Supplementation with High Doses of Vitamin D to Subjects without Vitamin D Deficiency May Have Negative Effects: Pooled Data from Four Intervention Trials in Tromsø.

Data were pooled from four randomized clinical trials with vitamin D performed in Tromsø with weight reduction, insulin sensitivity, bone density, and depression scores as endpoints. Serum lipids, glycated hemoglobin (HbA1c), and high sensitivity C-Reactive Protein, (HS-CRP) were measured at baseline and after 6-12 months of supplementation with vitamin D 20 000 IU-40 000 IU per week versus placebo. A total of 928 subjects who completed the interventions were included.

Effects of a 1-year supplementation with cholecalciferol on interleukin-6, tumor necrosis factor-alpha and insulin resistance in overweight and obese subjects.

Insufficient vitamin D status has been linked to autoimmune diseases, cancer and metabolic disorders, like obesity and insulin resistance. In vitro and animal studies suggest that vitamin D may play a crucial role in immune activation and inflammation. The relation between vitamin D and pro-inflammatory cytokines is not completely established.

Effect of smoking on the serum levels of 25-hydroxyvitamin D depends on the assay employed.

Objective: Because we found higher serum 25-hydroxyvitamin D (25(OH)D) levels among smokers than among non-smokers with analyses using an electrochemiluminescence immunoassay (ECLIA) from Roche, the purpose of the present study was to examine whether this difference between smokers and non-smokers was maintained using other serum 25(OH)D assays.

Design: A cross-sectional population-based study on 6932 participants from the Tromsø study, 1994-1995, and one validation study comparing six different serum 25(OH)D assays in 53 non-smokers and 54 smokers were performed.

Methods: The association between smoking, season and serum 25(OH)D as measured by ECLIA (Roche) was assessed in the population-based study using general linear models with multivariate adjustments.

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

Low serum 25-hydroxyvitamin D (25(OH)D) levels are associated with risk factors for cardiovascular disease, and they also appear to predict later development of type 2 diabetes, cancer, and an increased mortality rate. These predictions are all based on a single 25(OH)D measurement, but so far there are no known reports on tracking of serum 25(OH)D levels. In the present Norwegian study, serum 25(OH)D levels were measured 1) in 2,668 subjects in the 1994 and 2008 Tromsø surveys and 2) every third month for 1 year in 94 subjects randomly assigned to placebo in a vitamin D intervention study.

Cross-sectional and longitudinal relation between serum 25-hydroxyvitamin D and body mass index: the Tromsø study.

Purpose: The serum 25-hydroxyvitamin D (25(OH)D) levels are lower in obese than lean subjects. The present study examines the cross-sectional and longitudinal relations between body mass index (BMI) and serum 25(OH)D, and the serum 25(OH)D response to vitamin D supplementation in relation to BMI.

Methods: The Tromsø study is a longitudinal population-based multipurpose study.

No effect of supplementation with cholecalciferol on cytokines and markers of inflammation in overweight and obese subjects.

Epidemiological studies indicate a relation between vitamin D status and autoimmune diseases, and in vitro studies demonstrate an effect of 1,25-dihydroxyvitamin D on immune activation. However, the relation between serum levels of 25-hydroxyvitamin D (25(OH)D) and the effect of vitamin D supplementation on serum levels of cytokines are not settled. In the present study interleukin (IL)-2, IL-4, IL-5, IL-10, IL-12, IL-13, IL-17, intercellular adhesion molecule-1, interferon-gamma, monocyte chemotactic protein-1, and high sensitivity C-reactive protein, were measured in 437 overweight subjects and 324 completed a one year intervention with 40,000 IU vitamin D per week (group DD), 20,000 IU vitamin D per week (group DP), or placebo (group PP).

Parameters of the thrombogram are associated with serum 25-hydroxyvitamin D levels at baseline, but not affected during supplementation with vitamin D.

Introduction: In vitro studies indicate an anticoagulant effect of 1,25-dihydroxyvitamin D, and sun exposure may lower the risk of thrombotic events. Accordingly, an effect on haemostatic parameters could be expected after supplementation with vitamin D.

Materials And Methods: 158 obese or overweight subjects were included in a one year intervention study with supplementation with 40.

No significant effect on bone mineral density by high doses of vitamin D3 given to overweight subjects for one year.

Background: In meta-analyses supplementation with vitamin D appears to reduce incidence of fractures, and in cross-sectional studies there is a positive association between serum 25-hydroxyvitamin D (25(OH)D) levels and bone mineral density (BMD). However, the effect of supplementation with high doses of vitamin D on BMD is more uncertain and could in theory have both positive and negative effects.

Methods: The study was a one year, double blind placebo-controlled intervention trial performed at the University Hospital of North Norway.

Bone mineral density at the hip in Norwegian women and men--prevalence of osteoporosis depends on chosen references: the Tromsø Study.

This study describes bone mineral density (BMD) and the prevalence of osteoporosis in women and men between 30-89 years in an unselected population. BMD was measured in g/cm(2) at total hip and femoral neck by dual-energy-X-ray absorptiometry in 3,094 women and 2,132 men in the 2001 Tromsø Study. BMD levels were significantly explained by age and declined progressively in both sexes from middle into old age, with highest decline in women.

The association between serum parathyroid hormone and bone mineral density, and the impact of smoking: the Tromso Study.

Objective: To explore the relation between serum parathyroid hormone (PTH) and bone mineral density (BMD), adjusted for lifestyle factors including smoking.

Design: Cross-sectional study.

Methods: The Tromsø Study is a population-based study performed for the fifth time in 2001.