Screening for Vitamin D Deficiency in Black Americans: Comparison of Total,Free, Bioavailable 25 Hydroxy Vitamin D Levels with Parathyroid Hormone Levels and Bone Mineral Density

Objectives

There is debate surrounding the adequacy of total and free 25 hydroxy vitamin D [25(OH)D] levels in black Americans who have inherently high bone mineral density [BMD] and low serum concentration of vitamin D binding proteins [VDBP].

Design

Retrospective analysis of serum samples and BMD analyses from the African American Health Study [AAHS] cohort.

Setting

The AAHS is a population-based longitudinal study initiated to examine issues of disability and frailty among urban-dwelling black Americans in the city of Saint Louis, Missouri.

Participants

122 men and 206 women, age 60.2 ± 4.3 years.

Intervention

Retrospective analysis.

Measurements

Total 25(OH)D, VDBP, PTH, and BMD of the lumbar spine and hip by dual energy x-ray photometry (DXA). Free and bioavailable vitamin D levels were calculated using serum concentrations and affinity constants for the VDBP (Gc1F and Gc1S) phenotypes.

Results

Serum total 25(OH) D levels were 14.6 ± 8.9 ng/mL (36 ± 22 nmol/L). Vitamin D insufficiency was estimated by compensatory elevations of PTH above the normal range (> 65 pg/mL). PTH levels were within the normal reference range in > 95% of the samples at total 25(OH)D levels ≥ 20 ng/mL (≥50 nmol/L). There was no difference in the correlation of the reciprocal relationship of vitamin D vs parathyroid hormone between the VDBP phenotypes. Receiver operating characteristic curve analyses indicated that serum total 25(OH)D discriminated sufficiency from insufficiency at least as well as the calculated levels of the free and bioavailable vitamin D. Very low levels of total 25(OH)D (≤ 8 ng/mL, ≤20 nmol/L) were associated with decreased BMD (p=0.02), but higher levels of 25(OH)D did not show statistical differences in BMD.

Conclusion

Total 25(OH)D levels of ≤ 8ng/mL (≤20 nmol/L) are associated with clinically significant changes in BMD, whereas total 25(OH)D levels ≥ 20 ng/mL (≥50 nmol/L) suppressed PTH and were not associated with deficiencies in BMD. Lower levels of 25(OH)D may be acceptable for bone health in black than in white Americans.

     

Vitamin D status and bone health in healthy Thai elderly women

Objective

The prevalence of hypovitaminosis D varies in different countries. Therefore, the current study was designed to assess vitamin D status and bone health in elderly women in Thailand, which is situated near the equator.

Methods

This cross-sectional study was performed in 446 healthy women aged 60-97 y.

Results

Serum 25-hydroxyvitamin D (25(OH)D) was 67.6 ± 15.7 (mean ± SD) nmol/L. Daily calcium intake was 309.5 ± 147.2 mg/d. Serum 25(OH)D levels tended to decline with bone mineral density (BMD) status. Based on functional health-based reference values, plasma-intact parathyroid hormone began to rise below serum 25(OH)D level 70 nmol/L and increase significantly when serum 25(OH)D was ≤60 nmol/L. Thirty-two percent of elderly women had 25(OH)D insufficiency (≤60nmol/L). There was no trend toward a decrease in the concentration of serum 25(OH)D with age (r = −0.078, P = 0.10) and no significant inverse relationship with plasma intact parathyroid hormone values (r = −0.079, P = 0.097). However, a positive relationship was observed between serum 25(OH)D level and femoral neck BMD (r = 0.156, P = 0.001) but not lumbar spine L₂-L₄ BMD (r = 0.093, P = 0.050). In addition, BMD at the femoral neck but not lumbar spine of the vitamin D insufficiency group was significantly lower than that of the vitamin D sufficiency group.

Conclusion

The optimum level of serum 25(OH) value in Thai elderly women should be higher than 70 nmol/L. Vitamin D insufficiency is observed in one-third of elderly women in Bangkok.     

Hypovitaminosis D in psychogeriatric inpatients

Objectives

This study investigated the rate of hypovitaminosis D in psychogeriatric inpatients and explored whether any associations exist between vitamin D levels, cognitive function, and psychiatric diagnoses.

Design

Retrospective medical record review from November 2000 through November 2010.

Setting

Geriatric psychiatric ward of an academic tertiary care hospital.

Participants

Psychiatric inpatients aged 65 years or older.

Measurements and analysis methods

Serum 25-hydroxyvitamin D [25(OH)D] levels were measured at admission. Associations between 25(OH)D levels, Mini-Mental State Examination (MMSE) scores were analyzed using Spearman correlations, and psychiatric diagnoses were analyzed using logistic regression models and Fisher’s exact tests.

Results

In 141 subjects (mean age, 77. In 141 subjects (mean age, 77.8 years; 86 [61%] female; 135 [96%] white), the most frequent diagnoses were major depressive disorder in 81 patients (57%), dementia in 38 (27%), delirium in 13 (9%), anxiety in 12 (8.5%), and bipolar disorder in 11 (8%). Mean MMSE score was 24±6.4 (range, 3–30). Forty-three subjects (30.4%) had mild to moderate vitamin D deficiency [25(OH)D, 10–24 ng/mL], and 6 (4.2%) had severe deficiency [25(OH)D <10 ng/mL].

Conclusions

Hypovitaminosis D was common in elderly psychiatric inpatients. No associations were found between vitamin D levels and global cognitive function or psychiatric diagnoses.     

Vitamin D status in young Swedish women with anorexia nervosa during intensive weight gain therapy

Purpose

Anorexia nervosa (AN) is associated with reduced bone mass and an increased fracture risk. The aim was to evaluate the vitamin D status and the association with body mass index (BMI), fat mass and bone mineral density (BMD) in patients with severe AN during a prospective intervention study of intensive nutrition therapy.

Methods

This study comprised 25 Swedish female AN patients (20.1 ± 2.3 years), who were treated as inpatients for 12 weeks with a high-energy diet. Serum 25-hydroxyvitamin D (25(OH)D), calcium, phosphate and parathyroid hormone (PTH) were measured. BMD and body composition were assessed by dual-energy X-ray absorptiometry at study start and after 12 weeks.

Results

Twenty-two patients completed the study. The mean weight gain was 9.9 kg and BMI (mean ± SD) increased from 15.5 ± 0.9 to 19.0 ± 0.9 kg/m², P < 0.0001. Fat mass increased from median 12 to 27 %. The median serum 25(OH)D level was 84 nmol/L at baseline, which decreased to 76 nmol/L, P < 0.05. PTH increased from median 21.9 to 30.0 ng/L, P < 0.0001. BMC increased during the study period, P < 0.001.

Conclusions

Serum 25(OH)D levels were adequate both at study start and completion, however, nominally decreased after the 12-week nutritional intervention. PTH increased subsequently, which coincide with the decreased 25(OH)D levels. The reduction in 25(OH)D could be due to an increased storage of vitamin D related to the increase in fat mass since vitamin D is sequestered in adipose tissue.

     

Vitamin D supplementation in nursing home residents: Randomized single cholecalciferol loading protocol vs. individualized loading dose regimen

Objective

To assess the efficacy and safety of a single cholecalciferol loading protocol in nursing home (NH) residents taking no VitD supplementation at regular basis.

Design

Randomized single-blind controlled study.

Setting

One NH.

Participants

All residents.

Intervention

From March 21st to May 19th, 2015, NH residents were randomly assigned to either 4x100’000IU to be taken every 2 weeks (treatment group) or an individualized regimen according to baseline 25(OH)VitD level (control group).

Measurements

25(OH) VitD, calcium, phosphorus, parathyroid hormone, alkaline phosphatase, and creatinine serum levels were centrally measured at day 7 after the last dose in both groups, and at baseline in the control group.

Results

111 residents (mean age 85.1±6.7 years) were randomized to the treatment (N=53) or the control group (N=58). No significant difference in terms of demographic characteristics, risk for osteoporosis, and past history of VitD supplementation was measured. At baseline, 37.9%, 25.5% and 5.2% were respectively sub-optimal, insufficient, and deficient for VitD. Whatever the study group, at the 7th day after the last dose of cholecalciferol, 100% of residents reached serum values ≥20ng/mL (p value for non-inferiority <0.001 and p value for superiority p=1.00) and 93.6 vs. 88.2% reached values ≥30ng/mL in the treatment and control group respectively (p value for non-inferiority <0.01 and p value for superiority p=0.48). While mean value was higher in the treatment group (50.2±15.4 vs. 35.8±6.5ng/mL; p <0.0001), none of participants have seen their value >150 ng/mL. Not any biological adverse effects was measured.

Conclusion

This study confirmed that a single loading protocol is at least as effective and safe as tailored regimen in terms of the ability to rapidly normalize 25(OH)VitD values. The often required dosage of 25(OH)VitD is reasonably not necessary to initiate VitD supplementation protocol in this vulnerable population.

     

Vitamin D status in children and young adults with perinatally acquired HIV infection

Background & aims

To assess vitamin D (Vit-D) [serum 25-hydroxyvitamin D (25-OHD) concentrations] in children and young adults with perinatally acquired HIV compared to geographically similar healthy children.

Methods

25-OHD in children and young adults with HIV was compared to a healthy group. Vit-D deficiency and insufficiency were defined as 25-OHD <11 ng/mL and 25-OHD <30 ng/mL, respectively.

Results

Children with HIV (n = 81), mean age 13.8 ± 4.1 years, 48% female, 83% Black, were compared to healthy subjects (n = 372), mean age 12.4 ± 3.4 years, 51% female, 37% Black. For the HIV group, 84% were on HAART, 54% had plasma HIV RNA <400 cpm, and 35% had moderate to severe immunosuppression (CD4+ count <500 cells/mm). Vit-D deficiency/insufficiency was present in 36% and 89% of those with HIV, and 15% and 84% of the comparison group, respectively. Vit-D deficiency was more prevalent in those with HIV (unadjusted odds ratio: 3.25; 95% CI: 1.9–5.5). For both groups, prevalence of Vit-D deficiency increased with age, BMI Z-score, Black race, and in winter/spring months. Vit-D deficiency was associated with a greater degree of immunosuppression in the subjects with HIV.

Conclusions

Vit-D deficiency was increased in subjects with perinatally acquired HIV and may be associated with disease severity.     

Meta-analysis of All-Cause Mortality According to Serum 25-Hydroxyvitamin D

We examined the relationship between serum 25-hydroxyvitamin D (25[OH]D) and all-cause mortality. We searched biomedical databases for articles that assessed 2 or more categories of 25(OH)D from January 1, 1966, to January 15, 2013. We identified 32 studies and pooled the data.The hazard ratio for all-cause mortality comparing the lowest (0–9 nanograms per milliliter [ng/mL]) to the highest (> 30 ng/mL) category of 25(OH)D was 1.9 (95% confidence interval = 1.6, 2.2; P < .001). Serum 25(OH)D concentrations less than or equal to 30 ng/mL were associated with higher all-cause mortality than concentrations greater than 30 ng/mL (P < .01).Our findings agree with a National Academy of Sciences report, except the cutoff point for all-cause mortality reduction in this analysis was greater than 30 ng/mL rather than greater than 20 ng/mL.An inverse association was proposed between solar irradiance and incidence of colon and breast cancer, based on a mechanism involving insufficient vitamin D. Individuals with lower serum 25-hydroxyvitamin D (25[OH]D) have higher risk of breast1–3 and colon cancer,4–6 other specific cancers,7 all invasive cancers combined,8 and coronary heart disease.9,10 Physiological mechanisms for the inverse association of 25(OH)D with cancer have been reported.11Despite research on the association between low vitamin D status and many diseases,12 no consensus has emerged on the optimal serum 25(OH)D concentration. The concern is whether it is safe to maintain serum 25(OH)D concentrations in the range high enough to prevent some types of cancers13–15 and coronary heart disease.9,10We decided to analyze the strength and consistency of the inverse association between levels of serum 25(OH)D and age-adjusted mortality hazard ratios in a rapidly expanding field of public health. A previous meta-analysis summarized 12 studies,16 another summarized 14,17 and another summarized a broader range.18We hypothesized that lower serum 25(OH)D was associated with higher all-cause mortality hazard ratios, and defined the age-adjusted hazard ratio for death from any cause as the outcome addressed by the meta-analysis. This analysis includes all studies of all-cause mortality hazard ratios by categories of serum 25(OH)D in healthy or general medical clinic cohorts that met the eligibility criteria. Twenty new studies of serum 25(OH)D and all-cause mortality entered the literature since the Zittermann et al. review,17 for a total of 32 in this review.19–50 Two studies in the review by Zittermann et al. did not meet the stringent inclusion criterion of the present study, and were not included.     

High prevalence of vitamin D deficiency among children aged 1 month to 16 years in Hangzhou,China

Background

Recent studies have suggested that vitamin D deficiency in children is widespread. But the vitamin D status of Chinese children is seldom investigated. The objective of the present study was to survey the serum levels of 25-hydroxyvitamin D [25(OH)D] in more than 6,000 children aged 1 month to 16 years in Hangzhou (latitude: 30°N), the capital of Zhejiang Province, southeast China.

Methods

The children aged 1 month to 16 years who came to the child health care department of our hospital, the children's hospital affiliated to Zhejiang university school of medicine, for health examination were taken blood for 25(OH) D measurement. Serum 25(OH) D levels were determined by direct enzyme-linked immunosorbent assay and categorized as < 25, < 50, and < 75 nmol/L.

Results

A total of 6,008 children aged 1 month to 16 years participated in this cross-sectional study. All the subjects were divided into subgroups according to their age: 0-1y, 2-5y, 6-11y and 12-16y representing infancy, preschool, school age and adolescence stages respectively. The highest mean level of serum 25(OH)D was found in the 0-1y stage (99 nmol/L) and the lowest one was found in 12-16y stage (52 nmol/L). Accordingly, the prevalence of serum 25(OH)D levels of < 75 nmol/L and < 50 nmol/L were at the lowest among infants (33.6% and 5.4% respectively) and rose to the highest among adolescents (89.6% and 46.4% respectively). The mean levels of serum 25(OH)D and the prevalence of vitamin D deficiency changed according to seasons. In winter and spring, more than 50% of school age children and adolescents had a 25(OH)D level at < 50 nmol/L. If the threshold is changed to < 75 nmol/L, all of the adolescents (100%) had low 25(OH)D levels in winter and 93.7% school age children as well.

Conclusions

The prevalence of vitamin D deficiency and insufficiency among children in Hangzhou Zhejiang province is high, especially among children aged 6-16 years. We suggest that the recommendation for vitamin D supplementation in Chinese children should be extended to adolescence.

     

Relation among 25(OH)D,aquatic exercises,and multifunctional fitness on functional performance of elderly women from the community

Objectives

The aim of this study was to investigate if there is a relation among 25(OH)D, aquatic training, and multifunctional fitness on functional performance of elderly woman from the community. Design: Cross-sectional study.

Setting

Community.

Participants

We evaluated elderly women aged ≥ 60 years (67±5 years old). One-hundred eighty were engaged in aquatic training (AT), 119 in multifunctional fitness (MF) for at least one year, and sedentary group (SED) with 162 independent elderly women from the community centers who had not practicing any regular physical exercise at least one year before.

Measurements

Timed up-and-go (TUG), 2-minute step test (2MST), 30-second chair stand (CS), arm curl (AC), functional reach test (FRT), unipedal balance test (UB) with visual control, handgrip right (HR) and handgrip left (HL) portable dynamometer for strength hip flexors (Hip strength) and knee extensors (Knee strength), serum 25(OH)D, intact parathyroid hormone (PTH), and creatinine clearance.

Results

Physical and functional tests showed differences among the three groups (ST; TUG, CS, AC, FR and USB = p <0.001). The PTH and the TUG test correlated inversely with 25(OH)D (r = -0.29 - p <0.001/ r = - 0.16 - p <0.001), also between 25(OH)D and BMI for AT and MF groups respectively (r= -0,15; p=0,04/ r= - 0,19; p=0,036). The AC test showed positive correlation (r = 0, 1 - p <0.001). The age and 25(OH)D were controlled and assumed to be a covariates in the statistical analysis that employed ANCOVA. There was difference on the performance of TUG test (p= 0.049).

Conclusion

TUG performance was associated with age, exercise type and serum levels of 25(OH)D. The 25(OH)D insufficiency was common in elderly women from subtropical areas.

     

25-Hydroxyvitamin D in the Range of 20 to 100 ng/mL and Incidence of Kidney Stones

Objectives. Increasing 25-hydroxyvitamin D serum levels can prevent a wide range of diseases. There is a concern about increasing kidney stone risk with vitamin D supplementation. We used GrassrootsHealth data to examine the relationship between vitamin D status and kidney stone incidence.Methods. The study included 2012 participants followed prospectively for a median of 19 months. Thirteen individuals self-reported kidney stones during the study period. Multivariate logistic regression was applied to assess the association between vitamin D status and kidney stones.Results. We found no statistically significant association between serum 25-hydroxyvitamin D and kidney stones (P = .42). Body mass index was significantly associated with kidney stone risk (odds ratio = 3.5; 95% confidence interval = 1.1, 11.3).Conclusions. We concluded that a serum 25-hydroxyvitamin D level of 20 to 100 nanograms per milliliter has no significant association with kidney stone incidence.An issue of possible concern related to the use of vitamin D supplementation is a reported increase in risk of kidney stones.1 Mounting evidence indicates that a 25-hydroxyvitamin D (25[OH]D) serum level in the range of 40 to 60 nanograms per milliliter (ng/mL) is needed for substantial reduction in risk of a wide range of diseases including breast cancer,2 colorectal cancer,3 multiple sclerosis,4 and type 1 diabetes.5,6 However, few people can achieve 25(OH)D in the range higher than 40 ng/mL without supplementation.7GrassrootsHealth is a nonprofit public health research organization that runs a large population cohort study of participants who reach and sustain, if desired, a 25(OH)D serum level of their choice and tracking subsequent health outcomes. GrassrootsHealth has assembled a database that includes information on serum 25(OH)D concentrations, demographic characteristics, and health status measures. These data include values from 5552 individuals with daily supplemental intakes averaging 3600 international units (IU) per day and an average 25(OH)D level of 45 ng/mL, which is higher than the ranges found in most other cohorts.2,4In this study we investigated whether serum 25(OH)D concentration in the range of 20 to 100 ng/mL was associated with incidence of kidney stones in all participants who provided data at 2 or more sampling times.     

Physical Performance and Serum 25(OH)Vitamin D Status in Community Dwelling Old Mobility Limited Adults: A Cross-Sectional Study

Objectives

To examine the potential association between serum 25(OH) vitamin D and the performance on the Short Physical Performance Battery (SPPB) including the sub-components; five repeated chair stands test, 4 meters walk test and balance in older mobility-limited community-dwelling men and women.

Design

A cross sectional study was performed in American and Swedish subjects who were examined for potential participation in a combined exercise and nutrition intervention trial. Logistic regression analysis and linear regression analyses were performed to evaluate the association for 25(OH)D with the overall score on the SBBP, chair stand, gait speed and balance.

Participants

Community-dwelling (mean age 77.6 ± 5.3 years) mobility limited American (n=494) and Swedish (n=116) females (59%) and males.

Measurements

The SPPB (0-12 points) includes chair stand (s), gait speed (m/s) and a balance test. Mobility limitation i.e., SPPB score ≤ 9 was an inclusion criterion. A blood sample was obtained to measure serum 25(OH)vitamin D concentrations.

Results

No clear association of 25(OH)D with SPPB scores was detected either when 25(OH)D was assessed as a continuous variable or when categorized according to serum concentrations of <50, 50-75 or <75 nmol/L. However, when analyzing the relationship between 25(OH)D and seconds to perform the chair stands, a significant quadratic relationship was observed. Thus, at serum levels of 25(OH)D above 74 nmol/L, higher concentrations appeared to be advantageous for the chair stand test, whereas for serum levels below 74 nmol/L this association was not observed.

Conclusion

This cross- sectional study lacked clear association between serum 25(OH)D and physical performance in mobility limited adults. A potentially interesting observation was that at higher serum levels of 25(OH)D a better performance on the chair stand test was indicated.

     

Is the 25-hydroxy-vitamin D serum concentration a good marker of frailty?

Introduction

The phenotype proposed by Fried and colleagues is a widely used operational definition of frailty defining such state of extreme vulnerability of older persons. Low serum 25-hydroxy-vitamin D (25(OH)D) has been suggested as biomarker of frailty in literature.

Study design

Cross-sectional.

Objectives

To explore the association of 25(OH)D concentrations with the frailty phenotype and its criteria.

Methods

321 subjects referred by their general practitioner to a geriatric frailty clinic were assessed between January 1, 2013 and September 23, 2013. Adjusted logistic regression models were performed between serum concentrations of 25(OH)D and the frailty phenotype (global score as well as its specific criteria). Receivers operating curves were established in order to explore the existence of a possible threshold of vitamin D levels highly predictive of frailty.

Results

Two hundred forty-one (75%) participants had 25(OH)D levels lower than 22 ng/ml. No significant association was reported between 25(OH)D levels and frailty. Among the five criteria of frailty, 25(OH)D was only associated with sedentariness (odds ratio 0.97 [95% confidence interval 0.95-0.99]).

Conclusion

In our sample, no association was found between 25(OH)D levels and phenotype of frailty or the different frailty criterion except for sedentariness.

     

Season,dietary factors,and physical activity modify 25-hydroxyvitamin D concentration during pregnancy

Purpose

The objectives of this cross-sectional study were to define maternal and umbilical cord blood (UCB) 25-hydroxyvitamin D (25(OH)D) to characterize maternal factors modifying 25(OH)D during pregnancy and predict UCB 25(OH)D in two subgroups with Declined [Δ25(OH)D?<0 nmol/l] and Increased [Δ25(OH)D?>0 nmol/l] 25(OH)D concentration.

Methods

A complete dataset was available from 584 women. 25(OH)D was determined at gestational weeks 6–13 and in UCB. Baseline characteristics were collected retrospectively using questionnaires. Δ25(OH)D was calculated as UCB 25(OH)D?early pregnancy 25(OH)D. Dietary patterns were generated with principal component analysis. Multivariate regression models were applied.

Results

Vitamin D deficiency was scarce, since only 1% had 25(OH)D concentration?<50 nmol/l both in early pregnancy and in UCB. Shared positive predictors of UCB 25(OH)D in the subgroups of Declined and Increased, were early pregnancy 25(OH)D (P?<?0.001) and supplemental vitamin D intake (P?<?0.04). For the Increased subgroup summer season at delivery (P?=?0.001) and “sandwich and dairy” dietary pattern characterized with frequent consumption of vitamin D fortified margarine and milk products (P?=?0.009) were positive predictors of UCB 25(OH)D. Physical activity (P?=?0.041) and maternal education (P?=?0.004) were additional positive predictors in the Declined group

Conclusions

Maternal and newborn vitamin D status was sufficient, thus public health policies in Finland have been successful. The key modifiable maternal determinants for 25(OH)D during pregnancy, and of the newborn, were supplemental vitamin D intake, frequent consumption of vitamin D fortified foods, and physical activity.

     

Vitamin D Binding Protein and Vitamin D Levels in Multi-Ethnic Population

Introduction

Low levels of 25-hydroxyvitamin D (25(OH)D) has been associated with many negative health outcomes including falls and fractures. 25(OH)D is largely bound to vitamin D binding protein (VDBP). There is increasing evidence that free or bioavailable 25(OH)D may be a better measure of vitamin D deficiency.

Objective

To determine the prevalence of 25(OH)D deficiency and VDBP levels in multi-ethnic population, and its impact on muscle strength.

Design and methods

Cross-sectional study of older adults in Western region of Singapore. 295 participants from three ethnic groups were selected from the Healthy Older People Everyday (HOPE) cohort for measurements of total 25(OH)D and VDBP levels. Total 25(OH)D, VDBP, frailty status, Timed-Up-and-Go (TUG) and grip strength (GS) were assessed. Albumin, free and bioavailable 25(OH)D were only available for 256 participants.

Results

53% of Malay and 55% of Indians were deficient in 25(OH)D compared with 18.2% of ethnic Chinese participants. Chinese also had higher total 25(OH)D concentrations with a mean of 29.1 ug/l, (p = <0.001). Chinese had the lowest level of VDBP (169.6ug/ml) followed by Malay (188.8 ug/ml) and Indian having the highest (220.1 ug/ml). Calculated bioavailable and free 25(OH)D levels were significantly higher in Chinese, followed by Malays and Indians, which also correlated with better grip strength measures amongst the Chinese.

Conclusion

The Malays and Indians had overall lower free, bioavailable and total 25(OH)D compared with ethnic Chinese. Chinese ethnic group also had the lowest VDBP and better overall grip strength.

     

Evaluation of cognitive subdomains, 25-hydroxyvitamin D,and 1,25-dihydroxyvitamin D in the European Male Ageing Study

Purpose

Although lower levels of vitamin D have been related to poor cognitive functioning and dementia in older adults, evidence from longitudinal investigations is inconsistent. The objective of this study was to determine whether 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)₂D] levels are associated with specified measures of cognitive decline in ageing men.

Methods

The European Male Ageing Study (EMAS) followed 3369 men aged 40–79 over 4.4 years. 25(OH)D levels at baseline were measured by radioimmunoassay, and 1,25(OH)₂D levels were obtained with liquid chromatography–tandem mass spectrometry. Visuoconstructional abilities, visual memory, and processing speed at baseline and follow-up were assessed using the Rey–Osterrieth Complex Figure Test (ROCF), Camden Topographical Recognition Memory (CTRM), and the Digit Symbol Substitution Test (DSST).

Results

Following attritions, a total of 2430 men with a mean (SD) age of 59.0 (10.6) were included in the analyses. At baseline, the mean 25(OH)D concentration was 64.6 (31.5) nmol/l, and mean 1,25(OH)₂D level was 59.6 (16.6) pmol/l. In age-adjusted linear regression models, high 25(OH)D concentrations were associated with a smaller decline in the DSST (β = 0.007, p = 0.020). Men with low 25(OH)D levels (<50 nmol/l) showed a greater decline in the CTRM compared to men with higher (≥75 nmol/l) levels (β = ?0.41, p = 0.035). However, these associations disappeared after adjusting for confounders such as depressive symptoms, BMI, and comorbidities. There was no indication of a relationship between 1,25(OH)₂D and decline in cognitive subdomains.

Conclusion

We found no evidence for an independent association between 25(OH)D or 1,25(OH)₂D levels and visuoconstructional abilities, visual memory, or processing speed over on average 4.4 years in this sample of middle-aged and elderly European men.

     

Effects of sun exposure and dietary vitamin D intake on serum 25-hydroxyvitamin D status in hemodialysis patients

BACKGROUND/OBJECTIVES

Vitamin D deficiency is common in hemodialysis patients. The aim of this study was to identify whether or not sun exposure and dietary vitamin D intake have effects on serum 25-hydroxyvitamin D (25(OH)D) status in hemodialysis (HD) patients. The objective was to identify the main determinants of serum vitamin D status in the study subjects.

SUBJECTS/METHODS

A cross-sectional study of 47 HD patients (19 males and 28 females) was performed. We assessed serum 25(OH)D and 1,25(OH)₂D levels between August and September 2012 and analyzed the prevalence of vitamin D deficiency in HD patients. To evaluate the determinants of serum 25(OH)D levels, we surveyed dietary vitamin D intake, degree of sun exposure, and outdoor activities. To compare biological variables, serum 25(OH)D was stratified as below 15 ng/ml or above 15 ng/ml.

RESULTS

Mean 25(OH)D and 1,25(OH)₂D levels were 13.5 ± 5.8 ng/ml and 20.6 ± 11.8 pg/ml, respectively. The proportions of serum 25(OH)D deficiency (< 15 ng/ml), insufficiency (15-< 30 ng/ml), and sufficiency (≥ 30 ng/ml) in subjects were 72.4%, 23.4%, and 4.3%, respectively. Prevalence of vitamin D deficiency in female patients was 78.6%, whereas that in males was 63.2% (P = 0.046). Vitamin D intake and sun exposure time were not significantly different between the two stratified serum 25(OH)D levels. Dietary intake of vitamin D did not contribute to increased serum 25(OH)D levels in HD patients. The main effective factors affecting serum 25(OH)D status were found to be the sun exposure and active outdoor exercise.

CONCLUSIONS

Hypovitaminosis D is common in HD patients and is higher in females than in males. Sun exposure is the most important determinant of serum 25(OH)D status in HD patients.     

Dietary influence on calcitropic hormones and adiposity in Caucasian and African American postmenopausal women assessed by structural equation modeling (SEM)

Objectives

To examine differences in hydroxycholecalciferol (25(OH)D) and parathyroid hormone (PTH) concentrations between Caucasian and African American (AA) postmenopausal women, as well as the effects of dietary calcium, protein and vitamin D intakes on 25(OH)D, PTH, and body adiposity using structural equation modeling (SEM).

Design

Population-based prospective cohort study.

Setting

Academic research using the baseline data from two longitudinal studies.

Participants

Included n=113 Caucasian and n=40 African American, postmenopausal women who completed the baseline data collection and met inclusion criteria (dietary calcium intake <900 mg/day and being generally healthy) between 2006 and 2010.

Main Outcome

Dietary intake of calcium and vitamin D, assessed by dietary records, were examined in relation to calcitropic hormones concentrations and adiposity markers. Independent t-tests, confirmatory factor analysis, SEM and multi-group analyses were conducted to examine the aforementioned relationships as well as group differences among hormones, dietary intake, anthropometrics, age and other factors.

Results

Dietary calcium and protein intakes were significantly lower in AA women. Years since menopause were significantly higher in AA compared to Caucasian women. PTH and 25(OH)D levels were significantly lower in AA compared to Caucasian women. Dietary calcium and protein intakes did not influence body adiposity in either group of women. Dietary vitamin D had minimal indirect (via 25(OH)D levels) influence on adiposity.

Conclusion

The study confirmed the positive relationship of 25(OH)D with adiposity markers and both AA and Caucasian women. The study provides a unique example of the use of SEM in nutrition research within a clinical context. This model should be further tested in other populations.

     

A systematic review of vitamin D status in southern European countries

Purpose

Despite an acknowledged dearth of data on serum 25-hydroxyvitamin D (25(OH)D) concentrations from Southern European countries, inter-country comparison is hampered by inconsistent data reporting. The purpose of the current study was to conduct a systematic literature review of available data on serum 25(OH)D concentrations and estimate vitamin D status in Southern European and Eastern Mediterranean countries, both at a population level and within key population subgroups, stratified by age, sex, season and country.

Methods

A systematic review of the literature was conducted to identify and retrieve scientific articles reporting data on serum 25(OH)D concentration and/or vitamin D status following standard procedures.

Results

Data were extracted from 107 studies, stratified by sex and age group, representing 630,093 individuals. More than one-third of the studies reported mean 25(OH)D concentrations below 50 nmol/L and ~?10% reported mean serum 25(OH)D concentrations below 25 nmol/L. Overall, females, neonates/ infants and adolescents had the higher prevalence of poor vitamin D status. As expected, there was considerable variability between studies. Specifically, mean 25(OH)D ranged from 6.0 (in Italian centenarians) to 158 nmol/L (in elderly Turkish men); the prevalence of serum 25(OH)D?<?50 nmol/L ranged from 6.8 to 97.9% (in Italian neonates).

Conclusions

Contrary to expectations, there was a high prevalence of low vitamin D status in the Southern Europe and the Eastern Mediterranean regions, despite abundant sunshine. These data further emphasize the need for strategies, such as fortification of foods with vitamin D and/or vitamin D supplementation, which will be tailored to the needs of specific population groups with higher risk of insufficiency or deficiency, to efficiently tackle the pandemic of hypovitaminosis D in Europe.

     

Low serum levels of 25-hydroxyvitamin D are associated with stroke recurrence and poor functional outcomes in patients with ischemic stroke

Objective

To evaluate the association between serum 25(OH) D levels and functional outcome and stroke recurrence events in a 6-month follow-up study in a cohort of patients with an acute ischemic stroke (AIS).

Methods

From March 2014 to August 2015, consecutive first-ever AIS patients admitted to the Department of Emergency of our hospital were identified. Serum 25(OH) D levels were measured at admission. Functional outcome was evaluated at 6-month using the modified Rankin scale (m-Rankin). We used logistic regression models to assess the relationship between 25(OH) levels and risk of recurrent stroke or functional outcome.

Results

We recorded 277 stroke patients. There were significantly negative correlation between levels of 25(OH) D and NHISS (P<0.001), and the infarct volume (P< 0.001). Thirty-one patients (11.9%) had a stroke recurrence, while 82 patients (29.6) were with poor functional outcomes. In multivariate logistic regression analyses, serum 25(OH) D level was an independent marker of poor functional outcome and stroke recurrence [odds ratio (OR) 2.55 (1.38-3.96) and 3.03(1.65–4.12), respectively, P<0.001 for both, adjusted for NHISS, other predictors and vascular risk factors] in patients with AIS.

Conclusion

Our results demonstrate that low 25(OH) D levels are associated with stroke recurrence and support the hypothesis that 25(OH) D may serve as a biomarker of poor functional outcome after stroke.

     

Vitamin D status and elevated red cell distribution width in community-dwelling adults: Results from the National Health and Nutrition Examination Survey 2001–2006

Objectives

Elevated red cell distribution width (RDW) is associated with morbidity and mortality in community-dwelling individuals. Although RDW is traditionally used to diagnose anemia, it may also be a marker of systemic inflammation. Since vitamin D is a potent modulator of inflammatory cytokines our goal was to investigate whether 25-hydroxyvitamin D levels (25OHD) are associated with RDW in non-hospitalized adults.

Design

To investigate this association, we conducted a cross-sectional study. Stepwise multivariable linear and logistic regression models were used to assess the independent association of 25OHD with RDW. Elevated RDW was defined as >14.5%.

Setting

Nationwide sample of non-hospitalized adults within the United States.

Participants

Individuals from the National Health and Nutrition Examination Survey from 2001-2006.

Results

15,162 individuals comprised the analytic cohort. Mean 25OHD was 24.9 ng/mL (SE 0.4) and the prevalence of elevated RDW was 6.3%. Linear regression analysis, controlling for age, sex, race, mean corpuscular volume, albumin, and neutropenia, demonstrated that 25OHD was inversely associated with RDW (β=-0.01; 95%CI -0.01 to -0.01). Logistic regression analysis, controlling for the same covariates, also demonstrated an inverse association of 25OHD with elevated RDW (OR 0.96; 95%CI 0.94-0.99). Individuals with 25OHD <30 ng/mL were more likely to have elevated RDW (OR 1.65; 95%CI 1.13-2.40) compared to those individuals with levels ≥30ng/mL.

Conclusions

In a nationwide sample of non-hospitalized adults within the United States, low 25OHD was associated with increased likelihood of elevated RDW. Further studies are needed to determine whether optimizing vitamin D status can reduce the prevalence of elevated RDW, and thereby reduce morbidity and mortality in the general population.