Vitamin D: how much do we need, and how much is too much?

Bone turnover in pregnancy, measured by urinary CTX, is influenced by vitamin D supplementation and is associated with maternal bone health: findings from the Maternal Vitamin D Osteoporosis Study (MAVIDOS) trial

BACKGROUND

The pattern of change in maternal bone turnover throughout pregnancy is poorly characterized.

OBJECTIVES

We investigated changes across pregnancy in a marker of maternal bone resorption, urinary C-terminal telopeptide of type I collagen (CTX), the influence of gestational vitamin D supplementation, and associations between CTX and maternal postnatal bone indices.

METHODS

MAVIDOS (the Maternal Vitamin D Osteoporosis Study) is a randomized, double-blind, placebo-controlled trial of 1000 IU cholecalciferol/d compared with placebo from 14 weeks of gestation to birth. Maternal second-void urinary α- and β-CTX were measured (ELISA) at 14 and 34 weeks of gestation; DXA was performed within 2 wk postpartum. The Mann-Whitney Rank Sum test, Spearman's rank correlation, and linear regression were used to compare median CTX values within and between groups from early to late pregnancy, and associations with maternal bone outcomes.

RESULTS

In total, 372 women had CTX and 25-hydroxyvitamin D [25(OH)D] measured in early and late pregnancy. CTX at 14 and 34 weeks of gestation were correlated in both placebo (r = 0.31) and cholecalciferol (r = 0.45) groups (P < 0.0001). Median CTX increased from 14 to 34 weeks of gestation in both groups (n = 372 total) [placebo (n = 188): from 223.6 to 449.7 μg/mmol creatinine; cholecalciferol (n = 184): from 222.3 to 419.3 μg/mmol creatinine; P = 0.03 for placebo compared with cholecalciferol difference in CTX at 34 weeks of gestation]. The conditional mean ± SD increase in CTX [z-score (SD)] from early to late pregnancy was greater in the placebo group (n = 188) than in the cholecalciferol group (n = 184) (placebo: 0.16 ± 0.92; cholecalciferol: -0.16 ± 1.06; P-difference < 0.01). Higher CTX at 34 weeks of gestation was associated, similarly in both groups, with lower maternal total hip and lumbar spine bone mineral content and bone mineral density (BMD) (e.g., lumbar spine BMD: β = -0.02 g · cm-2 · SD-1 increase in CTX; 95% CI: -0.027, -0.002 g · cm-2 · SD-1; P = 0.02, n = 283).

CONCLUSIONS

Maternal urinary CTX, a bone resorption marker, rises through pregnancy, although to a lesser degree with gestational cholecalciferol supplementation, and is inversely associated with maternal bone mass postpartum.This trial was registered at www.isrctn.com as ISRCTN 82927713 and eudract.ema.europa.eu as EudraCT 2007-001716-23.

The Pattern of Vitamin D Levels in Children 0-4 Years of Age in Yunnan Province

OBJECTIVE

Vitamin D is an essential nutrient that regulates the activity of calcium and bone hormones throughout life; however, vitamin D levels in children, which is the most crucial period during human development, has not been established.

METHODS

As the first descriptive study of serum vitamin D levels in children in Yunnan Province, we determined the serum vitamin D levels in children 0‒4 years of age who underwent physical examinations at Kunming Children's Hospital, and the association between the serum vitamin D level and the calcium, phosphorus and alkaline levels.

RESULTS

Vitamin D levels in children were highest in the summer months and lowest in the winter months. Vitamin D deficiency was more common in girls than boys. A social-economic effect was shown, as evidenced by the significantly higher serum vitamin D levels in children from the top five cities compared with the lower-ranked cities. Moreover, we also demonstrated a significant correlation between vitamin D and serum calcium levels.

CONCLUSION

Our study suggested that sex and age affected the vitamin D levels of children, and a reasonable reference range in children 0-4 years of age in Yunnan Province was determined.

Vitamin D status in preschool children in Algeria

It is well established today that an optimal vitamin D intake plays a crucial role in the constitution of optimal osseous mass during childhood, and hence in the prevention of the osteoporosis in adults. The prevalence of the vitamin D deficiency is increasing globally and Algeria is no exception in this regard. Our study is the first to be carried out with healthy children of preschool age in North Africa.

AIMS

The study aimed to evaluate the vitamin D status of a pediatric population, during all four seasons of the year, living in the north of Algeria, as well as to estimate the prevalence of vitamin D deficiency, identifying the potential risk factors.

MATERIAL AND METHODS

This was an analytic and cross-sectional study carried out between March 2014 and March 2016 with healthy preschool infants from an urban environment in the town of Hussein Dey. A total of 1016 infants aged 9-72 months were included during this period. The consensual threshold value was 20ng/mL.

RESULTS

The sex ratio was of 1.47 (535 boys/481 girls) and the average age of the children was 36.5±1.79 months. The daily average calcium ratio was 395±23 mg/with food contributions in vitamin D at an estimated average of 164 UI/day (4.1μg/day). The average concentration of the total 25-OHD for all four seasons of the year was 18.6±10.4ng/mL with an average rate of parathyroid hormone (PTH) of 30.9±14.6pg/mL. There was a highly significant inverse correlation between the serum level of vitamin D and PTH (r=-0.57; P=0.0001), the point of inflection was situated at 34.1ng/mL. The prevalence of vitamin D deficiency follows a seasonal variation that is statistically significant (P=0.0001), and the prevalence is higher during the autumn-winter period. The risk factors identified by multiple logistic regression were autumn-winter season (OR: 7; 95% CI: 3-11; P=0.001), age less than 24 months (OR: 3.8; 95% CI: 3.4-4.4; P=0.0001), high body mass index (OR: 2; 95% CI: 1.2-3.2; P=0.3), darker skin pigmentation (OR: 2.8; 95% CI: 2.2-5.2; P=0.001), duration of sunlight exposure less than 15min (OR: 6.1; 95% CI: 3.6-10.2; P=0.0001), low socioeconomic status (OR: 3.9; 95% CI: 1.5-4.3; P=0.01), calcium intake lower than 500 mg/day (OR: 2.5; 95% CI: 1.8-6; P=0.001), and a weekly dietary intake of vitamin D lower than 200 UI (OR: 2.6; 95% CI: 1.6-4.2; P=0.02).

DISCUSSION

No studies have been conducted in north Africa or Algeria concerning healthy preschool children; however, this population has a rapid growth rate and deserves special attention. The prevalence of vitamin D deficiency in the children of this study was higher than that reported in studies of children of the same age living in Europe or America, despite the fact that Algeria is closer to the equator (36° latitude north).

CONCLUSION

The changes experienced by Algerian society and the shorter exposure of the population to the sun call for more efforts regarding the detection and treatment of vitamin D deficiency, as well as an update of the vitamin D supplementation schedule.

Concerns about vitamin D and sun exposure behaviour among Australians

ISSUES ADDRESSED

Australians' concerns about vitamin D and influence on sun protection were last quantified a decade ago in Queensland amidst media attention on emerging evidence of non-skeletal benefits of vitamin D. Meanwhile these circumstances persist and impact is worth assessing.

METHODS

Measures of concern about vitamin D were included in three recent population-based cross-sectional surveys of Australians' sun-related behaviours during summer months (2010-2011, 2013-2014 and 2016-2017). We analysed characteristics, beliefs and behaviours associated with vitamin D concerns regarding regular sunscreen use among adults in 2016-2017 (N = 3614).

RESULTS

Concerns about vitamin D continued to persist among adults surveyed between 2010-2011 and 2016-2017. Vitamin D concerns regarding the sunscreen use were more common among women, older respondents and adults with skin that tans or is not susceptible to sunburn. Respondents concerned about vitamin D were more likely to exhibit pro-tanning beliefs, scepticism about sunscreen safety and have attempted a suntan. They were also less likely to use sun protection in everyday activities outdoors and less likely to use sunscreen on summer weekends.

CONCLUSIONS

Vitamin D concerns related to sunscreen use remained common among Australian adults. Skin cancer control advocates may be reassured that those with the greatest skin cancer risk (burn only) were less likely to hold these concerns, while the related infrequent sun protection and tanning among concerned adults are problematic. SO WHAT?: Continued education and research is needed to ensure that the general public understand the risks and benefits of sun exposure in Australia.

Clinical and immunological effects of vitamin D supplementation during the pollen season in children with allergic rhinitis

INTRODUCTION

Vitamin D deficiency has been proposed as a potential contributing factor in patients with allergic diseases. We compared the clinical and immunological effects of vitamin D supplementation to placebo during the pollen season in children with allergic rhinitis.

MATERIAL AND METHODS

Thirty-eight children aged 5-12, sensitive to grass pollen, participated in a prospective, randomized, double-blind, placebo-controlled trial. Children received either vitamin D 1000 IU daily supplementation or placebo. We studied symptoms/medication score, lung function, exhaled nitric oxide concentration (FENO), methacholine bronchial provocation test and serum level of 25(OH)D, as well as; CD4+CD25+Foxp3+ cells, TLR4, IL-1, IL-6, TNF and the IL-10 and transforming growth factor β1 (TGF-β1) levels in cell culture supernatants.

RESULTS

Vitamin D therapy was effective in reduction of the symptoms/medication score (p = 0.0371). In vitamin D group an increase in the CD4+CD25+Foxp3+ cells (7.06 vs. 10.5%; p = 0.0013) and serum 25(OH)D concentration (49.6 vs. 96.6 ng/ml; p = 0.0001) and in control group an increase in FENO (15.6 vs. 21 ppb; p = 0.0331) and serum 25(OH)D level were observed (82.9 vs. 100.3 ng/ml; p = 0.0003).We revealed a higher increase from baseline in the percentage of CD4+CD25+Foxp3+ cells in the vitamin D group compared to the control group (p = 0.0058). A significant correlation between CD4+CD25+Foxp3+ cell induction and FENO reduction in the vitamin D group was observed (p = 0.0217).

CONCLUSIONS

Vitamin D 1000 IU as a supplementary treatment of grass pollen allergy in children with allergic rhinitis during the pollen season significantly reduced the symptoms/medication score. The study revealed an immunological effect of vitamin D.

Vitamin D serum levels in children with allergic and vasomotor rhinitis

Purpose

In addition to regulating calcium and phosphorus homeostasis and bone metabolism, vitamin D is known as an immune modulator. Recently, there has been increased worldwide interest in the association between low levels of vitamin D and allergic diseases. The purpose of this study was to assess the relationship between serum vitamin D levels and allergic/vasomotor rhinitis (AR/VR) in children.

Methods

This study included 164 patients. The sample included 59 patients with AR, 42 patients with VR, and 63 controls. Their ages ranged from 0 to 16 years. We examined the levels of 25-hydroxyvitamin D, Immunoglobulin E, specific IgE, and eosinophil cationic protein; peripheral blood eosinophil count; and the results of a skin prick test.

Results

Serum 25-hydroxyvitamin D levels were 19.0±8.5 ng/mL in the AR group, 25.5±10.9 ng/mL in the VR group, and 26.9±10.7 ng/mL in the control group. After adjustment for body mass index and season at the time of blood sampling, vitamin D levels in the AR group were lower than those of the VR group (P=0.003) and control group (P<0.001). Vitamin D levels were inversely correlated with Immunoglobulin E levels (r=-0.317, P<0.001). AR patients with food allergy or atopic dermatitis did not have lower levels of 25-hydroxyvitamin D than AR patients without these diseases.

Conclusion

This study demonstrates a possible relationship between vitamin D levels and allergic rhinitis in Korean children.

Competitive Protein-binding assay-based Enzyme-immunoassay Method, Compared to High-pressure Liquid Chromatography, Has a Very Lower Diagnostic Value to Detect Vitamin D Deficiency in 9-12 Years Children

Background:

The most reliable indicator of Vitamin D status is circulating concentration of 25-hydroxycalciferol (25(OH) D) routinely determined by enzyme-immunoassays (EIA) methods. This study was performed to compare commonly used competitive protein-binding assays (CPBA)-based EIA with the gold standard, high-pressure liquid chromatography (HPLC).

Methods:

Concentrations of 25(OH) D in sera from 257 randomly selected school children aged 9–11 years were determined by two methods of CPBA and HPLC.

Results:

Mean 25(OH) D concentration was 22 ± 18.8 and 21.9 ± 15.6 nmol/L by CPBA and HPLC, respectively. However, mean 25(OH) D concentrations of the two methods became different after excluding undetectable samples (25.1 ± 18.9 vs. 29 ± 14.5 nmol/L, respectively; P = 0.04). Based on predefined Vitamin D deficiency as 25(OH) D < 12.5 nmol/L, CPBA sensitivity and specificity were 44.2% and 60.6%, respectively, compared to HPLC. In receiver operating characteristic curve analysis, the best cut-offs for CPBA was 5.8 nmol/L, which gave 82% sensitivity, but specificity was 17%.

Conclusions:

Though CPBA may be used as a screening tool, more reliable methods are needed for diagnostic purposes.

Relationship between nutritional profile, measures of adiposity, and bone mineral density in postmenopausal Saudi women

BACKGROUND

Osteoporosis remains a major health problem in all developed countries and is a condition in which several dietary factors have been implicated.

OBJECTIVE

To assess the nutritional status and levels of adiposity of postmenopausal women in relation to bone mineral density.

DESIGN

A cross-sectional study in which dietary intake was estimated by a food frequency questionnaire in 300 Saudi postmenopausal women aged 46-88 years. Bone profile biochemistry (serum calcium, phosphate, parathyroid hormone [PTH], vitamin D) and bone mineral density (BMD) in 3 skeletal sites were determined for all participants.

RESULTS

Overweight and obesity were highly prevalent among the study population. No significant correlation was found between dietary calcium and vitamin D and bone mass at any site. Dietary intake of calcium and vitamin D was significantly less than the recommended levels for a large proportion of the cohort. Energy-adjusted intakes of carbohydrates, fat, protein, and unsaturated fatty acids were associated with BMD in the postmenopausal women. Age, body weight, and residency type were predictors of BMD at all sites. Serum-intact PTH was a predictor of BMD at lumbar spine and femoral neck. Waist : hip ratio (WHR) was a predictor for BMD at femoral neck.

CONCLUSIONS

These results suggest that BMD is influenced by dietary factors other than calcium and vitamin D. However, nondietary factors such as age, WHR, PTH, and body weight may be important determinants of BMD in postmenopausal women.

Technical and clinical evaluation of the VITROS® Immunodiagnostic Products 25-OH Vitamin D Total Assay--comparison with marketed automated immunoassays and a liquid chromatography-tandem mass spectrometry method

BACKGROUND

The study was conducted to evaluate the technical and clinical performance of the VITROS® Immunodiagnostic Products 25-OH Vitamin D Total Assay, and compare it with the performance of five marketed automated assays and a liquid chromatography/mass spectrometry reference method (LC-MS/MS).

METHODS

Three hundred patient serum samples were used to compare the correlation of the VITROS® 25-OH Vitamin D Total Assay with both the other immunoassays and the LC-MS/MS method, using Passing-Bablok regression and Bland-Altman analyses. Concordance of the diagnosis of vitamin D status was calculated to test the agreement between the different assays. In addition, samples containing vitamin D2 were used to test the assay's ability to detect the D2 form of the vitamin.

RESULTS AND CONCLUSIONS

These results from the VITROS® 25-OH Vitamin D Total Assay generally correlated well with those from most of the marketed immunoassays. Cross-reactivity of the D2 form was calculated as being close to 100%. Additionally, we found substantial variability in performance amongst the various assays, which suggests the need for optimisation and recalibration of commercial methods.

Prevalence of vitamin D inadequacy in European women aged over 80 years

Inadequate vitamin D status is associated with secondary hyperparathyroidism and increased bone turnover and bone loss, which in turn increases fracture risk. The objective of this study is to assess the prevalence of inadequate vitamin D status in European women aged over 80 years. Assessments of serum 25-hydroxyvitamin D levels (25(OH)D) were performed on 8532 European women with osteoporosis or osteopenia of which 1984 were aged over 80 years. European countries included in the study were: France, Belgium, Denmark, Italy, Poland, Hungary, United Kingdom, Spain and Germany. Two cut-offs of 25(OH)D inadequacy were fixed: <75 nmol/L (30 ng/ml) and <50 nmol/L (20 ng/ml). Mean (SD) age of the patients was 83.4 (2.9) years, body mass index was 25.0 (4.0) kg/m(2) and level of 25(OH)D was 53.3 (26.7) nmol/L (21.4 [10.7] ng/ml). There was a highly significant difference of 25(OH)D level across European countries (p<0.0001). In these women aged over 80 years, the prevalence of 25(OH)D inadequacy was 80.9% and 44.5% when considering cut-offs of 75 and 50 nmol/L, respectively. In the 397 (20.0%) patients taking supplemental vitamin D with or without supplemental calcium, the mean serum 25(OH)D level was significantly higher than in the other patients (65.2 (29.2) nmol/L vs. 50.3 (25.2) nmol/L; P<0.001). This study indicates a high prevalence of vitamin D (25(OH)D) inadequacy in old European women. The prevalence could be even higher in some particular countries.

Allergic rhinitis and serum 25-hydroxyvitamin D level in Korean adults

BACKGROUND

Recently, it has been suggested that airway hyper-responsiveness, asthma, and atopic dermatitis are associated with a low vitamin D level.

OBJECTIVE

To evaluate whether the occurrence of allergic rhinitis (AR) is related to serum vitamin D levels in the general Korean adult population.

METHODS

Data obtained as part of the fourth annual Korean National Health and Nutrition Examination Survey (2009) of 8,012 adults older than 18 years were analyzed. The correlation between serum 25-hydroxyvitamin D (25[OH]D) level and presence of AR using questionnaires on symptoms, history of diagnosis of AR, and rhinoscopic findings were analyzed. All estimates were calculated based on sampling weight.

RESULTS

Mean age was 44.41 years and men constituted 49.8% of the sample. Participants with diagnosed AR constituted 11.1%. The mean 25(OH)D level of the AR group was lower than that of the non-AR group (16.71 ± 0.30 vs 17.75 ± 0.25 ng/mL, P < .001). A comparison of the prevalence of AR in the 3 groups showed that AR steadily decreased in the higher 25(OH)D groups (13.0% in group I [<15 ng/mL], 11.5% in group II [≥15-<25 ng/mL], and 7.2% in group III [≥25 ng/mL], P < .001). After adjusting for body mass index, smoking status, age, sex, sun exposure, income quartile, exercise, and body fat percentage, lower serum 25(OH)D levels remained significantly associated with the presence of AR compared with group III (hazard ratio 1.559 in group I and 1.430 in group II).

CONCLUSION

This study suggested a potential association between low vitamin D levels and AR prevalence in Korean adults.

Associations of serum 25-hydroxyvitamin D with overall and breast cancer-specific mortality in a multiethnic cohort of breast cancer survivors

PURPOSE

Despite limited evidence on the association of vitamin D with outcomes in breast cancer survivors, some clinicians advise breast cancer patients to use vitamin D supplements. More evidence is needed to inform these recommendations.

METHODS

In the Health, Eating, Activity, and Lifestyle study, we examined associations of post-treatment serum concentrations of 25-hydroxyvitamin D (25(OH)D) on overall and breast cancer-specific mortality in 585 breast cancer survivors from western Washington State, New Mexico, and Los Angeles County. 25(OH)D was measured in stored blood collected 2 years post-enrollment. Outcomes were ascertained from the Surveillance, Epidemiology, and End Results registries and medical records. Cox proportional hazards models were fit to assess associations of serum 25(OH)D with overall and breast cancer-specific mortality.

RESULTS

After a median follow-up of 9.2 years; 110 women died, including 48 from breast cancer. Standard cut points classified 211 (31.6 %) women as serum 25(OH)D deficient (<20 ng/mL), 189 (32.2 %) as insufficient (20-30 ng/mL), and 185 (36.2 %) as sufficient (>30 ng/mL). Compared to women with deficient 25(OH)D, those in the sufficient ranges had a decreased risk of overall mortality (age-adjusted HR = 0.58; 95 % CI 0.36-0.96); however, multivariate adjustments attenuated the association (HR = 0.90; 95 % CI 0.50-1.61). No association was found between serum 25(OH)D and breast cancer-specific mortality (sufficient: HR = 1.21; 95 % CI 0.52-2.80) in multivariate models.

CONCLUSION

In this breast cancer cohort, higher serum 25(OH)D may be associated with improved survival, but results were not statistically significant and must be interpreted with caution. The potential prognostic effect of vitamin D from diet, supplements, or both should be evaluated in future larger studies with additional endpoints from breast cancer patients.

Contribution of vitamin D insufficiency to the pathogenesis of multiple sclerosis

The contribution of vitamin D insufficiency to the pathogenesis of multiple sclerosis (MS) is reviewed. Among the multiple recently discovered actions of vitamin D, an immunomodulatory role has been documented in experimental autoimmune encephalomyelitis and in humans. This action in the peripheral immune system is currently the main known mechanism through which vitamin D might influence MS, but other types of actions could be involved within the central nervous system. Furthermore, vitamin D insufficiency is widespread in temperate countries and in patients with MS at the earliest stages of the disease, suggesting that the deleterious effects related to vitamin D insufficiency may be exerted in these patients. In fact, many genetic and environmental risk factors appear to interact and contribute to MS. In genetics, several human leukocyte antigen (HLA) alleles (more particularly HLA-DRB1*1501) could favour the disease whereas some others could be protective. Some of the genes involved in vitamin D metabolism (e.g. CYP27B1) also play a significant role. Furthermore, three environmental risk factors have been identified: past Epstein-Barr virus infection, vitamin D insufficiency and cigarette smoking. Interactions between genetic and environmental risk or protective factors may occur during the mother's pregnancy and could continue during childhood and adolescence and until the disease is triggered in adulthood, therefore possibly modulating the MS risk throughout the first decades of life. Furthermore, some clinical findings already strongly suggest that vitamin D status influences the relapse rate and radiological lesions in patients with MS, although the results of adequately powered randomized clinical trials using vitamin D supplementation have not yet been reported. While awaiting these incontrovertible results, which might be long in coming, patients with MS who are currently in vitamin D insufficiency should be supplemented, at least for their general health status, using moderate doses of the vitamin.

The impact of secondary hyperparathyroidism on the efficacy of antiresorptive therapy

BACKGROUND

The aim of the present study was to assess whether the efficacy of bisphosphonate treatment is influenced by PTH levels measured in newly diagnosed osteoporotic patients and to identify the threshold value, beyond which PTH level negatively influences therapeutic efficacy.

METHODS

One hundred and thirty-eight osteoporotic patients were enrolled into the study. All subjects underwent laboratory screening, bone densitometry with DEXA, and x-ray imaging. The changes in bone density were evaluated after a mean follow-up period of 13.37 ± 1.29 months. Correlation analysis was performed on the clinical data of patients, the percentage changes of BMD values, and the PTH levels measured at the beginning of study, using SPSS software.

RESULTS

The mean age of the subjects was 64.82 ± 10.51 years, and the female-to-male ratio was 116/22. Baseline BMD value measured with AP DEXA scanning was 0.854 ± 0.108 g/cm(2) in the L(1-4) vertebrae and 0.768 ± 0.115 g/cm(2) in the left femoral neck. By the end of the follow-up period, these values changed to 0.890 ± 0.111 g/cm(2) and 0.773 ± 0.111 g/cm(2), respectively. We found a statistically significant, negative correlation between PTH levels and the percentage changes of lumbar BMD values measured at the end of the follow-up (correlation coefficient R(2) = 0.121, p < 0.0001). The analysis of frequency histograms suggested that negative effects on bone might be expected above a PTH level of 60 pg/mL (7.3 pmol/L).

CONCLUSION

Our findings imply that a baseline PTH level over 60 ng/mL can reduce the efficacy of bisphosphonate treatment.

Relationship between 25-OH-D serum level and relapse rate in multiple sclerosis patients before and after vitamin D supplementation

BACKGROUND

Vitamin D could play a protective role in multiple sclerosis.

METHODS

In an observational, uncontrolled study, vitamin D3 supplementation (3010 IU/day on average) was given to 156 consecutive patients with relapsing-remitting multiple sclerosis, under first-line immunomodulatory therapy and with initial 25-OH-D serum level lower than 100 nmol/l (40 ng/ml). Relapses were determined for 29.1 ± 8.4 months during vitamin D and 29.8 ± 10.1 months before supplementation. The 25-OH-D level was measured before supplementation and several times during supplementation. The incidence rate of relapses before and during supplementation was estimated using negative binomial regression models with follow-up durations as offset terms. The incidence rate and incidence rate ratio of relapses at various 25-OH-D levels were also calculated using negative binomial regression models.

RESULTS

In 76 patients, immunomodulatory therapy preceded vitamin D supplementation (by 4.2 ± 2.7 years) and in 80 patients both treatments were started simultaneously. Under supplementation, the 25-OH-D level increased from 49 ± 22 nmol/l to 110 ± 26 nmol/l on average. Pooling data collected before and during supplementation, we found a significant strong inverse relationship between the relapse incidence rate and the 25-OH-D level (p < 0.0001), suggesting that vitamin D did indeed influence the relapse rate. Results of univariate, bivariate and multivariate analyses were analogous: in the multivariate model adjusted for age, disease duration and previous use of immunomodulatory therapy, every 10 nmol increase in 25-OH-D level was associated with a reduction in the relapse incidence rate of 13.7%. Dividing iteratively the population made up of pooled periods into two subgroups according to the 25-OH-D levels, the relapse incidence rate ratio decreased as the 25-OH-D level increased up to 110 nmol/l, but a plateau effect was observed beyond this limit.

CONCLUSION

Further studies are warranted for accurate quantification of the vitamin D effect.

Vitamin D supplementation during exercise training does not alter inflammatory biomarkers in overweight and obese subjects

The purpose of this study was to examine the effects of vitamin D supplementation on inflammatory biomarkers in overweight and obese adults participating in a progressive resistance exercise training program. Twenty-three (26.1 ± 4.7 years) overweight and obese (BMI 31.3 ± 3.2 kg/m2) adults were randomized into a double-blind vitamin D supplementation (Vit D 4,000 IU/day; female 5, male 5) or placebo (PL, female 7; male 6) intervention trial. Both groups performed 12 weeks (3 days/week) of progressive resistance exercise training (three sets of eight exercises) at 70-80% of one repetition maximum. Whole-blood lipopolysaccharide (LPS)-stimulated tumor necrosis factor (TNF) α production as well as circulating C-reactive protein (CRP), TNFα, interleukin 6 (IL-6), and alanine aminotransferase (ALT) were assessed at baseline and after the 12-week intervention. No main effects of group or time were detected for circulating CRP, TNFα, IL-6, and ALT. As expected, when PL and Vit D groups were combined, there was a significant correlation between percent body fat and CRP at baseline (r = 0.45, P = 0.04), and between serum 25OHD and CRP at 12 weeks (r = 0.49, P = 0.03). The PL group had a significant increase in 25 μg/ml LPS + polymixin B-stimulated TNFα production (P = 0.04), and both groups had a significant reduction in unstimulated TNFα production (P < 0.05) after the 12-week intervention. Vitamin D supplementation in healthy, overweight, and obese adults participating in a resistance training intervention did not augment exercise-induced changes in inflammatory biomarkers.

Is hypovitaminosis D one of the environmental risk factors for multiple sclerosis?

The role of hypovitaminosis D as a possible risk factor for multiple sclerosis is reviewed. First, it is emphasized that hypovitaminosis D could be only one of the risk factors for multiple sclerosis and that numerous other environmental and genetic risk factors appear to interact and combine to trigger the disease. Secondly, the classical physiological notions about vitamin D have recently been challenged and the main new findings are summarized. This vitamin could have an important immunological role involving a number of organs and pathologies, including autoimmune diseases and multiple sclerosis. Furthermore, human requirements for this vitamin are much higher than previously thought, and in medium- or high-latitude countries, they might not be met in the majority of the general population due to a lack of sunshine and an increasingly urbanized lifestyle. Thereafter, the different types of studies that have helped to implicate hypovitaminosis D as a risk factor for multiple sclerosis are reviewed. In experimental autoimmune encephalomyelitis, vitamin D has been shown to play a significant immunological role. Diverse epidemiological studies suggest that a direct chain of causality exists in the general population between latitude, exposure to the sun, vitamin D status and the risk of multiple sclerosis. New epidemiological analyses from France support the existence of this chain of links. Recently reported immunological findings in patients with multiple sclerosis have consistently shown that vitamin D significantly influences regulatory T lymphocyte cells, whose role is well known in the pathogenesis of the disease. Lastly, in a number of studies on serum levels of vitamin D in multiple sclerosis, an insufficiency was observed in the great majority of patients, including at the earliest stages of the disease. The questionable specificity and significance of such results is detailed here. Based on a final global analysis of the cumulative significance of these different types of findings, it would appear likely that hypovitaminosis D is one of the risk factors for multiple sclerosis.

[Effect of vitamin D deficiency on cardiovascular risk]

Vitamin D deficiency affects almost 50 % of the population worldwide. Besides its classical effects on bone and calcium metabolism, vitamin D displays a wide spectrum of non classical effects. Among these effects, those targeting the cardiovascular system are mostly documented by observational, experimental and small intervention trials that most often evaluated intermediate parameters. The time has now come for large placebo-controlled trials targeting clinical endpoints such as the incidence of major cardiovascular events and mortality.

Vitamin D and primary hyperparathyroidism (PHPT)

Vitamin D deficiency and PHPT are two common conditions, especially in postmenopausal women. Vitamin D deficiency is said to be even more frequent in PHPT patients than in the general population due to an accelerated conversion of 25OHD into calcitriol or 24-hydroxylated compounds. Although several studies have reported worsening of PHPT phenotype (larger tumours, higher PTH levels, more severe bone disease) when vitamin D deficiency coexists whereas vitamin D supplementation in PHPT patients with a serum calcium level<3 mmol/L has been shown to be safe (no increase in serum or urinary calcium) and to decrease serum PTH concentration, that many physicians are afraid to give vitamin D to already hypercalcemic PHPT patients. On the other hand, it is possible that, in some patients, a persistent vitamin D deficiency induces, in the long-term, an autonomous secretion of PTH (i.e. tertiary hyperparathyroidism). The mechanism by which this could occur is unclear however. Finally, as many, otherwise normal, subjects with vitamin D insufficiency may have an increased serum PTH level we believe that those with vitamin D insufficiency should be excluded from a reference population for serum PTH levels. By doing that, we found that the upper normal limit for serum PTH was 25-30% lower than in the whole population.

Vitamin D and depression: where is all the sunshine?

Depression in its own right is a disabling condition impairing all aspects of human function. In persons with a chronic medical disease, depression often makes the management of chronic illness more difficult. Recently, vitamin D has been reported in the scientific and lay press as an important factor that may have significant health benefits in the prevention and the treatment of many chronic illnesses. Most individuals in this country have insufficient levels of vitamin D. This is also true for persons with depression as well as other mental disorders. Whether this is due to insufficient dietary intake, lifestyle (e.g., little outdoor exposure to sunshine), or other factors is addressed in this paper. In addition, groups at risk and suggested treatment for inadequate vitamin D levels are addressed. Effective detection and treatment of inadequate vitamin D levels in persons with depression and other mental disorders may be an easy and cost-effective therapy which could improve patients' long-term health outcomes as well as their quality of life.

Measurement uncertainty of 25-OH vitamin D determination with different commercially available kits: impact on the clinical cut offs

SUMMARY

Due to "measurement uncertainty", the "true" 25-OH vitamin D (25(OH)D) of a patient (whatever the commercially available assay tested) will be >80 nmol/L if its measured concentration is >100 nmol/L. Thus, if a physician considers that a normal VTD status is a 25(OH)D level >or=80 nmol/L, he should ensure that the patient's results are >or=100 nmol/L.

INTRODUCTION

Many experts recommend that serum levels of 25(OH)D should be above a lower normal limit of 75-80 nmol/L. However, the value delivered by laboratories is only an estimation of the "true" value due to "measurement uncertainty." When using a cut off, measurement uncertainty around the cut off is important because therapeutic actions may differ if the measured value is below or above the limit. We aimed to establish the "measurement uncertainty" at different levels of concentration for several commercially available 25(OH)D analytical techniques.

METHODS

We constituted three pools of serum with different 25(OH)D concentrations. Each pool was assayed in triplicate during 5 days with the DiaSorin RIA, Liaison, Elecsys, and Chromsystems-HPLC assays.

RESULTS

We report a relatively high "measurement uncertainty" for the measurement of 25(OH)D for the four different techniques: the mean relative uncertainties, all techniques confounded were 19.4%, 16.0%, and 11.3% for pool 1 (35.3 nmol/L), pool 2 (79.5 nmol/L), and pool 3 (126.1 nmol/L), respectively.

CONCLUSIONS

Our results show that, whatever the assay, the "true" 25(OH)D of a patient will be >80 nmol/L if its measured concentration is >100 nmol/L. In other words, if a physician considers that a normal VTD status is defined by a 25(OH)D level >or=80 nmol/L, he should ensure that the patients present a 25(OH)D >or=100 nmol/L.

[Vitamin D deficiency in morbidly obese patients. A case-control study]

OBJECTIVES

Recent studies show a high prevalence of vitamin D deficiency in the general population, especially in the elderly. There are also studies reporting the same observations in the morbidly obese, although few of these studies have compared morbidly obese individuals with non-obese persons. The objectives of this study were to estimate the prevalence of vitamin D deficiency and secondary hyperparathyroidism in both groups and to assess whether there is a relationship between obesity and vitamin D deficiency.

METHODS

This study was carried out in 138 patients in the Guadalajara University Hospital (Spain) between December 2008 and December 2009. Of these, 50.7% were morbidly obese and 49.3% were not obese. Fasting blood samples were taken from both groups for determination of 25-hydroxyvitamin D, intact parathyroid hormone, calcium, albumin and phosphorus, among other biochemical parameters.

RESULTS

The mean concentration of 25-hydroxyvitamin D was 16.6+/-8.12 ng/ml in the morbidly obese group and 21.9+/-7.34 ng/ml in the non-obese group (p<0.0001). The prevalence of vitamin D deficiency was 80% in morbidly obese patients and 41% in non-obese patients (p<0.0001). There were no statistically significant differences in concentrations of parathyroid hormone, calcium or phosphorus between the two groups.

CONCLUSIONS

A high prevalence of vitamin D deficiency was found in both groups studied, although the concentration of 25-hydroxyvitamin D was significantly lower in the morbidly obese. Morbid obesity is closely linked to vitamin D deficiency. To prevent this deficiency, determination of 25-hydroxyvitamin D should be included in clinical practice guidelines for the treatment of obesity.

Suppression of C-terminal telopeptide in hypovitaminosis D requires calcium as well as vitamin D

We compared the effects of oral calcium and vitamin D separately and together on relevant variables in 22 postmenopausal volunteers with initial serum 25OHD levels below 60 nmol/L. Subjects were allocated randomly to two regimens: group 1 received 1 week of calcium 1,000 mg, followed by 7 weeks with additional vitamin D3 1,000 i.u. daily; group 2 received 7 weeks of D3 1,000 i.u. daily, followed by 1 week with additional calcium 1,000 mg. We measured serum calcium, phosphate, PTH, 25OHD, CTX, and ALP at baseline and after 1 and 8 weeks in group 1 and after 7 and 8 weeks in group 2. There were no significant changes in ALP from either vitamin D or calcium. Calcium caused significant elevation of serum 25OHD as well as major suppression of serum CTX, which could not easily be accounted for by suppression of PTH. Vitamin D caused no significant change in any variable except elevation of serum 25OHD. The suppressive effect of calcium (whether given first or second) on serum CTX was threefold greater than that of vitamin D (whether given first or second) (P < 0.001), although their suppressive effects on serum PTH were the same. Calcium and vitamin D yielded greater and more significant effects on all variables (except ALP) than either treatment alone. We suggest that calcium may elevate serum 25OHD by prolonging its half-life and that it may have an inhibitory effect on bone resorption independent of, or in addition to, its suppression of PTH.

Hypovitaminosis D in glycogen storage disease type I

Glycogen storage disease type I (GSD I) is caused by inherited defects of the glucose 6-phosphatase complex, resulting in fasting hypoglycemia, lactic acidosis, hyperuricemia and hyperlipidemia. Sixteen out of 26 (61.5%) GSD I patients in our study had suboptimal levels (<30 ng/ml) of 25-hydroxyvitamin-D (25(OH)D) despite supplementation of vitamin D and/or vitamin D + calcium based on WHO standards in 24/26 (92.3%) patients. The restrictive nature of the GSD I diet, metabolic derangements and intestinal malabsorption seen in GSD I are possible reasons for the observed hypovitaminosis D. Our results suggest that measurement of 25(OH)D should be considered in the routine evaluation of GSD I patients.

Threshold for effects of vitamin D deficiency on glucose metabolism in obese female African-American adolescents

CONTEXT

Vitamin D status can influence insulin resistance.

OBJECTIVE

The aim of the study was to determine the prevalence of vitamin D deficiency in obese African-American (AA) adolescent females in a southeastern latitude and to determine the relationship of 25-hydroxyvitamin D [25(OH)D] with insulin and glucose dynamics.

DESIGN

We conducted a cross-sectional study in a University Children's Hospital.

METHODS

Serum 25(OH)D, fasting glucose, PTH, serum calcium, serum lipids, serum transaminases, and C-reactive protein were assessed. Indices of insulin sensitivity and resistance were determined from an oral glucose tolerance test. Subjects were classified as vitamin D deficient or sufficient, based on the traditional vitamin D deficiency definition [serum 25(OH)D <20 ng/ml] and also by a lower 25(OH)D cut-point of 15 ng/ml or less.

RESULTS

A total of 51 AA adolescent females (body mass index, 43.3 +/- 9.9 kg/m(2); age, 14 +/- 2 yr) were studied. Serum 25(OH)D concentrations were 20 ng/ml or less in 78.4% and 15 ng/ml or less in 60.8% of subjects. There were no significant group differences in the metabolic outcomes when subjects were classified using the traditional vitamin D deficiency definition. The Matsuda index of insulin sensitivity was significantly lower (P = 0.02), and insulin area under the curve was significantly higher (P = 0.04) in subjects with 25(OH)D concentrations of 15 ng/ml or less vs. those with higher concentrations.

CONCLUSIONS

Vitamin D deficiency is highly prevalent in obese, AA female adolescents and may promote insulin resistance. Our data suggest that a 25(OH)D concentration of 15 ng/ml or less may be the threshold by which vitamin D deficiency confers negative effects on insulin sensitivity.

Vitamin D status and common risk factors for bone fragility as determinants of quantitative ultrasound variables in a nationally representative population sample

Calcaneal quantitative ultrasound (QUS) can predict bone strength and fracture risk. Bone fragility has no single cause but results from a complex interplay of several etiologic or contributing factors. Vitamin D is essential for bone health even though it is still unclear how much of this vitamin is required to maintain bone strength and prevent fractures. Measurements of serum 25-hydroxyvitamin D [S-25(OH)D] have indicated a high prevalence of inadequate vitamin D status in a number of studies mostly based on selected study populations. The objective of this study was to examine the associations between S-25(OH)D, common risk factors for bone fragility, and QUS variables in a large unselected population sample. The study population consisted of 2736 men and 3299 women from a nationally representative population sample, aged 30 years or over. Information on lifestyle was elicited by means of interviews and questionnaires. Body fat mass was estimated using an impedance-meter. S-25(OH)D was measured by radioimmunoassay. Calcaneal QUS was performed on the Hologic Sahara apparatus recording broadband ultrasound attenuation (BUA) and speed of sound (SOS). The potential determinants of BUA and SOS were analysed using separate multiple linear regression models for men and women. S-25(OH)D proved to be an independent determinant of BUA (P<0.0001 for men, P<0.001 for women) and SOS (P<0.0001 for men, P<0.05 for women). BUA was also independently associated with age, height, weight, alcohol consumption, and postmenopausal status in women, and with weight, alcohol consumption, smoking and physical activity in men. All of the above variables, except for weight in women, were also found to be independent determinants of SOS in both men and women. A reverse association was found between S-25(OH)D and adiposity in spite of higher intakes of vitamin D in those with higher fat mass. In this unselected sample of men and women, vitamin D status, several lifestyle factors and physical characteristics proved to be significant determinants of BUA and SOS. Inadequate vitamin D status was common, and measures ensuring adequate intakes of vitamin D in the population thus deserve continued attention. Obesity should be taken into account in future assessments of vitamin D status in Finland as in other countries.

Alendronate/vitamin D3 70 mg/2800 IU with and without additional 2800 IU vitamin D3 for osteoporosis: results from the 24-week extension of a 15-week randomized, controlled trial

Although vitamin D supplementation is a fundamental part of osteoporosis treatment, many patients do not regularly take adequate amounts. A once-weekly (OW) alendronate (ALN) preparation that includes 2800 IU of vitamin D3 in a single combination tablet (ALN+D2800) is available for treating patients and ensuring intake of vitamin D that is consistent with existing guidelines. This randomized, double-blind study extension was conducted to evaluate the safety and tolerability of ALN+D2800 and ALN+D2800 plus an additional 2800 IU vitamin D3 single tablet supplement (ALN+D5600) administered for 24 weeks in men and postmenopausal women with osteoporosis previously treated OW for 15 weeks with either ALN or ALN+D2800. The primary endpoint was the proportion of participants who developed hypercalciuria (defined as a 24-hour urine calcium >300 mg in women or >350 mg in men and an increase of >25% versus randomization baseline) at week 39. The key secondary endpoint was the proportion of participants with vitamin D insufficiency (serum 25(OH)D <15 ng/mL [37.4 nmol/L]) at the end of the study. Hypercalciuria incidence (4.2% [ALN+D5600] vs. 2.8% [ALN+D2800]), did not differ between groups (p = 0.354). No participants developed hypercalcemia. Among the participants with vitamin D insufficiency at the week 0 baseline, the prevalence of insufficiency at the end of the study was reduced by 92% in the ALN+D5600 group and by 86% in the ALN+D2800 group. The incidences of clinical adverse experiences, including drug-related adverse experiences, were similar in both groups. In subjects previously treated with ALN+D2800 for 15 weeks, the addition of 2800 IU D3 for 24 weeks did not produce hypercalcemia nor increase the risk of hypercalciuria.

Highest prevalence of vitamin D inadequacy in institutionalized women compared with noninstitutionalized women: a case-control study

The reduced capacity of older skin to synthesize vitamin D(3) under the influence of ultraviolet light makes older persons at risk of vitamin D deficiency. The risk could even be increased in institutionalized persons owing to their lower sunshine exposure. It has been reported that an inadequate vitamin D level is associated with secondary hyperparathyroidism, increased bone turnover, and bone loss, which increase fracture risk. The objective of this study was to assess the prevalence of inadequate serum vitamin D levels in institutionalized, postmenopausal, osteoporotic women. Assessment of 25-hydroxyvitamin D [25(OH)D] was performed in 445 institutionalized, osteoporotic women from nine countries (Australia, Belgium, France, Germany, Hungary, Italy, Poland, Spain and UK). For each institutionalized woman, three age-matched, noninstitutionalized, osteoporotic controls were also included. Four cutoffs of 25(OH)D inadequacy were fixed: less than 80, less than 75, less than 50 and less than 30 nmol/l. Mean age was 79.7 years (standard deviation [SD] = 5.8) for the institutionalized women and 79.5 years (SD = 5.5) for the noninstitutionalized women (p = 0.45). Significantly fewer institutionalized women received vitamin D supplements (13.2 vs 24.0%; p < 0.0001). In women without vitamin D supplements, the level of 25(OH)D was significantly lower in institutionalized women (56.9 [SD = 23.9] nmol/l) compared with noninstitutionalized women (63.2 [SD = 22.0] nmol/l; p < 0.0001). In institutionalized women (without vitamin D supplements), the prevalence of 25(OH)D inadequacy was 10.4, 41.2, 80.3 and 84.2% when considering cutoffs of 80, 75, 50 and 30 nmol/l, respectively. In the control group, the prevalence was 2.7, 22.9, 74.4 and 81.7%, respectively. The prevalence of vitamin D inadequacy was significantly higher in institutionalized women when considering the 75, 50 and 30 nmol/l cutoffs but not when considering the 80 nmol/l cutoff. This study highlights a high prevalence of vitamin D inadequacy in institutionalized, osteoporotic women. Compared with age-matched osteoporotic controls, the prevalence of severe vitamin D inadequacy was substantially more important in institutionalized women. We believe that a greater awareness of the importance of vitamin D inadequacy is needed in order to address this public health problem.

Macroautophagy: the key ingredient to a healthy diet?

Dietary compounds can influence the risk of cancer and other diseases through diverse mechanisms which include the activation or inhibition of macroautophagy. Macroautophagy is a catabolic process for the lysosomal degradation and recycling of cytoplasmic constituents which has been implicated in several pathologies, including cancer and neurodegeneration. In some instances, macroautophagy acts to suppress tumor formation and neural degeneration. Thus, it may be feasible to design diets, supplements or therapeutics that can alter the level of macroautophagy within cells to prevent or treat disease. While critical questions still need to be answered before we can safely and effectively implement such a strategy, we provide here a review of the literature regarding dietary constituents that have a demonstrated macroautophagy-modulating function.

Vitamin D: current status and perspectives

The role of vitamin D in maintaining bone health has been known for decades. Recently, however, the discovery that many tissues expressed the vitamin D receptor and were able to transform the 25-OH vitamin D into its most active metabolite, 1,25-(OH)

Clin Chem Lab Med 2009;47:120–7.

Vitamin D-deficiency and post-fracture changes in lower extremity function and falls in women with hip fractures

We determined the prevalence of vitamin D deficiency and lower extremity function in women with hip fractures. Women with extremely low vitamin D levels had reduced lower extremity muscle function and increased falls 1 year later. Ensuring vitamin D sufficiency after a hip fracture may improve function and reduce falls.

INTRODUCTION

Hip fractures are the most devastating of fractures, commonly leading to loss of independent ambulation and living. In this retrospective analysis we determined the prevalence of vitamin D deficiency in women with hip fractures and the association between 25-hydroxyvitamin D [25(OH)D] levels and functional impairment one year later.

METHODS

One hundred ten community-dwelling women with hip fractures were recruited from Boston, MA (n = 30) and Baltimore, MD (n = 80) before 1998 and 25(OH)D levels were measured by radioimmunoassay. In a subset of women from Baltimore, a performance measure of the lower extremities using the lower extremity gain scale (LEGS) was measured at 2, 6, and 12 months. Falls, grip strength, chair rise time, walking speed, and balance were also determined.

RESULTS

Vitamin D insufficiency defined as a 25(OH)D <or=32 ng/mL was present in 96% of the women with hip fractures and 38% had extremely low levels <or=9 ng/mL. At 1 year post-fracture, compared to women with a 25(OH)D >9 ng/mL, those with 25(OH)D <or=9 ng/mL had poorer LEGS performance (p < 0.0001) and higher fall rates, without group differences in grip strength or balance.

CONCLUSION

Vitamin D sufficiency may have important effects on lower extremity function following hip fractures, without excessive healthcare costs.

Evaluation and correction of low vitamin D status

Low vitamin D status, which is endemic due to inadequate oral intake combined with sun avoidance, contributes to musculoskeletal and other pathologies. Although controversial, it is increasingly recommended that serum 25-hydroxyvitamin D (25D) concentrations less than 30 ng/mL be considered suboptimal. Clinicians should appreciate that 25(OH)D measurements, like all quantitative laboratory tests, are subject to assay and biologic variability. Additionally, international standardized calibrators do not exist for 25(OH)D measurement. As such, a single 25(OH)D value of "30 ng/mL" may have substantial variability surrounding it, thereby making 25(OH)D levels of approximately 35 to 40 ng/mL a reasonable therapeutic goal to assure vitamin D adequacy. Achieving such levels often requires vitamin D supplementation. Vitamin D3 (cholecalciferol) or D2 (ergocalciferol) may be used; whether vitamin D3 is more potent than vitamin D2 in maintaining 25(OH)D is controversial.

Vitamin D inadequacy in French osteoporotic and osteopenic women

OBJECTIVE

Studies have shown that low serum vitamin D levels are associated with secondary hyperparathyroidism, which decreases bone strength and increases fracture risk, most notably after 50 years of age. The objective of this study was to evaluate the vitamin D status of postmenopausal women in France.

METHODS

We conducted a cross-sectional observational study of 1292 menopausal women with osteoporosis or osteopenia. The age range was 52-94 years. Serum 25-OH-vitamin D was assayed in each patient. Based on data in the literature, we used four 25-OH-D cutoffs to define vitamin D deficiency: 30, 50, 75, and 80 nmol/L (<12, <20, <30, and <32 ng/ml).

RESULTS

Mean serum 25-OH-D was 51.5+/-26.1 nmol/L (about 20.6+/-10.4 ng/ml). In the 343 (26.5%) patients taking supplemental vitamin D with or without supplemental calcium, the mean serum 25-OH-D level was significantly higher than in the other patients (65.0+/-26.0 ng/ml vs. 46.6+/-18.6 ng/ml; P<0.001). In the subgroup not taking vitamin D supplements, the prevalence of vitamin D deficiency was 27.3%, 54.1%, 89.9%, and 93.2% with the 30, 50, 75, and 80 nmol/L cutoffs, respectively. The mean 25-OH-D level varied across seasons (P<0.001), with the highest value being obtained in summer (53.4+/-18.7 nmol/L; about 21.3+/-7.5 ng/ml).

CONCLUSION

Vitamin D deficiency is common among postmenopausal women with osteoporosis or osteopenia in France.

Prevalence of vitamin D depletion among subjects seeking advice on osteoporosis: a five-year cross-sectional study with public health implications

We assessed vitamin D nutritional status in unselected consecutive patients seeking advice on osteoporosis. The prevalence of vitamin D depletion ranged from 15-72% depending upon the cut-off levels used for serum 25-hydroxyvitamin D, and the prevalence did not change over the 5 years of the study.

INTRODUCTION

Vitamin D depletion is a significant public health problem and has been studied in different populations using different cut-off levels, but the optimal level is yet to be established.

METHODS

In a cross-sectional study of 2,924 patients seen for osteoporosis advice we determined the prevalence of vitamin D depletion, as assessed by 25-hydroxyvitamin D (25-OHD), using three different cut-off levels stratified by gender, race and the year of the study over 5 years.

RESULTS

Mean age was 68.3 +/- 10.0 years; 90% women and 88% white. Mean 25-OHD level was 24.6 +/- 10 ng/ml and mean PTH was 48.4 +/- 32 pg/ml. The prevalence of vitamin D depletion was 15% with a cut-off level of <15 ng/ml, and rose to 32% and 72% with cut-off levels <20 ng/ml and <30 ng/ml, respectively. The prevalence was higher in men and blacks and remained constant over 5 years, regardless of the cut-off level. The expected inverse relationship between 25-OHD and PTH was observed irrespective of gender or ethnicity.

CONCLUSIONS

The prevalence of vitamin D depletion in patients seeking advice for osteoporosis is high and did not change over the 5 years of the study.

Prevalence of vitamin D inadequacy in European postmenopausal women

OBJECTIVE

Inadequate vitamin D level is associated with secondary hyperparathyroidism and increased bone turnover and bone loss, which in turn increases fracture risk. The objective of this study is to assess the prevalence of inadequate serum vitamin D levels in postmenopausal European women. There are no clear international agreements on what constitutes a level of vitamin D inadequacy, but recent publications suggest that the circulating level of vitamin D should be over 80 nmol/L or at least between 50 and 80 nmol/L.

MATERIAL AND METHODS

Assessment of 25-hydroxyvitamin D [25(OH)D] was performed in 8532 European postmenopausal women with osteoporosis or osteopenia. European countries included France, Belgium, Denmark, Italy, Poland, Hungary, United Kingdom, Spain and Germany. Two cut-offs of 25(OH)D inadequacy were fixed : < 80 nmol/L and < 50 nmol/L.

RESULTS

Mean (SD) age of the patients was 74.2 (7.1) years, body mass index was 25.7 (4.1) kg/m(2). Level of 25(OH)D was 61.0 (27.2) nmol/L. There was a highly significant difference of 25(OH)D level across European countries (p < 0.0001). The lowest level of 25(OH)D was found in France [51.5 (26.1) nmol/L] and the highest in Spain [85.2 (33.3) nmol/L]. In the whole study population, the prevalence of 25(OH)D inadequacy was 79.6% and 32.1% when considering cut-offs of 80 and 50 nmol/L, respectively and when considering patients aged less than 65 years, the prevalence reached 86% (cut-off of 80 nmol/L) and 45% (cut-off of 50 nmol/L).

CONCLUSION

This study indicates a high prevalence of vitamin D [25(OH)D] inadequacy in European postmenopausal women. The prevalence could be even higher in some particular countries. A greater awareness of the importance of vitamin D inadequacy is needed to address this public health problem.

Patient assessment in the diagnosis, prevention, and treatment of osteoporosis

Assessment of the patient with osteoporosis includes history and physical examination, laboratory testing, and imaging studies. Information gathered during this assessment assists clinicians in targeting strategies to prevent fractures. The medical history should contain items such as personal and family history of fractures, lifestyle, intake of substances such as vitamin D, calcium, corticosteroids, and other medications. The physical examination can reveal relevant information such as height loss and risk of falls. Bone mineral density (BMD), most commonly determined by dual-energy x-ray absorptiometry, best predicts fracture risk in patients without previous fracture. BMD testing is most efficient in women over 65 years old but is also helpful for men and women with risk factors. Serial BMD tests can identify individuals losing bone mass, but clinicians should be aware of what constitutes a significant change. Laboratory testing can detect other risk factors and can provide clues to etiology. Selection of laboratory tests should be individualized, as there is no consensus regarding which tests are optimal. Biochemical markers of bone turnover have a potential role in fracture risk assessment and in gauging response to therapy, but are not widely used at present. Clinicians should be aware of problems with vitamin D measurement, including seasonal variation, variability among laboratories, and the desirable therapeutic range. Careful assessment of the osteoporotic patient is essential in developing a comprehensive plan that reduces fracture risk and improves quality of life.

Vitamin D and its implications for musculoskeletal health in women: an update

Vitamin D is a hormone that controls phosphorus, calcium, and bone metabolism and neuromuscular function. Vitamin D synthesis is a process in which the skin, liver, and kidney are sequentially involved. The vitamin D pool is completed by the amount taken with food and supplements. Vitamin D deficiency causes osteopenia, precipitates and exacerbates osteoporosis, causes a painful disease, osteomalacia, and increases muscle weakness, which worsens the risk of falls and fractures. A high prevalence of vitamin D insufficiency exists in the apparently healthy population, osteoporotic patients, and patients with prior fractures. Factors contributing to low vitamin D levels include low sunlight exposure, decreased skin synthesis and intestinal absorption, and inadequate diet. The simplest way to correct hypovitaminosis is adequate nutrition and supplements. However, few patients with osteoporosis and/or fractures, receive adequate supplements. Vitamin D insufficiency may alter the regulatory mechanisms of parathyroid hormone and may induce a secondary hyperparathyroidism that increases the risk of osteoporosis and fractures, although the necessary degree of this is not established. Monitoring of serum 25-hydroxyvitamin D levels is the only way to assess vitamin D status. The ideal healthy blood levels of 25-hydroxyvitamin D are controversial, although a range from 30 to 60ng/mL is widely accepted. The role of vitamin D supplementation is to provide humans with the nutrient in an amount closer to the biological norm for our species. This amount of vitamin D results in optimal function of many aspects of health, including balance and muscle strength, thus reducing the risk of fracture beyond what is possible via the quality and quantity of bone itself.

Low vitamin D status despite abundant sun exposure

CONTEXT

Lack of sun exposure is widely accepted as the primary cause of epidemic low vitamin D status worldwide. However, some individuals with seemingly adequate UV exposure have been reported to have low serum 25-hydroxyvitamin D [25(OH)D] concentration, results that might have been confounded by imprecision of the assays used.

OBJECTIVE

The aim was to document the 25(OH)D status of healthy individuals with habitually high sun exposure.

SETTING

This study was conducted in a convenience sample of adults in Honolulu, Hawaii (latitude 21 degrees ).

PARTICIPANTS

The study population consisted of 93 adults (30 women and 63 men) with a mean (sem) age and body mass index of 24.0 yr (0.7) and 23.6 kg/m(2) (0.4), respectively. Their self-reported sun exposure was 28.9 (1.5) h/wk, yielding a calculated sun exposure index of 11.1 (0.7).

MAIN OUTCOME MEASURES

Serum 25(OH)D concentration was measured using a precise HPLC assay. Low vitamin D status was defined as a circulating 25(OH)D concentration less than 30 ng/ml.

RESULTS

Mean serum 25(OH)D concentration was 31.6 ng/ml. Using a cutpoint of 30 ng/ml, 51% of this population had low vitamin D status. The highest 25(OH)D concentration was 62 ng/ml.

CONCLUSIONS

These data suggest that variable responsiveness to UVB radiation is evident among individuals, causing some to have low vitamin D status despite abundant sun exposure. In addition, because the maximal 25(OH)D concentration produced by natural UV exposure appears to be approximately 60 ng/ml, it seems prudent to use this value as an upper limit when prescribing vitamin D supplementation.

Vitamin D insufficiency in male osteoporosis

Osteoporosis is an important public health issue among men, affecting up to 20% of all men in the United States >50 years of age. The social and economic costs of male osteoporosis are profound but can be minimized by a preventive approach, including early identification and treatment of men at risk for this potentially crippling disease. As part of this preventive approach, clinicians should screen susceptible patients for vitamin D deficiency, a commonly occurring, highly correctable risk factor for osteoporosis. Appropriate detection of vitamin D deficiency in men at risk for osteoporosis and adequate correction of this deficiency will significantly reduce morbidity and mortality associated with male osteoporosis.

Pakistani immigrant children and adults in Denmark have severely low vitamin D status

OBJECTIVE

To determine vitamin D and bone status in adolescent girls, pre-menopausal women and men of Pakistani origin, to single out determinants of vitamin D status and to determine the association between vitamin D status, bone metabolism and bone status.

SUBJECTS/METHODS

Cross-sectional study, Copenhagen (55 degrees N), January-November. Serum 25-hydroxyvitamin D (S-25OHD), serum intact parathyroid hormone (S-iPTH), bone turnover markers and whole body and lumbar spine bone mineral density were measured. Sun, smoking and clothing habits, age, body mass index (BMI), and vitamin D and calcium from food and from supplements were recorded. Thirty-seven girls (median age, range: 12.2 years, 10.1-14.7), 115 women (36.2 years, 18.1-52.7) and 95 men (38.3 years, 17.9-63.5) of Pakistani origin (immigrants or descendants with Pakistani parents) took part in the study.

RESULTS

Median concentration of S-25OHD was 10.9, 12.0 and 20.7 nmol/l for girls, women and men, respectively. Forty-seven per cent of the girls, 37% of the women and 24% of the men had elevated S-iPTH, and there was a negative relationship between S-iPTH and S-25OHD. Use of vitamin D-containing supplements had a positive association with S-25OHD for men (P=0.04) and women (P=0.0008). Twenty-one per cent of the women and 34% of the men had osteopenia. Neither S-25OHD nor S-iPTH was associated with lumbar spine or whole body bone mineral content.

CONCLUSIONS

Severely low vitamin D status and elevated S-iPTH is common among Pakistani immigrants in Denmark. The low vitamin D status is not associated with bone markers or bone mass among relatively young Pakistanis.

Is vitamin D important for preserving cognition? A positive correlation of serum 25-hydroxyvitamin D concentration with cognitive function

This study investigates the association of vitamin D status with cognitive function and discusses potential mechanisms for such an effect. The relationship of vitamin B12 with cognition was also assessed. A retrospective review of older adults presenting to a university-affiliated clinic providing consultative assessments for memory problems was performed. Charts of all patients (n=80) presenting for initial visits were reviewed to identify those who had serum 25-hydroxyvitamin D (25(OH)D), vitamin B12, and mini-mental state examination score (MMSE) all obtained on their first visit (n=32). Correlation analyses between MMSE and 25(OH)D and vitamin B12 levels were performed. Serum 25(OH)D concentration and MMSE showed a (p=0.006) positive correlation; no (p=0.875) correlation was observed between serum B12 concentration and MMSE. In conclusion, the positive, significant correlation between serum 25(OH)D concentration and MMSE in these patients suggests a potential role for vitamin D in cognitive function of older adults.

Nouvelles définitions de l'insuffisance vitaminique D, retentissement sur les normes de PTH

SCOPE

Knowledge concerning vitamin D has greatly improved during the past few years. Vitamin D can no longer be considered only as a preventive therapy for rickets-osteomalacia. Indeed, beside its role in the prevention of osteoporotic fractures in the elderly, many data suggest that it may be involved in the prevention of various diseases including cancers and auto-immune diseases.

CURRENT SITUATION AND SALIENT POINTS

Vitamin D status may be easily assessed by the measurement of 25OHD serum concentration. However, many specialists in the field regard most 25OHD reference values as being too low, and believe that the 25OHD threshold below which vitamin D status can be considered as insufficient is somewhere between 50 and 100 nmol/L (20 to 40 ng/mL). It then appears that usually recommended amounts of supplemental vitamin D may be too low to reach these 25OHD concentrations, and thus need to be revised. We have proposed that PTH reference values should be established in healthy subjects with a normal vitamin D status. This supposes that 25OHD is measured in the reference population beforehand, and that the subjects with vitamin D insufficiency are eliminated from the reference group.

PERSPECTIVES

Although more complicated than the usual way to establish normative data, we have shown that it decreases the upper limit of normal by 25-35%, enhancing thus the diagnostic sensitivity for hyperparathyroidism without a decrease in specificity.