Vitamin D, parathyroid hormone and their associations with hypertension in a Chinese population. PLoS One. 2012;7:e43344. [PMID: 22937036 PMCID: PMC3420866 DOI: 10.1371/journal.pone.0043344]

The relationship between serum 25-hydroxy vitamin D status and hypertension in Syrian population: retrospective cohort study

Introduction

Vitamin D is a liposoluble steroid hormone that plays a crucial role in the maintenance of bone metabolism and calcium homoeostasis. Many studies on the effects of vitamin D on general health have been significantly increased, driven by new findings concerning the systemic and extraskeletal effects of this hormone. This study was performed to determine whether low levels of vitamin D were associated with hypertension in Syrian people.

Materials and methods

This retrospective cohort study consisted of 207 subjects, including 83 (40.1%) patients suffering from essential hypertension and 124 (59.9%) patients with normal blood pressure. Aged older than 18 years, who was referred to the endocrinology clinic from September 2022 to September 2023. The data were analysed by using SPSS (version 25). Logistic regression analyses were performed with adjustments for age, sex, and waist circumference.

Results

Hypertension rates were 73%, 20%, and 5% in 25-hydroxyvitamin D groups less than 12 ng/ml, 12-20 ng/mL, and greater than or equal to 20 ng/ml, respectively. Odds ratios (95% CIs) for hypertension adjusting for age, sex, and waist circumference were 178.6 (30.5_1045.6), 5.13 (0.9_26.5) for 25-hydroxyvitamin D levels less than 12 ng/ml, and 12-20 ng/ml, respectively, compared with the greater than or equal to 20 ng/ml group.

Conclusions

This study has shown a high prevalence of low vitamin D levels (25OHVD/20 ng/ml) among a sample of Syrian people (78.3%). The lowest 25OHVD group was associated with a higher prevalence of hypertension, which refers to an adverse association between vitamin D level and essential hypertension. Further research is needed to confirm this relationship.

Association of serum vitamin D levels and TaqIrs731236 among patients with hypertensive coronary heart disease

The development of cardiovascular diseases (CVD) is influenced through multiple risk factor and hypertension. It may increase the risk of cardiac events, and has a significant impact when combined with other risk factors including low levels of vitamin D and genetic variations like single nucleotide variations (SNV) (TaqIrs731236) in vitamin D receptor (VDR) gene. Blood samples from 500 study participants gathered including 250 hypertensive coronary heart disease patients, 250 age and gender matched healthy controls. To isolate genomic DNA, conventional salting out procedure used followed by amplification of targeted variations through Amplification Refractory Mutation System- Polymerase Chain Reaction (ARMS-PCR) Assay. The amplicon consists of 148 base pairs which was visualized on 2 % agarose gel electrophoresis and confirmed by DNA sequencing. The compared clinical parameters including systolic blood pressure (SBP), diastolic blood pressure (DBP), body mass index (BMI), high density lipoproteins (HDL), low density lipoproteins (LDL), cholesterol, triglycerides found significantly different among patients when compared with controls (P < 0.001). The Vitamin D exhibited insufficient levels at different stages of hypertension which were statistically, found significantly associated among patients with hypertensive coronary heart disease showing compared to controls (P < 0.001). The genotype association SNV (TaqIrs731236) T > C showed significant association with hypertensive coronary heart disease compared to healthy controls (Chi-Square χ2 = 60.75 and P < 0.00001). Further, the odds ratio of allelic association for risk allele (C) showed the strength of association with risk of disease, which increases by 2.02 times(P = 0.01). The results suggest that (TaqIrs731236) T > C as genetic predisposition factor, may contribute to develop the risk of hypertensive coronary heart disease. Hypertension as a risk factor along with insufficient levels of vitamin D and SNV (TaqIrs731236) as genetic variations may have been an important contributor to disease risk of hypertensive coronary heart disease.

Serum Vitamin D Levels in Relation to Hypertension and Pre-hypertension in Adults: A Systematic Review and Dose–Response Meta-Analysis of Epidemiologic Studies

Background

Findings of observational studies that evaluated the association of serum vitamin D status and high blood pressure were contradictory. This meta-analysis of epidemiologic studies assessed the relation of serum vitamin D levels to hypertension (HTN) and pre-hypertension in adults.

Methods

We conducted a systematic search of all published articles up to March 2021, in four electronic databases (MEDLINE (PubMed), Web of Science (ISI), Embase and Scopus), and Google scholar. Seventy epidemiologic studies (10 prospective cohort, one nested case–control, and 59 cross-sectional investigations) that reported relative risks (RRs), odds ratios (ORs), hazard ratios, or prevalence ratios with 95% CIs for HTN or pre-hypertension in relation to serum vitamin D concentrations in adults were included in the analysis.

Results

In prospective studies, a 16% decrease in risk of hypertension was observed in participants with high levels of serum vitamin D compared to low levels (RR: 0.84; 95%CI: 0.73, 0.96; 12 effect sizes). Dose–response analysis in prospective studies revealed that each 25 nmol/L increase in serum vitamin D concentrations resulted in 5% reduced risk of HTN (RR: 0.95; 95% CI: 0.90, 1.00). Also, a significant nonlinear relationship between serum vitamin D levels and HTN was found (P_nonlinearity < 0.001). In cross-sectional investigations, highest vs. lowest level of serum vitamin D was related to reduced odds of HTN (OR: 0.84; 95%CI: 0.79, 0.90; 66 effect sizes) and pre-hypertension (OR: 0.75; 0.95%CI: 0.68, 0.83; 9 effect sizes). Dose–response analysis in these studies showed that each 25 nmol/L increase in serum vitamin D levels was related to a significant 6% reduction in odds of hypertension in all populations (RR: 0.94; 95%CI: 0.90, 0.99) and 3% in studies with representative populations (RR: 0.97; 95%CI: 0.95, 0.99).

Conclusion

This meta-analysis of epidemiologic studies disclosed that serum vitamin D concentrations were inversely related to the risk of HTN in adults, in a dose–response manner in both prospective cohort and cross-sectional studies.

Systematic Review Registration:http://www.crd.york.ac.uk/Prospero, identifier: CRD42021251513.

Environmental Factors That Affect Parathyroid Hormone and Calcitonin Levels

Calciotropic hormones, parathyroid hormone (PTH) and calcitonin are involved in the regulation of bone mineral metabolism and maintenance of calcium and phosphate homeostasis in the body. Therefore, an understanding of environmental and genetic factors influencing PTH and calcitonin levels is crucial. Genetic factors are estimated to account for 60% of variations in PTH levels, while the genetic background of interindividual calcitonin variations has not yet been studied. In this review, we analyzed the literature discussing the influence of environmental factors (lifestyle factors and pollutants) on PTH and calcitonin levels. Among lifestyle factors, smoking, body mass index (BMI), diet, alcohol, and exercise were analyzed; among pollutants, heavy metals and chemicals were analyzed. Lifestyle factors that showed the clearest association with PTH levels were smoking, BMI, exercise, and micronutrients taken from the diet (vitamin D and calcium). Smoking, vitamin D, and calcium intake led to a decrease in PTH levels, while higher BMI and exercise led to an increase in PTH levels. In terms of pollutants, exposure to cadmium led to a decrease in PTH levels, while exposure to lead increased PTH levels. Several studies have investigated the effect of chemicals on PTH levels in humans. Compared to PTH studies, a smaller number of studies analyzed the influence of environmental factors on calcitonin levels, which gives great variability in results. Only a few studies have analyzed the influence of pollutants on calcitonin levels in humans. The lifestyle factor with the clearest relationship with calcitonin was smoking (smokers had increased calcitonin levels). Given the importance of PTH and calcitonin in maintaining calcium and phosphate homeostasis and bone mineral metabolism, additional studies on the influence of environmental factors that could affect PTH and calcitonin levels are crucial.

Joint effect of 25-hydroxyvitamin D and secondhand smoke exposure on hypertension in non-smoking women of childbearing age: NHANES 2007-2014

BACKGROUND

Vitamin D deficiency (VDD) may increase the risk of hypertension in women of childbearing age, who may be exposed to secondhand smoke (SHS) simultaneously. Till now, few studies have investigated the joint effects of VDD and SHS on hypertension in this population. We evaluated whether exposure to SHS modified the association between VDD and hypertension.

METHODS

Data from National Health and Nutrition Examination Surveys (NHANES) 2007-2014 were analyzed. Our research subjects were 2826 nonsmoking and nonpregnant women of childbearing age (20-44 years old). Hypertension was defined based either on systolic blood pressure (SBP) ≥ 130 mmHg and/or diastolic blood pressure (DBP) ≥ 80 mmHg or on now taking prescribed medicine for hypertension. The directed acyclic graphs (DAG) and the back-door criterion were used to select a minimal sufficient adjustment set of variables (MSAs) that would identify the unconfounded effect of 25(OH)D and hypertension. The interactive effect of VDD and SHS on hypertension was evaluated by using logistic regression models, followed by strata-specific analyses.

RESULTS

The prevalence of VDD in the hypertension group was significantly higher than that in the non-hypertension group (48.2% vs 41.0%, P = 0.008), as well as the exposure rate of SHS (39.1% vs 33.8%, P = 0.017). VDD was independently associated with nearly 50% increased risk of hypertension [adjusted odds ratio (aOR) = 1.43, 95% confidence interval (CI): 1.01, 2.04], while no significant association was observed between SHS and hypertension. However, SHS showed a significant synergistic effect on VDD with a higher aOR of 1.79 (95% CI: 1.14, 2.80) (P_interaction = 0.011). This synergistic effect was more obvious when stratified by BMI (in overweight women, aOR, 95% CI =4.74, 1.65-13.60 for interaction vs 2.33, 1.01-5.38 for VDD only) and race (in Non-Hispanic Black women, aOR, 95% CI =5.11, 1.58-16.54 for interaction vs 2.69, 1.10-6.62 for VDD only).

CONCLUSION

There exist synergistic effects of SHS and VDD on the prevalence of hypertension in American women of childbearing age, with more significant effects in women who were overweight or Non-Hispanic Black. Further studies are warranted to verify this finding in other populations, and the molecular mechanisms underlying the joint effect of SHS and VDD need to be elucidated.

Sleep duration is associated with vitamin D deficiency in older women living in Macao, China: A pilot cross-sectional study

Chinese women are known to have both a high prevalence of metabolic syndrome (MetS) and vitamin D deficiency (serum 25-hydroxyvitamin D (25OHD) <50 nmol/l). Associations between sleep duration and circulating 25OHD have recently been reported but, to our knowledge, these associations have not been studied in older Chinese populations. We thus investigated whether sleep duration was associated with vitamin D status in a population from Macao, China, and whether sleep duration modified the association between MetS and vitamin D deficiency. In 207 older (>55 years) Macanese, anthropometry, blood samples and validated questionnaires, including sleep duration and cardiovascular risk factors, were simultaneously collected. On multivariable categorical analyses, those women, not men, who had short sleep duration (≤6 hours (h)) were at a 2-fold risk for vitamin D deficiency (both <50 nmol/L and <37 nmol/L; OR = 1.94, 95%CI 1.29–2.92; OR = 2.05, 95%CI 1.06–3.98, respectively) and those who had longer sleep duration (>8 h) were 3-fold more likely to have vitamin D deficiency (OR = 3.07, 95%CI 1.47–6.39; OR = 2.75, 95%CI 1.08–7.00, respectively) compared to those with normal sleep duration (6–8 h). Both women and men with MetS were 2-fold more likely to have vitamin D deficiency (women: OR = 2.04, 95%CI 1.31–3.17; OR = 2.15, 95%CI 1.11–4.17, respectively; men: OR = 2.01, 95%CI 1.23–3.28; OR = 2.04, 95%CI 1.00–4.29, respectively). Moreover, women with both short sleep duration and MetS had an increased risk of vitamin D deficiency (OR = 3.26, 95%CI 1.10–9.64). These associations were not found in those with longer sleep. Men with longer sleep and MetS had a 5-fold risk of vitamin D deficiency (OR = 5.22; 95%CI 2.70–10.12). This association was non-significant for men with shorter sleep. We conclude that both short and long sleep duration were associated with vitamin D deficiency in older Chinese women. Further research is needed in larger cohorts or with intervention studies to further examine the associations between reduced sleep, metabolic syndrome and vitamin D deficiency.

Association of serum 25-hydroxyvitamin D levels with primary hypertension: a study from south India

Hypertension is a major risk factor for cardiovascular and cerebrovascular disease. Recent studies have identified an association between low vitamin D levels and hypertension. We investigated the association between vitamin D levels and hypertension in the general population. We recruited 400 hypertensive subjects and compared them with 400 age- and sex-matched normotensive subjects. This study was carried out at Yashoda Hospital, Hyderabad, India from January 2015 to December 2017. Both groups underwent risk factor evaluation, estimation of serum 25-hydroxyvitamin D levels, and C-reactive protein (CRP) and liver function tests. Out of the 400 hypertensive subjects, 164 (40.2%) had serum 25-hydroxyvitamin D deficiency, compared with 111 (27.7%) normotensive subjects (p = 0.0001). Deficiency of serum 25-hydroxyvitamin D in hypertensive subjects was significantly associated with CRP positivity, low levels of mean serum calcium, low levels of mean serum phosphorous, high levels of mean alkaline phosphatase (p < 0.0001), and abnormal alanine transaminase (ALT) (p = 0.0015) compared with the same parameters in the normotensive subjects. After adjustment in the multiple logistic regression analysis, serum 25-hydroxyvitamin D deficiency (odds: 1.78; 95% CI: 1.31-2.41), CRP positivity (odds: 1.48; 95% CI: 1.48-2.32) and abnormal ALT (odds: 1.2; 95% CI: 0.98-1.94) were significantly associated with hypertension. Serum 25-hydroxyvitamin D deficiency was significantly associated with hypertension.

Plasma Betaine Is Positively Associated with Developmental Outcomes in Healthy Toddlers at Age 2 Years Who Are Not Meeting the Recommended Adequate Intake for Dietary Choline

Background

Choline is an important nutrient during development. However, there are limited data on dietary choline intake and status in toddlers and the relation to neurodevelopmental outcomes.

Objective

This study assessed dietary choline intake and status in healthy toddlers at ages 1 and 2 y and determined the relation to neurodevelopmental outcomes.

Methods

This is a secondary analysis of data from healthy toddlers enrolled in a double-blind, randomized controlled trial of long-chain polyunsaturated fatty acid supplementation between ages 1 and 2 y. Dietary intakes of betaine and choline were estimated by 3-d food records; plasma free choline, betaine, and dimethylglycine were quantified by liquid chromatography-tandem mass spectrometry. Developmental outcomes were assessed at age 2 y with the use of the Bayley Scales of Infant and Toddler Development, 3rd edition (Bayley-III), Cognitive and Language composites, and the Beery-Buktenica Developmental Test of Visual-Motor Integration (Beery-VMI).

Results

The mean ± SD daily intake for total choline at age 1 y was 174 ± 56.2 mg/d and increased (P < 0.001) to 205 ± 67.5 mg/d at age 2 y. At ages 1 and 2 y, 71.8% and 55.8%, respectively, of toddlers did not meet the recommended 200-mg/d Adequate Intake (AI) for dietary choline. At age 1 y, mean ± SD plasma free choline, betaine, and dimethylglycine concentrations were 10.4 ± 3.3, 41.1 ± 15.4, and 4.1 ± 1.9 µmol/L, respectively. Plasma free choline (8.5 ± 2.3 µmol/L) and dimethylglycine (3.2 ± 1.3 µmol/L) concentrations were lower (P < 0.001) at age 2 y. Plasma betaine concentrations were positively associated with the Beery-VMI (β = 0.270; 95% CI: 0.026, 0.513; P = 0.03) at age 2 y.

Conclusions

These findings suggest that most toddlers are not meeting the recommended AI for dietary choline and that higher plasma betaine concentrations are associated with better visual-motor development at age 2 y. Further work is required to investigate choline metabolism and its role in neurodevelopment in toddlers. The trial is registered at clinicaltrials.gov as NCT01263912.

Vitamin D deficiency and risk of cardiovascular diseases: a narrative review

Vitamin D, a fat-soluble prohormone, has wide-ranging roles in the regulation of many physiological processes through their interactions with the vitamin D receptors (VDR). It plays a major role in bones and calcium metabolism. Vitamin D deficiency is not uncommon and it has been associated with many health-related issues, including skeletal and non-skeletal complications. The association of low vitamin D and cardiovascular diseases and risk factors has been explored in both animal and human studies. However, studies and trials on the effect of vitamin D supplementation on cardiovascular risk factors and hypertension are conflicting with inconsistent results. Therefore, large, well-powered randomized controlled trials are warranted. If successful, supplementation with easy and low-cost vitamin D can impact our health positively. Here, we summarized the evidence for the association of vitamin D, cardiovascular diseases and risk factors, including coronary artery diseases, stroke, and hypertension, and mortality, with special consideration to resistant hypertension.

High prevalence of vitamin D deficiency and influencing factors among urban and rural residents in Tianjin, China

There was a high prevalence of vitamin D deficiency among residents in Tianjin, China, especially among female residents, rural young adults, and elderly individuals. This is the first large-scale study evaluating vitamin D status in Tianjin, China, and we believe that it makes a significant contribution to the literature.

PURPOSE

Vitamin D deficiency has been documented as a worldwide public health problem. To our knowledge, there has not been any large-scale study on vitamin D status in Tianjin, China. The aim of this study was to investigate vitamin D status among Tianjin residents and to determine influencing factors.

METHODS

This is a community-based study, and residents from both urban and rural areas of Tianjin were enrolled. Each participant completed a questionnaire regarding basic characteristics and lifestyle information. Serum 25-hydroxyvitamin D [25(OH)D] levels were statistically analyzed according to sex, age, and region. Other factors associated with vitamin D deficiency were also explored.

RESULTS

A total of 1814 participants were included, with mean serum 25(OH)D level of 49.44 ± 14.9 nmol/L; only 47.63% achieved the optimal (50-125 nmol/L) 25(OH)D level. Serum 25(OH)D levels were higher among male participants than among female participants (53.44 ± 13.94 versus 46.55 ± 14.91 nmol/L, P < 0.05) and among urban participants than among rural participants (50.4 ± 16.32 versus 48.65 ± 13.58 nmol/L, P < 0.05). Serum 25(OH)D levels were significantly higher among the age group of 40-49 years (50.7 ± 17.99 nmol/L) than among the ≥ 70 years (48.45 ± 14.49 nmol/L) or 18-29 years (47.81 ± 13.08 nmol/L) age groups.

CONCLUSIONS

There was a high prevalence of vitamin D deficiency/inadequacy among Tianjin residents, especially among female participants, rural young adults, and elderly individuals. Vitamin D supplementation is imperative for these high-risk vitamin D-deficient residents.

Association of parathyroid hormone and vitamin D with untreated hypertension: Is it different in white-coat or sustained hypertension?

BACKGROUND

Previous reports about the relationship between a high parathyroid hormone (PTH) and low vitamin D levels with blood pressure in different hypertension groups are conflicting.

OBJECTIVE

We studied serum PTH and vitamin D levels in white-coat (WCHT) and sustained hypertension (SHT) patients who had not been on antihypertensive treatment. We also investigated the association between serum PTH and vitamin D levels with respect to blood pressure in SHT and WCHT patients.

METHODS

We included 52 SHT patients (54.06 ± 9.2 years, 32 newly diagnosed and 20 previously diagnosed with SHT who had not been treated with antihypertensive medication for 3 months or more), 48 WCHT patients (53.64 ± 9.5 years), and 50 normotensive (NT) healthy controls (53.44 ± 8.4 years) in our study. In addition to routine tests, PTH and vitamin D levels were measured.

RESULTS

Serum PTH levels were significantly higher in SHT patients not taking antihypertensive medications than in WCHT patients and NT controls (p = 0.004). Although PTH levels were higher in WCHT than in NT groups, the difference was not statistically significant. In SHT patients, PTH levels showed a positive correlation with office systolic (r = 0.363, p = 0.008), office diastolic (r = 0.282, p = 0.038), home systolic (r = 0.390, p = 0.004), and home diastolic blood pressures (r = 0.397, p = 0.003). Serum vitamin D levels were similar in SHT, WCHT and NT groups. Vitamin D levels were not associated with blood pressures in the entire study group. Furthermore, no significant relation was found between vitamin D and PTH levels in SHT and WCHT groups.

CONCLUSION

PTH levels are significantly higher in untreated SHT patients than WCHT patients and NT subjects. However, vitamin D levels are similar in SHT, WCHT and NT groups. There is a significant association between PTH levels and blood pressures suggesting PTH has a role in increase of blood pressure in SHT.

Evaluation of the Relationship between Serum 25-Hydroxy Vitamin D and Hypertension in Hamadan, Iran-A Case Control Study

INTRODUCTION

Hypertension or high blood pressure is one of the main reasons of fatality in the world. The role of vitamin D in developing hypertension has not been proved yet. Some studies have shown positive correlation between low serum vitamin D level and hypertension. Due to this fact, recognising hypertension risk factors such as potential impact of low serum vitamin D level seems to be required.

AIM

This study was conducted to evaluate potential impact of serum vitamin D level on hypertension.

MATERIALS AND METHODS

This case-control study had 188 subjects including 55 cases suffering from hypertension and 133 controls with normal blood pressure in Hamadan, Iran. After taking the medical history and physical examination, 5 cc of their blood was taken to measure their serum 25-Hydroxyvitamin D [25(OH)D] level through ELISA test. Data analysis was done by version 16.0 of SPSS software and used independent sample t-test and Chi-square test for related comparisons.

RESULTS

Mean and standard deviation of serum 25(OH)D level in patients suffering from hypertension was 13.10±9.7 ng/ml and in control group was 20.87±10.34 ng/ml. This variance was statistically significant (p<0.001). Mean serum 25(OH)D level in both case and control groups was measured after gender and age stratification. Mean serum 25(OH)D level in cases and controls was 13.12±11.4 ng/ml and 21.38±11.47 ng/ml in males (p=0.016) and 13.10±9.91 ng/ml and 19.19±10.55 ng/ml (p=0.004) in females, respectively. Mean serum 25(OH)D level in under 50-year-old was 10.82±8.73 ng/ml and 20.07±11.17 ng/ml in cases and controls respectively (p<0.001). In over 50-year-old, there was no significant relationship between mean serum 25(OH)D and blood pressure levels (p>0.05).

CONCLUSION

According to this study, reverse relationship between serum 25(OH)D and blood pressure levels was seen.

Vitamin D and hypertension: Prospective study and meta-analysis

OBJECTIVES

The study sought to determine the link between vitamin D concentrations and incident hypertension in prospective study and meta-analysis.

METHODS

The study was embedded in the Kailuan Study, a population-based cohort of adults that contains underground miners. In 2012, we studied 2,456 men and women free of prevalent hypertension, age 21 to 67 at baseline. Serum 25-hydroxyvitamin D was measured from previously frozen baseline samples using ELISA (Enzyme-Linked ImmunoadSorbent Assay). We use the logistic regression analysis to estimate the odd radio (ORs) 95% confidence intervals (CIs) for 25-hydroxyvitamin D [25(OH)D] concentrations with incident hypertension. To help place our new data in context, we conducted a systemic review and meta-analysis of previous prospective reports of vitamin D and hypertension.

RESULTS

During a median follow-up of 2 years, 42.6% of the cohort (n = 1047) developed hypertension. Compared with the 25-hydroxyvitamin D >30ng/ml, 25-hydroxyvitamin D <20 ng/ml was associated with a greater hypertension risk (OR: 1.225 [95% CI: 1.010 to 1.485] p = 0.04), although the association was attenuated and not statistically significant after adjusting for potential confounders (OR: 1.092 [95% CI: 0.866 to 1.377] p = 0.456). This meta-analysis included seven prospective studies for 53,375 participants using adjusted HR founded a significant association between vitamin D deficiencies and incident hypertension (HRs = 1.235 (95% CI: 1.083 to 1.409, p = 0.002)).

CONCLUSION

Lower serum 25-hydroxyvitamin D concentrations were not associated with a greater risk of incident hypertension. More research is needed to further determine the role of 25-hydroxyvitamin D in hypertension prevention and therapy.

Does Vitamin D Deficiency Lead to Hypertension?

Hypertension (HTN) or high blood pressure is one of the most chronic and deadliest disorders in the world. There are many risk factors responsible for HTN which include age, race, using tobacco, high salt intake, etc. One of the risk factors we would like to highlight is low vitamin D levels. While there is strong evidence that Vitamin D plays an important role in maintaining bone and muscle health, there has been recent debate regarding its role in hypertension. However, there are many studies that have shown an indirect relation between 25-hydroxyvitamin D serum level and blood pressure. However, we suggest that more studies, especially randomised trials, should be conducted.

Parathyroid hormone and the risk of incident hypertension: the Atherosclerosis Risk in Communities study

BACKGROUND

Recent evidence suggests that parathyroid hormone (PTH) has effects on vascular smooth muscle cells, the rennin-angiotensin system and kidney function, but less is known about its role in the development of hypertension. The distribution of serum PTH also varies by race.

METHODS AND RESULTS

Therefore, we examined the relation between PTH and incident hypertension and tested for interaction by race among 7504 Atherosclerosis Risk in Communities participants (1264 black, 6240 white, median age 56 years) without initial hypertension in 1990-1992. During a median follow-up of 6 years, 1487 white and 509 black participants developed hypertension. In the overall study population, PTH was not associated with incident hypertension after adjustment for demographics and behavioral risk factors [hazard ratio highest vs. lowest quintiles, 95% confidence interval: 1.11 (0.96-1.28); P for linear trend 0.02]. Although the interaction was not statistically significant (P = 0.60), there was some evidence that the PTH-hypertension association differed by race. Among blacks, PTH was positively associated with incident hypertension, independent of demographics, and behavioral risk factors (P for linear trend 0.003). Among whites, PTH was not associated with hypertension risk. Results were similar when comparing participants with elevated versus nonelevated PTH (≥65 vs. <65 pg/ml): hazard ratio in blacks: 1.24 (1.02-1.54); hazard ratio in whites: 0.95 (0.78-1.16).

CONCLUSIONS

In this large community-based cohort, PTH levels, overall, were not independently associated with the risk of hypertension. However, we found some evidence that PTH may be associated with hypertension in blacks. Future research should continue to explore potential race differences in the PTH-hypertension association.

Serum concentrations of 25-hydroxyvitamin D and its association with bone mineral density and serum parathyroid hormone levels during winter in urban males from Guiyang, Southwest China

Serum vitamin D (25-hydroxyvitamin D (25OHD)) may influence serum parathyroid hormone (PTH) levels and bone mineral density (BMD). In the present study, we assessed serum 25OHD concentration and its association with PTH and BMD in urban males from Guiyang (N26.57°), the capital city of Guizhou province, Southwest China. We recruited 634 males aged >20 years from the Guiyang Health Measures Survey, and stratified them into three groups according to age: young (20-39 years), middle aged (40-59 years) and older (60-79 years). We measured serum concentrations of 25OHD, PTH levels and BMD of the lumbar spine (L1-L4), femoral neck and total hip. In addition, we also explored the relationship between 25OHD and lifestyle, socio-economic characteristics and medical history by applying covariance analysis and locally weighted regression plots. The results showed that serum 25OHD was 75 nmol/l in 12·6 % of the subjects. Higher level of serum PTH was detected in relation to lower concentrations of serum 25OHD up to 50 nmol/l. A negative correlation between serum 25OHD and PTH concentrations was observed (r -0·207, P=0·003). Mean concentration of serum PTH increased gradually and plateaued while concentrations of serum 25OHD decreased to 50 nmol/l. Gradual increase in serum PTH was observed as 25OHD concentration was <25 nmol/l (P=0·004). BMD values at all sites were greater in the higher serum 25OHD concentration group. This study shows that low concentrations of serum 25OHD were common in males, and bone health was likely to be improved when serum 25OHD values were between 30 and 50 nmol/l.

Dissociation between Low Vitamin D Level and Hypertension in Coal Mine Workers: Evidence from the Kailuan Study

Objective The aim of this study was to evaluate the vitamin D status and the relationship between the vitamin D status and hypertension in a relatively large cohort in northern China. Methods This study was a part of the Kailuan study, consisting of 3,788 coal mine workers (including 2,532 underground workers and 1,256 surface workers) who received periodic health examinations between September 13, 2012 and December 24, 2012. Information on demographic factors, personal history and medical history were collected. The height, weight, blood pressure and serum25-hydroxyvitamin D [25(OH)D] level of each patient were measured. Results The mean 25(OH)D level in this cohort was 21.73±15.82 nmol/L. The number (%) of patients with vitamin D deficiency, insufficiency, inadequacy and sufficiency were 2,509 (66.24%), 1,051 (27.75%), 201 (5.31%) and 27 (0.71%), respectively. In all the participants, after adjusting for the age, salt intake, physical activity, smoking status, alcohol drinking status, work type, work environment, body mass index, diabetes and hyperlipidemia, the odds ratios for hypertension with 25(OH)D level ≥50, 25-50 and <25 nmol/L were 1.00 (reference), 1.44 (95%CI, 0.99-2.11) and 1.39 (95%CI, 0.97-1.99), respectively. Logistic regression models to evaluate the odds ratios and 95% CIs of hypertension for each quintile of the 25(OH)D level did not determine significant associations between the vitamin D status and hypertension. No significant associations were found in the underground workers or in the surface workers. Conclusion There was a high proportion of coal mine workers with vitamin D deficiency and insufficiency in Kailuan. However, no significant association between low vitamin D levels and hypertension was found in this cohort. Further investigations are needed to determine the relationship between vitamin D levels and hypertension.

Defining Vitamin D Deficiency and Its Relationship to Hypertension in Postmenopausal Korean Women

BACKGROUND

Inconsistent results regarding the association between low vitamin D level and hypertension (HTN) have led to uncertainty in clinical practice as to the use of vitamin D cutoff value. The aims of this study were to investigate the association between vitamin D deficiency and HTN in postmenopausal women and to determine the clinically significant cutoff value for vitamin D deficiency.

METHODS

We analyzed data from the Korean National Health and Nutrition Examination Survey 5 database (4107 postmenopausal women, aged 50-79 years). The cutoff value for vitamin D deficiency was based on the changes in parathyroid hormone (PTH) level according to serum 25(OH)D value.

RESULTS

PTH levels were significantly higher in groups with serum 25(OH)D <15 ng/mL (p < 0.001). When a serum 25(OH)D value of 15 ng/mL was used as a cutoff value, 35.2% of the subjects were found to be vitamin D deficient. Although the association between 25(OH)D level <15 ng/mL and systolic blood pressure did not remain significant after adjusting for season (p = 0.30), multiple logistic regression analysis revealed that 25(OH)D level <15 ng/mL was an independent risk factor for HTN (adjusted odds ratio [OR] 1.285, 95% confidence interval [CI] 1.024-1.614, p = 0.031).

CONCLUSIONS

Using serum PTH level, we defined vitamin D deficiency as 25(OH)D <15 ng/mL in postmenopausal women. Vitamin D deficiency [25(OH)D <15 ng/mL] was a significant risk factor for HTN in postmenopausal women.

Serum N(1)-Methylnicotinamide Is Associated With Obesity and Diabetes in Chinese

CONTEXT

Nicotinamide N-methyltransferase (NNMT) is a novel histone methylation modulator that regulates energy metabolism, and NNMT knockdown prevents diet-induced obesity in mice. However, whether NNMT plays a role in human obesity and type 2 diabetes (T2DM) remains to be elucidated.

OBJECTIVE

NNMT catalyzes methylation of nicotinamide to generate N(1)-methylnicotinamide (me-NAM). We aimed to investigate the associations of serum me-NAM with obesity and T2DM in Chinese.

DESIGN, SETTING, AND PARTICIPANTS

The study subjects (n = 1160) were recruited from Dali, a city of Yunnan Province, in southwest China. Anthropometric phenotypes, fasting glucose, and serum lipids were measured. Serum me-NAM was measured by liquid chromatography-mass spectrometry.

RESULTS

Serum me-NAM was positively correlated with body mass index and waist circumference and negatively with high-density lipoprotein (P ≤ .03). The correlations remained highly significant in the multivariate adjusted correlation analyses. In men (n = 691), positive correlations between me-NAM and fasting glucose, low-density lipoprotein, liver function, and serum creatinine levels were also observed in both simple and multivariate adjusted correlation analyses. In multiple logistic regression analyses, elevated serum me-NAM was associated with higher risks for overweight/obesity (odds ratios, 2.36 and 5.78; 95% confidence intervals, 1.10-5.08 and 1.78-18.76 for men and women, respectively; P ≤ .03) and diabetes (odds ratios, 1.56 and 1.86; 95% confidence intervals, 1.10-2.22 and 1.05-3.31 for men and women, respectively; P ≤ .03).

CONCLUSIONS

This first large-scale population study shows that me-NAM, as an indicator of NNMT activity, is strongly associated with obesity and diabetes, supporting NNMT as a potential target for treating obesity and diabetes in humans.

Vitamin D status and hypertension: a review

Vitamin D is a steroid prohormone synthesized in the skin following ultraviolet exposure and also achieved through supplemental or dietary intake. While there is strong evidence for its role in maintaining bone and muscle health, there has been recent debate regarding the role of vitamin D deficiency in hypertension based on conflicting epidemiological evidence. Thus, we conducted a scoping systematic literature review and meta-analysis of all observational studies published up to early 2014 in order to map trends in the evidence of this association. Mixed-effect meta-analysis was performed to pool risk estimates from ten prospective studies (n=58,262) (pooled risk for incident hypertension, relative risk [RR] =0.76 (0.63–0.90) for top vs bottom category of 25-hydroxyvitamin D [25OHD]) and from 19 cross-sectional studies (n=90,535) (odds ratio [OR] =0.79 (0.73–0.87)). Findings suggest that the better the assessed quality of the respective study design, the stronger the relationship between higher 25OHD levels and hypertension risk (RR =0.67 (0.51–0.88); OR =0.77 (0.72–0.89)). There was significant heterogeneity among the findings for both prospective and cross-sectional studies, but no evidence of publication bias was shown. There was no increased risk of hypertension when the participants were of older age or when they were vitamin D deficient. Younger females showed strong associations between high 25OHD levels and hypertension risk, especially in prospective studies (RR =0.36 (0.18–0.72); OR =0.62 (0.44–0.87)). Despite the accumulating evidence of a consistent link between vitamin D and blood pressure, these data are observational, so questions still remain in relation to the causality of this relationship. Further studies either combining existing raw data from available cohort studies or conducting further Mendelian analyses are needed to determine whether this represents a causal association. Large randomized controlled trials are also needed to determine whether vitamin supplementation may be beneficial in the prevention or the treatment of hypertension.

Vitamin D and parathyroid hormone status in a representative population living in Macau, China

Associations between documented sun-exposure, exercise patterns and fish and supplement intake and 25-hydroxyvitamin D (25OHD) and parathyroid hormone (PTH) were investigated in a random household survey of Macau residents (aged 18-93). Blood samples (566) taken in summer were analyzed for 25OHD and PTH. In this Chinese population, 55% were deficient (25OHD <50nmol/L: median (interquartile range)=47.7 (24.2) nmol/L). Vitamin D deficiency was greatest in those aged <50 years: median (interquartile range)=43.3 (18.2) nmol/L, females: median (interquartile range)=45.5 (19.4) nmol/L and those with higher educational qualifications: median (interquartile range)=43.1 (18.7) nmol/L. In the total Macau population, statistically significant (p<0.01) modifiable associations with lower 25OHD levels were sunlight exposure (β=0.06), physical activity (PA) (measured as hours(hrs)/day: β=0.08), sitting (measured as hrs/day β=-0.20), intake of fish (β=0.08) and calcium (Ca) supplement intake (β=0.06) [linear regression analysis adjusting for demographic risk factors]. On similar analysis, and after adjustment for 25OHD, the only significant modifiable associations in the total population with PTH were sitting (β=-0.17), Body Mass Index (β=0.07) and Ca supplement intake (β=-0.06). In this Macau population less documented sun exposure, fish and Ca supplement intake and exercise were associated with lower 25OHD levels, especially in the younger population, along with the interesting finding that more sitting was associated with both lower 25OHD and high PTH blood levels. In conclusion, unlike findings from Caucasian populations, younger participants were significantly more vitamin D deficient, in particular highly educated single females. This may indicate the desire of young females to be pale and avoid the sun. There are also big differences in lifestyle between the older generation and the younger, in particular with respect to sun exposure and PA. This article is part of a Special Issue entitled '17th Vitamin D Workshop'.

Modifiable risk factors including sunlight exposure and fish consumption are associated with risk of hypertension in a large representative population from Macau

Chinese populations are known to be at risk for vitamin D deficiency, with some evidence that this is due to lack of exposure to sunlight. Vitamin D deficiency and/or low sun exposure have been associated with higher incidence of hypertension in Caucasians. Thus, we investigated these associations in a Chinese population with a high rate of hypertension. From a random household survey of 1410 residents aged ≥18 years, height, weight and blood pressure were measured and demographic, exercise and dietary data were collected, as well as estimated hours of sunlight exposure on weekdays and weekends (in winter and summer). Modifiable predictors of hypertension in these data were lack of sunlight exposure and low intake of fish as well as smoking, obesity and lack of exercise. When investigated in a linear model, sunlight exposure was negatively associated with hypertension (β=-0.072, p<0.001) as was physical activity (β=-0.021, p<0.001) and fish consumption (β=-0.177, p<0.001). In contrast body mass index (weight/height(2)) was positively associated with hypertension (β=+0.62, p<0.001), as were pack-years of smoking (β=+0.27, p<0.001). On multivariate categorical analysis taking into account demographic risk factors in these data (age, gender and occupation) having more than half an hour's sun exposure per day compared to none was associated with less hypertension (OR=0.6, 95% CI: 0.4-0.8). Similarly, consuming either oily fish or seafood more than four times per week compared to less was also associated with less hypertension (oily fish (OR=0.4, 95% CI: 0.3-0.5); seafood consumption (OR=0.8, 95% CI: 0.7-0.9)). Having daily moderate physical activity compared to none was also associated with a lower risk of hypertension (OR=0.8, 95% CI: 0.7-0.9). In contrast, being obese compared to normal weight and having more than five pack-years of smoking compared to none were associated with a higher risk of hypertension (OR=4.6, 95% CI: 3.7-5.7; OR=1.4, 95% CI: 1.0-1.8, respectively). The major new findings of this study are that more sun exposure and high weekly fish consumption (especially oily fish) may be potentially modifiable independent factors for protecting against risk of hypertension in this population. This article is part of a Special Issue entitled '16th Vitamin D Workshop'.

Potential pathophysiological role for the vitamin D deficiency in essential hypertension

Vitamin D deficiency has been indicated as a pandemic emerging public health problem. In addition to the well-known role on calcium-phosphorus homeostasis in the bone, vitamin D-mediated processes have been recently investigated on other diseases, such as infections, cancer and cardiovascular diseases. Recently, both the discovery of paracrine actions of vitamin D (recognized as “local vitamin D system”) and the link of vitamin D with renin-angiotensin-aldosterone system and the fibroblast growth factor 23/klotho pathways highlighted its active cardiovascular activity. Focusing on hypertension, this review summarizes the more recent experimental evidence involving the vitamin D system and deficiency in the cardiovascular pathophysiology. In particular, we updated the vascular synthesis/catabolism of vitamin D and its complex interactions between the various endocrine networks involved in the regulation of blood pressure in humans. On the other hand, the conflicting results emerged from the comparison between observational and interventional studies emphasize the fragmentary nature of our knowledge in the field of vitamin D and hypertension, strongly suggesting the need of further researches in this field.

Parathyroid hormone has an important role in blood pressure regulation in vitamin D-insufficient individuals

OBJECTIVE

The aim of the present study was to evaluate whether vitamin D status is related to blood pressure (BP) in adults.

METHODS

We evaluated the relationship between vitamin D status, intact parathyroid hormone (iPTH) and BP in 332 adults. Anthropometric measurements, BP, and a fasting blood sample was obtained. Participants were stratified into the following BP categories: 1) normal BP; 2) high BP; 3) normal BP through medication. Vitamin D insufficiency was defined as 25-hydroxvitamin D ≤ 75 nmol/L; high iPTH as > 65 pg/mL. The relationships between vitamin D status, iPTH and BP were adjusted for body mass index, waist circumference, blood lipids, physical activity, and sunscreen use.

RESULTS

No differences in prevalences of vitamin D insufficiency and high iPTH were observed among BP groups. No significant association was observed between BP and vitamin D status. Positive correlations were observed between iPTH and systolic BP (r = 0.168; P = 0.002) and between iPTH and diastolic BP (r = 0.168; P = 0.002). iPTH remained correlated with BP even with adjustments.

CONCLUSIONS

The present study contributes to the understanding of calcemic hormones and BP regulation.

Serum 25(OH)D and vitamin D status in relation to VDR, GC and CYP2R1 variants in Chinese

Previous studies have identified several common genetic variants in VDR, GC and CYP2R1 to be associated with circulating levels of 25-hydroxyvitamin D [25(OH)D] and vitamin D deficiency in Western populations. We aimed to investigate the associations of these variants with serum levels of 25(OH)D and vitamin D status in 1,199 Chinese. Nine common variants of VDR, GC and CYP2R1 were genotyped using multiple SNaPshot assay, and serum 25(OH)D was detected by radioimmunoassay. The prevalence of vitamin D deficiency (<50 nmol/L) was 38.8%, which is higher in women (46.2%) than in men (34.3%, P<0.0001). The risk alleles of three common variants of GC (rs7041, rs4588, and rs2282679) were significantly associated with a lower serum levels of 25(OH)D (-1.789 ≤β ≤-3.549, P ≤0.006), while common variants in VDR and CYP2R1 were not associated with serum levels of 25(OH)D after adjusted for covariates (P ≥0.30). None of the nine common variants were associated with the presence of vitamin D deficiency in multivariable adjusted logistic regression analyses (P ≥0.17). Haplotype-based analyses of GC-rs7041 and rs4588 showed that the haplotype Gc2-2 (rs7041 AA and rs4588 TT) had the lowest levels of 25(OH)D compared with other haplotypes that contained at least one copy of Gc1 allele (Ptrend <0.0001). Our results suggest that the common variants of GC are genetic determinants of serum 25(OH)D in Chinese.

Adiposity and the relationship between vitamin D and blood pressure

OBJECTIVE

Circulating vitamin D (25OHD) concentrations are negatively associated with blood pressure (BP) but little is known about the mechanisms for this relationship. Adiposity is positively associated with BP and inversely with circulating 25OHD concentrations but no studies have assessed the relationship between plasma 25OHD and adiposity on BP. The goal of this study is to investigate if the association between plasma 25OHD and BP is mediated by adiposity.

MATERIALS/METHODS

The relationship between plasma 25OHD, systolic and diastolic BP, and adiposity [BMI, waist circumference, visceral adipose tissue (VAT)] was assessed in a multi-ethnic cross-sectional study of Aboriginal (n=151), Chinese (n=190), European (n=170), and South Asian (n=176) participants by linear regression models.

RESULTS

Plasma 25OHD concentrations were negatively associated with systolic (standardized B=-0.191, P<0.001) and diastolic BP (standardized B=-0.196, P<0.001) in models adjusted for age, sex, ethnicity, family history of CVD, smoking status, alcohol consumption, and physical activity. The negative relationship between plasma 25OHD concentrations and systolic and diastolic BP was attenuated after the addition of BMI, waist circumference, and VAT to the models, but the relationship remained significant. Plasma 25OHD concentrations accounted for 0.7% and 0.8% of the variance in systolic and diastolic BP, respectively.

CONCLUSION

These findings suggest that the relationship between vitamin D and BP is independent of adiposity. Further studies are required to determine the mechanisms by which vitamin D affects BP.

Poststroke hip fracture: prevalence, clinical characteristics, mineral-bone metabolism, outcomes, and gaps in prevention

Objective. To assess the prevalence, clinical and laboratory characteristics, and short-term outcomes of poststroke hip fracture (HF). Methods. A cross-sectional study of 761 consecutive patients aged ≥60 years (82.3 ± 8.8 years; 75% females) with osteoporotic HF. Results. The prevalence of poststroke HF was 13.1% occurring on average 2.4 years after the stroke. The poststroke group compared to the rest of the cohort had a higher proportion of women, subjects with dementia, history of TIA, hypertension, coronary artery disease, secondary hyperparathyroidism, higher serum vitamin B12 levels (>350 pmol/L), walking aid users, and living in residential care facilities. The majority of poststroke HF patients had vitamin D insufficiency (68%) and excess bone resorption (90%). This group had a 3-fold higher incidence of postoperative myocardial injury and need for institutionalisation. In multivariate analysis, independent indicators of poststroke HF were female sex (OR 3.6), history of TIA (OR 5.2), dementia (OR 4.1), hypertension (OR 3.2), use of walking aid (OR 2.5), and higher vitamin B12 level (OR 2.3). Only 15% of poststroke patients received antiosteoporotic therapy prior to HF. Conclusions. Approximately one in seven HFs occurs in older stroke survivors and are associated with poorer outcomes. Early implementation of fracture prevention strategies is needed.

Oral supplementation with probiotic L. reuteri NCIMB 30242 increases mean circulating 25-hydroxyvitamin D: a post hoc analysis of a randomized controlled trial

CONTEXT

Low serum 25-hydroxyvitamin D is a risk factor for osteoporosis, cardiovascular disease, diabetes, and cancer. Disruption of noncholesterol sterol absorption due to cholesterol-lowering therapies may result in reduced fat-soluble vitamin absorption.

OBJECTIVE

We have previously reported on the cholesterol-lowering efficacy and reduced sterol absorption of probiotic bile salt hydrolase active Lactobacillus reuteri NCIMB 30242; however, the effects on fat-soluble vitamins was previously unknown and the objective of the present study. DESIGN, SETTINGS, PATIENTS, AND INTERVENTION: The study was double-blind, placebo-controlled, randomized, parallel-arm, multicenter lasting 13 weeks. A total of 127 otherwise healthy hypercholesterolemic adults with low-density lipoprotein-cholesterol >3.4 mmol/L, triglycerides <4.0 mmol/L, and body mass index of 22 to 32 kg/m² were included. Subjects were recruited from 6 private practices in Prague, Czech Republic, and randomized to consume L. reuteri NCIMB 30242 or placebo capsules over a 9-week intervention period.

OUTCOME MEASURES

The primary outcome measure was the change in serum low-density lipoprotein-cholesterol over the 9-week intervention. Analysis of fat-soluble vitamins at weeks 0 and 9 were performed post hoc.

RESULTS

There were no significant differences between L. reuteri NCIMB 30242 and placebo capsule groups in serum vitamin A, vitamin E, or β-carotene or dietary intake over the intervention period (P > .05). L. reuteri NCIMB 30242 increased serum 25-hydroxyvitamin D by 14.9 nmol/L, or 25.5%, over the intervention period, which was a significant mean change relative to placebo of 17.1 nmol/L, or 22.4%, respectively (P = .003).

CONCLUSIONS

To our knowledge, this is the first report of increased circulating 25-hydroxyvitamin D in response to oral probiotic supplementation.

A glimpse of vitamin D status in Mainland China

As an essential dietary micronutrient, vitamin D plays a pivotal role in promoting calcium absorption in the intestine and maintaining a healthy skeletal system throughout life. Beyond bone health, an emerging volume of scientific studies shows that vitamin D also may provide cardiovascular, metabolic, and immunologic benefits and reduce mortality. To our knowledge, in mainland China no national surveys have been conducted to date to depict the overall vitamin D status in the population. Therefore, the purpose of this contribution was to provide the best possible evaluation of vitamin D deficiency/insufficiency in China by reviewing publications that measured plasma/serum 25-hydroxyvitamin-D (25[OH]D) levels in various age groups and in different areas of China from January 2000 to June 2012. From these investigations conducted throughout the country and from newborns to adults to the elderly, it has been found that vitamin D deficiency/insufficiency is prevalent in the Chinese population in almost all age groups and areas if individuals are not taking vitamin D-fortified products/supplements or are lacking sufficient sunshine exposure. Some studies showed severe deficiency (25[OH]D <25 nmol/L) in Nanjing (north latitude 31) during the winter months and in Beijing (north latitude 40) in the fall. This unoptimistic situation represents a significant but modifiable public health risk that deserves greater attention and more efficient and timely management.