Serum 25-hydroxyvitamin D3 and body composition in an elderly cohort from Germany: a cross-sectional study

Association of vitamin D levels with anthropometric and adiposity indicators across all age groups: a systematic review of epidemiologic studies

Objectives

It has not been established whether vitamin D deficiency is associated with anthropometric state; therefore, this systematic review examined the relationship between serum vitamin D levels with anthropometrics and adiposity across different ages.

Methods

Studies that examined vitamin D deficiency with adiposity measures in different age groups were searched in the PubMed, Scopus, Embase, and Google Scholar databases until November 2023. Two investigators independently reviewed titles and abstracts, examined full-text articles, extracted data, and rated the quality in accordance with the Newcastle-Ottawa criteria.

Results

Seventy-two studies, with a total of 59,430 subjects, were included. Of these studies, 27 cross-sectional studies and one longitudinal study (with 25,615 participants) evaluated the possible link between 25(OH)D serum concentrations and anthropometric/adiposity indices in the pediatric population. Forty-two cross-sectional studies and two cohort investigations (with 33,815 participants) investigated the relationship between serum 25(OH)D levels and adiposity measures in adults and/or the elderly population. There is evidence supporting links between vitamin D deficiency and obesity, and revealed an inverse association between vitamin D and adiposity indicators, specifically in female subjects. However, the effects of several confounding factors should also be considered.

Conclusion

Most published studies, most of which were cross-sectional, reported a negative association between vitamin D and female adiposity indicators. Therefore, serum vitamin D levels should be monitored in overweight/obese individuals.

Vitamin D status among Kashmiri tribal population: A cross-sectional community-based study

Background & objectives

Vitamin D deficiency (VDD) is prevalent across all age groups in general population of India but studies among tribal populations are scanty. This study aimed to evaluate the prevalence of VDD in the indigenous tribal population of the Kashmir valley and examine associated risk factors.

Methods

In this cross-sectional investigation, a total of 1732 apparently healthy tribal participants (n=786 males and n=946 females) were sampled from five districts of Kashmir valley by using probability proportional to size method. Serum 25-hydroxy vitamin D (25(OH)D) levels were classified as per the Endocrine Society (ES) recommendations: deficiency (<20 ng/ml), insufficiency (20-30 ng/ml) and sufficiency (>30 ng/ml). The serum 25(OH)D levels were assessed in relation to various demographic characteristics such as age, sex, education, smoking, sun exposure, body mass index and physical activity.

Results

The mean age of the male participants was 43.79±18.47 yr with a mean body mass index (BMI) of 20.50±7.53 kg/m^[2], while the mean age of female participants was 35.47±14.92 yr with mean BMI of 22.24±4.73 kg/m². As per the ES guidelines 1143 of 1732 (66%) subjects had VDD, 254 (14.71%) had insufficient and 334 (19.3%) had sufficient serum 25(OH)D levels. VDD was equally prevalent in male and female participants. Serum 25(OH)D levels correlated positively with serum calcium, phosphorous and negatively with serum alkaline phosphatase. Gender, sun exposure, altitude, physical activity and BMI did not seem to contribute significantly to VDD risk.

Interpretation & conclusions

VD deficiency is highly prevalent among Kashmiri tribals, although the magnitude seems to be lower as compared to the general population. These preliminary data are likely to pave way for further studies analyzing the impact of vitamin D supplementation with analysis of functional outcomes.

How can the orthopedic surgeon ensure optimal vitamin D status in patients operated for an osteoporotic fracture?

In this narrative review, the role of vitamin D deficiency in the pathophysiology, healing of fragility fractures, and rehabilitation is discussed. Vitamin D status can be assessed by measuring serum 25(OH)-vitamin D level with standardized assays. There is a high prevalence of vitamin D insufficiency (25(OH)D < 50 nmol/l (i.e., 20 ng/mL)) or deficiency (25(OH)D < 25 nmol/l (i.e., 10 ng/mL)) in patients with fragility fractures and especially in those with a hip fracture. The evidence on the effects of vitamin D deficiency and/or vitamin D supplementation on fracture healing and material osseointegration is still limited. However, it appears that vitamin D have a rather positive influence on these processes. The fracture liaison service (FLS) model can help to inform orthopedic surgeons, all caregivers, and fractured patients about the importance of optimal vitamin D status in the management of patients with fragility fractures. Therefore, vitamin D status should be included in Capture the Fracture® program as an outcome of FLS in addition to dual-energy X-ray absorptiometry (DXA) and specific antiosteoporosis medication. Vitamin D plays a significant role in the pathophysiology and healing of fragility fractures and in rehabilitation after fracture. Correction of vitamin D deficiency should be one of the main outcomes in fracture liaison services.

Vitamin D levels in IBD: a randomised trial of weight-based versus fixed dose vitamin D supplementation

Objectives: Body weight is one of the factors affecting blood levels of 25-hydroxyvitamin D (25OHD). The aim of this study was to establish whether a vitamin D (vitD) weight-based dosing is more appropriate to a fixed daily dose in patients with inflammatory bowel disease (IBD).Materials/methods: This was an open label randomised trial. Patients with IBD were assigned to receive oral cholecalciferol at a dose of 28 IU/kg (IU/kg) or 2000 IU per day (IU/day) for 12 weeks during winter months. 25OHD plasma levels and other biochemical parameters were measured at baseline and after supplementation period. The primary outcome measure was 25OHD level after a follow-up period.Results: A total of 173 patients were analysed. The mean BMI was 25.5 ± 5.1 and initial mean 25OHD level was 62.7 ± 25.5 nmol/l. A similar increase (9.7 ± 26.9 vs 9.8 ± 26.7 nmol/l) in 25OHD levels occurred both in IU/kg and IU/day group. The proportion of subjects with normal and sub-normal levels following the substitution was comparable irrespective of body weight. The change in 25OHD level correlated positively only with the dose of vitD (p < .001) and negatively with the baseline 25OHD level (p < .001). A sustained 25OHD level of 75 nmol/l corresponds with a calculated daily vitD dose of 2034 IU.Conclusions: Weight-based dosing of vitamin D is not superior to a fixed dose in order to maintain stable 25OHD levels in IBD patients. Cholecalciferol dose of 2,000 IU/day is safe and sufficient during winter period.

Targeted 25-hydroxyvitamin D concentration measurements and vitamin D3 supplementation can have important patient and public health benefits

Over the past two decades, many studies reported the benefits of higher 25-hydroxyvitamin D [25(OH)D] concentrations for nonskeletal effects. Researchers found significant benefits in reducing risk of acute respiratory tract infections, many types of cancer, type 2 diabetes mellitus, premature death, and adverse pregnancy and birth outcomes. In addition, 25(OH)D concentrations are low for various reasons in several categories of people, including the obese, those with dark skin living at higher latitudes, the elderly, and those who do not eat much eggs, fish, meat, or vitamin D fortified milk. Measuring 25(OH)D concentrations is one way to both increase the awareness of vitamin D's importance in maintaining good health and to encourage vitamin D supplementation or increased solar ultraviolet-B exposure to sustain well-being throughout life by reducing disease incidence. Although 20 ng/ml seems adequate to reduce risk of skeletal problems and acute respiratory tract infections, concentrations above 30 ng/ml have been associated with reduced risk of cancer, type 2 diabetes mellitus, and adverse pregnancy and birth outcomes. Thus, judicious testing of 25(OH)D concentrations could reduce disease incidence and make treatment expenditures more cost-effective.

Vitamin D status of overweight and obese Bangladeshi adults

Background:

Both obesity and vitamin D deficiency are pandemics and both have influences on cardiovascular parameters. The reported prevalence of vitamin D deficiency in obesity is high. Data relating to vitamin D status in obese is currently lacking in Bangladesh.

Objective:

To discover the vitamin D status in Bangladeshi overweight and obese adults.

Subjects and Methods:

This cross-sectional study, conducted in a specialized endocrine center of Bangladesh, evaluated 500 consecutive overweight or obese subjects, diagnosed according to body mass index (BMI) categories applicable to the south Asian population. Serum 25(OH)D was measured by using the enzyme-linked fluorescent assay (ELFA) method, and the cutoffs described by the Endocrine Society were used to define vitamin D status.

Results:

The mean age of the study subjects was 45.85 (±11.41) years; most (59.6%) of them were in the age group 40–59 years; almost three-fourth (72.4%) were females; an almost equal number of them came from urban (33.8%), semi-urban (29.6%), and rural (36.6%) areas; three-fourth (74.2%) were homemaker. Their mean BMI was 29.54 (±3.11) kg/m²; the frequencies of overweight, class I obesity, class II obesity, and class III obesity were 27.6%, 57.4%, 12.2%, and 2.8%, respectively. The mean serum 25(OH)D level was 25.25 (±11.97) ng/mL. 27.4% were sufficient, and 33.4% were insufficient for vitamin D, whereas 39.2% had vitamin D deficiency. The 25(OH)D level did not differ across different age groups, gender, residence, education status, occupation, and income status. The 25(OH)D levels were also indifferent in overweight, obese class I, obese class II, and obese class III subjects. None of the demographic, anthropometric, and biochemical variables (except low-density lipoprotein cholesterol) correlated with 25(OH)D levels.

Conclusions:

The prevalence of vitamin D deficiency in overweight and obese Bangladeshi adults is very high.

Linking the metabolic syndrome and obesity with vitamin D status: risks and opportunities for improving cardiometabolic health and well-being

The global death toll from noncommunicable diseases is exceptionally high, reported to cause 71% of global deaths worldwide. Metabolic syndrome risk factors, especially excessive adiposity and obesity, are at the heart of the problem resulting in increased co-morbidities such as cardiometabolic diseases and cancer, increased health costs, poorer quality of life, and shortened survival. Vitamin D3 can positively reverse many of these adverse effects and outcomes through blocking signaling mechanisms that predispose to cardiometabolic and metastatic disease. As an affordable natural agent, vitamin D3 can be used to counteract obesity-induced inflammation, block early adipogenesis, enhance glucose uptake, counteract hyperleptinemia, ameliorate insulin resistance, and reduce hypertension. This is supported by data from in vitro, in vivo and epidemiological studies and clinical trials. We propose that everyone in general and obese patients in particular consider raising 25-hydroxyvitamin D levels through UVB exposure and/or supplemental vitamin D3 intake to reduce cardiometabolic and metastatic disease and increase longevity.

Relation of Serum 25(OH)-Vitamin D to Fat Mass and Lean Mass, Bone Mineral Content and Body Composition in Adults – a DXA-Based Study

Obesity has been linked with vitamin D deficiency in a number of cross-sectional studies, reviews and meta-analyses. The aim of the present study was to assess the correlations of plasma 25(OH) vitamin D levels with indices of body composition examined by DXA with an emphasis on lean and bone mass as well as on indices such as android/gynoid fat, appendicular lean mass, fat-mass indexes (FMI) and fat-free mass indexes (FFMI). 62 adult subjects consented to participate – 27 men (43.5%) and 35 women (56.5%). Their mean age was 45.3 ± 9.5 years. Fan-beam dual-energy X-ray (DXA) body composition analysis was performed on a Lunar Prodigy Pro bone densitometer with software version 12.30. Vitamin D was measured by electro-hemi-luminescent detection as 25(OH) D Total (ECLIA, Elecsys 2010 analyzer, Roche Diagnostics). Statistical analyses were done using the SPSS 23.0 statistical package. The serum 25(OH)D level was correlated significantly only to the whole body bone mineral content, the appendicular lean mass index (ALMI) and the ALM-to-BMI index, underlining a predominant role for lean and fat-free mass. Vitamin D showed a very weak correlation to % Body Fat and the Fat Mass Index (FMI) in men only. Moreover, the multiple regression equation including the associated parameters could explain only 7% of the variation in the serum 25(OH) D levels. Our conclusion was, that there are differences in the associations of the vitamin D levels with the different body composition indices, but these associations are generally very weak and therefore – negligible.

Cross-sectional and longitudinal associations between serum 25‑hydroxyvitamin D and anti-oxidative status in older adults

OBJECTIVE

Emerging evidence indicates that vitamin D has anti-oxidative properties. The present study investigates whether serum 25‑hydroxyvitamin D [25(OH)D] is associated with biomarkers of anti-oxidative status in community-dwelling older adults using cross-sectional and longitudinal data.

METHODS

A total of 302 subjects aged 62 to 92 years from Germany (50.6°N) were analysed via cross-sectional approach. For longitudinal analysis, data of 153 subjects were available. Fasting blood samples from 2004 and 2012 were analysed for 25(OH)D concentrations, total anti-oxidative status (TAOS) as well as anti-oxidative enzymes, such as catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD). Multiple regression analyses were performed to examine the associations between 25(OH)D and parameters of anti-oxidative status.

RESULTS

In cross-sectional analyses, 25(OH)D was a significant predictor of CAT (β = -0.166; P = 0.010), lg₁₀ GPx (β = 0.136; P = 0.037) and TAOS (β = 0.121; P = 0.048) after adjusting for age, sex, percentage total body fat (TBF), month of blood sampling, smoking behaviour and use of vitamin D supplements. Longitudinal change in 25(OH)D concentration positively predicted change in TAOS (β = 0.224; P = 0.006) after adjusting for sex, baseline TAOS, age, smoking behaviour, use of vitamin D supplements and change in TBF, physical activity level, current time spent outdoors and dietary vitamin D intake.

CONCLUSION

The maintenance of an adequate vitamin D status may have a beneficial impact on the anti-oxidative defence system in older adults on a long-term perspective.

Italian Association of Clinical Endocrinologists (AME) and Italian Chapter of the American Association of Clinical Endocrinologists (AACE) Position Statement: Clinical Management of Vitamin D Deficiency in Adults

Vitamin D deficiency is very common and prescriptions of both assay and supplementation are increasing more and more. Health expenditure is exponentially increasing, thus it is timely and appropriate to establish rules. The Italian Association of Clinical Endocrinologists appointed a task force to review literature about vitamin D deficiency in adults. Four topics were identified as worthy for the practicing clinicians. For each topic recommendations based on scientific evidence and clinical practice were issued according to the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) System. (1) What cut-off defines vitamin D deficiency: even though 20 ng/mL (50 nmol/L) can be considered appropriate in the general population, we recommend to maintain levels above 30 ng/mL (75 nmol/L) in categories at risk. (2) Whom, when, and how to perform screening for vitamin D deficiency: categories at risk (patients with bone, liver, kidney diseases, obesity, malabsorption, during pregnancy and lactation, some elderly) but not healthy people should be screened by the 25-hydroxy-vitamin D assay. (3) Whom and how to treat vitamin D deficiency: beyond healthy lifestyle (mostly sun exposure), we recommend oral vitamin D (vitamin D2 or vitamin D3) supplementation in patients treated with bone active drugs and in those with demonstrated deficiency. Dosages, molecules and modalities of administration can be profitably individually tailored. (4) How to monitor the efficacy of treatment with vitamin D: no routine monitoring is suggested during vitamin D treatment due to its large therapeutic index. In particular conditions, 25-hydroxy-vitamin D can be assayed after at least a 6-month treatment. We are confident that this document will help practicing clinicians in their daily clinical practice.

Role of Parathyroid Hormone in Determination of Fat Mass in Patients with Vitamin D Deficiency

BACKGROUND

Obesity has become a global epidemic and it is rising is Asia. Vitamin D deficiency (VDD) is widely prevalent in the Indian subcontinent. Studies have linked VDD to obesity and shown correlation between parathyroid hormone (PTH), 25-hydroxy Vitamin D (25(OH)D), and fat mass (FM). However, studies on the role of PTH among subjects with VDD are lacking.

OBJECTIVE

The objective of this study is to study the role of PTH in the determination of FM in participants with VDD.

SUBJECTS

Five hundred and fifty-one adults (m:247, f:304) were included in this study.

MATERIALS AND METHODS

Total and regional (trunk, arm, and leg) FM was assessed by dual X-ray absorptometry. Biochemical and hormonal parameters such as calcium, phosphorus, alkaline phosphatase, ionic calcium, 25(OH)D, and PTH were also analyzed.

RESULTS

The mean age of the study population was 58.8 ± 15.8 years (Male: [63.3 ± 13.1], Female: [55.2 ± 16.9]). FM and body mass index were significantly lower in females with higher levels of serum 25(OH)D. Total FM was negatively correlated with serum 25(OH)D (r = -0.363, P < 0.0001) and positively correlated with serum PTH (r: 0.262, P < 0.0001) in females only. Females with VDD and secondary hyperparathyroidism had higher FM than those with normal PTH.

CONCLUSIONS

Females with VDD had higher total and regional FM. However, this correlation was evident only in those with high serum PTH levels, suggesting a potential role of PTH in the accumulation of FM.

Association of 25-hydroxyvitamin D and parathyroid hormone with the metabolic syndrome in black South African women

The relationship between 25 hydroxyvitamin D (25(OH)D), parathyroid hormone (PTH) and metabolic traits appear to differ among ethnicities and may be influenced by obesity. The aim of the study was to examine the association of serum 25(OH)D or PTH with metabolic syndrome (MetS) while controlling for adiposity in black women. Using a cross-sectional study design, 209 urban black women aged ≥ 43 years from the North West Province, South Africa, were included. Multiple regression models were used to explore the relationship between 25(OH)D or PTH and body composition. To explore the association between 25(OH)D or PTH and MetS, a separate variable was created including at least 3 of the MetS criteria, but excluding elevated waist circumference as a diagnostic criterion in a logistic regression model. The majority of the women (69.9%) were overweight or obese and 65.5% of the women had excessive adiposity using the age-specific cut-off points for body fat percentage. All body composition variables were positively associated with PTH, whereas body mass index and waist circumference, but not body fat percentage, had negative associations with 25(OH)D also after adjusting for confounders. Before and after adjusting for age, body fat, habitual physical activity, tobacco use, season of data collection, and estimated glomerular filtration rate, neither 25(OH)D nor PTH showed significant associations with MetS. Although PTH was positively associated and 25(OH)D was negatively associated with adiposity in black women, there was no association between either 25(OH)D or PTH and MetS in this study population, nor did adiposity influence these relationships.

Three doses of vitamin D, bone mineral density, and geometry in older women during modest weight control in a 1-year randomized controlled trial

The effects of higher than recommended vitamin D doses on bone mineral density (BMD) and quality are not known. In this study, higher intakes, in postmenopausal women undergoing weight control over 1 year, had no effect on areal or volumetric BMD but prevented the deterioration in cortical bone geometry.

INTRODUCTION

Studies examining how bone responds to a standard dose of vitamin D supplementation have been inconsistent. In addition, the effects of higher doses on BMD and quality are not known. Postmenopausal women undergoing weight control to improve health outcomes are particularly at risk for bone loss and might benefit from supplemental vitamin D intake above the recommended allowance.

METHODS

This 1-year-long, randomized, double-blind controlled study addresses whether vitamin D supplementation, in healthy overweight/obese older women, affects BMD and bone structural parameters. In addition, bone turnover and serum total, free, and bioavailable 25-hydroxyvitamin D (25OHD) responses to one of three daily levels of vitamin D₃ (600, 2000, 4000 IU) with 1.2 Ca g/day during weight control were examined.

RESULTS

Fifty-eight women (age, 58 ± 6 years; body mass index, 30.2 ± 3.8 kg/m², serum 25OHD, 27.3 ± 4.4 ng/mL) were randomized to treatment. After 1 year, serum 25OHD concentrations increased to 26.5 ± 4.4, 35.9 ± 4.5, and 41.5 ± 6.9 ng/mL, in groups 600, 2000, and 4000 IU, respectively, and differed between groups (p < 0.01). Weight change was similar between groups (-3.0 ± 4.1 %). Cortical (Ct) thickness of the tibia changed by -1.5 ± 5.1 %, +0.6 ± 3.2 %, and +2.0 ± 4.5 % in groups 600, 2000, and 4000 IU, respectively, and each group was significantly different from each other (p < 0.05).

CONCLUSION

The decline in Ct thickness was prevented with higher vitamin D₃ supplementation, but there were no other significant changes due to treatment over 1 year. Whether these findings translate to changes in biomechanical properties leading to reduced fracture risk should be addressed in future studies.

Vitamin D deficiency and airflow limitation in the Baltimore Longitudinal Study of Ageing

BACKGROUND

Vitamin D deficiency is common in patients with chronic obstructive pulmonary disease (COPD) and has also been linked to comorbidities often present in COPD.

AIM

The aim of this study was to investigate whether vitamin D deficiency was related specifically to airflow limitation or whether vitamin D deficiency was determined by conditions that frequently coexist with COPD: insulin resistance, hypertension, anaemia, obesity and hypercholesterolaemia.

METHODS

For this cross-sectional analysis, we included 897 subjects from the Baltimore Longitudinal Study of Aging. Subjects taking vitamin D supplements were excluded. Airflow limitation was defined as FEV1 /FVC < lower limit of normal. Logistic regression was used to assess the association between vitamin D deficiency (25-hydroxy vitamin D < 20 ng/mL) and possible determinants.

RESULTS

Vitamin D deficiency was not specific for subjects with airflow limitation. Body mass index (BMI) (OR: 1.05, P < 0.03) and obesity (BMI > 30 kg/m(2)) (OR: 1.9, P < 0.002) were significantly associated with vitamin D deficiency in the adjusted multivariate regression analysis. Physical activity was associated with a decreased risk of vitamin D deficiency.

CONCLUSIONS

Airflow limitation was not an independent determinant of vitamin D deficiency. The effect of weight loss and increased physical activity on vitamin D levels should be investigated further in intervention studies.

Association of serum vitamin D with change in weight and total body fat in a German cohort of older adults

We examined the association of baseline serum 25-hydroxyvitamin D (25(OH)D) with change in weight and total body fat in a cohort of community-dwelling older adults from Southern Germany. A total of 735 participants of the population-based KORA-Age Study (2009-2012), aged 65-90 years, were followed for 2.9±0.1 years. Body fat was assessed with bioelectrical impedance analysis. Linear and multinomial logistic models, adjusted for baseline covariables, were used to examine the association of 25(OH)D with percentage weight and body fat change during follow-up. 25(OH)D levels were not associated with overall weight change or body fat loss. Higher 25(OH)D levels were associated with a lower likelihood of having gained >3% of body fat in women but not in men. As we cannot exclude residual confounding by outdoor physical activity and diet, our results are not sufficient to support a causal role of 25(OH)D in the etiology of obesity in Caucasian older adults.

The lower vitamin C plasma concentrations in elderly men compared with elderly women can partly be attributed to a volumetric dilution effect due to differences in fat-free mass

Women show higher vitamin C plasma concentrations than men, but the reasons for this observation still require elucidation. The objective of the present study was to investigate whether sex differences in vitamin C plasma concentrations are present in elderly subjects and whether these differences are due to sex-specific lifestyles, total antioxidant status (TAOS) and/or body composition. Fasting plasma concentrations of vitamin C were assessed by photometric detection in a cross-sectional study of 181 women and eighty-nine men aged 62-92 years. Body composition was determined by bioelectrical impedance analysis. Vitamin C intake was assessed with a 3 d estimated dietary record. Stepwise multiple regression analyses were performed to investigate whether sex is an independent predictor of vitamin C plasma concentrations by controlling for age, vitamin C intake, lifestyle factors, TAOS and body composition. Women showed higher vitamin C plasma concentrations than men (76 v. 62 μmol/l, P< 0·0001). In the multiple regression analysis, male sex was a negative predictor of vitamin C plasma concentrations (β = -0·214), as long as absolute fat-free mass (FFM) was not considered as a confounder. When absolute FFM was included, sex was no longer a predictor of vitamin C plasma concentrations, whereas absolute FFM (β = -0·216), physical activity level (β = 0·165), intake of vitamin C supplements (β = 0·164), age (β = 0·147) and smoking (β = -0·125) affected vitamin C plasma concentrations. The results indicate that a higher absolute FFM, and thus a higher distribution volume of vitamin C, contributes to lower vitamin C plasma concentrations in men than women.

Sex-specific determinants of serum 25-hydroxyvitamin D3 concentrations in an elderly German cohort: a cross-sectional study

Background

Considering the suggested link between vitamin D insufficiency and several chronic diseases, attention should be given to approaches for improving vitamin D status. Elderly subjects are regarded as a high-risk group for developing an insufficient vitamin D status. Socioeconomic, dietary, lifestyle and environmental factors are considered as influencing factors, whereupon sex differences in predictors of vitamin D status are rarely investigated. The purpose of this study is to identify the main predictors of serum 25-hydroxyvitamin D₃ [25(OH)D₃] concentrations in elderly subjects by taking into account potential sex differences.

Methods

This is a cross-sectional study in 162 independently living German elderly aged 66 to 96 years. Serum 25(OH)D₃ concentrations were assessed by an electrochemiluminescence immunoassay. Multiple regression analyses were performed to identify predictors of 25(OH)D₃ concentrations stratified by sex.

Results

Median 25(OH)D₃ concentration was 64 nmol/L and none of the subjects had 25(OH)D₃ concentrations < 25 nmol/L. In women, intact parathyroid hormone (iPTH) (β = -0.323), % total body fat (β = -0.208), time spent outdoors (β = 0.328), month of blood sampling (β = 0.229) and intake of vitamin D supplements (β = 0.172) were the predominant predictors of 25(OH)D₃, whereas in men, iPTH (β = -0.254), smoking (β = -0.282), physical activity (β = 0.336) and monthly household net income (β = 0.302) predicted 25(OH)D₃ concentrations. The final regression models accounted for 30% and 32% of the variance in 25(OH)D₃ concentrations in women and men, respectively.

Conclusion

The findings indicate that 25(OH)D₃ concentrations are influenced by body composition, month of blood sampling, economic factors, lifestyle, supplement intake and iPTH, but may not be associated with age, sex, dietary factors, kidney function and presence of selected chronic diseases in community-dwelling elderly. Furthermore, our results provide evidence for sex-specific determinants of the vitamin D status, which ought to be considered for preventive strategies.

Associations of serum 25-hydroxycholecalciferol and parathyroid hormone with serum lipids differ by sex and vitamin D status

Objective

Although emerging evidence indicates an association between vitamin D and serum lipids, the data are still inconsistent. The purpose of the present study was to investigate whether 25-hydroxycholecalciferol (25-hydroxyvitamin D3; 25(OH)D3) or intact parathyroid hormone (iPTH) was independently related to serum lipids in elderly women and men.

Design

Cross-sectional study. Fasting serum levels of 25(OH)D3, iPTH, TAG, total cholesterol (TC), HDL cholesterol (HDL-C) and LDL cholesterol (LDL-C) were assessed. Body composition was measured by bioelectrical impedance analysis. Lifestyle factors, such as nutrient intake, time spent outdoors, physical activity, smoking, supplement intake and medication, were assessed by questionnaires. Multiple regression analyses were performed to examine associations of 25(OH)D3and iPTH with serum lipids.

Setting

Giessen, Germany.

Subjects

One hundred and ninety-three well-functioning German elderly aged 66–96 years.

Results

After adjusting for age, body fat, physical activity, smoking, alcohol intake, lipid-modifying drugs and either iPTH or 25(OH)D3, 25(OH)D3was a predictor of TAG (standardised coefficient beta (β)=–0·180), HDL-C (β=0·197), LDL-C:HDL-C (β=−0·298) and TC:HDL-C (β=−0·302) in women, whereas iPTH was a predictor of HDL-C (β=−0·297) in men. In sub-analysis, associations between 25(OH)D3and TC (β=−0·252), HDL-C (β=0·230), LDL-C (β=−0·324), LDL-C:HDL-C (β=−0·412) and TC:HDL-C (β=−0·380) were found in women with 25(OH)D3concentrations above or equal the median vitamin D status (62·3 nmol/l), but not in women with lower 25(OH)D3concentrations.

Conclusions

In the elderly, associations of 25(OH)D3and iPTH with serum lipids may differ by sex and may require a vitamin D status above 62 nmol/l.

Dietary intake and main food sources of vitamin D as a function of age, sex, vitamin D status, body composition, and income in an elderly German cohort

BACKGROUND

Elderly subjects are at risk of insufficient vitamin D status mainly because of diminished capacity for cutaneous vitamin D synthesis. In cases of insufficient endogenous production, vitamin D status depends on vitamin D intake.

OBJECTIVE

The purpose of this study is to identify the main food sources of vitamin D in elderly subjects and to analyse whether contributing food sources differ by sex, age, vitamin D status, body mass index (BMI), or household income. In addition, we analysed the factors that influence dietary vitamin D intake in the elderly.

DESIGN AND SUBJECTS

This is a cross-sectional study in 235 independently living German elderly aged 66-96 years (BMI=27±4 kg/m(2)). Vitamin D intake was assessed by a 3-day estimated dietary record.

RESULTS

The main sources of dietary vitamin D were fish/fish products followed by eggs, fats/oils, bread/bakery products, and milk/dairy products. Differences in contributing food groups by sex, age, vitamin D status, and BMI were not found. Fish contributed more to vitamin D intake in subjects with a household income of <1,500 €/month compared to subjects with higher income. In multiple regression analysis, fat intake and frequency of fish consumption were positive determinants of dietary vitamin D intake, whereas household income and percentage total body fat negatively affected vitamin D intake. Other parameters, including age, sex, physical activity, smoking, intake of energy, milk, eggs and alcohol, showed no significant association with vitamin D intake.

CONCLUSION

Low habitual dietary vitamin D intake does not affect vitamin D status in summer, and fish is the major contributor to vitamin D intake independent of sex, age, vitamin D status, BMI, and the income of subjects.

Variation in the MC4R gene is associated with bone phenotypes in elderly Swedish women

Osteoporosis is characterized by reduced bone mineral density (BMD) and increased fracture risk. Fat mass is a determinant of bone strength and both phenotypes have a strong genetic component. In this study, we examined the association between obesity associated polymorphisms (SNPs) with body composition, BMD, Ultrasound (QUS), fracture and biomarkers (Homocysteine (Hcy), folate, Vitamin D and Vitamin B12) for obesity and osteoporosis. Five common variants: rs17782313 and rs1770633 (melanocortin 4 receptor (MC4R); rs7566605 (insulin induced gene 2 (INSIG2); rs9939609 and rs1121980 (fat mass and obesity associated (FTO) were genotyped in 2 cohorts of Swedish women: PEAK-25 (age 25, n = 1061) and OPRA (age 75, n = 1044). Body mass index (BMI), total body fat and lean mass were strongly positively correlated with QUS and BMD in both cohorts (r² = 0.2–0.6). MC4R rs17782313 was associated with QUS in the OPRA cohort and individuals with the minor C-allele had higher values compared to T-allele homozygotes (TT vs. CT vs. CC: BUA: 100 vs. 103 vs. 103; p = 0.002); (SOS: 1521 vs. 1526 vs. 1524; p = 0.008); (Stiffness index: 69 vs. 73 vs. 74; p = 0.0006) after adjustment for confounders. They also had low folate (18 vs. 17 vs. 16; p = 0.03) and vitamin D (93 vs. 91 vs. 90; p = 0.03) and high Hcy levels (13.7 vs 14.4 vs. 14.5; p = 0.06). Fracture incidence was lower among women with the C-allele, (52% vs. 58%; p = 0.067). Variation in MC4R was not associated with BMD or body composition in either OPRA or PEAK-25. SNPs close to FTO and INSIG2 were not associated with any bone phenotypes in either cohort and FTO SNPs were only associated with body composition in PEAK-25 (p≤0.001). Our results suggest that genetic variation close to MC4R is associated with quantitative ultrasound and risk of fracture.

Association of vitamin D with adiposity measures and other determinants in a cross-sectional study of Cypriot adolescents

OBJECTIVE

To assess vitamin D status among Cypriot adolescents and investigate potential determinants including BMI and body fat percentage (BF%).

DESIGN

Participants had cross-sectional assessments of serum vitamin D, physical activity, dietary vitamin D intake and sun exposure. Linear and logistic regression models were used to explore the associations of vitamin D with potential predictors.

SETTING

Hospitals, Cyprus, November 2007-May 2008.

SUBJECTS

Adolescents (n 671) aged 16-18 years.

RESULTS

Mean serum vitamin D was 22·90 (sd 6·41) ng/ml. Only one in ten children had sufficient levels of vitamin D (≥30 ng/ml), while the prevalence of vitamin D deficiency (12-20 ng/ml) and severe deficiency (<12 ng/ml) was 31·7 % and 4·0 %, respectively. Lower vitamin D was associated with winter and spring season, female gender, reduced sun exposure in winter and darker skin. Participants with highest BMI and BF% when compared with a middle reference group had increased adjusted odds of vitamin D insufficiency (OR = 3·00; 95 % CI 1·21, 7·45 and OR = 5·02; 95 % CI 1·80, 13·97, respectively). A similar pattern, although not as strong, was shown for vitamin D deficiency with BF% (OR = 1·81; 95 % CI 1·04, 3·16) and BMI (OR = 1·51; 95 % CI 0·85, 2·67). Participants in the lowest BMI and BF% groups also displayed compromised vitamin D status, suggesting a U-shaped association.

CONCLUSIONS

Vitamin D deficiency in adolescence is very prevalent in sunny Cyprus, particularly among females, those with darker skin and those with reduced sun exposure in winter. Furthermore, vitamin D status appears to have a U-shaped association with adiposity measures.

Vitamin D status and dietary intake in a Swedish COPD population

INTRODUCTION

Emerging evidence indicates that patients with chronic obstructive pulmonary disease (COPD) have a poorer vitamin D status than the general population, possibly affecting several comorbidities. In northern latitudes, these problems could be even more accentuated in wintertime because of the low ultraviolet B radiation.

OBJECTIVES

To examine the dietary intake of vitamin D and the levels of 25-hydroxyvitamin D (25-OH-D) in a COPD population compared with a reference group in Swedish settings.

METHODS

Ninety-eight COPD patients (forced expiratory volume in 1 s/vital capacity ratio < 0.65) recruited from the outpatient clinics at the university hospitals in Gothenburg and Uppsala, Sweden were included in this cross-sectional study. The reference group (149 individuals) was randomly selected from the Swedish National Registry. The serum concentrations of 25-OH-D, intact parathyroid hormone, creatinine and calcium were measured. A trained dietitian conducted a dietary history interview to evaluate food intake of vitamin D, prescribed drugs and supplements containing vitamin D.

RESULTS AND CONCLUSIONS

The mean serum concentration of 25-OH-D was significantly higher in the reference group (57.6 ± 23 nmol/L) compared with the COPD group (51.5 ± 22 nmol/L) (P = 0.039). The dietary intake was predominantly below the recommendations in both groups. Mean total daily intake of vitamin D and mean daily supplementation of vitamin D was significantly higher in the COPD group (P = 0.012 and P = 0.030, respectively). Low intake of vitamin D and low serum levels of 25-OH-D are common in both COPD patients and an elderly Swedish population. Monitoring vitamin D status and possibly routinely treating COPD patients with vitamin D and calcium should be considered to minimise the risk of severe vitamin D deficiency among COPD patients.

The effect of vitamin D supplementation on serum 25(OH)D in thin and obese women

Obese people are known to have lower serum 25OHD levels compared to non-obese people. It is not known whether it is due to storage of vitamin D in fat, inadequate input from sunlight, diet or other unknown factors. We examined the relationship at study baseline of serum 25OHD, PTH, 1,25(OH)2D with body composition measurements using dual energy X-ray absorptiometry. The results showed a significant inverse relation between total body fat mass and serum 25OHD (p<0.0001) and serum 1,25(OH2)D (p=034) and an independent positive correlation between serum PTH and total body fat mass (p<0.0001). In a randomized controlled study of seven doses of vitamin D (400-4800IU/d) the increase in serum 25OHD levels was compared in women with a normal body mass index to obese women. The response to the low doses of vitamin D (400-800IU/d) was significantly less than that of the medium (1600-2400IU/d) and high doses groups (3200-4800IU) (p<0.0001) in all BMI categories. The increase in serum 25OHD in the medium and high dose groups was not significantly different with increasing level of obesity. But thinner women with a normal BMI (<25kg/m(2)) showed a much higher response to vitamin D at any dose level compared to other BMI groups. There was no significant change in total body fat mass after treatment with vitamin D or calcitriol in our randomized trials. In summary, the response to vitamin D is dependent on body weight. Women with BMI <25kg/m(2) develop much higher levels of serum 25OHD after vitamin D supplementation compared to those with BMI of >25kg/m(2). The differences in serum 25OHD levels between normal and obese women may be due to differences in volume dilution. After vitamin D supplementation, all obese women reach adequate levels of serum 25OHD but normal women (BMI<25kg/m(2)) reach much higher levels of 25OHD and in this group smaller doses of vitamin D used should be used. This article is part of a Special Issue entitled 'Vitamin D Workshop'.

Dietary vitamin D intake is not associated with 25-hydroxyvitamin D3 or parathyroid hormone in elderly subjects, whereas the calcium-to-phosphate ratio affects parathyroid hormone

This cross-sectional study investigates whether serum 25-hydroxyvitamin D3 [25(OH)D3] and intact parathyroid hormone (iPTH) are affected by vitamin D, calcium, or phosphate intake in 140 independently living elderly subjects from Germany (99 women and 41 men; age, 66-96 years). We hypothesized that habitual dietary intakes of vitamin D, calcium, and phosphate are not associated with 25(OH)D3 or iPTH and that body mass index confounds these associations. Serum 25(OH)D3 and iPTH were measured by an electrochemiluminescence immunoassay. Dietary intake was determined using a 3-day estimated dietary record. The median dietary intake levels of vitamin D, calcium, and phosphate were 3 μg/d, 999 mg/d, and 1250 mg/d, respectively. Multiple regression analyses confirmed that dietary vitamin D and calcium did not affect 25(OH)D3 or iPTH; however, supplemental intakes of vitamin D and calcium were associated with 25(OH)D3 after adjustment for age, sex, body composition, sun exposure, physical activity, and smoking. In addition, phosphate intake and the calcium-to-phosphate ratio were associated with iPTH after multiple adjustments. In a subgroup analysis, calcium and vitamin D supplements, as well as phosphate intake, were associated with 25(OH)D3 and/or iPTH in normal-weight subjects only. Our results indicate that habitual dietary vitamin D and calcium intakes have no independent effects on 25(OH)D3 or iPTH in elderly subjects without vitamin D deficiency, whereas phosphate intake and the calcium-to-phosphate ratio affect iPTH. However, vitamin D and calcium supplements may increase 25(OH)D3 and decrease iPTH, even during the summer, but the impact of supplements may depend on body mass index.

The beneficial role of vitamin D in obesity: possible genetic and cell signaling mechanisms

The prevalence rates of overweight and obesity are considered an important public issue in the United States, and both of these conditions are increasing among both children and adults. There is evidence of aberrations in the vitamin D-endocrine system in obese subjects. Vitamin D deficiency is highly prevalent in patients with obesity, and many studies have demonstrated the significant effect of calcitriol on adipocytes. Genetic studies have provided an opportunity to determine which proteins link vitamin D to obesity pathology, including the vitamin D receptor, toll-like receptors, the renin-angiotensin system, apolipoprotein E, vascular endothelial growth factor, and poly (ADP-ribose) polymerase-1. Vitamin D also exerts its effect on obesity through cell-signaling mechanisms, including matrix metalloproteinases, mitogen-activated protein kinase pathways, the reduced form of nicotinamide adenine dinucleotide phosphate, prostaglandins, reactive oxygen species, and nitric oxide synthase.

In conclusion, vitamin D may have a role in obesity. The best form of vitamin D for use in the obese individuals is calcitriol because it is the active form of the vitamin D₃ metabolite, its receptors are present in adipocytes, and modulates inflammatory cytokine expression.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

The association between serum vitamin d levels with general and abdominal obesity among patients with migraine

BACKGROUND

Obesity is a common health problem around the world. Studies have shown inverse relationship between serum vitamin D levels with obesity among patients and healthy population. The aim of this present study is to examine the relationship between serum vitamin D levels with general and abdominal obesity among migraine patients.

METHODS

The present study is a cross-sectional and 66 migraine patients aged 19-61 years were included for analysis. Partial correlation was performed to assess association between serum 25-OH-D with general and abdominal obesity. Adjustments were performed for age, sex, and education.

RESULTS

No relationship was found between serum levels of vitamin D with general and abdominal obesity. However, a significant association was shown between waist circumferences (WC) with body mass index (BMI).

CONCLUSIONS

Serum levels of 25-OH-D were not associated with WC and BMI. Furthermore, after adjustment for confounder variables, no association was observed.

Significant positive association between parathyroid hormone and fat mass and lean mass in chronic hemodialysis patients

BACKGROUND

It has been reported that there is a significant positive relationship between PTH and body weight or body mass index in the general population. However, little is known about this relationship in dialysis patients in whom PTH levels are higher. It is also not known whether fat mass or lean mass is associated with serum PTH among these patients. In the present study, we examined the association of intact PTH with fat mass and lean mass in hemodialysis patients.

METHODS

Serum intact PTH, calcium, and phosphate were measured in 590 hemodialysis patients (age, 60.2 ± 12.2 y; median hemodialysis duration, 59.6 mo; 343 males and 247 females; diabetics, 27.7%). Fat mass and lean mass were measured by dual-energy x-ray absorptiometry.

RESULTS

Intact PTH correlated significantly and positively with body weight and body mass index in all patients. Intact PTH correlated significantly and positively with fat mass and lean mass in males (P < .01), and tended to correlate positively with fat mass and lean mass in females (P < .1). In multiple regression analyses after adjustment for age, gender, hemodialysis duration, calcium, phosphate, vitamin D use, and phosphate binder use, intact PTH was associated significantly with body weight (β = .190; P < .0001), body mass index (β = .177; P < .0001), fat mass (β = .142; P < .0005), and lean mass (β = .192; P < .01). Furthermore, intact PTH was associated significantly and independently with both fat mass and lean mass after adjustment (R(2) = .206; P < .0001).

CONCLUSION

Serum intact PTH in chronic hemodialysis patients is associated significantly and positively with body composition of fat mass and lean mass.

Vitamin d levels in subjects with prostate cancer compared to age-matched controls

Prostate cancer (PCa) is the second most common cancer in men worldwide and the second leading cause of cancer deaths in men in the United States. Vitamin D is considered to have anticancer properties, currently thought to work mainly through its nuclear receptor or vitamin D receptor. In this retrospective study, we compared vitamin D levels in subjects with PCa with those of age-matched men without PCa. Study subjects included 479 in each group with a mean age of 73 and a mean creatinine of 1.05 and 1.15. Levels of 25 (OH) vitamin D were 28.4 ± 0.54 and 28.05 ± 0.62 in subjects with and without PCa. Levels of 1,25 (OH) vitamin D were 47.2 ± 6.8 and 47.1 ± 7.11 in subjects with and without PCa. In contrast to other studies, we did not find a significant difference in vitamin D levels. Among prostate cancer patients, vitamin D levels correlated positively with age (r = 0.12, P < 0.02), and were negatively associated with BMI (r = -0.13, P = 0.003), glucose (r = -0.12, P < 0.007), HbA1C (r = -0.16, P = 0.001), and PTH (r = -0.21; P < 0.0001). The data do not show the causal effect of vitamin D levels on PCa.