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Free access

Moira Strand Hutchinson, Guri Grimnes, Ragnar Martin Joakimsen, Yngve Figenschau, and Rolf Jorde

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.

Design

The Tromsø study is a longitudinal population-based multipurpose study initiated in 1974 with focus on lifestyle-related diseases. Our data are based on the fourth Tromsø study carried out in 1994–1995.

Methods

Information about death and cause of death was registered by obtaining information from the National Directory of Residents and the Death Cause Registry. Serum 25(OH)D was measured in 7161 participants in the fourth Tromsø study. Results are presented for smokers (n=2410) and non-smokers (n=4751) separately as our immunoassay seems to overestimate 25(OH)D levels for smokers.

Results

During a mean 11.7 years of follow-up, 1359 (19.0%) participants died. In multivariate regression models, there was a significantly increased risk of all-cause mortality (hazard ratio (HR) 1.32, confidence interval (CI) 1.07–1.62) among non-smoking participants in the lowest 25(OH)D quartile when compared with participants in the highest quartile. Equivalent results for smokers were not significant (HR 1.06, CI 0.83–1.35).

Conclusions

Low serum 25(OH)D levels were associated with increased all-cause mortality for non-smokers, but the results did not reach statistical significance for smokers. However, low 25(OH)D levels are known to be associated with impaired general health, and randomized controlled studies are needed to address the question of causality.

Free access

Allan Didriksen, Guri Grimnes, Moira Strand Hutchinson, Marie Kjærgaard, Johan Svartberg, Ragnar M Joakimsen, and Rolf Jorde

Objective

The serum 25-hydroxyvitamin D (25(OH)D) level is not only dependent on vitamin D intake and production in the skin but also dependent on genetic factors. Thus, in large genome-wide association studies, it has been shown that single nucleotide polymorphisms (SNPs) in the vitamin D binding protein (DBP), as well as in enzymes related to activation or degradation of vitamin D and its metabolites, are as important for the serum 25(OH)D level as the effect of season. How these SNPs affect the serum 25(OH)D response to vitamin D supplementation is uncertain.

Design and methods

Data were pooled from three randomized controlled trials where 40 000 IU vitamin D/week was given for 6 months. Serum 25(OH)D was measured before and at the end of the intervention, and the subjects were genotyped for SNPs related to the serum 25(OH)D level.

Results

Baseline 25(OH)D levels were significantly related to SNPs in the DBP and CYP2R1 genes. Those with SNPs associated with the lowest baseline 25(OH)D levels also had the smallest increase (delta) after supplementation. Those with the lowest baseline serum 25(OH)D (without regard to genotypes) had the highest increase (delta) after supplementation. Subjects with high BMI had lowest baseline 25(OH)D levels and also the smallest increase (delta) after supplementation.

Conclusions

The serum 25(OH)D response to supplementation depends on genes, baseline level, and BMI. However, whether this is clinically important or not depends on the therapeutic window of vitamin D, an issue that is still not settled.

Free access

Guri Grimnes, Bjørg Almaas, Anne Elise Eggen, Nina Emaus, Yngve Figenschau, Laila Arnesdatter Hopstock, Moira Strand Hutchinson, Paal Methlie, Albena Mihailova, Monica Sneve, Peter Torjesen, Tom Wilsgaard, and Rolf Jorde

The authors and the journal apologise for errors in the Introduction section of this paper published in the European Journal of Endocrinology 2010 vol 163 pp 339–348. Lines 11–14 of the Introduction section should read as follows:

This reflects the amount of vitamin D ingested from food (ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3)) and the amount of vitamin D produced in the skin during ultraviolet B (UVB) exposure (vitamin D3)

and not as published.

Free access

Guri Grimnes, Bjørg Almaas, Anne Elise Eggen, Nina Emaus, Yngve Figenschau, Laila Arnesdatter Hopstock, Moira Strand Hutchinson, Paal Methlie, Albena Mihailova, Monica Sneve, Peter Torjesen, Tom Wilsgaard, and Rolf Jorde

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. In the validation study, serum levels of 25(OH)D were analysed with liquid chromatography coupled with mass spectrometry assay from two different laboratories, RIA (DiaSorin), HPLC, RIA (IDS) and ECLIA (Roche). T-tests and linear mixed model analyses were performed to compare the serum 25(OH)D levels in smokers and non-smokers within and between the methods.

Results

In the population-based study, the serum levels of 25(OH)D using the ECLIA method were 51.9, 53.2 and 72.0 nmol/l in never, former and current smokers (P<0.01). In the validation study, the serum concentration of 25(OH)D was 10.3 nmol/l higher in smokers than in non-smokers (P<0.01) using the ECLIA (Roche), while non-significantly lower serum levels of 25(OH)D were found in smokers using the other five methods.

Conclusions

These two studies indicate that the ECLIA (Roche) overestimates serum 25(OH)D levels in smokers by unknown mechanisms. If confirmed, this might have clinical consequences, and the issue needs further exploration.

Open access

Dina B Stensen, Lars Småbrekke, Karina Olsen, Guri Grimnes, Christopher Sivert Nielsen, Johanna U E Sollid, Gunnar Skov Simonsen, Bjørg Almås, and Anne-Sofie Furberg

Objective

Staphylococcus aureus is a major human pathogen, and nasal carriers have an increased risk for infection and disease. The exploration of host determinants for nasal carriage is relevant to decrease infection burden. Former studies demonstrate lower carriage prevalence in women and among users of progestin-only contraceptives. The aim of this study was to investigate the possible associations between circulating sex-steroid hormones and nasal carriage of Staphylococcus aureus in a general population.

Methods

In the population-based sixth Tromsø study (2007–2008) nurses collected nasal swab samples from 724 women aged 30–87 not using any exogenous hormones, and 700 of the women had a repeated nasal swab taken (median interval 28 days). We analysed a panel of serum sex-steroids by liquid chromatography tandem mass spectrometry, and collected information about lifestyle, health and anthropometric measures. Multivariable logistic regression was used to study the association between circulating sex-steroids and Staphylococcus aureus carriage (one swab) and persistent carriage (two swabs), while adjusting for potential confounding factors. Women in luteal phase were excluded in the analysis of androgens.

Results

Staphylococcus aureus persistent nasal carriage prevalence was 22%. One standard deviation increase in testosterone and bioavailable testosterone was associated with lower odds of persistent nasal carriage, (OR = 0.57; 95% CI = 0.35–0.92 and OR = 0.52, 95% CI = 0.30–0.92) respectively. Analysis stratified by menopause gave similar findings. Persistent carriers had lower average levels of androstenedione and DHEA, however, not statistically significant.

Conclusion

This large population-based study supports that women with lower levels of circulating testosterone may have increased probability of Staphylococcus aureus persistent carriage.