Calcium urolithiasis is often associated with increased intestinal absorption and urine excretion of calcium, and has been suggested to result from increased vitamin D production. The role of the enzyme 1 alpha-hydroxylase, the rate-limiting step in active vitamin D production, was evaluated in 36 families, including 28 sibships with at least a pair of affected sibs, using qualitative and quantitative trait linkage analyses. Sibs with a verified calcium urolithiasis passage (n = 117) had higher 24-h calciuria (P = 0.03), oxaluria (P = 0.02), fasting and postcalcium loading urine calcium/creatinine (Ca/cr) ratios (P = 0.008 and P = 0.002, respectively), and serum 1,25(OH)2 vitamin D levels (P = 0.02) compared with nonstone-forming sibs (n = 120). Markers from a 9-centiMorgan interval encompassing the VDD1 locus on chromosome 12q13-14 (putative 1 alpha-hydroxylase) were analyzed in 28 sibships (146 sib pairs) of single and recurrent stone formers and in 14 sibships (65 sib pairs) with recurrent-only (> or = 3 episodes) stone-forming sibs. Two-point and multipoint analyses did not reveal excess in alleles shared among affected sibs at the VDD1 locus. Linkage of stone formation to the VDD1 locus could be excluded, respectively, with a lambda d of 2.0 (single and recurrent stone formers) and 3.25 (recurrent stone formers). Quantitative trait analyses revealed no evidence for linkage to 24-h calciuria and oxaluria, serum 1,25(OH)2 vitamin D levels, and Ca/cr ratios. This study shows absence of linkage of the putative 1 alpha-hydroxylase locus to calcium stone formation or to quantitative traits associated with idiopathic hypercalciuria. In addition, there is coaggregation of calciuric and oxaluric phenotypes with stone formation.
Plasma 25-hydroxycholecalciferol (25-H.C.C.) has been measured in 67 consective cases of fracture of the proximal femur. The values found in these patients were not different from values found in these patients were not different from those in control groups at the same time of the year. Plasma 25-H.C.C. was not correlated to plasma calcium or phosphorus, the Ca times P product, or the alkaline phosphatase. X-rays showed Looser zones in only 1 patient, in whom the lowest plasma 25-H.C.C. was found. Osteomalacia is not uncommon among elderly people in Denmark, but it is more likely to depend on a decline in the renal efficiency to convert 25-H.C.C. to 1,25-dihydroxycholecalciferol than a low dietary intake of vitamin D.
During half of the year, cutaneous synthesis of 25-hydroxyvitamin D (25(OH)D) is not detectable at northern latitudes, leaving the population dependent on other sources for optimal vitamin D status. During April to September, 25(OH)D status may be improved by solar exposure. In this study, we measured seasonal differences in serum 25(OH)D concentrations and identified the major predictors of summer 25(OH)D concentrations.
We assessed serum 25(OH)D concentrations during both winter and summer amongst 100 women, aged 61-83 years, randomly sampled from the Swedish Mammography Cohort. Participants completed two detailed questionnaires covering diet, use of dietary supplements and sun-related behaviour, the first in January through March and a second time in August through September.
The mean seasonal increase in serum 25(OH)D concentrations was 38% from mean 72 +/- 23 nmol L(-1) during winter to 99 +/- 29 nmol L(-1) in summer. High summer 25(OH)D concentrations were associated with higher winter concentrations, preference of staying in sun instead of shade, having a nonsensitive skin type and normal body mass index. Based on multiple linear regression modelling, preferring sun, having nonsensitive skin type and normal weight as compared with preferring shade, having sensitive skin type and being obese, was associated with a 64 nmol L(-1) higher 25(OH)D concentrations during summer.
Women with high winter 25(OH)D serum concentrations, with preference of staying in the sun instead of shade during summer, a skin type allowing for longer sun exposure and a normal weight had the highest summer 25(OH)D concentrations.
(1) Background: We aimed to examine if 25-hydroxyvitamin D (25(OH)D) was related to the peripheral immunological and inflammatory signature both at birth, and in newly diagnosed patients with childhood type 1 diabetes (T1D) and their healthy controls; (2) Methods: The birth cohort consisted of 470 patients and 500 healthy controls. Dried blood samples were collected from the neonates in the period 1981-1999. The newly diagnosed cohort consisted of 460 patients and 453 siblings. Serum samples were collected in the period 1997-2005. A variety of peripheral immune mediators were measured and compared to total 25(OH)D levels (25(OH)D2 + 25(OH)D3). For each immune mediator, the relative change (RC) in the mean level was modeled by robust log-normal regression and correction for multiple testing was performed; (3) Results: Two associations were identified; there was a negative association between 25(OH)D (10 nmol/L increase) and leptin (RC (95% confidence interval (CI)), 0.98 (0.96; 1.00)), and a positive association between 25(OH)D (10 nmol/L increase) and the chemokine, chemokine (c-x-c motif) ligand (CXCL) 8 (RC (95% CI), 1.07 (1.01; 1.13)); (4) Conclusion: CXCL8 and leptin have significant associations with levels of 25(OH)D in the newly diagnosed cohort. These results do not indicate a strong influence of 25(OH)D on the peripheral immunological or inflammatory signature.
We tested the hypothesis that low plasma concentrations of 25-hydroxyvitamin D are associated with increased risk of symptomatic ischemic stroke in the general population.
We measured plasma 25-hydroxyvitamin D in 10,170 individuals from the general population, the Copenhagen City Heart Study. During 21 years of follow-up, 1,256 and 164 persons developed ischemic and hemorrhagic stroke, respectively. In a meta-analysis of ischemic stroke, we included 10 studies, 58,384 participants, and 2,644 events.
Stepwise decreasing plasma 25-hydroxyvitamin D concentrations were associated with stepwise increasing risk of ischemic stroke both as a function of seasonally adjusted percentile categories and as a function of clinical categories of 25-hydroxyvitamin D (p for trend = 2 × 10(-3)). In a Cox regression model comparing individuals with plasma 25-hydroxyvitamin D concentrations between the 1st and 4th percentiles to individuals with 25-hydroxyvitamin D concentrations between the 50th and 100th percentiles, multivariate adjusted hazard ratio of ischemic stroke was 1.82 (95% confidence interval, 1.41-2.34). Comparing individuals with clinical categories of severe vitamin D deficiency (
Higher vitamin D status, lower adiposity, and longer telomere length are each reportedly associated with lower risk of several chronic diseases and all-cause mortality. However, direct relationships between vitamin D status (measured by circulating 25-hydroxyvitamin D (25(OH)D) concentration), adiposity, and telomere length are not well established. We conducted a cross-sectional analysis of associations of 25(OH)D and body mass index (BMI; weight (kg)/height (m)(2)) with mean relative leukocyte telomere length (LTL) using data gathered on 5,096 participants from Northern Finland Birth Cohort 1966 at age 31 years (1997). 25(OH)D was not associated with LTL in either basic or confounder/mediator-adjusted models. BMI was inversely associated with LTL after adjustment for potential confounding by age, sex, socioeconomic position, physical activity, diet, smoking, alcohol intake, and use of oral contraceptives (per 1-unit increase in BMI, mean difference in LTL = -0.4%, 95% confidence interval: -0.6, -0.2). The BMI-LTL association was also independent of 25(OH)D and was attenuated slightly, but remained, after adjustment for C-reactive protein, a marker of low-grade inflammation (mean difference in LTL = -0.3%, 95% confidence interval -0.6, -0.1). These findings suggest that vitamin D status is unlikely to be an important determinant of LTL, at least by young adulthood. Inflammation may partly mediate associations of adiposity with LTL.
Vitamin D has potential antithrombotic effects, suggesting that vitamin D analogs could be used as adjunctive antithrombotic agents. However, epidemiologic evidence of an association between reduced 25-hydroxyvitamin D concentrations and the risk of venous thromboembolism is lacking.
To test the hypothesis that reduced plasma 25-hydroxyvitamin D concentrations are associated with an increased risk of venous thromboembolism in the general population.
We prospectively studied 18 791 participants from the Copenhagen City Heart Study and the Copenhagen General Population Study. During up to 30 years of follow-up, 950 participants were diagnosed with venous thromboembolism. Plasma 25-hydroxyvitamin D concentrations were adjusted for seasonal variation.
The cumulative incidence of venous thromboembolism as a function of age increased with decreasing tertiles of seasonally adjusted plasma 25-hydroxyvitamin D (log-rank trend: P = 4 × 10(-4) ). On comparison of participants in the lowest and the highest tertile of plasma 25-hydroxyvitamin D concentrations, the crude risk estimate in a model adjusted for age and sex was a 37% (95% confidence interval [CI] 15-64%) increased risk of venous thromboembolism. The corresponding risk increase in a model adjusted for age, sex, body mass index, smoking and cancer was 26% (95% CI 5-51%), and in a multivariable-adjusted model also including physical activity, hormone replacement therapy, menopausal status, oral contraception use and lipid-lowering therapy it was 28% (95% CI 6-53%). Furthermore, corresponding risk increases with attempts to correct for regression dilution bias were 103% (95% CI 37-202%), 70% (95% CI 14-155%) and 73% (95% CI 15-160%) in the three models, respectively.
In these large general population studies, we observed a stepwise increasing risk of venous thromboembolism with decreasing tertiles of seasonally adjusted plasma 25-hydroxyvitamin D concentrations.
The 25-hydroxyvitamin D concentration (25-OHD) in maternal and cord blood of 192 mothers was determined at delivery from June to the end of November. Ninety-nine mothers had received a daily supplementation of 12.5 micrograms of vitamin D during pregnancy and this group had a significantly higher 25-OHD concentration both in maternal and in cord blood than in the corresponding non-supplemented group. A daily supplement of 2.5 micrograms of vitamin D was given to 63 of the mothers during lactation. Of these mothers 44 were still lactating after 6 months. The dietary vitamin D intake of 31 mothers was calculated. We found a significant correlation between the maternal serum 25-OHD concentration 16-18 weeks after delivery and the total vitamin D intake. The intake (5.5 micrograms/d, including supplementation) was lower than that recommended for lactating mothers which is 10 micrograms/d (Food and Nutrition Board, 1980).
To determine whether and to what extent vitamin D deficiency is associated with multiple sclerosis (MS) risk.
We conducted a prospective nested case-control study among women in the Finnish Maternity Cohort (FMC). The FMC had 1.8 million stored serum samples taken during the pregnancies of over 800,000 women at the time of this study. Through linkages with hospital and prescription registries, we identified 1,092 women with MS diagnosed between 1983 and 2009 with at least 1 serum sample collected prior to date of MS diagnosis; =2 serum samples were available for 511 cases. Cases were matched to up to 3 controls (n = 2,123) on date of birth (±2 years) and area of residence. 25-Hydroxyvitamin D (25[OH]D) levels were measured using a chemiluminescence assay. We used conditional logistic regression adjusted for year of sample collection, gravidity, and parity to estimate relative risks (RRs) and 95% confidence intervals (CIs).
A 50 nmol/L increase in 25(OH)D was associated with a 39% reduced risk of MS (RR 0.61, 95% CI 0.44-0.85), p = 0.003. Women with 25(OH)D levels