Prevention of urinary tract infections with vitamin D supplementation 20,000 IU per week for five years. Results from an RCT including 511 subjects.

Background: In observational studies vitamin D deficiency is associated with increased risk of infections, whereas the effect of vitamin D supplementation in randomized controlled trials is non-conclusive.

Methods: Five hundred and eleven subjects with prediabetes were randomized to vitamin D3 (20,000 IU per week) versus placebo for five years. Every sixth month, a questionnaire on respiratory tract infections (RTI) (common cold, bronchitis, influenza) and urinary tract infection (UTI) was filled in.

Vitamin D 20,000 IU per Week for Five Years Does Not Prevent Progression From Prediabetes to Diabetes.

Context: Vitamin D deficiency is associated with insulin resistance and risk of future diabetes.

Objective: The objective of the study was to test whether supplementation with vitamin D to subjects with prediabetes will prevent progression to type 2 diabetes mellitus (T2DM).

Design: This was a randomized controlled trial performed in 2008 through 2015.

Effects of vitamin D binding protein phenotypes and vitamin D supplementation on serum total 25(OH)D and directly measured free 25(OH)D.

Objective: To determine the relationship between serum total 25-hydroxyvitamin D (25(OH)D), directly measured free 25(OH)D and calculated free 25(OH)D with regard to vitamin D-binding protein (DBP) phenotypes, sex, BMI, age and season, and their interrelationship to vitamin D supplementation.

Design, Patients And Interventions: A randomized controlled trial with 20 000 IU of vitamin D3 per week or placebo for 12 months was designed. A total of 472 subjects, 236 in each of the intervention groups, were included in the analyses.

No effect of high-dose vitamin D supplementation on glycemic status or cardiovascular risk factors in subjects with prediabetes.

Objective: In observational studies, low serum 25-hydroxyvitamin D [25(OH)D] concentrations have been associated with insulin resistance and other risk factors for cardiovascular disease.

Research Design And Methods: We present 1-year data from an ongoing 5-year trial in 511 individuals with impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) randomly assigned to 20,000 IU/week vitamin D3 or placebo. An oral glucose tolerance test was performed at baseline and after 1 year.

The phosphodiesterase 8B gene rs4704397 is associated with thyroid function, risk of myocardial infarction, and body height: the Tromsø study.

Objective: High serum thyrotropin (TSH) levels predict cardiovascular disease (CVD). Recently several single nucleotide polymorphisms (SNPs) associated with TSH levels have been identified, one of them being the rs4704397 SNP in the phosphodiesterase 8B (PDE8B) gene. If the relation between thyroid function and CVD is causal, one could also expect rs4704397 genotypes to predict CVD and possibly health in general.

Effects of Age and Sex on Estimated Diabetes Prevalence Using Different Diagnostic Criteria: The Tromsø OGTT Study.

HbA(1c) 6.5% has recently been recommended as an alternative diagnostic criterion for diabetes. The aims of the study were to evaluate the effects of age, sex, and other factors on prevalence of diabetes and to compare risk profiles of subjects with diabetes when defined by HbA(1c) and glucose criteria.

Effect of vitamin D supplement on depression scores in people with low levels of serum 25-hydroxyvitamin D: nested case-control study and randomised clinical trial.

Aims: To compare depressive symptoms in participants with low and high serum 25-hydroxyvitamin D (25(OH)D) levels and to examine whether supplementation with vitamin D(3) would improve symptoms in those with low serum 25(OH)D levels.

Method: Participants with low 25(OH)D levels were randomised to either placebo or 40 000 IU vitamin D(3) per week for 6 months. Individuals with high serum 25(OH)D levels were used as nested controls.

Serum 25-hydroxyvitamin D levels in subjects with reduced glucose tolerance and type 2 diabetes - the Tromsø OGTT-study.

The relationships between vitamin D concentrations, hyperglycemia, and insulin resistance remain uncertain. During 2008 - 2010, an oral glucose tolerance test was performed in 3520 subjects from Tromsø, Norway. Serum 25-hydroxyvitamin D [25(OH)D] was measured in 1193 subjects with normal glucose tolerance, in 304 with isolated impaired fasting glucose, in 254 with isolated impaired glucose tolerance, in 139 with a combination of the two, and in 194 subjects with type 2 diabetes.

Vitamin D supplementation did not prevent influenza-like illness as diagnosed retrospectively by questionnaires in subjects participating in randomized clinical trials.

Background: Vitamin D deficiency has been associated with a number of diseases, including influenza. Whether or not this reflects a causal relationship is unknown. We therefore wanted to examine if supplementation with vitamin D would affect the incidence and severity of influenza-like disease.

Serum 25-hydroxyvitamin D levels are inversely associated with glycated haemoglobin (HbA(1c)). The Tromsø Study.

Animal and human studies have shown an association between serum 25-hydroxyvitamin D (25(OH)D) level and insulin secretion and sensitivity. Accordingly, an association between 25(OH)D and glycated haemoglobin (HbA(1c)) is to be expected, and this was tested for in the present study. The Tromsø Study is a longitudinal population-based study initiated in 1974.

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.

Low serum 25-hydroxyvitamin D levels are associated with increased all-cause mortality risk in a general population: the Tromsø study.

Objective: Ecologic and observational studies have suggested an association between serum 25-hydroxyvitamin D (25(OH)D) levels and cardiovascular disease (CVD) risk factors, CVD mortality, and cancer mortality. Based on this, low serum 25(OH)D levels should be associated with higher all-cause mortality in a general population. This hypothesis was tested in the present study.

Serum 25-hydroxyvitamin D levels are strongly related to systolic blood pressure but do not predict future hypertension.

Vitamin D receptors have been detected in vascular smooth muscle cells, and 1,25-dihydroxyvitamin D inhibits the renin mRNA expression. Epidemiological studies show an inverse relation between serum 25-hydoxyvitamin D levels and blood pressure, and low serum 25-hydoxyvitamin D levels are reported to be predictors of future development of hypertension. This may indicate an important role for vitamin D in blood pressure regulation.