especially via a stabilization of vitamin D coverage throughout the seasons. The best dietary strategy to achieve optimal 25(OH)D concentrations all year round in the general population requires more research.

The cross-sectional relationship between dietary calcium intake and metabolic syndrome among men and women aged 40 or older in rural areas of Korea

BACKGROUND/OBJECTIVES

Studies conducted in Western populations have suggested that dietary calcium may protect against metabolic abnormalities, but there is little evidence of this effect in Asians, who have relatively low calcium intake. We evaluated the cross-sectional relationship between dietary calcium and metabolic syndrome among Korean men and women aged 40 years and over.

SUBJECTS/METHODS

A total of 6,375 subjects aged 40 years and over and were recruited between January 2005 and February 2010 from the baseline study of the Multi-Rural Communities Cohort Study in Rural Communities (MRCohort). A food frequency questionnaire was used to collect dietary information. Metabolic syndrome was defined using the modified criteria published in the Third Report of the National Cholesterol Education Program Adult Treatment Panel.

RESULTS

Calcium intake was related inversely to metabolic syndrome in women (P-value = 0.0091), but not in men (P = 0.1842). Among metabolic components, high waist circumference (WC) (P = 0.0426) and high blood glucose (P = 0.0027) in women and hypertriglyceridemia (P = 0.0017) in men were inversely correlated with calcium intake. Excluding those who used calcium or multinutrient supplements did not attenuate the relationship between dietary calcium and metabolic abnormalities.

CONCLUSION

Dietary calcium intake from foods may be inversely related to metabolic syndrome, WC, and blood glucose among women in rural areas of Korea.

Hypertension, Antihypertensive Medications, and Risk of Incident Primary Hyperparathyroidism

CONTEXT

Hypertension is associated with higher PTH levels, and specific antihypertensive medications may modulate PTH. Whether hypertension or the use of specific antihypertensive medications influences the risk of developing incident primary hyperparathyroidism (P-HPTH) is not known.

OBJECTIVE

The purpose of this study was to investigate whether a history of hypertension and the use of specific antihypertensive medications determine the risk for developing P-HPTH in a large prospective study.

DESIGN/PARTICIPANTS

A longitudinal prospective cohort of female nurses in the Nurses' Health Study I (n = 75 600), who did not have P-HPTH at baseline and completed a questionnaire assessment of lifetime history of P-HPTH were followed from 1986 to 2008. Most participants were white and postmenopausal.

SETTING

The study was a nationwide cohort study.

MAIN OUTCOME MEASURE

Incident P-HPTH was assessed initially via questionnaire and then was confirmed by medical record review. Cox proportional hazards models were used to adjust for potential confounders.

RESULTS

We documented 347 incident cases of P-HPTH during 1 719 416 person-years of follow-up. The age-adjusted relative risk (RR) for incident P-HPTH associated with hypertension was 1.80 (95% confidence interval [CI], 1.43-2.26), and the multivariate-adjusted RR was 1.45 (95% CI, 1.10-1.91). Among participants with a history of hypertension, the use of furosemide, when compared with the use of other antihypertensive medications, was associated with increased risk for developing P-HPTH; age-adjusted RR for incident P-HPTH was 1.79 (95% CI, 1.15-2.79) and multivariate-adjusted RR was 1.71 (95% CI, 1.08-2.71).

CONCLUSIONS

In a large longitudinal prospective cohort study of mostly older white women, a history of hypertension and use of furosemide were associated with a significantly higher risk of developing P-HPTH.

Carotid intima-media thickness is not associated with vitamin D and PTH levels in patients admitted to an Internal Medicine Department

Vitamin D (25OHD) and/or parathyroid hormone (PTH) levels have been associated with common carotid intima-media thickness (IMT). We investigated such associations in inpatients consecutively admitted to an Internal Medicine Department. In 168 consecutive patients admitted to our department, 25 hydroxyvitamin D (25OHD) was measured by means of RIA and PTH by means of ICMA, whereas IMT by means of ultrasonography. The main cardiovascular risk factors were also explored. In patients with either diabetes, or hypertension, or both, 25OHD values were not significantly lower than in other patients. No difference was found among the IMT values across tertiles of 25OHD level, as like as in the 25OHD, PTH, PTH/25OHD ratio values of patients either grouped by tertiles of IMT, or categorized according to IMT of <0.9, 0.9-1.5, and >1.5 mm. IMT did not significantly associate with 25OHD, PTH, and PTH/25OHD ratio, whereas it positively associated with age (r = 0.281; p < 0.001) and BMI (r = 0.138; p = 0.074), and negatively with eGFR (r = -154; p = 0.046). Multiple regression models showed that IMT was significantly associated to age and BMI, while 25OHD, PTH, or PTH/25OHD ratio did not increase the significance of the models. IMT assessment does not seem to be associated with 25OHD and PTH levels in unselected inpatients.

Vitamin D: An overview of vitamin D status and intake in Europe

In recent years, there have been reports suggesting a high prevalence of low vitamin D intakes and vitamin D deficiency or inadequate vitamin D status in Europe. Coupled with growing concern about the health risks associated with low vitamin D status, this has resulted in increased interest in the topic of vitamin D from healthcare professionals, the media and the public. Adequate vitamin D status has a key role in skeletal health. Prevention of the well-described vitamin D deficiency disorders of rickets and osteomalacia are clearly important, but there may also be an implication of low vitamin D status in bone loss, muscle weakness and falls and fragility fractures in older people, and these are highly significant public health issues in terms of morbidity, quality of life and costs to health services in Europe. Although there is no agreement on optimal plasma levels of vitamin D, it is apparent that blood 25-hydroxyvitamin D [25(OH)D] levels are often below recommended ranges for the general population and are particularly low in some subgroups of the population, such as those in institutions or who are housebound and non-Western immigrants. Reported estimates of vitamin D status within different European countries show large variation. However, comparison of studies across Europe is limited by their use of different methodologies. The prevalence of vitamin D deficiency [often defined as plasma 25(OH)D <25 nmol/l] may be more common in populations with a higher proportion of at-risk groups, and/or that have low consumption of foods rich in vitamin D (naturally rich or fortified) and low use of vitamin D supplements. The definition of an adequate or optimal vitamin D status is key in determining recommendations for a vitamin D intake that will enable satisfactory status to be maintained all year round, including the winter months. In most European countries, there seems to be a shortfall in achieving current vitamin D recommendations. An exception is Finland, where dietary survey data indicate that recent national policies that include fortification and supplementation, coupled with a high habitual intake of oil-rich fish, have resulted in an increase in vitamin D intakes, but this may not be a suitable strategy for all European populations. The ongoing standardisation of measurements in vitamin D research will facilitate a stronger evidence base on which policies can be determined. These policies may include promotion of dietary recommendations, food fortification, vitamin D supplementation and judicious sun exposure, but should take into account national, cultural and dietary habits. For European nations with supplementation policies, it is important that relevant parties ensure satisfactory uptake of these particularly in the most vulnerable groups of the population.

Gender differences in the relationship between risk of hypertension and fruit intake

OBJECTIVE

To investigate the relationship between hypertension and fruit intake in an Asian population.

METHOD

This study was based on the data from 2007, 2008 and 2009 Korea National Health and Nutrition Examination Survey. In the final analysis, a total of 9791 subjects (men=3819, women=5972) were included. Daily energy and nutrient intakes were assessed using 24-h recall. The odds ratios (ORs) for hypertension were assessed by using logistic regression and multivariable models.

RESULTS

A total of 10.6% of individuals were classified as having hypertension. Compared with the lowest quintile of fruit intake, the fifth quintile showed the lowest likelihood of hypertension (OR 0.73; 95% confidence interval [CI], 0.61-0.88) after adjusting for age and gender. For women, the likelihood of hypertension in the 2nd, 3rd, 4th and 5th quintiles of fruit intake decreased to 0.67 (95% CI, 0.34-1.30), 0.76 (0.56-1.05), 0.90 (0.67-1.22) and 0.54 (0.38-0.77), respectively, after adjusting for confounding factors (P value for trend=0.0011). An inverse association of fruit intake and hypertension was shown only in non-obese women. For men and obese women, there was no relationship between fruit intake and hypertension.

CONCLUSION

Dietary fruit recommendation for hypertension should be taken into account together with ethnic background, gender as well as the presence of obesity in individuals.

Vitamin D modulates the association of circulating insulin-like growth factor-1 with carotid artery intima-media thickness

OBJECTIVE

Experimental evidence indicates that circulating insulin-like growth factor-1 (IGF-1) counteracts vascular aging and atherosclerosis, for which increased carotid artery intima-media thickness (IMT) is a marker. Yet, IGF-1 concentrations have been inconsistently associated with carotid IMT in epidemiological studies. Since vitamin D is also implicated in vascular protection and affects IGF-1 biology, we hypothesized that it would influence the effect of IGF-1 on IMT.

METHODS

The relationship between carotid IMT and fasting serum IGF-1 was examined across strata of 25-hydroxyvitamin D [25(OH)D] in 472 participants in the Baltimore Longitudinal Study of Aging (BLSA) with well-controlled blood pressure and in 165 treatment-naive patients with essential hypertension from the Microalbuminuria: A Genoa Investigation on Complications (MAGIC) study. Moreover, the interplay between vitamin D and IGF-1 was preliminarily explored in EA.hy926 endothelial cells.

RESULTS

After adjusting for age, sex, BMI, renal function, smoking, systolic blood pressure, LDL-cholesterol, glycemia, antihypertensive or lipid-lowering therapy, season, parathyroid hormone, and vitamin D supplementation, IGF-1 was significantly and negatively associated with carotid IMT only within the lowest 25(OH)D quartile (range 6.8-26 ng/mL) of the BLSA (β -0.095, p = 0.03). Similarly, a significant negative correlation between IGF-1 and carotid IMT was found after full adjustment only in MAGIC patients with 25(OH)D concentrations below either the deficiency cut-off of 20 ng/mL (β -0.214, p = 0.02) or 26 ng/mL (β -0.174, p = 0.03). Vitamin D dose-dependently decreased hydrogen peroxide-induced endothelial cell oxidative stress and apoptosis, which were further inhibited by IGF in the presence of low, but not high vitamin D concentration.

CONCLUSIONS

Circulating IGF-1 is vasoprotective primarily when vitamin D levels are low. Future studies should address the mechanisms of vitamin D/IGF-1 interaction.

The role of the intraplaque vitamin d system in atherogenesis

Vitamin D has been shown to play critical activities in several physiological pathways not involving the calcium/phosphorus homeostasis. The ubiquitous distribution of the vitamin D receptor that is expressed in a variety of human and mouse tissues has strongly supported research on these "nonclassical" activities of vitamin D. On the other hand, the recent discovery of the expression also for vitamin D-related enzymes (such as 25-hydroxyvitamin D-1 α -hydroxylase and the catabolic enzyme 1,25-dihydroxyvitamin D-24-hydroxylase) in several tissues suggested that the vitamin D system is more complex than previously shown and it may act within tissues through autocrine and paracrine pathways. This updated model of vitamin D axis within peripheral tissues has been particularly investigated in atherosclerotic pathophysiology. This review aims at updating the role of the local vitamin D within atherosclerotic plaques, providing an overview of both intracellular mechanisms and cell-to-cell interactions. In addition, clinical findings about the potential causal relationship between vitamin D deficiency and atherogenesis will be analysed and discussed.

Vitamin D status and resistance exercise training independently affect glucose tolerance in older adults

We assessed the influence of serum 25-hydroxyvitamin D (25[OH]D) and parathyroid hormone (PTH) concentrations on oral glucose tolerance, body composition, and muscle strength in older, nondiabetic adults who performed resistance exercise training (RT) while consuming diets with either 0.9 or 1.2 g protein kg(-1) d(-1). We hypothesized that individuals with insufficient 25(OH)D and/or high PTH would have less improvement in glucose tolerance after 12 weeks of RT compared with individuals with sufficient 25(OH)D and lower PTH. Sixteen men and 19 women (aged 61 ± 8 years; range, 50-80 years; body mass index, 26.3 ± 3.6 kg/m(2)) performed RT 3 times/wk for 12 weeks, with oral glucose tolerance tests done at baseline and postintervention. Protein intake did not influence the responses described below. Plasma glucose area under the curve (P = .02) and 2-hour plasma glucose concentration (P = .03) were higher for vitamin D-insufficient subjects (25[OH]D <50 nmol/L, n = 7) vs vitamin D-sufficient subjects (25[OH]D ≥50 nmol/L, n = 28). These differences remained significant after adjustment for age and body mass index. Resistance exercise training reduced fat mass (mean ± SD, -6% ± 7%; P < .001) and increased lean body mass (2% ± 3%, P < .001) and whole-body muscle strength (32% ± 17%, P < .001) in these weight-stable subjects but did not affect 25(OH)D or PTH concentrations. Oral glucose tolerance improved after RT (-10% ± 16% in glucose area under the curve and -21% ± 40% in 2-hour glucose, P = .001), but baseline 25(OH)D and PTH did not influence these RT-induced changes. These findings indicate that vitamin D status and RT independently affect glucose tolerance, and a training-induced improvement in glucose tolerance does not offset the negative effect of insufficient vitamin D status in older, nondiabetic adults.

A systematic review of vitamin D status in populations worldwide

Vitamin D deficiency is associated with osteoporosis and is thought to increase the risk of cancer and CVD. Despite these numerous potential health effects, data on vitamin D status at the population level and within key subgroups are limited. The aims of the present study were to examine patterns of 25-hydroxyvitamin D (25(OH)D) levels worldwide and to assess differences by age, sex and region. In a systematic literature review using the Medline and EMBASE databases, we identified 195 studies conducted in forty-four countries involving more than 168 000 participants. Mean population-level 25(OH)D values varied considerably across the studies (range 4·9-136·2 nmol/l), with 37·3 % of the studies reporting mean values below 50 nmol/l. The highest 25(OH)D values were observed in North America. Although age-related differences were observed in the Asia/Pacific and Middle East/Africa regions, they were not observed elsewhere and sex-related differences were not observed in any region. Substantial heterogeneity between the studies precluded drawing conclusions on overall vitamin D status at the population level. Exploratory analyses, however, suggested that newborns and institutionalised elderly from several regions worldwide appeared to be at a generally higher risk of exhibiting lower 25(OH)D values. Substantial details on worldwide patterns of vitamin D status at the population level and within key subgroups are needed to inform public health policy development to reduce risk for potential health consequences of an inadequate vitamin D status.

Dietary calcium intake is associated with adiposity, metabolic profile, inflammatory state and blood pressure, but not with erythrocyte intracellular calcium and endothelial function in healthy pre-menopausal women

Recent studies have suggested that dietary Ca may have beneficial effects on adiposity, insulin resistance, dyslipidaemia and blood pressure (BP). One potential mechanism underlying these benefits involves modifications in intracellular Ca concentration ([Ca2+]i). The present study aimed to evaluate the associations of dietary Ca with adiposity, erythrocyte [Ca2+]i, metabolic profile, BP, inflammatory state and endothelial function in healthy pre-menopausal women. In the present cross-sectional study, seventy-six women aged 18–50 years were submitted to the evaluation of dietary intake, anthropometric parameters, body composition, erythrocyte [Ca2+]i, biochemical variables, endothelial function and BP. A FFQ was used to assess usual dietary intake. Endothelial function was evaluated by serum concentrations of adhesion molecules and by the peripheral arterial tonometry (PAT) method, using Endo-PAT 2000®. Participants were allocated into two groups according to Ca intake: low-Ca group (LCG; n 32; < 600 mg/d) and high-Ca group (HCG; n 44; ≥ 600 mg/d). Women in the LCG compared with those in the HCG exhibited, after adjustments for potential confounders, higher values of BMI, waist circumference, waist:height ratio, percentage of body fat, insulin, homeostasis model assessment of insulin resistance, leptin, diastolic and mean BP; and lower levels of HDL-cholesterol, adiponectin and vascular cell adhesion molecule 1. Endothelial function assessed by PAT and [Ca2+]i was similar in both groups. Subjects in the HCG had lower OR for prevalent overweight, obesity, abdominal obesity, insulin resistance, HDL-cholesterol < 600 mg/l and systolic BP >120 mmHg. The findings of the present study suggest that high Ca intake is inversely associated with some cardiovascular risk factors.

A global representation of vitamin D status in healthy populations

PURPOSE

This paper visualizes the available data on vitamin D status on a global map, examines the existing heterogeneities in vitamin D status and identifies research gaps.

METHODS

A graphical illustration of global vitamin D status was developed based on a systematic review of the worldwide literature published between 1990 and 2011. Studies were eligible if they included samples of randomly selected males and females from the general population and assessed circulating 25-hydroxyvitamin D [25(OH)D] levels. Two different age categories were selected: children and adolescents (1-18 years) and adults (>18 years). Studies were chosen to represent a country based on a hierarchical set of criteria.

RESULTS

In total, 200 studies from 46 countries met the inclusion criteria, most coming from Europe. Forty-two of these studies (21 %) were classified as representative. In children, gaps in data were identified in large parts of Africa, Central and South America, Europe, and most of the Asia/Pacific region. In adults, there was lack of information in Central America, much of South America and Africa. Large regions were identified for which the mean 25(OH)D levels were below 50 nmol/L.

CONCLUSIONS

This study provides an overview of 25(OH)D levels around the globe. It reveals large gaps in information in children and adolescents and smaller but important gaps in adults. In view of the importance of vitamin D to musculoskeletal growth, development, and preservation, and of its potential importance in other tissues, we strongly encourage new research to clearly define 25(OH)D status around the world.

Parathyroid hormone is associated with biomarkers of insulin resistance and inflammation, independent of vitamin D status, in obese adolescents

BACKGROUND

25-Hydroxyvitamin D [25(OH)D] and parathyroid hormone (PTH) have been shown to correlate with several markers of metabolic syndrome in adult populations. We evaluated the relationship between circulating intact parathyroid hormone (iPTH) and 25(OH)D and indices of metabolic syndrome in obese adolescents.

METHODS

Body mass index (BMI), body composition, 25(OH)D, iPTH, fasting lipids, glucose, high-sensitivity C-reactive protein (hsCRP), glycosylated hemoglobin (HbA1c), insulin, and the homeostatic model assessment for insulin resistance (HOMA-IR) were evaluated in 133 obese adolescents.

RESULTS

Vitamin D deficiency [25(OH)D <50 nmol/L] was present in 45.1% of all patients, with higher prevalence in African-American (AA) and Hispanic (H) than Caucasian (C) subgroups (63.9% and 56.4% vs. 25.9%; P<0.001). iPTH and 25(OH)D were inversely correlated (r=-0.75; P<0.0001), with AA displaying a higher iPTH: 25(OH)D ratio than H and C subgroups (P<0.05). Whereas fat mass (FM) was negatively correlated with 25(OH)D (r=-0.30; p<0.001), it was positively correlated with iPTH levels (r=0.38; P<0.0001). Metabolic syndrome was identified in 57.9% of the cohort with higher iPTH, iPTH:25(OH)D ratio, but lower 25(OH)D than participants without metabolic syndrome (P<0.02). Whereas iPTH showed main effects for hsCRP (β=0.24, t=2.61, P<0.05) and triglycerides:high-density lipoprotein cholesterol (TG:HDL-C) (β=0.21, t=2.13, p<0.05), independent of serum 25(OH)D, it did not reveal a main effect for HOMA-IR.

CONCLUSIONS

Metabolic syndrome is associated with a higher iPTH:25(OH)D ratio than those without metabolic syndrome, implying greater risk of cardiovascular morbidities among AA subjects than other ethnic groups. Furthermore, the serum iPTH level is a predictor of chronic inflammation and dyslipidemia, independent of 25(OH)D.

Is intake of vitamin D and calcium important for cardiovascular health in elderly obese patients?

There is compelling evidence that bariatric weight loss reduces cardiovascular complications; however, these still tend to be the most common cause of late death after surgical intervention. In a prospective cohort study, correlations of dietary nutrients with indexes of vascular health were sought, with emphasis on vitamin D and calcium. Clinically stable obese outpatient subjects (>60 years old, N = 44) were interviewed about dietary macro and micronutrients. Nutritional assessment targeted anthropometric and bioimpedance analysis (BIA), hematologic counts, lipid profile, glucose homeostasis, and inflammatory markers. Carotid intima-media thickness (IMT) and brachial flow-mediated dilation (FMD), along with related vascular measurements, were documented, and results were correlated by uni- and multivariate analysis, corrected for known risk factors. IMT, FMD, and also brachial basal flow were positively influenced by vitamin D (P < 0.001). Calcium appeared beneficial for brachial basal flow only (P = 0.010). No association with IMT occurred, and a negative result for FMD was elicited. Also, vitamins A and B12 were advantageous for FMD, whereas iron was deleterious for IMT. Intake of many micronutrients including calcium and vitamin D did not meet recommendations. Vitamin D displayed a beneficial profile regarding vascular health, and more attention to this nutrient should be given, especially concerning obese patients with cardiometabolic risk. Calcium exhibited less straightforward results but deserves focus as well, along with antioxidant vitamin A as well as the B-complex which were mostly deficient in this experience.

Is vitamin D status relevant to metabolic syndrome?

Review of the evidence on hypovitaminosis D as a risk factor for metabolic syndrome and its sequelae, T2DM and CVD, suggests long-term vitamin D repletion could reduce these risks. There is mechanistic evidence for protective effects for MetS and the balance of evidence, (cross-sectional and prospective), supports this postulate. Much of the data so far available from randomized controlled trials is weakened by inadequate power, low vitamin D dosages, starting supplementation too late in life or after MetS disorders have developed or, most importantly, by non-inclusion of many recognizable confounders. On balance, therefore, maintenance of US 2010 recommended intakes for bone protection has the potential to prove protective for MetS. Supplementation has been shown to increase survival in patients with cardiac disorders; whether higher doses would provide useful protection for apparently healthy people in the general population awaits the outcomes of ongoing randomized-controlled trials that, it is hoped, will prove or disprove causality for hypovitaminosis D in MetS and its long-term ill-effects.

Interactions of single nucleotide polymorphisms with dietary calcium intake on the risk of metabolic syndrome

BACKGROUND

Gene-nutrient interactions may be important in modulating susceptibility to metabolic disorders.

OBJECTIVES

The objectives of this study were to assess the association of dietary calcium intake with the risk of metabolic syndrome and to investigate the interaction effects between dietary calcium intake and candidate gene polymorphisms.

DESIGN

Subjects were participants in the Korea Association Resource project, which was initiated in 2007 as a large-scale, genomewide association analysis. A total of 8031 subjects were included in the study. Associations were assessed by using multivariable-adjusted logistic regression analyses.

RESULTS

High calcium intake appeared to be associated with a low risk of metabolic syndrome after covariates in both men (P-trend = 0.03) and women (P-trend = 0.0002) were controlled for. Among 27 single nucleotide polymorphisms (SNPs) selected as possible candidate gene polymorphisms affecting the risk of metabolic syndrome, 3 SNPs [rs6445834 in Rho guanine nucleotide exchange factor 3 (ARHGEF3), rs10850335 in T-box 5 (TBX5), rs180349 in BUD13 homolog (Saccaromyces cerevisiae) (BUD13)] showed significant interaction effects with calcium intake tertiles or sufficiency in both men and women. Subjects with major allele homozygotes of these gene polymorphisms and high calcium intakes generally had a lower risk of metabolic syndrome than did those with minor allele homozygotes and low calcium intakes.

CONCLUSION

Dietary calcium intake appears to be inversely associated with the risk of metabolic syndrome and may modulate susceptibility to the syndrome in subjects who are minor allele carriers of rs6445834 in ARHGEF3, rs10850335 in TBX5, or rs180349 in BUD13.

Low 25(OH)D3 levels are associated with total adiposity, metabolic syndrome, and hypertension in Caucasian children and adolescents

OBJECTIVES

Evidence of the association between vitamin D and cardiovascular risk factors in the young is limited. We therefore assessed the relationships between circulating 25-hydroxyvitamin D(3) (25(OH)D(3)) and metabolic syndrome (MetS), its components, and early atherosclerotic changes in 452 (304 overweight/obese and 148 healthy, normal weight) Caucasian children.

METHODS

We determined serum 25(OH)D(3) concentrations in relation to MetS, its components (central obesity, hypertension, low high-density lipoprotein (HDL)-cholesterol, hypertriglyceridemia, glucose impairment, and/or insulin resistance (IR)), and impairment of flow-mediated vasodilatation (FMD) and increased carotid intima-media thickness (cIMT) - two markers of subclinical atherosclerosis.

RESULTS

Higher 25(OH)D(3) was significantly associated with a reduced presence of MetS. Obesity, central obesity, hypertension, hypertriglyceridemia, low HDL-cholesterol, IR, and MetS were all associated with increased odds of having low 25(OH)D(3) levels, after adjustment for age, sex, and Tanner stage. After additional adjustment for SDS-body mass index, elevated blood pressure (BP) and MetS remained significantly associated with low vitamin D status. The adjusted odds ratio (95% confidence interval) for those in the lowest (<17 ng/ml) compared with the highest tertile (>27 ng/ml) of 25(OH)D(3) for hypertension was 1.72 (1.02-2.92), and for MetS, it was 2.30 (1.20-4.40). A similar pattern of association between 25(OH)D(3), high BP, and MetS was observed when models were adjusted for waist circumference. No correlation was found between 25(OH)D(3) concentrations and either FMD or cIMT.

CONCLUSIONS

Low 25(OH)D(3) levels in Caucasian children are inversely related to total adiposity, MetS, and hypertension.

Vitamin D and metabolic health with special reference to the effect of vitamin D on serum lipids

Considering that the vitamin D receptor as well as the 1-α-hydroxylase enzyme that converts 25-hydroxyvitamin D (25(OH)D) to its active form 1,25-dihydroxyvitamin D have been found in tissues throughout the body, it is likely that vitamin D is important for more than the calcium balance. Accordingly, low serum levels of 25(OH)D have been associated with mortality, cardiovascular disease, type 2 diabetes, hypertension and obesity. Low serum levels of 25(OH)D have also been associated with an unfavourable lipid profile, which could possible explain the relation with cardiovascular disease and mortality. However, the relation between vitamin D and lipids have so far received little attention and is therefore the main focus of the present review. A PubMed search identified 22 cross-sectional studies where serum levels of 25(OH)D and lipids were related and that included a minimum of 500 subjects, and 10 placebo-controlled double-blind intervention studies with vitamin D where more than 50 subjects were included. In all the cross-sectional studies serum 25(OH)D was positively associated with high-density lipoprotein cholesterol (HDL-C) resulting in a favourable low-density lipoprotein cholesterol (LDL-C) (or total cholesterol) to HDL-C ratio. There was also a uniform agreement between studies on a negative relation between serum 25(OH)D and triglycerides (TG). On the other hand, the intervention studies gave divergent results, with some showing a positive and some a negative effect of vitamin D supplementation. However, none of the intervention studies were specifically designed for evaluating the relation between vitamin D and lipids, none had hyperlipemia as an inclusion criterion, and none were sufficiently powered. In only one study was a significant effect seen with an 8% (0.28 mmol/L) increase in serum LDL-C and a 16% (0.22 mmol/L) decrease in serum TG in those given vitamin D as compared to the placebo group. Accordingly, the effect of vitamin D supplementation on serum lipids is at present uncertain. Considering the numerous other promising vitamins and minerals that when properly tested have been disappointing, one should wait for the results of forthcoming vitamin D intervention studies before drawing conclusions on potential beneficial effects of vitamin D.

Serum 25-hydroxyvitamin D and parathyroid hormone are independent determinants of whole-body insulin sensitivity in women and may contribute to lower insulin sensitivity in African Americans

BACKGROUND

Circulating 25-hydroxyvitamin D [25(OH)D] and parathyroid hormone (PTH) concentrations have been shown to be associated with insulin sensitivity; however, adiposity may confound this relation. Furthermore, African Americans (AAs) have lower insulin sensitivity and 25(OH)D concentrations than do European Americans (EAs); whether these differences are associated in a cause-and-effect manner has not been determined.

OBJECTIVES

The objectives of this study were to examine the relation of 25(OH)D and PTH concentrations with whole-body insulin sensitivity and to determine whether lower 25(OH)D concentrations in AAs compared with EAs contribute to the lower insulin sensitivity of AAs relative to that of EAs.

DESIGN

This was a cross-sectional study of 25 AA and 25 EA women. We determined the whole-body insulin sensitivity index (S(I)) with an intravenous glucose tolerance test and minimal modeling. Percentage body fat was determined with dual-energy X-ray absorptiometry, and intraabdominal adipose tissue (IAAT) was determined with computed tomography.

RESULTS

Multiple linear regression analysis indicated that 25(OH)D and PTH concentrations were independent determinants of S(I) [standardized β = 0.24 (P = 0.04) and -0.36 (P = 0.002), respectively] after adjustment for age, race, and IAAT. The mean ethnic difference in S(I) decreased from 2.70 [· 10(-4) · min⁻¹/(μIU/mL)] after adjustment for IAAT and percentage body fat to 1.80 [· 10(-4) · min⁻¹/(μIU/mL)] after further adjustment for 25(OH)D and PTH concentrations.

CONCLUSIONS

25(OH)D and PTH concentrations were independently associated with whole-body insulin sensitivity in a cohort of healthy women, which suggested that these variables may influence insulin sensitivity through independent mechanisms. Furthermore, ethnic differences in 25(OH)D concentrations may contribute to ethnic differences in insulin sensitivity.