B. H. Thuesen

Determinants of vitamin D status in a general population of Danish adults

BACKGROUND AND AIMSnDanish legislation regarding food fortification has been very restrictive and vitamin D deficiency is thought to be common in Denmark due to inadequate dietary intakes and the fact that in Denmark (latitude 56°N) vitamin D is only synthesized in the skin after exposure to solar radiation during summertime (April-September). The purpose of this study was to evaluate the vitamin D status of a general adult population in Denmark and, in addition, associations between vitamin D status and distinct lifestyle factors were studied.nnnMETHODSnA random sample of 6784 persons from a general population aged 30-60 years participated in a health examination in 1999-2001. Serum samples from all participants were stored and levels of 25-hydroxyvitamin D (25(OH)D) were measured by HPLC in 2009. The method was compared to another HPLC method. Information on dietary intake of vitamin D and other lifestyle factors were obtained by questionnaires. A total of 6146 persons defined as ethnic Danes and with successful measurements of 25(OH)D were included in the analyses.nnnRESULTSnThe overall prevalence of vitamin D deficiency (25(OH)D<25 nmol/l) and insufficiency (25(OH)D<50 nmol/l) were 13.8% and 52.2%, respectively. A marked seasonal fluctuation was seen in serum levels of 25(OH)D - median values of 25(OH)D were lowest in February and highest in August. In multiple logistic regression models (n=5506), low vitamin D status was significantly associated with obesity (BMI≥30), daily smoking and a sedentary lifestyle. However, measurements of 25(OH)D were not associated with the estimated dietary intake of vitamin D. Comparison of two HPLC methods demonstrated considerable differences in accuracy.nnnDISCUSSION AND CONCLUSIONSnOur results suggest that poor vitamin D status is common among adults in a Northern European country without food fortification with vitamin D. Methodological issues are, however, of great importance when using cut-off values to define poor vitamin D status. In addition, we demonstrated that low serum levels of 25(OH)D were associated with several lifestyle factors.

Insulin resistance as a predictor of incident asthma-like symptoms in adults.

Background There is accumulating evidence that obesity is associated with an increased risk of asthma. It has been hypothesized that insulin resistance may be involved in obesity‐induced asthma, but till date there is no prospective data on this issue.

Atopy, asthma, and lung function in relation to folate and vitamin B12 in adults

To cite this article: Thuesen BH, Husemoen LLN, Ovesen L, Jørgensen T, Fenger M, Gilderson G, Linneberg A. Atopy, asthma, and lung function in relation to folate and vitamin B12 in adults. Allergy 2010; 65: 1446–1454.

Serum 25(OH)D and incident type 2 diabetes: a cohort study.

BACKGROUND/OBJECTIVES:Mild to moderate vitamin D insufficiency has been proposed as a risk factor for several common chronic diseases including type 2 diabetes. This study aimed to examine the association between serum 25-hydroxy vitamin D (25(OH)D) and incident diabetes.SUBJECTS/METHODS:The MONICA10 cohort consists of 2656 participants (men and women aged 41–71 years) who participated in a 10-year follow-up examination during 1993–1994 as part of the MONICA 1 population survey. A total of 2571 participants free of diabetes at baseline and with successful measurement of serum 25(OH)D were included in the current study. The Danish National Diabetes register enabled identification of 288 cases of incident diabetes during follow-up (median: 16.4 years). Data were analysed by Cox proportional hazard models and associations were expressed as hazard ratios (HRs) with 95% confidence intervals (CIs).RESULTS:Serum 25(OH)D was inversely associated with incident diabetes adjusted for potential confounders (HR per 25u2009nmol/l=0.83; 95% CI: 0.72–0.95; P=0.009). A statistically significant interaction was observed between 25(OH)D and waist circumference (WC) (Pinteraction=0.042) suggesting an association in persons with a high WC (HR (95%CI) per 25u2009nmol/l=0.74 (0.63–0.88), 218 incident cases) and not in persons with a normal WC (HR (95%CI) per 25u2009nmol/l=0.98 (0.78–1.24), 70 incident cases).CONCLUSIONS:Low serum 25(OH)D was associated independently with incident diabetes. The inverse association was only found in overweight-obese and not in normal weight individuals, suggesting that obesity may modify the effect of vitamin D status on the risk of diabetes.

The association of serum 25-OH vitamin D with atopy, asthma, and lung function in a prospective study of Danish adults

Besides the important skeletal functions, it has been suggested that vitamin D is involved in the pathogenesis of allergy and asthma and related to lung function. However, previous studies are inconclusive.

The relationship of serum triglycerides, serum HDL, and obesity to the risk of wheezing in 85,555 adults

BACKGROUNDnAsthma has been linked to obesity and the presence of the metabolic syndrome.nnnOBJECTIVEnTo explore which components of the metabolic syndrome that were associated with wheezing, a main symptom of asthma. Further, to explore whether these associations were different in individuals with and without rhinitis symptoms.nnnMETHODSnWe used data from the Ibermutuamur Cardiovascular Risk Assessment Plan (ICARIA) including 85,555 Spanish workers (median agexa0=xa034, rangexa0=xa016-75 years) with assessments of self reported wheezing and rhinitis symptoms. Fasting blood samples were analysed for serum triglyceride (s-TG), HDL (s-HDL) and glucose; blood pressure, waist circumference (WC) and body mass index (BMI) were measured.nnnRESULTSnIn mutually adjusted analyses including all components of the metabolic syndrome and possible confounders, elevated WC (or BMI), elevated s-TG and low s-HDL were significantly associated with wheezing. Odds ratio (OR) with confidence interval (CI) were: elevated WCxa0=xa01.54 (1.46-1.62), elevated s-TGxa0=xa01.24 (1.18-1.30), low s-HDLxa0=xa01.17 (1.12-1.22). These associations were stronger in individuals without than in those with rhinitis symptoms, ORs (CIs) were WCxa0=xa0without rhinitis 1.70 (1.57-1.85) vs. with rhinitis 1.47 (1.37-1.58). Elevated s-TGxa0=xa0without rhinitis 1.36 (1.26-1.46) vs. with rhinitis 1.21 (1.13-1.29). Low s-HDLxa0=xa0without rhinitis 1.24 (1.15-1.34) vs. with rhinitis 1.11 (1.04-1.18).nnnCONCLUSIONSnHigh s-TG and low s-HDL were associated with wheezing after adjustment for adiposity. This may substantiate elevated s-TG and lowered s-HDL as markers or inducers of inflammation associated disease. The study supports the notion that these biochemical markers have differential effects on different types of wheezing.

Effect of Smoking on Blood Pressure and Resting Heart Rate - A Mendelian Randomization Meta-Analysis in the CARTA Consortium

Background— Smoking is an important cardiovascular disease risk factor, but the mechanisms linking smoking to blood pressure are poorly understood.nnMethods and Results— Data on 141 317 participants (62 666 never, 40 669 former, 37 982 current smokers) from 23 population-based studies were included in observational and Mendelian randomization meta-analyses of the associations of smoking status and smoking heaviness with systolic and diastolic blood pressure, hypertension, and resting heart rate. For the Mendelian randomization analyses, a genetic variant rs16969968/rs1051730 was used as a proxy for smoking heaviness in current smokers. In observational analyses, current as compared with never smoking was associated with lower systolic blood pressure and diastolic blood pressure and lower hypertension risk, but with higher resting heart rate. In observational analyses among current smokers, 1 cigarette/day higher level of smoking heaviness was associated with higher (0.21 bpm; 95% confidence interval 0.19; 0.24) resting heart rate and slightly higher diastolic blood pressure (0.05 mm Hg; 95% confidence interval 0.02; 0.08) and systolic blood pressure (0.08 mm Hg; 95% confidence interval 0.03; 0.13). However, in Mendelian randomization analyses among current smokers, although each smoking increasing allele of rs16969968/rs1051730 was associated with higher resting heart rate (0.36 bpm/allele; 95% confidence interval 0.18; 0.54), there was no strong association with diastolic blood pressure, systolic blood pressure, or hypertension. This would suggest a 7 bpm higher heart rate in those who smoke 20 cigarettes/day.nnConclusions— This Mendelian randomization meta-analysis supports a causal association of smoking heaviness with higher level of resting heart rate, but not with blood pressure. These findings suggest that part of the cardiovascular risk of smoking may operate through increasing resting heart rate.Background—Smoking is an important cardiovascular disease risk factor, but the mechanisms linking smoking to blood pressure are poorly understood. Methods and Results—Data on 141u2009317 participants (62u2009666 never, 40u2009669 former, 37u2009982 current smokers) from 23 population-based studies were included in observational and Mendelian randomization meta-analyses of the associations of smoking status and smoking heaviness with systolic and diastolic blood pressure, hypertension, and resting heart rate. For the Mendelian randomization analyses, a genetic variant rs16969968/rs1051730 was used as a proxy for smoking heaviness in current smokers. In observational analyses, current as compared with never smoking was associated with lower systolic blood pressure and diastolic blood pressure and lower hypertension risk, but with higher resting heart rate. In observational analyses among current smokers, 1 cigarette/day higher level of smoking heaviness was associated with higher (0.21 bpm; 95% confidence interval 0.19; 0.24) resting heart rate and slightly higher diastolic blood pressure (0.05 mmu2009Hg; 95% confidence interval 0.02; 0.08) and systolic blood pressure (0.08 mmu2009Hg; 95% confidence interval 0.03; 0.13). However, in Mendelian randomization analyses among current smokers, although each smoking increasing allele of rs16969968/rs1051730 was associated with higher resting heart rate (0.36 bpm/allele; 95% confidence interval 0.18; 0.54), there was no strong association with diastolic blood pressure, systolic blood pressure, or hypertension. This would suggest a 7 bpm higher heart rate in those who smoke 20 cigarettes/day. Conclusions—This Mendelian randomization meta-analysis supports a causal association of smoking heaviness with higher level of resting heart rate, but not with blood pressure. These findings suggest that part of the cardiovascular risk of smoking may operate through increasing resting heart rate.

No association between vitamin D and atopy, asthma, lung function or atopic dermatitis: a prospective study in adults

Studies suggest that vitamin D may be involved in the pathogenesis of allergic disorders, asthma and decreased lung function. However, results are inconsistent and only few prospective studies have examined adults. The purpose of this study was to investigate the association of serum 25‐hydroxy vitamin D (s25(OH)D) with atopy, atopic dermatitis (AD), asthma, wheezing and impaired lung function in a prospective study of Danish adults. A random sample of 3471 persons was examined in 2006–2008. Of these, 2308 were re‐examined 5 years later. s25(OH)D and specific IgE against four common inhalant allergens were measured by standard procedures. Wheezing, asthma and AD were assessed from questionnaires and lung function was measured by spirometry. We found no statistically significant associations between s25(OH)D and prevalence or incidence of atopy, AD, asthma or wheezing. Associations with lung function were inconsistent. We conclude that vitamin D status does not influence these conditions in adults.

Investigating the causal effect of vitamin D on serum adiponectin using a mendelian randomization approach

Background/Objectives:The aim was to examine the causal effect of vitamin D on serum adiponectin using a multiple instrument Mendelian randomization approach.Subjects/Methods:Serum 25-hydroxy vitamin D (25(OH)D) and serum total or high molecular weight (HMW) adiponectin were measured in two Danish population-based studies: the Inter99 study (6405 adults, 30–60 years) conducted in 1999–2001, and the MONICA10 study (2656 adults, 41–71 years) conducted in 1993–1994.Results:In the Inter99 study, serum 25(OH)D was positively associated with total adiponectin (the effect estimate in % per doubling of 25(OH)D was 4.78, 95% CI: 1.96, 7.68, P<0.001). Using variations in the vitamin D-binding protein gene and the filaggrin gene as instrumental variables, the causal effect in % was estimated to 61.46, 95% CI: 17.51, 120.28, P=0.003 higher adiponectin per doubling of 25(OH)D. In the MONICA10 cohort, no significant association was observed between the serum concentrations of 25(OH)D and HMW adiponectin (the effect estimate in % per doubling of 25(OH)D was −1.51, 95% CI: −5.80, 2.98, P=0.50), although the instrumental variables analysis to some extent supported a positive causal association (the effect estimate in % per doubling of 25(OH)D was 37.13, 95% CI: −3.67, 95.20, P=0.080).Conclusions:The results indicate a possible causal association between serum 25(OH)D and total adiponectin. However, the association was not replicated for HMW adiponectin. Thus, further studies are needed to confirm a causal relationship.

Predictive factors of self‐reported hand eczema in adult Danes – a population based cohort study with 5 year follow‐up

Information about predictive factors of hand eczema is crucial for primary prevention.