Vitamin D intake determines vitamin d status of postmenopausal women, particularly those with limited sun exposure

Association of Serum 25-Hydroxyvitamin D and Chronic Periodontitis in Postmenopausal Women after Non-Surgical Periodontal Therapy

Objectives: Vitamin D deficiency appears to have a major effect on periodontal tissue health. The present study aimed to assess the association of the serum level of 25-hydroxyvitamin D and chronic periodontitis in postmenopausal women. Materials and Methods: This research was done on 30 postmenopausal women with chronic periodontitis who all had at least 20 natural teeth. Intravenous blood samples were taken from the study population at baseline and after completion of non-surgical periodontal treatment. This was followed by assessment of serum levels of 25-hydroxyvitamin D. Next, clinical parameters of all teeth except for third molars were measured, which included pocket depth (PD), gingival index (GI), and plaque index (PI). Data were analyzed by paired t-test and its non-parametric equivalent, the Wilcoxon test. P<0.05 was considered significant. Results: The mean PD, PI and GI before and after the intervention were significantly different (P<0.05). There was, however, no significant difference between the mean vitamin D concentrations before and after treatment (P>0.05). Conclusion: According to the results obtained in the present study, there is no association between serum vitamin D concentrations and chronic periodontitis in postmenopausal women.

Association of vitamin D with incident glaucoma: findings from the Women's Health Initiative

The relationship between vitamin D and glaucoma is controversial. The objective of this study was to examine women from the Women's Health Initiative (WHI) to determine if there is an association between vitamin D and incident glaucoma in postmenopausal women. We examined the association between dietary vitamin D intake, vitamin D supplements and serum 25 hydroxyvitamin D (25(OH)D) levels and the risk of developing glaucoma. 143,389 postmenopausal women from the WHI including a subset with serum 25(OH) D measurements were examined to determine the association of dietary, supplemental and serum levels of vitamin D to the development of glaucoma. Dietary intakes of vitamin D, use of vitamin D supplements and serum levels of 25(OH) D were predictors examined for the main outcome of incident glaucoma. In multivariable models adjusted for demographic, clinical variables and medication use, dietary vitamin D, vitamin D supplements, total vitamin D intake (diet plus supplements) and serum 25 (OH) D measurements were not significantly associated with incident glaucoma. In the CaD placebo-controlled intervention clinical trial, there was also no association in the active intervention arm with glaucoma. We conclude that dietary vitamin D intake, supplements and serum levels are not significantly related to the risk of developing glaucoma in postmenopausal women.

Response of Vitamin D after Magnesium Intervention in a Postmenopausal Population from the Province of Granada, Spain

Menopause is a stage of hormonal imbalance in women which, in addition to other physiopathological consequences, poses a risk of deficiency of key micronutrients such as magnesium and vitamin D. A study was made of the influence of a magnesium intervention upon vitamin D status in a postmenopausal population from the province of Granada (Spain). Fifty-two healthy postmenopausal women between 44–76 years of age were included. Two randomized groups—placebo and magnesium (500 mg/day)—were treated during eight weeks. Nutrient intake was assessed using questionnaires based on 72-h recall. Vitamin D was analyzed by liquid chromatography—tandem mass spectrometry. Baseline vitamin D proved deficient in over 80% of the subjects. The administration of magnesium resulted in significantly increased vitamin D levels in the intervention group versus the controls (p < 0.05). Magnesium supplementation improved vitamin D status in the studied postmenopausal women.

Vitamin D Status in Japanese Adults: Relationship of Serum 25-Hydroxyvitamin D with Simultaneously Measured Dietary Vitamin D Intake and Ultraviolet Ray Exposure

Vitamin D insufficiency/deficiency is prevalent worldwide. We investigated the effect of vitamin D intake and ultraviolet ray (UV) exposure on serum vitamin D concentration in Japan. A total of 107 healthy adult participants were recruited from Hokkaido (43° N) and Kumamoto (33° N) prefectures. All participants undertook surveys in both summer and winter. Serum 25-hydroxyvitamin D (25(OH)D₃) was examined, and vitamin D intake was assessed with a diet history questionnaire. UV exposure was measured with a wearable UV dosimeter. Regression analysis was performed to investigate the relationship between these factors, with covariates such as sun avoidance behavior. The prevalence of vitamin D insufficiency (serum 25(OH)D₃; 12 ng/mL (30 nmol/L) ≤ and <20 ng/mL (50 nmol/L))/deficiency (<12 ng/mL) was 47.7% in summer and 82.2% in winter. UV exposure time was short in Kumamoto (the urban area), at 11.6 min in summer and 14.9 min in winter. In Hokkaido (the rural area), UV exposure time was 58.3 min in summer and 22.5 min in winter. Vitamin D intake was significantly associated with serum 25(OH)D₃, and a 1 μg/1000kcal increase in intake was necessary to increase 25(OH)D₃ by 0.88 ng/mL in summer and by 1.7 ng/mL in winter. UV exposure time was significantly associated with serum 25(OH)D₃ in summer, and a 10 min increase in UV exposure time was necessary to increase 25(OH)D₃ by 0.47 ng/mL. Although consideration of personal occupation and lifestyle is necessary, most Japanese may need to increase both vitamin D intake and UV exposure.

Multi-ethnic analysis shows genetic risk and environmental predictors interact to influence 25(OH)D concentration and optimal vitamin D intake

25-Hydroxyvitamin D (25(OH)D) concentration is a complex trait with genetic and environmental predictors that may determine how much vitamin D exposure is required to reach optimal concentration. Interactions between continuous measures of a polygenic score (PGS) and vitamin D intake (PGS*intake) or available ultraviolet (UV) radiation (PGS*UV) were evaluated in individuals of African (n = 1,099) or European (n = 8,569) ancestries. Interaction terms and joint effects (main and interaction terms) were tested using one-degree of freedom (1-DF) and 2-DF models, respectively. Models controlled for age, sex, body mass index, cohort, and dietary intake/available UV. In addition, in participants achieving Institute of Medicine (IOM) vitamin D intake recommendations, 25(OH)D was evaluated by level PGS. The 2-DF PGS*intake, 1-DF PGS*UV, and 2-DF PGS*UV results were statistically significant in participants of European ancestry (p = 3.3 × 10-18 , p =  2.1 × 10-2 , and p =  2.4 × 10-19 , respectively), but not in those of African ancestry. In European-ancestry participants reaching IOM vitamin D intake guidelines, the percent of participants achieving adequate 25(OH)D ( >20 ng/ml) increased as genetic risk decreased (72% vs. 89% in highest vs. lowest risk; p = .018). Available UV radiation and vitamin D intake interact with genetics to influence 25(OH)D. Individuals with higher genetic risk may require more vitamin D exposure to maintain optimal 25(OH)D concentrations.

Association between Body Fatness and Vitamin D3 Status in a Postmenopausal Population

Vitamin D is a micronutrient that plays a key role in phosphocalcic metabolism. The postmenopausal population presents a risk of deficiency in this vitamin due to hormonal alterations which, in the case of obesity, would be exacerbated. The objective was to assess the status of vitamin D in a postmenopausal population and determine the relationship of 25-hydroxivitamin D [25(OH)D] and its metabolites with anthropometric parameters. The study included 78 healthy postmenopausal women aged from 44 to 76. The nutrient intake assessment was carried out using the 24 h reminder (R24h). 25(OH)D was analyzed using ultra-high-performance liquid chromatography (UHPLC). A total of 80% and 68% of the women studied did not reach sufficient values of 25(OH)D and 25-hydroxivitamin D₃ [25(OH)D₃], respectively, which was inversely correlated with Body Mass Index (BMI) (r = −0.25, p = 0.04), hip perimeter (r = −0.26 and r = −0.24, all p < 0.05), arm circumference (r = −0.29, p = 0.01) and fat mass (r = −0.28 and r = −0.26, all p < 0.05). 25(OH)D₃ is the metabolite that contributed most to this association. In conclusion, 25(OH)D₃ levels are related to anthropometric parameters in the postmenopausal women in this study, confirming insufficient status in the majority of the population. Approach strategies are necessary to correct and avoid this risk in order to ensure future quality of life.

A simple questionnaire for the prediction of vitamin D deficiency in Japanese adults (Vitaimn D Deficiency questionnaire for Japanese: VDDQ-J)

Vitamin D deficiency (VDD) is associated with an increased risk of various diseases. Serum 25-hydroxyvitamin D [25(OH)D] concentration is the best marker for vitamin D status and its concentration < 20 ng/mL indicates VDD. However, its measurement is not easily applicable for the evaluation of vitamin D status in the general population because of its cost. Therefore, we aimed to develop a simple questionnaire for easily identifying the risk of VDD. From the total sample (649 healthy subjects aged 19-70 years), 434 and 215 subjects were randomly assigned to the derivation and the validation cohort, respectively. Prediction model for VDD was developed by backward logistic regression analysis. The regression β coefficients of the significant predictors were transformed into integral numbers and used for the individual score. These individual scores were summed to calculate the total risk score (VDD questionnaire for Japanese score: VDDQ-J score). VDD was present in 54.1% of the total subjects. The model for the prediction of VDD consisted of 7 predictors. Areas under the curve were 0.78 and 0.75 in the data set of internal validation and of the external validation, respectively. The cutoff value was determined to be 31 points (range 0-54) with the sensitivity/specificity and positive predictive value/negative predictive value of 61%/79%, and 81%/57%, respectively. Our VDDQ-J score is easy to answer by the wide range of subjects, and well predicts VDD. This risk score would be useful to identify subjects at risk for VDD both in clinical and epidemiological settings.

Prevalence of hypovitaminosis D in postmenopausal women: a systematic review

BACKGROUND

Hypovitaminosis D is considered a global public health issue. Knowledge of its true dimensions will allow us to design interventions and plan preventive measures that can have a significant impact on human health.

OBJECTIVES

The aim of this study was to evaluate the prevalence of hypovitaminosis D, defined as a serum 25-hydroxyvitamin D concentration < 30 ng/ml, in postmenopausal women around the world, as well as to identify the potential associated factors.

METHODS

A systematic review was performed in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analyses recommendations. Specific search terms were consulted in Medline, Excerpta Medica, and Latin-American and Caribbean Health Sciences Literature databases, with no restriction for the year or language of publication.

RESULTS

Of 451 studies initially identified, 32 were selected for analysis. Collectively, those 32 studies evaluated 21,236 postmenopausal women, of whom 16,440 (77.4%) had serum 25-hydroxyvitamin D concentrations < 30 ng/ml. The reported prevalence of hypovitaminosis D ranged from 29% (in the United States) to 99.4% (in China). In six of the studies, the prevalence was above 90%.

CONCLUSIONS

If the criterion is the 30 ng/ml cut-off point, the majority of postmenopausal women in the world could be classified as having hypovitaminosis D. Among the studies evaluated, the lowest prevalence reported was nearly 30%. Neither latitude, region of the world, nor laboratory methodology were found to be associated with the prevalence of hypovitaminosis D.

Therapeutic regimens for vitamin D deficiency in postmenopausal women: a systematic review

Introduction

We reviewed the most effective vitamin D3 regimen for vitamin D deficiency in postmenopausal women.

Material and methods

We searched for studies and clinical trials conducted on healthy postmenopausal women published on PubMed from 2000 to 2018 using the term "Vitamin D deficiency" combined with the following terms: "dose", "supplement", "supplementation", "cholecalciferol" or "cholecalciferol dose". We identified 1376 articles which matched the search criteria. Based on reviewing the title and abstract, 17 articles were eligible for a full-text review. Of those, 12 manuscripts were ultimately included.

Results

A majority of the studies (75%) reported using daily maintenance doses which were predominantly administered orally (83.3%). Two studies reported favorable results following therapy with a single oral dose of 300,000 IU. After one month, however, 25-hydroxy vitamin D [25(OH)D] was satisfactory; both studies failed to maintain adequate responses after 60 and 90 days. One study found that loading oral doses of 50,000 IU/day for 2 weeks followed by the same doses every 2 weeks for one year were effective. Five studies employed oral doses of 800 IU/day but none of them reported that this dose was adequate. Three studies used doses of 1000 IU/day but only two of them reported positive results. Three trials examined oral doses of 2000 IU/day and another 3 studies tested oral doses of 4000-4800 IU/day. All of them reported acceptable responses that lasted with continued treatment.

Conclusions

Oral maintenance doses of 2000-4800 IU/day satisfactorily corrected vitamin D deficiency and maintained 25(OH)D levels in postmenopausal women with continuous therapy.

Vitamin D restriction enhances periovarian adipose tissue inflammation in a model of menopause

Background: Menopause and deficiency in vitamin D (VD) are two health problems usually associated with aging women.Objective: We aimed to study inflammation in visceral adipose tissue when bilateral ovariectomy is combined with dietary restriction in VD.Methods: We studied 60 female C57BL/6 mice 3 months of age. Half of the animals had bilateral ovariectomy (Ovx group, n = 30) and half a sham procedure (Control [C] group, n = 30), and half of each Ovx or C group were fed a standard diet containing VD or a diet restricted in VD (D-) for an additional 12 weeks. Therefore, four groups were formed (n = 15 each group): C, C(D-), Ovx, and Ovx(D-). After sacrifice, the periovarian adipose tissue (PAT) was investigated.Results: In PAT, we observed different levels of hypertrophied adipocytes, enhanced proinflammatory cytokines, activation of inflammatory markers, and components of the extracellular signal-regulated kinase. The most affected PAT was seen in the Ovx(D-) group, followed by the Ovx group, the C(D-) group, and the C group (the least altered).Conclusion: The results demonstrate that ovariectomy and dietary restriction of VD are inducers of adverse effects on mouse visceral adipose tissue. When combined, these insults might enhance PAT inflammation.

Predicting serum vitamin D concentrations based on self-reported lifestyle factors and personal attributes

Evidence supports the role of vitamin D in various conditions of development and ageing. Serum 25-hydroxyvitamin D (25(OH)D) is the best indicator for current vitamin D status. However, the cost of its measurement can be prohibitive in epidemiological research. We developed and validated multivariable regression models that quantified the relationships between vitamin D determinants, measured through an in-person interview, and serum 25(OH)D concentrations. A total of 200 controls participating in a population-based case-control study in Montreal, Canada, provided a blood specimen and completed an in-person interview on socio-demographic, reproductive, medical and lifestyle characteristics and personal attributes. Serum 25(OH)D concentrations were quantified by liquid chromatography-tandem MS. Multivariable least squares regression was used to build models that predict 25(OH)D concentrations from interview responses. We assessed high-order effects, performed sensitivity analysis using the lasso method and conducted cross-validation of the prediction models. Prediction models were built for users and non-users of vitamin D supplements separately. Among users, alcohol intake, outdoor time, sun protection, dose of supplement use, menopausal status and recent vacation were predictive of 25(OH)D concentrations. Among non-users, BMI, sun sensitivity, season and recent vacation were predictive of 25(OH)D concentrations. In cross-validation, 46-47 % of the variation in 25(OH)D concentrations were explained by these predictors. In the absence of 25(OH)D measures, our study supports that predicted 25(OH)D scores may be used to assign exposure in epidemiological studies that examine vitamin D exposure.

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

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

Factors associated to serum 25-hydroxyvitamin D levels among older adult populations in urban and suburban communities in Shanghai, China

BACKGROUND

Vitamin D deficiency is widespread in China, particularly among older adults. Factors associated with suboptimal vitamin D levels are not well defined. The present study was a population-based study that included 10 urban and suburban communities in Shanghai, to evaluate vitamin D status and its correlates among older adults.

METHOD

This cross-sectional study was based on study data for 3924 healthy men and women aged 65-95 years. Anthropometric and socioeconomic data were collected in June-July 2014. Serum 25(OH)D levels were detected using a chemiluminescence immunoassay. The following socioeconomic data were obtained through self-administered questionnaires: education level, lifestyle, residency, and dietary habits. A logistic regression model was used to assess associations between anthropometric factors, socioeconomic factors and serum 25(OH)D levels.

RESULTS

Median levels of serum 25(OH)D in men and women were 22.73 and 19.99 ng/mL, respectively. Vitamin D deficiency was common in subjects, even though data collection was conducted during summer. The general prevalence of serum 25(OH)D levels <20 ng/mL were 35.4% and 50.5% for men and women respectively. The general prevalence of serum 25(OH)D levels <10 ng/mL were 2.73% and 5.9% for men and women respectively. A multivariable model indicated serum 25(OH)D levels ≥20 ng/mL were significantly and positively correlated with male sex, calcium or vitamin D supplementation, and residency in suburban communities. The model also indicated that high level of physical activity was protective factors of vitamin D deficiency for men and milk consumption for women, respectively. By contrast, deficient serum 25(OH)D levels were significantly correlated with education level (lower than primary school) or obesity [body mass index (BMI) ≥ 26.06 kg/m²] for men or women, respectively.

CONCLUSION

This cross-sectional study of older adults in communities in Shanghai demonstrates that key factors positively correlated with serum 25(OH)D levels ≥20 ng/mL include male sex, residency in suburban communities, calcium or vitamin D supplementation, high physical activity and education level (for men), and dairy consumption and maintenance of normal BMI (for women).

Serum 25-hydroxyvitamin D concentrations and lung cancer risk in never-smoking postmenopausal women

PURPOSE

Vitamin D has been implicated in lowering lung cancer risk, but serological data on the association among never-smoking women are limited. We report results examining the association of serum 25-hydroxyvitamin D [25(OH)D] concentrations with lung cancer risk among female never smokers. We also examined whether the association was modified by vitamin D supplementation and serum vitamin A concentrations.

METHODS

In the Women's Health Initiative, including the calcium/vitamin D (CaD) Trial, we selected 298 incident cases [191 non-small cell lung cancer (NSCLC) including 170 adenocarcinoma] and 298 matched controls of never smokers. Baseline serum 25(OH)D was assayed by a chemiluminescent method. Logistic regression was used to estimate odds ratios (ORs) for quartiles and predefined clinical cutoffs of serum 25(OH)D concentrations.

RESULTS

Comparing quartiles 4 versus 1 of serum 25(OH)D concentrations, ORs were 1.06 [95% confidence interval (CI) 0.61-1.84] for all lung cancer, 0.94 (95% CI 0.52-1.69) for NSCLC, and 0.91 (95% CI 0.49-1.68) for adenocarcinoma. Comparing serum 25(OH)D ≥ 75 (high) versus <30 nmol/L (deficient), ORs were 0.76 (95% CI 0.31-1.84) for all lung cancer, 0.71 (95% CI 0.27-1.86) for NSCLC, and 0.81 (95% CI 0.31-2.14) for adenocarcinoma. There is suggestive evidence that CaD supplementation (1 g calcium + 400 IU D3/day) and a high level of circulating vitamin A may modify the associations of 25(OH)D with lung cancer overall and subtypes (p interaction <0.10).

CONCLUSIONS

In this group of never-smoking postmenopausal women, the results did not support the hypothesis of an association between serum 25(OH)D and lung cancer risk.

Vitamin D and colorectal cancer: molecular, epidemiological and clinical evidence

In many cells throughout the body, vitamin D is converted into its active form calcitriol and binds to the vitamin D receptor (VDR), which functions as a transcription factor to regulate various biological processes including cellular differentiation and immune response. Vitamin D-metabolising enzymes (including CYP24A1 and CYP27B1) and VDR play major roles in exerting and regulating the effects of vitamin D. Preclinical and epidemiological studies have provided evidence for anti-cancer effects of vitamin D (particularly against colorectal cancer), although clinical trials have yet to prove its benefit. In addition, molecular pathological epidemiology research can provide insights into the interaction of vitamin D with tumour molecular and immunity status. Other future research directions include genome-wide research on VDR transcriptional targets, gene-environment interaction analyses and clinical trials on vitamin D efficacy in colorectal cancer patients. In this study, we review the literature on vitamin D and colorectal cancer from both mechanistic and population studies and discuss the links and controversies within and between the two parts of evidence.

Evaluation and treatment of vitamin D deficiency

Although evidence is inconsistent regarding the relationship between vitamin D deficiency and the causality of many chronic disease processes, the functions of vitamin D impact more than just bone health. By understanding basic vitamin D concepts and varied recommendations, nurse practitioners can provide safe, individualized, effective evaluation and treatment of each patient's vitamin D status to promote positive health outcomes.

Lifestyle and Other Factors Explain One-Half of the Variability in the Serum 25-Hydroxyvitamin D Response to Cholecalciferol Supplementation in Healthy Adults

BACKGROUND

Many factors have been associated with serum 25-hydroxyvitamin D [25(OH)D] concentrations in observational studies, with variable consistency. However, less information is available on factors affecting the magnitude of changes in serum 25(OH)D resulting from vitamin D supplementation.

OBJECTIVE

This study aimed to identify factors associated with the serum 25(OH)D response to supplementation with 1000 IU cholecalciferol/d during the first year of a large, multicenter, randomized, placebo-controlled colorectal adenoma chemoprevention trial.

METHODS

Eligible older adults who were not vitamin D-deficient [serum 25(OH)D ≥12 ng/mL] were randomly assigned in a modified 2 × 2 factorial design to 1 of 4 groups: daily 1000 IU cholecalciferol, 1200 mg Ca as carbonate, both, or placebo. Women could elect 2-group (calcium ± cholecalciferol) random assignment. In secondary analyses, we used multivariable models to assess factors associated with serum 25(OH)D concentrations in all enrollees (n = 2753) and with relative changes in serum 25(OH)D after 1 y cholecalciferol supplementation among those randomly assigned (n = 2187).

RESULTS

In multivariable models, 8 factors accounted for 50% of the variability of proportional change in serum 25(OH)D after cholecalciferol supplementation. Larger increases were associated with being female (34.5% compared with 20.5%; P < 0.001) and with lower baseline serum 25(OH)D (P < 0.0001), optimal adherence to study pill intake (P = 0.0002), wearing long pants and sleeves during sun exposure (P = 0.0002), moderate activity level (P = 0.01), use of extra vitamin D-containing supplements during the trial (P = 0.03), and seasons of blood draw (P ≤ 0.002). Several genetic polymorphisms were associated with baseline serum 25(OH)D and/or serum response, but these did not substantially increase the models' R² values. Other factors, including body mass index, were associated with serum 25(OH)D at baseline but not with its response to supplemental cholecalciferol.

CONCLUSIONS

The factors that most affected changes in serum 25(OH)D concentrations in response to cholecalciferol supplementation included sex, baseline serum 25(OH)D, supplement intake adherence, skin-covering clothes, physical activity, and season. Genetic factors did not play a major role. This trial was registered at www.clinicaltrials.gov as NCT00153816.

Weight and skin colour as predictors of vitamin D status: results of an epidemiological investigation using nationally representative data

OBJECTIVE

Current US dietary recommendations for vitamin D vary by age. Recent research suggests that body weight and skin colour are also major determinants of vitamin D status. The objective of the present epidemiological investigation was to clarify the role of age as a predictor of vitamin D status, while accounting for body weight and skin colour, among a nationally representative sample.

DESIGN

We calculated the mean serum 25-hydroxyvitamin D levels for the US population by age and weight, as well as by weight and race/ethnicity group. Multiple regression analyses were utilized to evaluate age and weight as predictors of vitamin D status: serum 25-hydroxyvitamin D levels with age alone, age and body weight, and age, body weight and their two-way interaction were modelled for the entire sample and each age subgroup. Graphical data were developed using B-spline non-linear regression.

SETTING

National Health and Nutrition Examination Survey (31 934 unweighted cases).

SUBJECTS

Individuals aged 1 year and older.

RESULTS

There were highly significant differences in mean vitamin D status among US residents by weight and skin colour, with those having darker skin colour or higher body weight having worse vitamin D status. Although a significant factor, the impact of age on vitamin D status was notably less than the impact of body weight.

CONCLUSIONS

Vitamin D status varied predominantly by body weight and skin colour. Recommendations by nutritionists for diet and supplementation needs should take this into account if vitamin D-related health disparities are to be meaningfully reduced across the USA.

Exploration of changes in disability after menopause in a longitudinal multiple sclerosis cohort

BACKGROUND

Onset of multiple sclerosis (MS) is typically in early adulthood. The impact, if any, of menopause on the MS course is unknown. Our objective was to determine whether menopause is associated with changes in MS severity in a longitudinal clinical cohort.

METHODS

Responses from an ongoing reproductive questionnaire deployed in all active female CLIMB observational study participants with a diagnosis of clinically isolated syndrome (CIS) or MS were analyzed when the response rate was 60%. Reproductive data were linked with clinical severity measures that were prospectively collected every six months, including our primary measure, the Expanded Disability Status Scale (EDSS).

RESULTS

Over one-half of the respondents (368 of 724 women) were postmenopausal. Median age at natural menopause was 51.5 years. In our primary analysis of 124 women who were followed longitudinally (mean duration 10.4 years) through their menopausal transition (natural or surgical), menopause represented an inflection point in their EDSS changes (difference of 0.076 units; 95% CI 0.010-0.14; p = 0.024). These findings were not explained by vitamin D levels, nor changes in treatment or smoking status over this period. There was no effect of hormone replacement therapy (HRT) exposure, but HRT use was low.

CONCLUSIONS

We observed a possible worsening of MS disability after menopause. Larger cohorts are required to assess any HRT effects.

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.