Canadian Aboriginal women have a higher prevalence of vitamin D deficiency than non-Aboriginal women despite similar dietary vitamin D intakes

Human Nutritional Sciences, Faculty of Medicine, University of Manitoba, Winnipeg, R3T 2N2 MB, Canada.
Journal of Nutrition (Impact Factor: 3.88). 03/2007; 137(2):461-5.
Source: PubMed


Canadian Aboriginal women have high rates of bone fractures, which is possibly due to low dietary intake of minerals or vitamin D. This study was undertaken to estimate dietary intake of calcium and vitamin D by designing a culturally appropriate dietary survey instrument and to determine whether disparities exist between Aboriginal and white women. After validation of a FFQ, 183 urban-dwelling and 26 rural-dwelling Aboriginal women and 146 urban white women completed the validated FFQ and had serum 25-hydroxyvitamin D [25(OH)D] measured. Urban Aboriginal women had lower (P=0.0004) intakes of total dietary calcium than urban white women; there was no difference in rural Aboriginal women. Only a minority of all women met the adequate intake (AI) for calcium intake. Ethnicity did not affect total vitamin D intake; however, rural Aboriginal women consumed all of their dietary vitamin D from food sources, which was more (P<0.03) than both urban Aboriginal and white women. Rural and urban Aboriginal women had lower (P<0.0004) serum 25(OH)D than urban white women. We found that 32% of rural Aboriginal, 30.4% of urban Aboriginal, and 18.6% of urban white women were vitamin D deficient, with serum 25(OH)D concentrations<37.5 nmol/L. The high prevalence of vitamin D deficiency among Aboriginal women, combined with lower dietary intake of calcium, especially in older women, likely contributes to the higher incidence of fracture in this population.

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Available from: Colleen Metge, Sep 29, 2014
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    • "Of note, AusDiab, a nation-wide Australian population-based study, reported that 31% of Australians had 25(OH)D levels <50 nmol/L, however only 0.9% of AusDiab participants identified as Aboriginal or Torres Strait Islander Australians [6]. High rates of vitamin D deficiency have been reported in other Indigenous populations internationally, including Aboriginal Canadian women (33%) [18], New Zealand Maori and Pacific Islander New Zealanders (61% and 69% respectively, compared to 46% of New Zealanders of European descent) [19]. However, direct comparison is limited as key characteristics (latitude, age, BMI, co-morbidities) differ between cohorts. "
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    ABSTRACT: Background Low levels of serum 25–hydroxy vitamin D (25(OH)D), have been associated with development of type 2 diabetes and cardiovascular disease (CVD); however there are limited data on serum 25(OH)D in Indigenous Australians, a population at high risk for both diabetes and CVD. We aimed to assess levels of serum 25(OH)D in Aboriginal and Torres Strait Islander Australians and to explore relationships between 25(OH)D and cardio-metabolic risk factors and diabetes. Methods 592 Aboriginal and/or Torres Strait Islander Australian participants of The eGFR (estimated glomerular filtration rate) Study, a cross-sectional analysis of a cohort study performed in 2007–2011, from urban and remote centres within communities, primary care and tertiary hospitals across Northern Territory, Far North Queensland and Western Australia. Assessment of serum 25(OH)D, cardio-metabolic risk factors (central obesity, diabetes, hypertension, history of cardiovascular disease, current smoker, low HDL-cholesterol), and diabetes (by history or HbA1c ≥6.5%) was performed. Associations were explored between 25(OH)D and outcome measures of diabetes and number of cardio-metabolic risk factors. Results The median (IQR) serum 25(OH)D was 60 (45–77) nmol/L, 31% had 25(OH)D <50 nmol/L. For participants with 25(OH)D < 50 vs ≥50 nmol/L, cardio-metabolic risk profile differed for: diabetes (54%, 36% p < 0.001), past history of cardiovascular disease (16%, 9%, p = 0.014), waist-hip ratio (0.98, 0.92, p < 0.001), urine albumin-creatinine ratio (2.7, 1.5 mg/mmol, p < 0.001). The OR (95% CI) for diabetes was 2.02 (1.03 – 3.95) for people in the lowest vs highest tertiles of 25(OH)D (<53 vs >72 nmol/L, respectively) after adjusting for known cardio-metabolic risk factors. Conclusion The percentage of 25(OH)D levels <50 nmol/L was high among Aboriginal and Torres Strait Islander Australians from Northern and Central Australia. Low 25(OH)D level was associated with adverse cardio-metabolic risk profile and was independently associated with diabetes. These findings require exploration in longitudinal studies.
    Full-text · Article · Jul 2014 · Diabetology and Metabolic Syndrome
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    • "Factors such as low socioeconomic status, diabetes [8] or the number of comorbidities and alcohol and drug use [9] were associated with higher fracture rates in these populations. Low calcium and vitamin D intake among Aboriginals, particularly older women [13], may also play a role. "
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    ABSTRACT: Aboriginal populations living in Canada's northern regions are exposed to a number of persistent organic pollutants through their traditional diet which includes substantial amounts of predator fish species. Exposure to dioxin-like compounds (DLCs) can cause a variety of toxic effects including adverse effects on bone tissue. This descriptive cross-sectional study was conducted to investigate the relationship between plasma concentrations of DLCs and bone quality parameters in Cree women of Eastern James Bay (Canada). Two hundred and forty-nine Cree women from seven communities in Eastern James Bay (Canada), aged 35 to 74 years old, participated in the study. In order to determine the total DLC concentration in plasma samples of participants, we measured the aryl hydrocarbon receptor-mediated transcriptional activity elicited by plasma sample extracts using a luciferase reporter gene assay. Plasma concentrations of mono-ortho-substituted dioxin-like polychlorinated biphenyls (DL-PCBs) 105, 118 and 156 were measured by gas chromatography--mass spectrometry. Bone quality parameters (speed of sound, m/s; broadband ultrasound attenuation, dB/MHz; stiffness index, %) were assessed by quantitative ultrasound at the right calcaneus with the Achilles InSight system. Several factors known to be associated with osteoporosis were documented by questionnaire. Multiple linear regression models were constructed for the three ultrasound parameters. DL-PCBs 105 and 118 concentrations, but not the global DLC concentration, were inversely associated with the stiffness index, even after adjusting for several confounding factors. The stiffness index (log) decreased by -0.22% (p=0.0414) and -0.04% (p=0.0483) with an increase of one mug/L in plasma concentrations of DL-PCB 105 and DL-PCB 118, respectively. Other factors, including age, height, smoking status, menopausal status and the percentage of omega-6 polyunsaturated fatty acids (PUFAs) in erythrocyte membranes were negatively associated with one of the ultrasound parameters, while the percentage of omega-3 PUFAs in these membranes and levels of physical activity and education were positively associated with them. Our results show that an increase in plasma concentrations of DL-PCBs 105 and 118 was negatively associated with stiffness index, a measure of bone quality/strength, in women of this population. In addition to environmental contaminants, future studies should also consider PUFA intake as a factor influencing bone quality.
    Full-text · Article · Jul 2013 · Environmental Health
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    • "Indeed findings of a Canadian cross sectional survey suggested that as many as three million Canadians have inadequate vitamin D levels and 1.1 million Canadians are vitamin D deficient (defined as a serum vitamin D level ≤27.5 nmol/L; to convert 25-hydroxyvitamin D levels from SI to conventional units divide by 2.496) [17]. Other specific sociodemographic factors have been reported to be associated with low vitamin D levels including advanced age and/or residence in a nursing home [24], cultural factors such as skin covering [25,26], aboriginal ancestry [27], low dietary intake of milk [17], darker skin pigmentation and/or non-white ethnicity [14,17,18,21,28], obesity [18,29], and lower education [30]. "
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    ABSTRACT: Background Low 25-hydroxyvitamin D levels are a global health problem with northern countries such as Canada at particular risk. A number of sociodemographic factors have been reported to be associated with low vitamin D levels but prior studies have been limited by the ability of the researchers to gather this data directly from clinical trial participants. The purpose of this study was to use a novel methodology of inferring sociodemographic variables to evaluate the correlates of vitamin D levels in individuals dwelling in the City of Calgary, Alberta, Canada. Methods We utilized data on vitamin D test results from Calgary Laboratory Services between January 1 2010 and August 31 2011. In addition to vitamin D level, we recorded age, sex, and vitamin D testing month as individual-level variables. We inferred sociodemographic variables by associating results with census dissemination areas and using Census Canada data to determine immigration status, education, median household income and first nations status as clustered variables. Associations between vitamin D status and the individual- and dissemination area-specific variables were examined using the population-averaged regression model by a generalized estimating equations approach to account for the clustering in the data. Results 158,327 individuals were included. Age, sex, month of vitamin D testing (at an individual level), and education, immigrant status, first nations status and income (at an aggregate level) were all statistically significant predictors of vitamin D status. Conclusions Vitamin D status was associated with a number of sociodemographic variables. Knowledge of these variables may improve targeted education and public health initiatives.
    Full-text · Article · Apr 2013 · BMC Public Health
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