Tracking of serum 25-hydroxyvitamin D levels during 14 years in a population-based study and during 12 months in an intervention study

Vitamin D as a Resilience Factor, Helpful for Survival of Potentially Fatal Conditions: A Hypothesis Emerging from Recent Findings of the ESTHER Cohort Study and the CHANCES Consortium

There is debate on whether vitamin D deficiency is a risk factor for major chronic diseases and premature death or whether observed associations were just confounded by general health status. Here, we review recent results from the Epidemiologische Studie zu Chancen der Verhütung, Früherkennung und optimierten Therapie chronischer Erkrankungen in der älteren Bevölkerung (ESTHER) cohort study and the Consortium on Heatlh and Ageing: Network of Cohorts from Europe and the United States (CHANCES) that suggest that vitamin D deficiency may not be a risk factor for the development of cardiovascular diseases and cancer but may be a risk factor for fatal instances of these diseases. Furthermore, analyses comprehensively adjusted for the health status showed that the association of vitamin D and mortality was very likely not confounded by general health status. These results suggest that vitamin D could be a marker of resilience to fatality of potentially fatal diseases. Sufficient vitamin D serum concentrations may be needed to regulate the response of the immune system when it is challenged by severe diseases to prevent a fatal course of the disease. If this hypothesis can be verified through basic research studies and adequately designed randomized controlled trials, it could have important public health implications because vitamin D deficiency is very common worldwide, and interventions could be implemented easily.

Serum 25 hydroxyvitamin D, bone mineral density and fracture risk across the menopause

CONTEXT

Low levels of serum 25 Hydroxyvitamin D [25(OH)D] have been linked to greater fracture risk in older women.

OBJECTIVE

This study aimed to determine whether higher 25(OH)D is associated with slower loss of bone mineral density (BMD) and lower fracture risk during the menopausal transition.

DESIGN, SETTING, AND PARTICIPANTS

This was a prospective cohort study at five clinical centers in the United States. Mean age was 48.5 ± 2.7 years. The fracture analysis included 124 women with an incident traumatic fracture, 88 with incident nontraumatic fracture, and 1532 women without incident fractures; average followup was 9.5 years. BMD analysis included 922 women with a documented final menstrual period.

MAIN OUTCOME MEASURES

Serum 25(OH)D was measured by liquid chromatography tandem mass spectrometry at the third annual clinic visit. BMD was measured and incident fractures ascertained at each annual visit.

RESULTS

The mean 25(OH)D was 21.8 ng/mL; seven-hundred two (43%) of the women had 25(OH)D values <20 ng/mL. There was no significant association between 25(OH)D and traumatic fractures. In multivariate adjusted hazards models, the hazard ratio (HR) for nontraumatic fractures (95% confidence interval [CI]) was 0.72 (0.54-0.96) for each 10-ng/mL increase in 25(OH)D. Comparing women whose 25(OH)D was ≥20 vs <20 ng/mL, the HR (95% CI) for fracture was 0.54 (0.32-0.89). Changes in lumbar spine and femoral neck bone mineral density across menopause were not significantly associated with serum 25(OH)D level.

CONCLUSION

Serum 25(OH)D levels are inversely associated with nontraumatic fracture in mid-life women. Vitamin D supplementation is warranted in midlife women with 25(OH)D levels <20 ng/mL.

Prospective association of vitamin D with frailty status and all-cause mortality in older adults: Results from the KORA-Age Study

OBJECTIVE

To assess the prospective association of serum 25-hydroxyvitamin D [25(OH)D] levels with frailty status and all-cause mortality in a cohort of community-dwelling participants of the population-based KORA [Cooperative Health Research in the Region of Augsburg]-Age Study.

METHODS

727 non-frail participants, aged ≥65years, with 25(OH)D measurement at baseline in 2009, were followed for 2.9±0.1years. Participants were classified as pre-frail or frail if they met 1-2 or ≥3, respectively, of the following five criteria: weight loss, exhaustion, physical inactivity, low walking speed, weakness. The association between 25(OH)D and mortality was assessed in 954 participants. Multivariable adjusted logistic regression models were calculated for each outcome.

RESULTS

The incidence of pre-frailty and frailty was 21.2% and 3.9% respectively. After multivariable adjustment, participants with very low 25(OH)D levels (<15ng/ml vs. ≥30ng/ml) had a significantly higher odds for pre-frailty (OR=2.43 [95% CI: 1.17-5.03]) and pre-frailty/frailty combined (OR=2.53 [95% CI: 1.23-5.22]), but not for frailty alone (OR=2.63 [95% CI: 0.39-17.67]). The association between 25(OH)D and mortality (OR=3.39 [95% CI: 1.08-10.65]) was partly mediated by frailty status.

CONCLUSION

Very low 25(OH)D levels were independently associated with incident pre-frailty, pre-frailty/frailty combined and all-cause mortality.

Serum 25-hydroxyvitamin D, vitamin D binding protein and risk of colorectal cancer in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial

The potential role of vitamin D in cancer prevention has generated substantial interest, and laboratory experiments indicate several anti-cancer properties for vitamin D compounds. Prospective studies of circulating 25-hydroxyvitamin D [25(OH)D], the accepted biomarker of vitamin D status, suggest an inverse association with colorectal cancer risk, but with some inconsistencies. Furthermore, the direct or indirect impact of the key transport protein, vitamin D binding protein (DBP), has not been examined. We conducted a prospective study of serum 25(OH)D and DBP concentrations and colorectal cancer risk in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, based on 476 colorectal cancer cases and 476 controls, matched on age, sex, race and date of serum collection. All subjects underwent sigmoidoscopic screening at baseline and once during follow-up. Conditional logistic regression estimated odds ratios (ORs) and 95% confidence intervals (CIs). Circulating 25(OH)D was inversely associated with colorectal cancer (OR = 0.60, 95% CI 0.38-0.94 for highest versus lowest quintile, p trend 0.01). Adjusting for recognized colorectal cancer risk factors and accounting for seasonal vitamin D variation did not alter the findings. Neither circulating DBP nor the 25(OH)D:DBP molar ratio, a proxy for free circulating 25(OH)D, was associated with risk (OR = 0.82, 95% CI 0.54-1.26, and OR = 0.79, 95% CI 0.52-1.21, respectively), and DBP did not modify the 25(OH)D association. The current study eliminated confounding by colorectal cancer screening behavior, and supports an association between higher vitamin D status and substantially lower colorectal cancer risk, but does not indicate a direct or modifying role for DBP.

Vitamin D3 increases in abdominal subcutaneous fat tissue after supplementation with vitamin D3

OBJECTIVE

The objective was to assess the amount of vitamin D3 stored in adipose tissue after long-term supplementation with high dose vitamin D3.

DESIGN

A cross-sectional study on 29 subjects with impaired glucose tolerance who had participated in a randomized controlled trial with vitamin D3 20 000 IU (500 μg) per week vs placebo for 3-5 years.

METHODS

Abdominal subcutaneous fat tissue was obtained by needle biopsy for the measurements of vitamin D3 and 25-hydroxyvitamin D3 (25(OH)D3). Body fat was measured with dual-energy X-ray absorptiometry, and serum 25(OH)D3 level was quantified.

RESULTS

In the subjects given vitamin D3, the median concentrations of serum 25(OH)D3, fat vitamin D3, and fat 25(OH)D3 were 99 nmol/l, 209 ng/g, and 3.8 ng/g, respectively; and correspondingly in the placebo group 62  nmol/l, 32 ng/g, and 2.5 ng/g. If assuming an equal amount of vitamin D3 stored in all adipose tissue in the body, the median body store was 6.6 mg vitamin D3 and 0.12 mg 25(OH)D3 in those given vitamin D3.

CONCLUSIONS

Subcutaneous adipose tissue may store large amounts of vitamin D3. The clinical importance of this storage needs to be determined.

Gender- and site-specific differences of colorectal neoplasia relate to vitamin D

BACKGROUND

The effect of vitamin D on colorectal adenomas may vary with regard to gender, localisation and histological type of the lesion.

AIM

To define the role of vitamin D and gender in a Caucasian cohort of subjects undergoing screening colonoscopy after consideration of established risk factors.

METHODS

One thousand five hundred and thirty-two subjects (813 males, 58.8 ± 9.7 years; 719 females, 59.7 ± 10.7 years) were allocated to tertiles of 25-hydroxyvitamin D3 [25(OH)D3 ] serum concentrations. The number, localisation, size and histology of the detected colonic lesions were recorded.

RESULTS

Among men, no association was found between vitamin D and the total number, size and histological stage of adenomas at any site. In female subjects, less women with adenomas were found in the highest vitamin D tertile (N = 42/239; 17.2%) as compared to the low vitamin D group (N = 60/240; 25.0%; P = 0.035). In particular, the number of women with adenomas in the proximal colon was significantly lower in the highest tertile (N = 21/239, 8.8%) compared to the low vitamin D group (N = 41/240; 17.1%; P = 0.007). The rates at other sites were not different. The inverse association of vitamin D serum concentrations with the presence of adenomas in the proximal colon was maintained after adjustment for potential confounders. In 80 women on vitamin D supplementation, the rate of adenomas was lower compared to those not on supplementation (3/80; 3.8%; vs. 90/719; 12.5%; P = 0.016).

CONCLUSIONS

A potential preventive effect of vitamin D on colorectal adenomas was found in the proximal colon in women. This observation is supported by further decrease of lesions in the proximal colon of women on vitamin D supplementation.

Serum vitamin D, vitamin D binding protein, and lung cancer survival

OBJECTIVES

Vitamin D may prolong cancer survival by inhibiting tumor progression and metastasis, however, there are limited epidemiologic studies regarding the association between circulating 25-hydroxyvitamin D (25(OH)D) and lung cancer survival. The aim of this study was to examine the relationship between serum 25(OH)D and lung cancer specific survival and to evaluate whether vitamin D binding protein (DBP) concentration modified this association.

MATERIALS AND METHODS

25(OH)D and DBP were measured in fasting serum samples from 500 male lung cancer cases in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CI) for lung cancer related death according to quartiles of season-specific 25(OH)D, DBP, and the molar ratio of 25(OH)D:DBP, a proxy for free circulating 25(OH)D.

RESULTS

Comparing highest to lowest quartiles, serum 25(OH)D (HR=1.18; 95% CI: 0.89-1.56) and DBP (HR=0.95; 95% CI: 0.71-1.26) were not associated with lung cancer survival and DBP concentration did not modify the association with 25(OH)D (p for interaction=0.56). There was suggestion of an association between higher serum 25(OH)D and better survival from adenocarcinoma (HR=0.64; 95% CI: 0.17-2.45) and small cell carcinoma (HR=0.55; 95% CI: 0.21-1.45), but these estimates were based on a relatively small number of cases.

CONCLUSION

Serum 25(OH)D was not associated with overall lung cancer survival regardless of DBP concentration, however, these findings should be examined in other studies that include women and subjects with higher 25(OH)D levels.

Predictors of serum 25(Oh)D increase following bimonthly supplementation with 100,000IU vitamin D in healthy, men aged 25-65 years

Vitamin D replenishment therapy typically entails standard dosages, but related increases in serum 25(OH)D levels vary between individuals. This study was aimed to identify factors that affect the efficacy of vitamin D supplementation.

SUBJECTS AND METHODS

79 healthy men aged 25-65 with 25(OH)D<20ng/ml participated in a vitamin D supplementation study. All participants received 100,000IU vitamin D bimonthly, e.g., 1666IU/day. Personal and demographic information, physical activity and sun-exposure questionnaires were completed by the participants. Weight, height, and waist circumference were recorded. Serum calcium, creatinine, 25(OH)D, PTH, lipid profile, and liver-enzyme levels were assessed. All measurements were repeated after 6 and 12 months. The difference between baseline serum 25(OH)D and 12-month measurements was calculated (delta). Linear regression was performed to identify predictors for increases in 25(OH)D levels.

RESULTS

Mean serum 25(OH)D level increases according to BMI were 12.6±5.29ng/ml for BMI≤25, 10.12±4.95ng/ml for 25<BMI<30, and only 6.39± 5.33ng/ml for BMI>30, which differed significantly from the other BMI categories (p=0.003). In a regression model to predict 25(OH)D increase, BMI was the main predictor (p<0.001), explaining 21.6% of the variance in serum 25(OH)D (inverse association). Age, sun-exposure, serum cholesterol, physical-activity, baseline 25(OH)D levels and seasonality were insignificant. The full model explained 27.9% of the variance in serum 25(OH)D.

CONCLUSION

This study's main findings are that BMI affect vitamin D response in healthy men. Quantitative supplementation adjustments may be warranted in obese men, for whom the dose may need to be doubled. This article is part of a special issue entitled '16th Vitamin D Workshop'.

Vitamin D status, liver enzymes, and incident liver disease and mortality: a general population study

Vitamin D deficiency is common among patients with liver diseases. Both cholestatic and non-cholestatic liver diseases can cause vitamin D deficiency. Whether vitamin D status can also affect liver function is poorly understood. To investigate the association between vitamin D status, liver enzymes, and incident liver disease, we included a total of 2,649 individuals from the Monica10 study conducted in 1993-1994. Vitamin D status as assessed by serum 25-hydroxyvitamin, serum alanine transaminase (ALT), aspartate transaminase (AST), and gamma glutamyl transferase (GGT) were measured at baseline. Information on fatal and non-fatal liver disease was obtained from the Danish National Patient Register and The Danish Registry of Causes of Death, respectively. Median follow-up time was 16.5 years, and there were 62 incident cases of fatal and non-fatal liver disease. Multivariable Cox regression analyses with age as underlying time axis and delayed entry showed a statistically significant inverse association between vitamin D status and incident liver disease with a hazard ratio = 0.88 (95 % confidence interval 0.79-0.99) per 10 nmol/l higher vitamin D status at baseline (adjusted for gender, season, alcohol consumption, smoking, physical activity, dietary habits, education, body mass index, and ALT). The risk of having a high level of ALT, AST, or GGT tended to be higher for lower vitamin D levels, although not statistically significant. In this general population study, vitamin D status was inversely associated with incident liver disease. Further studies are needed to determine whether patients in risk of developing impaired liver function should be screened for vitamin D deficiency for preventive purposes.

Vitamin D and cognitive function and dementia risk in a biracial cohort: the ARIC Brain MRI Study

BACKGROUND AND PURPOSE

Some recent studies in older, largely white populations suggest that vitamin D, measured by 25-hydroxyvitamin D [25(OH)D], is important for cognition, but such results may be affected by reverse causation. Measuring 25(OH)D in late middle age before poor cognition affects behavior may provide clearer results.

METHODS

This was a prospective cohort analysis of 1652 participants (52% white, 48% black) in the Atherosclerosis Risk in Communities (ARIC) Brain MRI Study. 25(OH)D was measured from serum collected in 1993-1995. Cognition was measured by the delayed word recall test (DWRT), the digit symbol substitution test (DSST) and the word fluency test (WFT). Dementia hospitalization was defined by ICD-9 codes. Adjusted linear, logistic and Cox proportional hazards models were used.

RESULTS

Mean age of participants was 62 years and 60% were female. Mean 25(OH)D was higher in whites than blacks (25.5 vs. 17.3 ng/ml, P < 0.001). Lower 25(OH)D was not associated with lower baseline scores or with greater DWRT, DSST or WFT decline over a median of 3 or 10 years of follow-up (P > 0.05). Over a median of 16.6 years, there were 145 incident hospitalized dementia cases. Although not statistically significant, lower levels of 25(OH)D were suggestive of an association with increased dementia risk [hazard ratio for lowest versus highest race-specific tertile: whites 1.32 (95% confidence interval 0.69, 2.55); blacks 1.53 (95% confidence interval 0.84, 2.79)].

CONCLUSIONS

In contrast to prior studies performed in older white populations, our study of late middle age white and black participants did not find significant associations between lower levels of 25(OH)D with lower cognitive test scores at baseline, change in scores over time or dementia risk.

Bioavailability of vitamin D2 from enriched mushrooms in prediabetic adults: a randomized controlled trial

BACKGROUND/OBJECTIVES

Based on the growing evidence of risk reduction from fresh fruit and vegetable consumption and an inverse relationship between serum 25-hydroxyvitamin D (25OHD) and the risk of type 2 diabetes (T2D), we determined the benefits of regularly consuming vitamin D-enriched mushrooms in a prediabetic cohort. Exposing edible mushrooms to ultraviolet B (UVB) light increases vitamin D2 (D2) and raises serum 25OHD2 in healthy young adults; however, their benefit to deficient prediabetics and glucose metabolism remains untested.

SUBJECTS/METHODS

Forty-three prediabetic, D-deficient adults (25OHD≤20 ng/ml), BMI>25 were randomized to four groups consuming daily entrées containing 100 g fresh sliced cooked mushrooms prepared by a chef for 16 weeks. Two groups were fed UVB-treated mushrooms initially containing: 600 IU D2 or 4000 IU D2; each one also received one capsule of placebo daily. Two control groups were fed untreated mushrooms and D3 dietary supplements at two label doses: 600 IU D3 and 4000 IU D3. D2 and D3 content were analyzed in mushrooms, before and after cooking and in over-the-counter supplements.

RESULTS

After 16 weeks, both D2-UVB-mushroom entrée doses, which were significantly lower after cooking, produced modest or no increases in 25OHD2 or total 25OHD relative to the positive control subjects who actually consumed about 1242 and 7320 IU per day of D3 (higher than stated on the label).

CONCLUSIONS

Unanticipated D2 cooking loss from fresh UVB mushrooms and probable low absorption and/or hydroxylation may explain the smaller increase in 25OHD2 in our prediabetic overweight/obese cohort compared with past findings in younger, healthy subjects. Moreover, no dose or vitamin D source was associated with modifying T2D risk factors.

Serum vitamin D, vitamin D binding protein, and risk of colorectal cancer

BACKGROUND

We previously reported a positive association between serum 25-hydroxyvitamin D (25(OH)D) and colorectal cancer risk. To further elucidate this association, we examined the molar ratio of 25(OH)D to vitamin D binding protein (DBP), the primary 25(OH)D transport protein, and whether DBP modified the association between 25(OH)D and colorectal cancer risk.

METHODS

In a nested case-control study within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, controls were 1∶1 matched to 416 colorectal cancer cases based on age and date of blood collection. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CI) for quartiles of 25(OH)D, DBP, and the molar ratio of 25(OH)D:DBP, a proxy for free, unbound circulating 25(OH)D.

RESULTS

Comparing highest to lowest quartiles, DBP was not associated with colorectal cancer risk (OR = 0.91; 95% CI: 0.58, 1.42, p for trend  = 0.58); however, a positive risk association was observed for the molar ratio of 25(OH)D:DBP (OR = 1.44; 95% CI: 0.92, 2.26, p for trend  = 0.04). In stratified analyses, the positive association between 25(OH)D and colorectal cancer was stronger among men with DBP levels above the median (OR = 1.89; 95% CI: 1.07, 3.36, p for trend  = 0.01) than below the median (OR = 1.20; 95% CI: 0.68, 2.12, p for trend  = 0.87), although the interaction was not statistically significant (p for interaction  = 0.24).

CONCLUSION

Circulating DBP may influence the association between 25(OH)D and colorectal cancer in male smokers, with the suggestion of a stronger positive association in men with higher DBP concentrations. This finding should be examined in other populations, especially those that include women and non-smokers.

Serum 25-hydroxyvitamin D and incidence of diabetes in elderly people: the PRO.V.A. study

CONTEXT

Increasing research has shown that low levels of serum 25-hydroxyvitamin (25OHD) predict the onset of diabetes, but no research is available on this issue in elderly people.

OBJECTIVE

Our objective was to examine whether low serum levels of 25OHD are associated with a higher risk of incident type 2 diabetes over a lengthy follow-up in a representative group of elderly people.

DESIGN AND SETTING

This was a population-based cohort study as part of the Progetto Veneto Anziani (Pro.V.A.) Study over a follow-up of 4.4 years in the general community.

PARTICIPANTS

PARTICIPANTS included 2227 participants (1728 with follow-up visits and 499 died during the follow-up) over 65 years of age without diabetes at baseline, of 2352 initially included.

MAIN OUTCOME MEASURE

The main outcome measure was incident diabetes.

RESULTS

There were no baseline differences in known factors for the onset of diabetes (body mass index, waist circumference, total cholesterol, renal function, and hemoglobin A1c levels) between the groups with different serum 25OHD levels (≤ 25, 25-50, 50-75, and ≥ 75 nmol/L). Over a 4.4-year follow-up, 291 individuals developed diabetes, with an incidence of 28 events per 1000 person-years. No significant difference in the incidence of diabetes emerged between the baseline 25OHD groups. Cox's regression analysis, adjusted for potential confounders, revealed no relationship between low vitamin D levels and incident diabetes during the follow-up (hazard ratio [HR] = 1.05, 95% confidence interval [CI] = 0.76-1.45, P = .77; HR = 1.44, 95% CI = 0.95-1.98, P = .12; and HR = 1.37, 95% CI = 0.87-2.16, P = .17 for those with 25OHD ≤25, 25-50, and 50-75 nmol/L, respectively).

CONCLUSION

Baseline serum concentrations of 25OHD were not associated with the incidence of diabetes in community-dwelling elderly people over a follow-up of 4.4 years.

Vitamin D and mortality: meta-analysis of individual participant data from a large consortium of cohort studies from Europe and the United States

OBJECTIVE

To investigate the association between serum 25-hydroxyvitamin D concentrations (25(OH)D) and mortality in a large consortium of cohort studies paying particular attention to potential age, sex, season, and country differences.

DESIGN

Meta-analysis of individual participant data of eight prospective cohort studies from Europe and the US.

SETTING

General population.

PARTICIPANTS

26,018 men and women aged 50-79 years.

MAIN OUTCOME MEASURES

All-cause, cardiovascular, and cancer mortality.

RESULTS

25(OH)D concentrations varied strongly by season (higher in summer), country (higher in US and northern Europe) and sex (higher in men), but no consistent trend with age was observed. During follow-up, 6695 study participants died, among whom 2624 died of cardiovascular diseases and 2227 died of cancer. For each cohort and analysis, 25(OH)D quintiles were defined with cohort and subgroup specific cut-off values. Comparing bottom versus top quintiles resulted in a pooled risk ratio of 1.57 (95% CI 1.36 to 1.81) for all-cause mortality. Risk ratios for cardiovascular mortality were similar in magnitude to that for all-cause mortality in subjects both with and without a history of cardiovascular disease at baseline. With respect to cancer mortality, an association was only observed among subjects with a history of cancer (risk ratio, 1.70 (1.00 to 2.88)). Analyses using all quintiles suggest curvilinear, inverse, dose-response curves for the aforementioned relationships. No strong age, sex, season, or country specific differences were detected. Heterogeneity was low in most meta-analyses.

CONCLUSIONS

Despite levels of 25(OH)D strongly varying with country, sex, and season, the association between 25(OH)D level and all-cause and cause-specific mortality was remarkably consistent. Results from a long term randomised controlled trial addressing longevity are being awaited before vitamin D supplementation can be recommended in most individuals with low 25(OH)D levels.

Vitamin D in heart failure

Evidence linking vitamin D to cardiovascular (CV) health has accumulated in recent years: numerous epidemiologic studies report deficiency as a significant CV risk factor, and rodent models suggest that active vitamin D can modulate critical remodeling processes, including cardiac hypertrophy and extracellular matrix remodeling. The presence of vitamin D signaling machinery within the human heart implies a direct role for this hormone in cardiac physiology and may explain associations between vitamin D status and CV outcomes. Heart failure (HF) represents a growing social and economic burden worldwide. Myocardial remodeling is central to HF development, and in the context of emerging evidence supporting mechanistic involvement of vitamin D, this review provides critical appraisal of scientific literature related to the role of vitamin D in CV disease, including data from epidemiologic and supplementation studies, as well as novel findings from animal models and in vitro work. Although associative data linking vitamin D and CV outcomes and evidence supporting a role for vitamin D in relevant pathogenic processes are both substantial, there are limited mechanistic data to indicate vitamin D supplementation as a viable therapeutic adjunct for the prevention of HF development following myocardial injury.

Longitudinal changes and seasonal variations in serum 25-hydroxyvitamin D levels in different age groups: results of the Longitudinal Aging Study Amsterdam

Vitamin D levels remained fairly stable during ageing with increasing levels in persons aged 55-65 years old and decreasing levels in persons aged 65-88 years old. The seasonal variation was larger than the longitudinal change. Our findings implicate that vitamin D supplementation becomes more important in older age groups and during wintertime.

INTRODUCTION

Longitudinal changes in serum 25-hydroxyvitamin D (25-OHD) levels during aging have not been studied extensively. Two studies showed increasing serum 25-OHD levels. One of these studies suggested that there might be decreasing levels in persons aged 65 years and older. The objectives of the current study are the following: (1) to examine longitudinal changes in serum 25-OHD levels in different age groups and (2) to describe the seasonal variation in different age groups.

METHODS

Data of the Longitudinal Aging Study Amsterdam (LASA), an ongoing cohort study, were used. Two different cohorts were included: (1) younger cohort: aged 55-65 years old at baseline, n = 738, follow-up of 6 years and (2) older cohort: aged 65-88 years old at baseline, n = 1,320, follow-up of 13 years.

RESULTS

At baseline, average levels were 56.5 nmol/L in the younger cohort and 51.1 nmol/L in the older cohort. In the younger cohort, a longitudinal increase in the mean serum 25-OHD levels of 4 nmol/L in 6 years was observed; in the older cohort, a longitudinal decrease in the mean serum 25-OHD levels of 4 nmol/L in 13 years was observed. The seasonal variation was ±12 nmol/L in the younger cohort and ±7 nmol/L in the older cohort.

CONCLUSIONS

Long-term serum 25-OHD levels remained fairly stable during aging with slightly increasing levels in persons aged 55-65 years old and slightly decreasing levels in persons aged 65-88 years old. On average, the seasonal variation was larger than the longitudinal change. Our findings implicate that vitamin D supplementation becomes more important in older age groups and during wintertime.

Association between serum 25-hydroxyvitamin D concentration and symptoms of respiratory tract infection in a Norwegian population: the Tromsø Study

OBJECTIVE

Previous studies have suggested anti-infection effects of vitamin D, although the associations reported between vitamin D (serum 25-hydroxyvitamin D (25(OH)D) concentration) and respiratory tract infection (RTI) are conflicting. The main aim of the present study was to explore this association in a Norwegian population.

DESIGN

We examined the association between serum 25(OH)D and recent RTI symptoms in 6350 middle-aged and elderly participants in the Tromsø Study 6. The main outcome measurement was self-reported RTI symptoms in the previous week.

SETTING

Tromsø, Norway, 69 °N.

SUBJECTS

Six thousand three hundred and fifty middle-aged and elderly residents of Tromsø.

RESULTS

Of the 6350 included, 791 (12.5%) reported RTI symptoms in the previous week. We classified serum 25(OH)D concentrations into quartiles and adjusted the data for current smoking habit and month of attendance. The prevalence of RTI symptoms did not increase with decreasing serum 25(OH)D level, was highest in quartile 3 (15.0%) followed by quartile 4 (12.4%), and was lowest in quartiles 1 and 2 (11.1% and 11.4%). There was no trend for increasing duration of illness with decreasing serum 25(OH)D. The prevalence of RTI symptoms was not significantly associated with the intake of fish, n-3 capsules or vitamin and/or mineral supplements, or sun exposure. Only use of cod-liver oil or fish oil capsules daily or sometimes was significantly associated with fewer RTI symptoms during the preceding 7 d (P = 0.04).

CONCLUSIONS

Low serum 25(OH)D was not associated with increased prevalence of recent RTI symptoms. Our findings do not support the idea that vitamin D supplementation can reduce the incidence of RTI in Norway.

Moderate vitamin D deficiency is associated with changes in knee and hip pain in older adults: a 5-year longitudinal study

BACKGROUND

Vitamin D is important for bone, cartilage and muscle function but there are few studies on its association with joint pain.

OBJECTIVE

To investigate whether serum vitamin D predicts change in knee and hip pain in older adults.

METHODS

Longitudinal population-based cohort study of randomly selected older adults (n=769) aged 50-80 years (mean 62 years); 50% were male. Serum 25-hydroxyvitamin D (25-OHD) was assessed at baseline by radioimmunoassay, and pain at baseline, 2.6 and/or 5 years using the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) questionnaire. We used linear regression with adjustment for age, sex, body mass index and season, then further adjusted for potential structural mechanisms (radiographic osteoarthritis, bone marrow lesions, chondral defects and muscle strength).

RESULTS

Mean total knee WOMAC score was 3.2 (range 0-39). 4.2% of participants had moderate vitamin D deficiency at baseline (25-OHD 12.5-25 nmol/l). 25-OHD <25 nmol/l predicted change in knee pain (using total WOMAC score) over 5 years (β=2.41, p=0.002) with a similar effect size for hip pain over 2.4 years (β=2.20, p=0.083). Results were consistent within pain subscales, and the association was independent of demographic, anthropometric and structural covariates. No association was present when 25-OHD was analysed as a continuous measure.

CONCLUSIONS

Moderate vitamin D deficiency independently predicts incident, or worsening of, knee pain over 5 years and, possibly, hip pain over 2.4 years. Therefore correcting moderate vitamin deficiency may attenuate worsening of knee or hip pain in elderly people but giving supplements to those with a higher 25-OHD level is unlikely to be effective.

Hip fractures and bone mineral density in the elderly--importance of serum 25-hydroxyvitamin D

Background

The significance of serum 25-hydroxyvitamin D [25(OH)D] concentrations for hip fracture risk of the elderly is still uncertain. Difficulties reaching both frail and healthy elderly people in randomized controlled trials or large cohort studies may in part explain discordant findings. We determined hazard ratios for hip fractures of elderly men and women related to serum 25(OH)D, including both the frail and the healthy segment of the elderly population.

Methods

The AGES-Reykjavik Study is a prospective study of 5764 men and women, age 66–96 years, based on a representative sample of the population of Reykjavik, Iceland. Participation was 71.8%. Hazard ratios of incident hip fractures and baseline bone mineral density were determined according to serum concentrations of 25(OH)D at baseline.

Results

Mean follow-up was 5.4 years. Compared with referent values (50–75 nmol/L), hazard ratios for hip fractures were 2.24 (95% CI 1.63, 3.09) for serum 25(OH)D <30 nmol/L, adjusting for age, sex, body mass index, height, smoking, alcohol intake and season, and 2.08 (95% CI 1.51, 2.87), adjusting additionally for physical activity. No difference in risk was associated with 30–50 nmol/L or ≥75 nmol/L in either model compared with referent. Analyzing the sexes separately, hazard ratios were 2.61 (95% CI 1.47, 4.64) in men and 1.93 (95% CI 1.31, 2.84) in women. Values <30 nmol/L were associated with significantly lower bone mineral density of femoral neck compared with referent, z-scores -0.14 (95% CI −0.27, −0.00) in men and −0.11 (95% CI −0.22, −0.01) in women.

Conclusions

Our results lend support to the overarching importance of maintaining serum 25(OH)D above 30 nmol/L for bone health of elderly people while potential benefits of having much higher levels could not be detected.

Vitamin D status and chronic obstructive pulmonary disease: a prospective general population study

OBJECTIVES

Vitamin D deficiency is common among persons with chronic obstructive pulmonary disease (COPD). Whether vitamin D affects the development and deterioration of COPD or is a consequence of the disease lacks clarity. We investigated the association between vitamin D status and prevalent and incident COPD in the general population.

METHODS

We included a total of 12,041 individuals from three general population studies conducted in 1993-94, 1999-2001, and 2006-2008, respectively, with vitamin D measurements. Information on COPD was obtained from the Danish National Patient Register and The Danish Registry of Causes of Death.

RESULTS

There were 85 prevalent and 463 incident cases of COPD (median follow-up 9.7 years). We found a statistically significant inverse association between vitamin D status and prevalent COPD with odds ratio = 0.89 (95% confidence interval, CI: 0.79, 1.0), but no statistically significant association with incident COPD with a hazard ratio = 0.98 (95% CI: 0.94, 1.0), respectively, per 10 nmol/l higher vitamin D status, when adjusted for possible confounders.

CONCLUSIONS

We found a statistically significant inverse cross-sectional association between vitamin D status and COPD, but no association between vitamin D status and incident COPD.

Inverse association between circulating vitamin D and mortality--dependent on sex and cause of death?

BACKGROUND AND AIMS

In various populations, vitamin D deficiency is associated with chronic diseases and mortality. We examined the association between concentration of circulating 25-hydroxyvitamin D [25(OH)D], a marker of vitamin D status, and all-cause as well as cause-specific mortality.

METHODS AND RESULTS

The study included 3404 participants of the general adult Swiss population, who were recruited between November 1988 and June 1989 and followed-up until the end of 2008. Circulating 25(OH)D was measured by protein-bound assay. Cox proportional hazards regression was used to examine the association between 25(OH)D concentration and all-cause and cause-specific mortality adjusting for sex, age, season, diet, nationality, blood pressure, and smoking status. Per 10 ng/mL increase in 25(OH)D concentration, all-cause mortality decreased by 20% (HR = 0.83; 95% CI 0.74-0.92). 25(OH)D concentration was inversely associated with cardiovascular mortality in women (HR = 0.68, 95% CI 0.46-1.00 per 10 ng/mL increase), but not in men (HR = 0.97; 95% CI 0.77-1.23). In contrast, 25(OH)D concentration was inversely associated with cancer mortality in men (HR = 0.72, 95% CI 0.57-0.91 per 10 ng/mL increase), but not in women (HR = 1.14, 95% CI 0.93-1.39). Multivariate adjustment only slightly modified the 25(OH)D-mortality association.

CONCLUSION

25(OH)D was similarly inversely related to all-cause mortality in men and women. However, we observed opposite effects in women and men with respect to cardiovascular and cancer mortality.

Vitamin D status and 5-year changes in urine albumin creatinine ratio and parathyroid hormone in a general population

Vitamin D is associated with cardiovascular disease and renal function but the mechanisms are as yet unexplained. Microalbuminuria is associated with a higher risk of kidney function loss, cardiovascular disease, and mortality. Parathyroid hormone is a predictor of cardiovascular mortality and negatively correlated with glomerular filtration rate. We investigated the association between vitamin D status and 5-year changes in urine albumin creatinine ratio (UACR) and parathyroid hormone (PTH). A random sample of 6,784 individuals aged 30-60 years from a general population participated in the Inter99 study in 1999-2001. Vitamin D (serum-25-hydroxyvitamin D) was measured at baseline by high-performance liquid chromatography. UACR and PTH were measured at baseline and follow-up. Increased UACR was defined as UACR >4.0 mg/g reflecting the upper quartile at baseline. We included 4,330 individuals who participated at 5-year follow-up. In multivariable linear regression analysis, a 10-nmol/l higher baseline level of vitamin D was associated with a 5-year decrease in UACR by 0.92 % (95 % confidence interval, CI 0.13, 1.71). In multivariable logistic regression analysis, the odds ratio of developing increased UACR during follow-up was 0.96 (95 % CI 0.92, 0.98) per 10 nmol/l higher baseline vitamin D level. We found a significant inverse cross-sectional (p < 0.0001) but no prospective association (p = 0.6) between baseline vitamin D status and parathyroid hormone. We found low vitamin D status to be a predictor of long-term development of increased UACR. It remains to be proven whether vitamin D deficiency is a causal and reversible factor in the development of albuminuria.

Season of infectious mononucleosis and risk of multiple sclerosis at different latitudes; the EnvIMS Study

BACKGROUND

Seasonal fluctuations in solar radiation and vitamin D levels could modulate the immune response against Epstein-Barr virus (EBV) infection and influence the subsequent risk of multiple sclerosis (MS).

METHODS

Altogether 1660 MS patients and 3050 controls from Norway and Italy participating in the multinational case-control study of Environmental Factors In Multiple Sclerosis (EnvIMS) reported season of past infectious mononucleosis (IM).

RESULTS

IM was generally reported more frequently in Norway (p=0.002), but was associated with MS to a similar degree in Norway (odds ratio (OR) 2.12, 95% confidence interval (CI) 1.64-2.73) and Italy (OR 1.72, 95% CI 1.17-2.52). For all participants, there was a higher reported frequency of IM during spring compared to fall (p<0.0005). Stratified by season of IM, the ORs for MS were 1.58 in spring (95% CI 1.08-2.31), 2.26 in summer (95% CI 1.46-3.51), 2.86 in fall (95% CI 1.69-4.85) and 2.30 in winter (95% CI 1.45-3.66).

CONCLUSIONS

IM is associated with MS independently of season, and the association is not stronger for IM during spring, when vitamin D levels reach nadir. The distribution of IM may point towards a correlation with solar radiation or other factors with a similar latitudinal and seasonal variation.

Dietary, lifestyle, and genetic determinants of vitamin D status: a cross-sectional analysis from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Germany study

PURPOSE

Considerable variation in 25-hydroxyvitamin D (25(OH)D) in populations worldwide that seems to be independent of latitude has been reported. Therefore, we aimed to assess vitamin D status of a mid-aged German general population and to identify its dietary, lifestyle, anthropometric, and genetic determinants.

METHODS

25(OH)D concentrations were measured by LC-MS/MS in plasma samples of a random subcohort of the German arm of the European Prospective Investigation into Cancer and Nutrition (EPIC) comprising 2,100 subjects aged 35-65 years. Associations between potential predictors and 25(OH)D were assessed by linear regression models.

RESULTS

32.8% of the variance in 25(OH)D was explained by a multivariable regression model, with season being the by far strongest predictor (semi-partial R²: 14.6%). Sex, waist circumference, leisure time physical activity, smoking, polymorphisms in the GC, CYP2R1, and DHCR7 genes, supplement use, exogenous hormone use, alcohol consumption, egg consumption, and fish consumption were significantly associated with 25(OH)D concentrations as well. However, none of these factors explained >2.3% of the variance in 25(OH)D.

CONCLUSION

Even with a comprehensive set of genetic, anthropometric, dietary, and lifestyle correlates, not more than 32.8% of the variation in 25(OH)D could be explained in the EPIC-Germany study, implying that vitamin D prediction scores may not provide an appropriate proxy for measured 25(OH)D. Food intake was only a weak predictor of 25(OH)D concentrations, while a strong seasonal fluctuation in 25(OH)D was shown.

Plasma 25-hydroxyvitamin D concentration and lymphoma risk: results of the European Prospective Investigation into Cancer and Nutrition

BACKGROUND

The relation between vitamin D status and lymphoma risk is inconclusive.

OBJECTIVE

We examined the association between prediagnostic plasma 25-hydroxyvitamin D [25(OH)D] and lymphoid cancer risk.

DESIGN

We conducted a study nested within the European Prospective Investigation into Cancer and Nutrition cohort of 1127 lymphoma cases and 1127 matched controls with a mean follow-up time of 7.1 y. Conditional logistic regression was used to estimate multivariable-adjusted incidence rate ratios of lymphoma risk in relation to plasma 25(OH)D. Season-standardized and season-specific 25(OH)D quartiles were used. We also analyzed 25(OH)D as a continuous variable and used predefined cutoffs.

RESULTS

No statistically significant association between plasma 25(OH)D and overall lymphoid cancer risk was observed. A positive association for B-cell non-Hodgkin lymphoma was noted only in those with a diagnosis made during the first 2 y of follow-up (P-heterogeneity = 0.03), which suggests the possibility of reverse causality. Further analysis restricted to participants with ≥2 y of follow-up time showed a significant association between 25(OH)D and chronic lymphocytic leukemia (CLL) (n = 161): adjusted incidence rate ratios were 0.40 (95% CI: 0.18, 0.90; P-trend = 0.05) and 0.31 (95% CI: 0.13, 0.76; P-trend = 0.03) for the top compared with the bottom season-standardized and season-specific quartiles, respectively. Data on dietary vitamin D intake provided further support for the observed association (incidence rate ratio: 0.33; 95% CI = 0.12, 0.89; P-trend = 0.006).

CONCLUSIONS

Our findings do not support a protective role of high 25(OH)D concentration in lymphoid cancers overall. However, they suggest that higher concentrations of 25(OH)D are associated with a reduced risk of CLL.

A systematic review of vitamin D status in populations worldwide

Vitamin D deficiency is associated with osteoporosis and is thought to increase the risk of cancer and CVD. Despite these numerous potential health effects, data on vitamin D status at the population level and within key subgroups are limited. The aims of the present study were to examine patterns of 25-hydroxyvitamin D (25(OH)D) levels worldwide and to assess differences by age, sex and region. In a systematic literature review using the Medline and EMBASE databases, we identified 195 studies conducted in forty-four countries involving more than 168 000 participants. Mean population-level 25(OH)D values varied considerably across the studies (range 4·9-136·2 nmol/l), with 37·3 % of the studies reporting mean values below 50 nmol/l. The highest 25(OH)D values were observed in North America. Although age-related differences were observed in the Asia/Pacific and Middle East/Africa regions, they were not observed elsewhere and sex-related differences were not observed in any region. Substantial heterogeneity between the studies precluded drawing conclusions on overall vitamin D status at the population level. Exploratory analyses, however, suggested that newborns and institutionalised elderly from several regions worldwide appeared to be at a generally higher risk of exhibiting lower 25(OH)D values. Substantial details on worldwide patterns of vitamin D status at the population level and within key subgroups are needed to inform public health policy development to reduce risk for potential health consequences of an inadequate vitamin D status.

Plasma 25-hydroxyvitamin D and its genetic determinants in relation to incident myocardial infarction and stroke in the European prospective investigation into cancer and nutrition (EPIC)-Germany study

Circulating 25-hydroxyvitamin D (25(OH)D) has been associated with cardiovascular disease (CVD) risk in observational studies. Also, SNPs to explain variation in 25(OH)D have been identified by genome-wide association studies. Detection of direct associations between SNPs that significantly affect 25(OH)D and CVD risk would indicate a causal role of vitamin D, as reverse causation could be excluded and confounding could be better controlled. Thus, a combined analysis of candidate SNPs in relation to circulating 25(OH)D and CVD risk was carried out. A case-cohort study within the EPIC-Germany study was conducted comprising a randomly drawn subcohort of 2,132 subjects (57.9% women, mean age: 50.6 years) and incident cases of myocardial infarction (n=559) and stroke (n=471) that occurred during a mean follow-up duration of 7.6 years. 25(OH)D concentrations were measured by LC-MS/MS in baseline plasma samples. Additionally, eight candidate SNPs were assayed. Associations between 25(OH)D, SNPs and the risks of myocardial infarction and stroke were assessed by multivariable regression analyses. Mean 25(OH)D level was 47.2 nmol/L in the subcohort. Four SNPs were associated with 25(OH)D (p<0.05). In subjects with 25(OH)D levels <25 nmol/L, the risks of CVD as composite endpoint (Hazard Ratio: 1.53, 95% confidence interval: 1.12–2.09), myocardial infarction, and stroke were significantly increased compared to subjects with levels ≥50 nmol/L, while no significant linear associations were observed. A SNP score was not related to the risks of total CVD (Hazard Ratio: 1.0, 95% confidence interval: 0.71–1.42), myocardial infarction, or stroke. The same was true concerning single SNPs. Given the lack of association between SNPs and the risks of stroke and myocardial infarction, the present findings do not point to a major causal role of vitamin D in the development of these diseases. However, a detection of modest associations between genetic markers and CVD risk in larger consortia cannot be ruled out.

Vitamin D supplementation and breast cancer prevention: a systematic review and meta-analysis of randomized clinical trials

In recent years, the scientific evidence linking vitamin D status or supplementation to breast cancer has grown notably. To investigate the role of vitamin D supplementation on breast cancer incidence, we conducted a systematic review and meta-analysis of randomized controlled trials comparing vitamin D with placebo or no treatment. We used OVID to search MEDLINE (R), EMBASE and CENTRAL until April 2012. We screened the reference lists of included studies and used the “Related Article” feature in PubMed to identify additional articles. No language restrictions were applied. Two reviewers independently extracted data on methodological quality, participants, intervention, comparison and outcomes. Risk Ratios and 95% Confident Intervals for breast cancer were pooled using a random-effects model. Heterogeneity was assessed using the I² test. In sensitivity analysis, we assessed the impact of vitamin D dosage and mode of administration on treatment effects. Only two randomized controlled trials fulfilled the pre-set inclusion criteria. The pooled analysis included 5372 postmenopausal women. Overall, Risk Ratios and 95% Confident Intervals were 1.11 and 0.74–1.68. We found no evidence of heterogeneity. Neither vitamin D dosage nor mode of administration significantly affected breast cancer risk. However, treatment efficacy was somewhat greater when vitamin D was administered at the highest dosage and in combination with calcium (Risk Ratio 0.58, 95% Confident Interval 0.23–1.47 and Risk Ratio 0.93, 95% Confident Interval 0.54–1.60, respectively). In conclusions, vitamin D use seems not to be associated with a reduced risk of breast cancer development in postmenopausal women. However, the available evidence is still limited and inadequate to draw firm conclusions. Study protocol code: FARM8L2B5L.

Circulating 25-hydroxyvitamin D, vitamin D-binding protein and risk of prostate cancer

We recently reported a significant positive association between 25-hydroxyvitamin D [25(OH)D], the accepted biomarker of vitamin D status, and prostate cancer risk. To further elucidate this association, we examined the influence of vitamin D-binding protein (DBP), the primary transporter of vitamin D compounds in the circulation. Prediagnostic serum concentrations of DBP were assayed for 950 cases and 964 matched controls with existing 25(OH)D measurements within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study of Finnish men. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs), and statistical tests were two sided. Serum DBP modified the association between serum 25(OH)D and prostate cancer, with higher risk for elevated 25(OH)D levels observed primarily among men having DBP concentrations above the median (OR = 1.81, 95% CI: 1.18-2.79 for highest vs. lowest quintile, p-trend = 0.001) compared to those with DBP below the median (OR = 1.22, 95% CI: 0.81-1.84, p-trend 0.97; p-interaction = 0.04). Serum DBP was not associated with prostate cancer risk overall (OR = 0.96, 95% CI: 0.70-1.33 for highest vs. lowest quintile); however, high serum DBP was associated with significantly decreased risk of prostate cancer in men with lower ( Collapse

Key Words

• vitamin d binding protein
• 25-hydroxyvitamin d
• prostate cancer
• serum biomarkers
• prospective study

Collapse

MESH Headings

• Adult
• Aged
• Humans
• Male
• Middle Aged
• Odds Ratio
• Prostatic Neoplasms/blood
• Prostatic Neoplasms/epidemiology
• Risk
• Vitamin D/analogs & derivatives
• Vitamin D/blood
• Vitamin D-Binding Protein/blood

Collapse

Grants

• N01-RC-45035 CCR NIH HHS
• ZIA CP010195 Intramural NIH HHS
• HHSN261200800001C NCI NIH HHS
• ZIA CP010195-06 Intramural NIH HHS
• HHSN261201000006C NCI NIH HHS
• N01RC37004 CCR NIH HHS
• N01 CN045165 NCI NIH HHS
• HHSN261200800001E NCI NIH HHS

Collapse

Affiliation(s)

Stephanie J. Weinstein Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland, 20892
Alison M. Mondul Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland, 20892
William Kopp Clinical Support Laboratory, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702
Helen Rager Clinical Support Laboratory, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702
Jarmo Virtamo Department of Chronic Disease Prevention, National Institute for Health and Welfare, Helsinki, Finland
Demetrius Albanes Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland, 20892

Collapse

Collaborators Collapse

Lack of a relation between serum 25-hydroxyvitamin D concentrations and asthma in adolescents

BACKGROUND

Decreased 25-hydroxyvitamin D [25(OH)D] concentrations have been associated with an increased prevalence and severity of asthma and a lower response to inhaled corticosteroids.

OBJECTIVE

The objective was to determine the association between serum 25(OH)D concentrations and asthma prevalence, severity, and response to asthma treatment.

DESIGN

Secondary analyses were conducted in 2 samples of adolescents 12-20 y of age: 1) NHANES 2001-2006 (n = 6487), a cross-sectional nationally representative sample of the US population, and 2) a cohort of inner-city adolescents with asthma managed prospectively for 46 wk with guidelines-based therapy in the Asthma Control Evaluation (ACE; n = 226) trial.

RESULTS

Mean (±SD) serum 25(OH)D concentrations in the NHANES and ACE samples were lower in African Americans than in non-African Americans (NHANES: 14.9 ± 6.5 compared with 23.0 ± 8.4 ng/mL, P < 0.0001; ACE: 11.2 ± 6.9 compared with 15.8 ± 7.1 ng/mL, P < 0.0001). In the NHANES sample, mean concentrations did not differ between participants without and with asthma (African Americans: 14.9 ± 6.4 compared with 15.0 ± 6.6 ng/mL, respectively, P = 0.87; non-African Americans: 23.0 ± 8.5 compared with 23.6 ± 8.2 ng/mL, respectively, P = 0.16). In the ACE models that used either a predefined cutoff (<20 ng/mL) or linear regression, 25(OH)D concentrations showed either no relation or minor contradictory correlations with indicators of asthma severity, treatment requirements, spirometry, or atopy/inflammation.

CONCLUSION

In 2 samples of adolescents, overall serum 25(OH)D concentrations were low and were not consistently associated with the presence of asthma, multiple asthma characteristics, asthma morbidity, or response to treatment. The ACE trial was registered at clinicaltrials.gov as NCT0011441.

Estimating mean annual 25-hydroxyvitamin D concentrations from single measurements: the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

The seasonal variation in circulating 25-hydroxyvitamin D [25(OH)D] concentrations is large relative to mean values. Single measurements may misclassify annual exposure, which may lead to bias in research and complicate clinical decision making.

OBJECTIVE

We aimed to develop and validate a model for adjusting a single measurement of a serum 25(OH)D concentration to the time of year it was measured.

DESIGN

We measured serum 25(OH)D concentrations by using mass spectrometry in 6476 participants from the Multi-Ethnic Study of Atherosclerosis at baseline and again in a subset of 368 participants at a median of 17 mo later. We estimated a cosinor model to describe the seasonal variability in 25(OH)D concentrations and evaluated this model by using follow-up 25(OH)D measurements.

RESULTS

The mean age of subjects was 62.1 y, 61.2% of participants were nonwhite, and 53.3% of participants were women. The cosinor model predicted follow-up 25(OH)D concentrations better than a single measurement [difference in root mean squared error (RMSE): 1.3 ng/mL; P< 0.001]. The cosinor model also better predicted the measured annual mean 25(OH)D concentration (difference in RMSE: 1.0 ng/mL; P< 0.001). Annual mean 25(OH)D concentrations estimated from the cosinor model reclassified 7.1% of participants with regard to 25(OH)D deficiency, which was defined as <20 ng/mL. An estimated annual mean 25(OH)D concentration <20 ng/mL was significantly associated with lower bone mineral density, whereas an untransformed 25(OH)D concentration <20 ng/mL was not.

CONCLUSIONS

Cross-sectional data can be used to estimate subject-specific mean annual 25(OH)D concentrations from single values by using a cosinor model. The tool we developed by using this approach may assist research and clinical care of adults in North America by reducing the misclassification of 25(OH)D deficiency.

Vitamin D deficiency associated with increased incidence of gastrointestinal and ear infections in school-age children

BACKGROUND

Vitamin D deficiency (VDD) is highly prevalent among children worldwide. The effects of VDD include alterations of the immune response and increased risk of infection but little evidence exists in school-age children. We investigated the association of vitamin D status with morbidity in a prospective study of school-age children from Bogotá, Colombia.

METHODS

We measured plasma 25-hydroxyvitamin D (25(OH)D) concentrations in a random sample of 475 children (mean ± standard deviation age: 8.9 ± 1.6 years) and followed them for an academic year. Caregivers were asked to record daily information on the incidence of morbidity episodes using pictorial diaries. Baseline vitamin D status was classified according to 25(OH)D concentrations as deficient (<50 nmol/L), insufficient (≥50 and <75 nmol/L) or sufficient (≥75 nmol/L). We used Poisson regression to estimate incidence rate ratios and 95% confidence intervals for days with diarrhea, vomiting, diarrhea with vomiting, cough with fever and earache or discharge with fever, comparing vitamin D-deficient with vitamin D-sufficient children. Estimates were adjusted for child's age, sex and household socioeconomic status.

RESULTS

The prevalence of VDD was 10%; an additional 47% of children were vitamin D-insufficient. VDD was associated with increased rates of diarrhea with vomiting (adjusted incidence rate ratio: 2.05; 95% confidence interval: 1.19, 3.53) and earache/discharge with fever (adjusted incidence rate ratio: 2.36; 95% confidence interval: 1.26, 4.44). VDD was not significantly related to cough with fever.

CONCLUSIONS

These results suggest that VDD is related to increased incidence of gastrointestinal and ear infections in school-age children. The effect of correcting VDD on reducing risk of these infections needs to be tested in supplementation trials.

Vitamin D status and incident cardiovascular disease and all-cause mortality: a general population study

Low vitamin D status has been associated with cardiovascular disease (CVD) and mortality primarily in selected groups, smaller studies, or with self-reported vitamin D intake. We investigated the association of serum vitamin D status with the incidence of a registry-based diagnosis of ischemic heart disease (IHD), stroke, and all-cause mortality in a large sample of the general population. A total of 9,146 individuals from the two population-based studies, Monica10 and Inter99, were included. Measurements of serum 25-hydroxyvitamin D at baseline were carried out using the IDS ISYS immunoassay system in Monica10 and High-performance liquid chromatography in Inter99. Information on CVDs and causes of death was obtained from Danish registries until 31 December 2008. There were 478 cases of IHD, 316 cases of stroke, and 633 deaths during follow-up (mean follow-up 10 years). Cox regression analyses with age as underlying time axis showed a significant association between vitamin D status and all-cause mortality with a HR = 0.95 (P = 0.005) per 10 nmol/l higher vitamin D level. We found no association between vitamin D status and incidence of IHD or stroke (HR = 1.01, P = 0.442 and HR = 1.00, P = 0.920, respectively). In this large general population study, the observed inverse association between serum vitamin D status and all-cause mortality was not explained by a similar inverse association with IHD or stroke.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Serum 25-hydroxyvitamin D and risk of major osteoporotic fractures in older U.S. adults

Results from previous prospective studies linking serum 25-hydroxyvitamin D (25OHD) with fracture risk have been inconsistent. The present study examined the relationship between serum 25OHD and risk of incident major osteoporotic fracture (hip, spine, radius, and humerus) in older U.S. adults. The study used a pooled cohort of 4749 men and women ages 65 years and older from the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994) and NHANES 2000-2004. Incident fractures were identified using linked mortality and Medicare records that were obtained for participants from both surveys. Serum 25OHD values were measured by radioimmunoassay in both surveys. Cox proportional hazards models were used to estimate the relative risk (RR) of fracture by serum 25OHD level. There were 525 incident major osteoporotic fractures (287 hip fractures) in the sample. Serum 25OHD was a significant linear predictor of major osteoporotic fracture and significant quadratic predictor of hip fracture in the total sample and among those with less than 10 years of follow-up, but it was not related to risk of either fracture type among those with ≥ 10 years of follow-up. Major osteoporotic fracture risk was increased by 26% to 27% for each SD decrease in serum 25OHD among those with less than 10 years of follow-up. Serum 25OHD was significantly related to risk of major osteoporotic fractures as a group and to hip fracture alone in this cohort of older U.S. adults from NHANES III and NHANES 2000-2004. However, the predictive utility of serum 25OHD diminished after 10 years. In addition, the relationship appeared to be linear when major osteoporotic fracture risk was considered but quadratic when hip fracture risk was assessed.

Vitamin d and the risk of uterine fibroids

BACKGROUND

Uterine leiomyomata (also known as fibroids) are benign tumors of uterine smooth muscle that are characterized by overproduction of extracellular matrix. Fibroids are the leading indication for hysterectomy in the United States. The active metabolite of vitamin D has been shown to inhibit cell proliferation and extracellular matrix production in fibroid tissue culture and to reduce fibroid volume in the Eker rat. No previous study has examined whether vitamin D is related to fibroid status in women.

METHODS

The National Institute of Environmental Health Sciences Uterine Fibroid Study enrolled randomly selected 35- to 49-year-old women who were members of an urban health plan during 1996-1999. Fibroid status was determined by ultrasound screening of premenopausal women (620 blacks, 416 whites). Vitamin D status was assessed in stored plasma by radioimmunoassay of 25-hydroxyvitamin D (25(OH)D) and questionnaire data on sun exposure. Associations were evaluated with logistic regression, controlling for potential confounders.

RESULTS

Only 10% of blacks and 50% of whites had levels of 25(OH)D regarded as sufficient (>20 ng/ml). Women with sufficient vitamin D had an estimated 32% lower odds of fibroids compared with those with vitamin D insufficiency (adjusted odds ratio [aOR] = 0.68, 95% confidence interval [CI] = 0.48-0.96). The association was similar for blacks and whites. Self-reported sun exposure ≥ 1 hour per day (weather permitting) was also associated with reduced odds of fibroids (aOR = 06. [0.4-0.9]), with no evidence of heterogeneity by ethnicity.

CONCLUSIONS

The consistency of findings for questionnaire and biomarker data, the similar patterns seen in blacks and whites, and the biological plausibility provide evidence that sufficient vitamin D is associated with a reduced risk of uterine fibroids.

Strong associations of 25-hydroxyvitamin D concentrations with all-cause, cardiovascular, cancer, and respiratory disease mortality in a large cohort study

BACKGROUND

Serum 25-hydroxyvitamin D [25(OH)D] concentration has been linked to mortality in several studies, but appropriate cutoffs to define risk categories are under debate.

OBJECTIVE

We aimed to conduct a repeated-measurements analysis on the association of serum 25(OH)D concentrations with all-cause and cause-specific mortality, with particular attention given to the shape of dose-response relations.

DESIGN

Concentrations of 25(OH)D were measured in n = 9578 baseline and n = 5469 5-y follow-up participants of the ESTHER study, which is a German population-based cohort aged 50-74 y at baseline. Deaths were recorded during 9.5 y of follow-up (median). Restricted cubic splines were used to assess dose-response relations, and Cox regression with time-dependent variables was used to estimate hazard ratios.

RESULTS

During follow-up, 1083 study participants died; of those, 350 individuals died of cardiovascular diseases, 433 individuals died of cancer, and 55 individuals died of respiratory diseases. The overall mortality [HR (95% CI)] of subjects with vitamin D deficiency [25(OH)D concentrations <30 nmol/L] or vitamin D insufficiency [25(OH)D concentrations from 30 to 50 nmol/L) was significantly increased [1.71 (1.43, 2.03) and 1.17 (1.02, 1.35), respectively] compared with that of subjects with sufficient 25(OH)D concentrations (>50 nmol/L)]. Vitamin D deficiency was also associated with increased cardiovascular mortality [1.39 (95% CI: 1.02, 1.89)], cancer mortality [1.42 (95% CI: 1.08, 1.88)] and respiratory disease mortality [2.50 (95% CI: 1.12, 5.56)]. The association of 25(OH)D concentrations with all-cause mortality proved to be a nonlinear inverse association with risk that started to increase at 25(OH)D concentrations <75 nmol/L.

CONCLUSIONS

In this large cohort study, serum 25(OH)D concentrations were inversely associated with all-cause and cause-specific mortality. In particular, vitamin D deficiency [25(OH)D concentration <30 nmol/L] was strongly associated with mortality from all causes, cardiovascular diseases, cancer, and respiratory diseases.

Prospective analysis of vitamin D and endometrial cancer risk

BACKGROUND

This is the first prospective cohort analysis on the association between vitamin D and endometrial cancer incorporating time-varying predicted plasma 25-hydroxyvitamin D [25(OH)D].

METHODS

The prospective cohort analysis of predicted 25(OH)D and total dietary vitamin D intake used the Cox proportional hazards model, and involved 644 incident endometrial cancer events from 1986 to 2006 in the Nurses' Health Study. Genotyping and unconditional logistic regression were carried out on 572 endometrial cancer cases and their matched controls on 12 single nucleotide polymorphisms (SNPs) in vitamin D-related genes.

RESULTS

There was no significant association between predicted 25(OH)D and endometrial cancer incidence, with the hazard ratio for the highest (versus the lowest) quintile of predicted 25(OH)D as 1.00 (95% CI 0.73-1.36) (p-trend = 0.33). There was also no significant association involving total dietary vitamin D. No significant associations between any of the vitamin D-related SNPs and endometrial cancer were observed.

CONCLUSION

Both predicted 25(OH)D and total dietary vitamin D intake were not associated with endometrial cancer incidence. These results suggest that vitamin D may not protect against the development of endometrial cancer. However, the low and narrow vitamin D exposure range in the cohort may limit generalizability of the results.

Serum 25-hydroxyvitamin D levels and overall mortality. A systematic review and meta-analysis of prospective cohort studies

OBJECTIVE

To provide a systematic review and meta-analysis of prospective, population-based cohort studies on the association of serum 25-hydroxyvitamin D (25(OH)D) and all-cause mortality.

METHODS

Relevant studies were identified by systematically searching Medline, EMBASE and ISI Web of Knowledge. Reported hazard ratios (HRs) for 25(OH)D categories were recalculated employing comprehensive trend estimation from summarized dose-response data and pooled in a random effects model meta-analysis.

RESULTS

Overall, 12 original studies were included in the review and meta-analysis comprising 32,142 mainly elderly study participants with measured 25(OH)D of whom 6921 died during follow-up. An inverse association between 25(OH)D levels and all-cause mortality was found in all but two studies that was statistically significant in several of the individual studies. In meta-analysis, 25(OH)D levels were significantly inversely associated with all-cause mortality with a pooled HR of 0.92 (95% confidence interval: 0.89-0.95) for a 20 nmol/l increase in 25(OH)D levels.

CONCLUSION

In this meta-analysis of prospective, population-based cohort studies, a 20 nmol/l increase in 25(OH)D levels was associated with an 8% lower mortality in the general elderly population. This agrees with results from meta-analyses on randomized controlled trials that found a decrease in mortality with vitamin D3 supplementation of a comparable magnitude.

Circulating levels of 25-hydroxyvitamin D and risk of breast cancer: a nested case-control study

Introduction

Experimental evidence suggests a protective role for circulating 25-hydroxyvitamin D (25(OH)D) in breast cancer development, but the results of epidemiological studies have been inconsistent.

Methods

We conducted a case-control study nested within two prospective cohorts, the New York University Women's Health Study and the Northern Sweden Mammary Screening Cohort. Blood samples were collected at enrollment, and women were followed up for breast cancer ascertainment. In total, 1,585 incident breast cancer cases were individually-matched to 2,940 controls. Of these subjects, 678 cases and 1,208 controls contributed two repeat blood samples, at least one year apart. Circulating levels of 25(OH)D were measured, and multivariate odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using conditional logistic regression.

Results

No association was observed between circulating levels of 25(OH)D and overall breast cancer risk (multivariate-adjusted model OR = 0.94, 95% CI = 0.76-1.16 for the highest vs. lowest quintile, p_trend = 0.30). The temporal reliability of 25(OH)D measured in repeat blood samples was high (intraclass correlation coefficients for season-adjusted 25(OH)D > 0.70). An inverse association between 25(OH)D levels and breast cancer risk was observed among women who were ≤ 45 years of age (OR_Q5-Q1 = 0.48, 95% CI = 0.30-0.79, p_trend = 0.01) or premenopausal at enrollment (OR_Q5-Q1 = 0.67, 95% CI = 0.48-0.92, p_trend = 0.03).

Conclusions

Circulating 25(OH)D levels were not associated with breast cancer risk overall, although we could not exclude the possibility of a protective effect in younger women. Recommendations regarding vitamin D supplementation should be based on considerations other than breast cancer prevention.

Vitamin d: are we ready to supplement for breast cancer prevention and treatment?

Vitamin D deficiency is a potentially modifiable risk factor that may be targeted for breast cancer prevention and treatment. Preclinical studies support various antitumor effects of vitamin D in breast cancer. Numerous observational studies have reported an inverse association between vitamin D status, including circulating 25-hydroxyvitamin D (25(OH)D) levels, and breast cancer risk. The relationship between vitamin D and mammographic density, a strong predictor of breast cancer risk, remains unclear. Studies analyzing the link between genetic polymorphisms in vitamin D pathway genes and breast cancer incidence and prognosis have yielded inconsistent results. Vitamin D deficiency among breast cancer patients has been associated with poorer clinical outcomes and increased mortality. Despite a number of clinical trials of vitamin D supplementation, the efficacy, optimal dosage of vitamin D, and target blood level of 25(OH)D for breast cancer prevention have yet to be determined. Even with substantial literature on vitamin D and breast cancer, future studies need to focus on gaining a better understanding of the biologic effects of vitamin D in breast tissue. Despite compelling data from experimental and observational studies, there is still insufficient data from clinical trials to make recommendations for vitamin D supplementation for breast cancer prevention or treatment.