Nina Odgaard Nielsen

Vitamin D Status during Pregnancy and the Risk of Subsequent Postpartum Depression: A Case-Control Study

Epidemiological studies have provided evidence of an association between vitamin D insufficiency and depression and other mood disorders, and a role for vitamin D in various brain functions has been suggested. We hypothesized that low vitamin D status during pregnancy might increase the risk of postpartum depression (PPD). The objective of the study was thus to determine whether low vitamin D status during pregnancy was associated with postpartum depression. In a case-control study nested in the Danish National Birth Cohort, we measured late pregnancy serum concentrations of 25[OH]D3 in 605 women with PPD and 875 controls. Odds ratios [OR) for PPD were calculated for six levels of 25[OH]D3. Overall, we found no association between vitamin D concentrations and risk of PPD (p = 0.08). Compared with women with vitamin D concentrations between 50 and 79 nmol/L, the adjusted odds ratios for PPD were 1.35 (95% CI: 0.64; 2.85), 0.83 (CI: 0.50; 1.39) and 1.13 (CI: 0.84; 1.51) among women with vitamin D concentrations < 15 nmol/L, 15–24 nmol/L and 25–49 nmol/L, respectively, and 1.53 (CI: 1.04; 2.26) and 1.89 (CI: 1.06; 3.37) among women with vitamin D concentrations of 80–99 nmol/L and ≥ 100 nmol/L, respectively. In an additional analysis among women with sufficient vitamin D (≥ 50 nmol/L), we observed a significant positive association between vitamin D concentrations and PPD. Our results did not support an association between low maternal vitamin D concentrations during pregnancy and risk of PPD. Instead, an increased risk of PPD was found among women with the highest vitamin D concentrations.

Development and Validation of a Vitamin D Status Prediction Model in Danish Pregnant Women: A Study of the Danish National Birth Cohort

Vitamin D has been hypothesized to reduce risk of pregnancy complications such as preeclampsia, gestational diabetes mellitus, and preterm delivery. However, many of these outcomes are rare and require a large sample size to study, representing a challenge for cohorts with a limited number of preserved samples. The aims of this study were to (1) identify predictors of serum 25-hydroxy-vitamin D (25(OH)D) among pregnant women in a subsample (N = 1494) of the Danish National Birth Cohort (DNBC) and (2) develop and validate a score predicting 25(OH)D-status in order to explore associations between vitamin D and maternal and offspring health outcomes in the DNBC. In our study sample, 42.3% of the population had deficient levels of vitamin D (<50 nmol/L 25(OH)D) and average levels of 25(OH)D-status were 56.7(s.d. 24.6) nmol/L. A prediction model consisting of intake of vitamin D from diet and supplements, outdoor physical activity, tanning bed use, smoking, and month of blood draw explained 40.1% of the variance in 25(OH)D and mean measured 25(OH)D-level increased linearly by decile of predicted 25(OH)D-score. In total 32.2% of the women were placed in the same quintile by both measured and predicted 25(OH)D-values and 69.9% were placed in the same or adjacent quintile by both methods. Cohens weighted kappa coefficient (Κ = 0.3) reflected fair agreement between measured 25(OH)D-levels and predicted 25(OH)D-score. These results are comparable to other settings in which vitamin D scores have shown similar associations with disease outcomes as measured 25(OH)D-levels. Our findings suggest that predicted 25(OH)D-scores may be a useful alternative to measured 25(OH)D for examining associations between vitamin D and disease outcomes in the DNBC cohort, but cannot substitute for measured 25(OH)D-levels for estimates of prevalence.

Serum ferritin, α-tocopherol, β-carotene and retinol levels in lymphatic filariasis

Based on a cross-sectional study conducted among 100 adults in 1993 in Tanga, Tanzania, the relationship between Wuchereria bancrofti infection and markers of iron, vitamin A and vitamin E status was assessed. Potential predictors assessed were elephantiasis, hydrocoele, W. bancrofti microfilaria intensity and antigen concentration, and intensity of Schistosoma haematobium, hookworm, Trichuris trichiura and Ascaris lumbricoides infection, while controlling for age, sex and elevated serum α-1 antichymotrypsin. Of the 100 adults, 62 had W. bancrofti antigenaemia and 43 microfilaraemia, and 21 had elephantiasis. Of the 64 males, 31 had hydrocoele. W. bancrofti microfilaria intensity was a positive predictor of serum ferritin and a negative predictor of serum α-tocopherol. In contrast, negative relationships observed between W. bancrofti microfilaria intensity and serum β-carotene and retinol were not significant. Neither antigen concentration nor clinical manifestations were predictors of micronutrient status. Intensity of hookworm infection was associated with lower serum ferritin. S. haematobium egg output was not a significant predictor of serum ferritin, but was a positive predictor of serum β-carotene. In conclusion, W. bancrofti microfilaria intensity was associated with higher serum ferritin, but lower serum α-tocopherol. The associations probably reflect increased oxidative stress due to microfilariaehost interactions, which could play a role in the pathogenesis.

Predicted vitamin D status in mid-pregnancy and child allergic disease

Vitamin D deficiency in pregnancy may be a risk factor for child allergic disease. However, less is known about disease risk across different levels of vitamin D.

Population surveys in Greenland 1993-2009: Temporal trend of PCBs and pesticides in the general Inuit population by age and urbanisation

The purpose of the study was to analyse temporal trends (1993-2009) of the concentrations of organochlorine contaminants (14 congeners of polychlorinated biphenyls (PCB) and 11 pesticides) in the blood of Greenland Inuit according to age and urbanisation. Statistical determinants for the contaminant concentrations included (for PCB congener 153) age (Δr(2)=0.35), marine diet (Δr(2)=0.10), smoking (Δr(2)=0.02), and sex (Δr(2)=0.01) with comparable results for other organochlorine contaminants. After adjustment for age, diet, smoking, and sex a significant decreasing trend was present for all contaminants ranging from 41% for mirex to 56% for hexachlorobenzene. The temporal trend was most pronounced among participants below the age of 65 years. The decrease started later in villages than in towns. The decrease was present in all age groups and in the capital, other towns, and villages. The decrease is probably due to a combination of reduced concentrations of the contaminants in the wildlife and a slight temporal reduction in the consumption of marine mammals. The significant downwards trend of legacy POPs shows that the legislation works but it must be kept in mind that according to the cumulated scientific evidence there are a multitude of non-regulated persistent organic contaminants in the diet as well as high levels of methylmercury.

Cardiovascular Disease Susceptibility and Resistance in Circumpolar Inuit Populations

Cardiovascular disease (CVD) is a major public health issue in indigenous populations in the Arctic. These diseases have emerged concomitantly with profound social changes over the past 60 years. The aim of this study was to summarize the literature on CVD risk among Arctic Inuit. Literature on prevalence, incidence, and time trends for CVD and its risk factors in Arctic Inuit populations was reviewed. Most evidence supports a similar incidence of coronary heart disease and a higher incidence of cerebrovascular disease among Arctic Inuit than seen in western populations. Factors that may increase CVD risk include aging of the population, genetic susceptibility, and a rapid increase in obesity, diabetes, and hypertension in parallel with decreasing physical activity and deterioration of the lipid profile. In contrast, and of great importance, there has been a decrease in smoking and alcohol intake (at least documented in Greenland), and contaminant levels are declining. Although there have been marked socioeconomic and dietary changes, it remains unsolved and to some extent controversial how this may have influenced cardiovascular risk among Arctic Inuit. The increase in life expectancy, in combination with improved prognosis for patients with manifest CVD, will inevitably lead to a large increase in absolute numbers of individuals affected by CVD in Arctic Inuit populations, exacerbated by the rise in most CVD risk factors over the past decades. For preventive purposes and for health care planning, it is crucial to carefully monitor disease incidence and trends in risk factors in these vulnerable Arctic populations.

Decrease in vitamin D status in the Greenlandic adult population from 1987-2010.

Background Low vitamin D status may be pronounced in Arctic populations due to limited sun exposure and decreasing intake of traditional food. Objective To investigate serum 25(OH)D3 as a measure of vitamin D status among adult Inuit in Greenland, predictors of low serum 25(OH)D3 concentrations and the trend from 1987 to 2005–2010. Design A total of 2877 randomly selected Inuit (≥18 years) from the Inuit Health in Transition study were included. A sub-sample (n = 330) donated a blood sample in 1987 which allowed assessment of time trends in vitamin D status. Results The geometric mean serum 25(OH)D3 (25[OH]D2 concentrations were negligible and not reported) in 2005–2010 was lowest among the 18–29 year old individuals (30.7 nmol/L; 95% CI: 29.7; 31.7) and increased with age. In all age-groups it decreased from 1987 to 2005–2010 (32%–58%). Low 25(OH)D3 concentrations (<50 nmol/L) were present in 77% of the 18–29 year old and decreased with age. A characteristic seasonal variation in 25(OH)D3 concentrations was observed (range 33.2–57.1 nmol/L, p<0.001), with the highest concentrations in August to October. Age (2.0% per year increase; CI: 1.7, 2.2), female gender (7.1%; CI: 2.0; 12.5), alcohol intake (0.2% per increase in drinks/week; 0.0; 0.4), and traditional diet (10.0% per 100 g/d increase; CI: 7.9; 12.1) were associated with increased serum 25(OH)D3, whereas smoking (−11.6%; CI: −16.2; −6.9), BMI (−0.6%; CI: −1.1; −0.2) and latitude (−0.7% per degree increase; CI: −1.3; −0.2) were associated with decreased concentrations. Conclusion We identified a remarkable decrease in vitamin D status from 1987 to 2005–2010 and a presently low vitamin D status among Inuit in Greenland. A change away from a traditional diet may well explain the observed decline. The study argues for the need of increased dietary intake of vitamin D and supplementation might be considered.

Associations between Vitamin D Status and Type 2 Diabetes Measures among Inuit in Greenland May Be Affected by Other Factors.

Objective Epidemiological studies have provided evidence of an association between vitamin D insufficiency and type 2 diabetes. Vitamin D levels have decreased among Inuit in Greenland, and type 2 diabetes is increasing. We hypothesized that the decline in vitamin D could have contributed to the increase in type 2 diabetes, and therefore investigated associations between serum 25(OH)D3 as a measure of vitamin D status and glucose homeostasis and glucose intolerance in an adult Inuit population. Methods 2877 Inuit (≥18 years) randomly selected for participation in the Inuit Health in Transition study were included. Fasting- and 2hour plasma glucose and insulin, C-peptide and HbA1c were measured, and associations with serum 25(OH)D3 were analysed using linear and logistic regression. A subsample of 330 individuals who also donated a blood sample in 1987, were furthermore included. Results After adjustment, increasing serum 25(OH)D3 (per 10 nmol/L) was associated with higher fasting plasma glucose (0.02 mmol/L, p = 0.004), 2hour plasma glucose (0.05 nmol/L, p = 0.002) and HbA1c (0.39%, p<0.001), and with lower beta-cell function (-1.00 mmol/L, p<0.001). Serum 25(OH)D3 was positively associated with impaired fasting glycaemia (OR: 1.08, p = 0.001), but not with IGT or type 2 diabetes. Conclusions Our results did not support an association between low vitamin D levels and risk of type 2 diabetes. Instead, we found weak positive associations between vitamin D levels and fasting- and 2hour plasma glucose levels, HbA1c and impaired fasting glycaemia, and a negative association with beta-cell function, underlining the need for determination of the causal relationship.

Cytokine responses in relation to age, gender, body mass index, Mycobacterium tuberculosis infection, and otitis media among Inuit in Greenland

To evaluate the cytokine response pattern in Inuit in Greenland in relation to age, gender, body mass index (BMI), Mycobacterium tuberculosis infection (MTI), and otitis media (OM) to assess whether Inuit may have signs of impaired immune responsiveness to infection.

Association between whole blood mercury and glucose intolerance among adult Inuit in Greenland.

OBJECTIVES The Arctic diet is partly constituted by traditional food characterized by top predator animals such as whales, walrus, and seals with high mercury content. Mercury exposure has been associated with glucose intolerance in Western populations. We studied the association between whole blood mercury and glucose intolerance in a highly exposed non-Western population METHODS Cross-sectional study of 2640 Inuit (18+ years) with information on ancestry, smoking, waist circumference, total energy intake, and physical activity. Mercury, fasting- and 2-h plasma glucose, insulin, and c-peptide were measured in blood. Fasting participants without diabetes were classified into normal glucose tolerance, impaired glucose tolerance, impaired fasting glycemia, or type 2 diabetes. We calculated hepatic insulin resistance with homoeostatic model assessment - insulin resistance index, peripheral insulin sensitivity by ISI0,120., and relative beta cell function by c-peptide/insulin ratio. We conducted adjusted linear- and logistic regression analyses. RESULTS For an increase in whole blood mercury of 5 µg/L we found a positive association with fasting glucose [% change=0.25 (95% CI: 0.20; 0.30); p<0.001], and 2-h glucose [% change=0.23 (95% CI: 0.05; 0.40); p=0.01]. Mercury was weakly associated with impaired fasting glycemia [OR=1.03 (95% CI: 1.02; 1.05)], and type 2 diabetes [OR=1.02 (95% CI: 1.01; 1.04)]. CONCLUSION While the study found a weak but statistically significant association between whole blood mercury and both impaired fasting glycemia and type 2 diabetes, no associations were found with measures of underlying disturbances in glucose homoeostasis.