The association between serum 25-hydroxyvitamin D levels and psoriasis in a large population-based cohort: a cross-sectional analysis of The Tromsø Study 2015-16.

Background: Case-control studies indicate an association between lower serum 25-hydroxyvitamin D [25(OH)D] levels and psoriasis. Data from larger population-based cohorts including mild cases are sparse.

Objectives: To investigate the association between 25(OH)D and psoriasis in a large population-based cohort, and assess possible effect modification by overweight.

Vitamin D Status During Adolescence and the Impact of Lifestyle Changes: 2 Years' Follow-up From the Fit Futures Study.

Context: Longitudinal data regarding vitamin D status in adolescence is scarce. This study presents population-based data from an Arctic adolescent population (n = 589) at 16 and 18 years.

Objective: The aims of this study were to investigate changes in vitamin D status during 2 years in adolescence, and whether lifestyle changes were associated with serum 25-hydroxyvitamin D (s-25(OH)D) at follow-up.

Effect of Vitamin D Supplementation on Psoriasis Severity in Patients With Lower-Range Serum 25-Hydroxyvitamin D Levels: A Randomized Clinical Trial.

Importance: Topical vitamin D analogues are routine treatment for psoriasis, but the effect of oral supplementation has not been established.

Objective: To examine the effect of vitamin D supplementation on psoriasis severity throughout the winter.

Design, Setting, And Participants: This randomized, double-blind placebo-controlled clinical trial with 2 parallel groups was performed through 2 winter seasons (2017 to 2018 and 2018 to 2019).

Vitamin D and Risk for Type 2 Diabetes in People With Prediabetes : A Systematic Review and Meta-analysis of Individual Participant Data From 3 Randomized Clinical Trials.

Background: The role of vitamin D in people who are at risk for type 2 diabetes remains unclear.

Purpose: To evaluate whether administration of vitamin D decreases risk for diabetes among people with prediabetes.

Data Sources: PubMed, Embase, and ClinicalTrials.

Longitudinal changes in vitamin D concentrations and the association with type 2 diabetes mellitus: the Tromsø Study.

Aim: We aimed to investigate the relationship between pre- and post-diagnostic 25-hydroxyvitamin D (25(OH)D) concentrations and type 2 diabetes (T2DM) over a period of 30 years in individuals who developed T2DM compared to healthy controls.

Methods: This case-control study included 254 participants with blood samples collected at five different time-points (T1-T5) between 1986 and 2016. Of the 254 participants, 116 were diagnosed with T2DM between T3 and T4, and were considered cases; the remaining 138 were controls.

Associations of serum 25-hydroxyvitamin D and subjective sleep measures in an arctic population: Insights from the population-based Tromsø Study.

Objective: To investigate the relation between serum 25-hydroxyvitamin D (s-25(OH)D) and subjective sleep measures in an Arctic population (69°N).

Methods: Cross-sectional data was collected from 21,083 individuals (aged ≥40 years) participating in the population based Tromsø Study: Tromsø7 (2015-2016). The present study included 20,438 participants, after having excluded respondents missing data on s-25(OH)D (n = 161) and/or subjective sleep measures (including sleep duration, insomnia, and daytime sleepiness)(n = 490).

100 YEARS OF VITAMIN D: Combined hormonal contraceptives and vitamin D metabolism in adolescent girls.

Objective: Combined hormonal contraceptive (CHC) use has been associated with higher total 25-hydroxyvitamin D (25(OH)D) levels. Here, we investigate the relation between CHC use and vitamin D metabolism to elucidate its clinical interpretation.

Methods: The cross-sectional Fit Futures 1 included 1038 adolescents.

No improvement of sleep from vitamin D supplementation: insights from a randomized controlled trial.

Background: Vitamin D has been linked to sleep health in observational studies. Data from randomized controlled trials (RCTs) with vitamin D is scarce.

Methods: This study presents the results of a secondary analysis of 189 vitamin D insufficient participants (47.

Trends in known and undiagnosed diabetes, HbA1c levels, cardiometabolic risk factors and diabetes treatment target achievement in repeated cross-sectional surveys: the population-based Tromsø Study 1994-2016.

Objectives: The aim of this study was to investigate time trends in known and undiagnosed diabetes, glycated haemoglobin (HbA1c) levels and other cardiometabolic risk factors in the general population as well as treatment target achievement among those with diabetes.

Design And Setting: Repeated cross-sectional surveys in the population-based Tromsø Study.

Methods: We used age-adjusted generalised estimating equation models to study trends in self-reported and undiagnosed (HbA1c ≥6.

Tracking of serum 25-hydroxyvitamin D during 21 years.

Background/objectives: Our objective was to evaluate the degree of tracking for serum levels of 25-hydroxyvitamin D [25(OH)D] over time, by using data from three previously conducted surveys of the Tromsø study collected in the years 1994/1995 (Tromsø 4), 2007/2008 (Tromsø 6), and 2015/2016 (Tromsø 7).

Subjects/methods: Subjects with valid 25(OH)D measurements in all three surveys were included. 25(OH)D z-scores were used to adjust for seasonal variation.

Increased calcium intake is associated lower serum 25-hydroxyvitamin D levels in subjects with adequate vitamin D intake: a population-based observational study.

Background: There are indications that an increased intake of calcium has a vitamin D sparing effect, which might be explained by a decreased catabolism of 25-hydroxyvitamin D (25(OH)D). However, there are only a few studies where this has been examined.

Method: In the seventh survey of the Tromsø study, serum 25(OH)D and parathyroid hormone were measured, and questionnaires on calcium and vitamin D intakes filled in.

Vitamin D Supplementation for Prevention of Type 2 Diabetes Mellitus: To D or Not to D?

Context: Over the last decade, vitamin D has emerged as a risk determinant for type 2 diabetes and vitamin D supplementation has been hypothesized as a potential intervention to lower diabetes risk. Recently, several trials have reported on the effect of vitamin D supplementation on diabetes prevention in people with prediabetes.

Evidence Acquisition: A comprehensive literature review was performed using PubMed, Embase, and ClinicalTrials.

Serum PTH is not a good marker for defining a threshold for vitamin D deficiency.

Objective: In addition to its skeletal effects, vitamin D may also be important for health in general. It is uncertain what level of serum 25-hydroxyvitamin D (25(OH)D), marker of vitamin D status, is sufficient for these effects. With decreasing serum 25(OH)D levels there is an increase in serum PTH.

Four months vitamin D supplementation to vitamin D insufficient individuals does not improve muscular strength: A randomized controlled trial.

Main Objective: The inconsistent results on the effects of vitamin D on muscle strength reported by intervention trials may partly be explained by inclusion of vitamin D sufficient individuals. The main objective was to study whether vitamin D supplementation will improve muscle strength in men and women with low serum vitamin D status, as measured by 25-hydroxyvitamin D (25(OH)D) at baseline.

Methods: 417 men and women aged 40-80 years were included and randomized to receive a loading dose of 100 000 IU (2500 ug) vitamin D3 followed by 20 000 IU (500 ug)/week, or placebo.

Smoking and other determinants of bone turnover.

The balance between bone resorption and formation may be assessed by measurement of bone turnover markers (BTMs), like carboxyl-terminal cross-linked telopeptide of type 1 collagen (CTX-1) and procollagen type 1 amino-terminal propeptide (P1NP). Smoking has been shown to influence bone turnover and to reduce bone mass density (BMD), the exact mechanism for this is, however, not settled. In this post-hoc study including 406 subjects (mean age 51.

Polymorphisms in the vitamin D system and mortality - The Tromsø study.

Vitamin D deficiency is associated with diabetes, cancer, immunological and cardiovascular diseases as well as increased mortality. It has, however, been difficult to show a causal relation in randomized, controlled trials. Mendelian randomization studies provide another option for testing causality, and results indicate relations between the serum 25-hydroxyvitamin D (25(OH)D) level and some diseases, including mortality.

Alanine Aminotransferase and Body Composition in Obese Men and Women.

There is a known relationship between serum alanine aminotransferase (ALT) and obesity in humans, but the mechanism(s) are not clarified. This study investigated the associations between serum ALT and body composition in an overweight and obese population. The results are based on data from a previous randomized controlled trial treating obesity with vitamin D.

Effects of vitamin D supplementation on bone turnover markers and other bone-related substances in subjects with vitamin D deficiency.

In observational studies, vitamin D deficiency is a risk factor for low bone density and future fractures, whereas a causal relation has been difficult to show in randomized controlled trials (RCTs). Similarly, vitamin D deficiency has been associated with increased bone turnover, but RCTs with vitamin D have not shown conclusive effects. This could be due to inclusion of vitamin D sufficient subjects and low vitamin D doses.

The Role of Vitamin D Binding Protein, Total and Free 25-Hydroxyvitamin D in Diabetes.

Vitamin D is important for bone health, but may also have extra-skeletal effects. Vitamin D and its binding protein DBP have immunological effects and may therefore be important in the development of type 1 diabetes (T1DM), and low serum levels of 25-hydroxyvitamin D (25(OH)D) are associated with later development of type 2 diabetes (T2DM). However, it has so far been difficult to convincingly show an effect of vitamin D supplementation on prevention or treatment of diabetes.

Effect of Genetically Low 25-Hydroxyvitamin D on Mortality Risk: Mendelian Randomization Analysis in 3 Large European Cohorts.

The aim of this study was to determine if increased mortality associated with low levels of serum 25-hydroxyvitamin D (25(OH)D) reflects a causal relationship by using a Mendelian randomisation (MR) approach with genetic variants in the vitamin D synthesis pathway. Individual participant data from three European cohorts were harmonized with standardization of 25(OH)D according to the Vitamin D Standardization Program. Most relevant single nucleotide polymorphisms of the genes (rs12794714, rs10741657) and (rs12785878, rs11234027), were combined in two allelic scores.

Lost relation between blood pressure and serum 25-hydroxyvitamin D.

Background: Low serum 25-hydroxyvitamin D (25(OH)D) levels have consistently been associated with hypertension. During the last decades there has been an unexplained reduction in blood pressure (BP) in Western countries. We therefore examined the relation between serum 25(OH)D and BP in the 7th survey of the Tromsø study 2015/2016.