Serum 25-hydroxyvitamin D concentrations in 16-year-old Icelandic adolescent and its association with bone mineral density.

OBJECTIVE: The aim of the study was to assess the potential association between serum 25-hydroxyvitamin D (25(OH)D) and whole-body bone mineral density (BMD) among 16-year-old adolescents and to study the prevalence of 25(OH)D insufficiency, defined as concentration under 50 nmol/l. DESIGN: A cross-sectional study. SETTING: Reykjavik, Iceland, latitude 64°08'N. Measurements took place in the Icelandic Heart Association's research lab during April-June 2015. PARTICIPANTS: In total, 411 students in Reykjavik, Iceland, were invited to participate, 315 accepted the invitation (76·6 %) and 289 had valid data (mainly Caucasian). RESULTS: 25(OH)D < 50 nmol/l was observed in 70 % of girls and 66·7 % of boys. 25(OH)D ≥ 50 nmol/l was significantly associated with higher whole-body BMD after adjusting for the influence of sex, height, fat mass and lean mass. A linear relationship between 25(OH)D and whole-body BMD was significant for 25(OH)D < 50 nmol/l (n 199, P < 0·05) but NS for 25(OH)D ≥ 50 nmol/l (n 86, P = 0·48). CONCLUSIONS: Our results are in line with some but not all previous studies on the relationship between BMD and 25(OH)D in adolescents. The observed difference in BMD between those with above v. below a 25(OH)D concentration of 50 nmol/l was of about a fifth of one SD, which may have a clinical relevance as one SD decrease in volumetric BMD has been associated with a 89 % increase in 2 years risk of fracture. Icelandic adolescents should be encouraged to increase their vitamin D intake as it is possible that their current intake is insufficient to achieve optimal peak bone mass.

Helicobacter pylori infection in Icelandic children.

OBJECTIVE: The prevalence of Helicobacter pylori (HP) infection is decreasing in the western world. The seroprevalence among 25-50-year-old Icelandic adults was recently shown to be 30-40%. Information on the seroprevalence in Nordic children is limited. We aimed at ascertaining the infection prevalence among healthy Icelandic children. METHODS: The infection status in stored frozen blood samples from two cross-sectional studies on the health of 7-9-year-old children (n = 125) and 16-18-year-old adolescents (n = 80) was determined by enzyme-linked immunosorbent assay (ELISA). Information on family demographics and GI symptoms was obtained by standardized questionnaires. RESULTS: Overall, 3.4% (7/205) of the children were infected with H. pylori. The prevalence was 2.6% (5/190), missing data n = 3, among children with both parents born in a low prevalence country compared to 17% (2/12) among those with at least one parent born in a high prevalence area (p = .026). When at least one parent was born in a high prevalence country, the odds ratio for being H. pylori seropositive was 2.2 (95% CI, 1.02-54.67), when adjusted for the educational status of the mother. There was no significant association between H. pylori infection and gastrointestinal symptoms. CONCLUSION: Prevalence of H. pylori infection in Iceland has become very low, suggesting a great reduction in transmission from older generations. There was an association between H. pylori infection and origin from high prevalence areas but not with gastrointestinal symptoms. The results mirror recent studies of children of Scandinavian ancestry.