Forearm bone mineral density varies as a function of adiposity in inuit women 40-90 years of age during the vitamin D-synthesizing period

Forearm bone density is not elevated in Inuit women with impaired fasting glucose or type 2 diabetes mellitus

Bone mineral density (BMD) and fracture risk are elevated in adults with impaired fasting glucose (IFG) or type 2 diabetes mellitus (T2D). This study aimed to compare bone health among Inuit women with IFG, T2D and normoglycemia. The study included Inuit women (≥40 y) with IFG (n = 57), T2D (n = 72) or normoglycemia (n = 340) from the International Polar Year Inuit Health Survey 2007-2008 in Canada. Distal one-third forearm BMD (FaBMD) was measured using a peripheral instantaneous x-ray imager. Anthropometry, fasting plasma glucose (FPG), serum adiponectin, leptin and 25-hydroxyvitamin D (25(OH)D) were measured. Traditional food intakes were surveyed. Data were analysed using mixed model ANOVA and regression models. The median age was 53 (IFG: IQR 48, 67) y and 56 (T2D: IQR 49, 63) y. Compared to normoglycemic women, FaBMD and T-scores were significantly lower in women with T2D, but not with IFG. Frequency of marine mammal intakes (ß = 0.145; 95%CI: 0.018, 0.053, p = 0.0001) positively related to FaBMD. The odds ratio of having a T-score consistent with osteoporosis was lower among women with T2D and higher BMI, while aging increased the risk. Although T2D associates with lower BMD among Inuit women, risk of osteoporosis is tempered, possibly by maintenance of a traditional lifestyle.

Vitamin D status and intake of lactating Inuit women living in the Canadian Arctic

OBJECTIVE

To determine the prevalence and correlates of healthy vitamin D status in lactating Inuit women living in remote regions of the Arctic.

DESIGN

Cross-sectional.

SETTING

Households were selected randomly in thirty-six communities of Nunavut, Nunatsiavut and Inuvialuit Settlement Region. Dietary intake was assessed using a 24 h recall and an FFQ. Anthropometric measurements, household living conditions, supplement use and health status were assessed. In fasting samples, serum 25-hydroxyvitaimn D (25(OH)D) was measured using a chemiluminescent assay (LIAISON; Diasorin Inc.).

SUBJECTS

Lactating Inuit women participating in the 2007-2008 International Polar Year Inuit Health Survey conducted in the months of August to October.

RESULTS

Among participants (n 34), 8·8, 26·5 and 50·0 % had 25(OH)D concentrations at or above 75, 50 and 40 nmol/l, respectively. More than one-third of participants did not consume traditional foods during the previous day and only 11·3 % of total energy intake was derived from traditional foods. Only 14·7 % of the sample consumed the daily number of milk servings recommended by Canada's Food Guide (two servings) for First Nations, Inuit and Métis. Using multivariable logistic regression to examine 25(OH)D≥40 nmol/l, only higher body fat was inversely correlated with 25(OH)D concentration.

CONCLUSIONS

The present study is the first to assess simultaneously vitamin D status and other known factors that affect it among lactating Inuit women living in remote communities in the Arctic. Healthy maternal vitamin D status was observed in 25 % of participants during the late summer and early autumn. This requires further assessment in a larger sample spanning more seasons.

Comparison of Bone Mineral Density by Dual-Energy X-Ray Absorptiometry and Bone Strength by Speed-of-Sound Ultrasonography in Adults With Gaucher Disease

Patients with the lysosomal disorder Gaucher disease (GD) are at risk of osteoporosis and/or avascular necrosis, but to date, no adequate biomarkers are available to ascertain individual predilections. Bone mineral density by dual-energy X-ray absorptiometry (DXA) has traditionally been used to monitor trends. With the availability of a speed-of-sound (SOS) ultrasonography to assess bone strength/elasticity, we aimed to ascertain whether these modalities are complimentary or comparable so SOS, with no radiation risk, might be used more routinely as a potential biomarker. A prospective comparative study in adult GD patients undergoing routine follow-up of bone mineral density T- and Z-scores at forearm (FA), femoral neck, and lumbar spine, and SOS Z-scores at FA was initiated. Interpretation was by qualitative categorization of Z-scores. The kappa measure of agreement beyond chance was calculated between pairs of measurements and the McNemar test was then applied. This noninterventional trial (ClinicalTrials.gov Identifier: NCT02067247) was approved by the institutional ethics committee. There were 89 patients (ages 21-78 years, 61% female, 62% common Ashkenazi genotype, 18% splenectomized, and 18% with avascular necrosis/fractures). When comparing Z-scores at FA by DXA and SOS, only 39.3% correlated, while the remaining results were in disagreement; no trend was noted. Similarly, when comparing Z-scores at the femoral neck by DXA with those at FA by SOS, 44.9% of the results were in agreement; no trend was noted; and Z-scores at the lumbar spine by DXA with FA by SOS, 46% were in agreement and no trend was noted. DXA at the 3 sites did not track in the same direction or the same magnitude of difference with SOS at FA in adult patients with GD. Due to the fundamental differences between the 2 measurements and their clinical correlates, plus the lack of long-term follow-up to assess outcome, the potential added value of the measurements at the FA by SOS in patients with GD awaits further studies.

Relationship between the esterase paraoxonase-1 (PON1) and metal concentrations in the whole blood of Inuit in Canada

The esterase paraoxonase (PON1), a major component of high-density lipoprotein (HDL), protects against the development of atherosclerosis in humans. Although variation in PON1 activity is primarily governed by PON1 genotype, there is growing evidence that environmental chemicals may also modulate its activity. This cross-sectional study aimed to determine whether environmental exposure to various metals is associated with PON1 activity in Inuit people routinely exposed to mercury (Hg), cadmium (Cd), lead (Pb), and (Se) selenium. PON1 activity and metal concentrations were measured in blood collected from 2172 healthy participants. Sociodemographic, anthropometric and lifestyle variables were also assessed. The associations between PON1 activity and blood metal concentrations, HDL, omega-3 fatty acid blood levels, age, sex, body mass index (BMI), and lifestyle habits (e.g. smoking and alcohol consumption) were explored via multiple linear regression. PON1 activity was positively associated with Se blood concentration (β=0.056, P=0.001) but was negatively associated with Cd blood concentration (β=-0.025, P<0.001). No association was observed between PON1 activity and Hg or Pb blood concentrations. Our results suggest that: PON1 activity is modulated by metal exposure, and Inuit traditional foods may confer health benefit by increasing PON1 activity via higher Se intakes. These findings underline that current environmental metal exposures among Inuit living in the Canadian Arctic are associated with paraoxonase activity, a toxicologically-relevant biochemical parameter.

Age-related variation in limb bone diaphyseal structure among Inuit foragers from Point Hope, northern Alaska

Age-related deterioration of limb bone diaphyseal structure is documented among precontact Inuit foragers from northern Alaska. These findings challenge the concept that bone loss and fracture susceptibility among modern Inuit stem from their transition away from a physically demanding traditional lifestyle toward a more sedentary Western lifestyle.

INTRODUCTION

Skeletal fragility is rare among foragers and other traditional-living societies, likely due to their high physical activity levels. Among modern Inuit, however, severe bone loss and fractures are apparently common. This is possibly because of recent Western influences and increasing sedentism. To determine whether compromised bone structure and strength among the Inuit are indeed aberrant for a traditional-living group, data were collected on age-related variation in limb bone diaphyseal structure from a group predating Western influences.

METHODS

Skeletons of 184 adults were analyzed from the Point Hope archaeological site. Mid-diaphyseal structure was measured in the humerus, radius, ulna, femur, and tibia using CT. Structural differences were assessed between young, middle-aged, and old individuals.

RESULTS

In all bones examined, both females and males exhibited significant age-related reductions in bone quantity. With few exceptions, total bone (periosteal) area did not significantly increase between young and old age in either sex, nor did geometric components of bending rigidity (second moments of area).

CONCLUSIONS

While the physically demanding lifestyles of certain traditional-living groups may protect against bone loss and fracture susceptibility, this is not the case among the Inuit. It remains possible, however, that Western characteristics of the modern Inuit lifestyle exacerbate age-related skeletal deterioration.

Dietary advice on Inuit traditional food use needs to balance benefits and risks of mercury, selenium, and n3 fatty acids

Elevated concentrations of mercury (Hg) are commonly found in the traditional foods, including fish and marine mammals, of Inuit living in Canada's Arctic. As a result, Inuit often have higher dietary Hg intake and elevated Hg blood concentrations. However, these same traditional foods are excellent sources of essential nutrients. The goals of this study were 1) to identify the traditional food sources of Hg exposure for Inuit, 2) to estimate the percentage of Inuit who meet specific nutrient Dietary Reference Intakes and/or exceed the Toxicological Reference Values (TRVs), and 3) to evaluate options that maximize nutrient intake while minimizing contaminant exposure. A participatory cross-sectional survey was designed in consultation with Inuit in 3 Canadian Arctic jurisdictions (Nunatsiavut, Nunavut, and the Inuvialuit Settlement Region). Estimated intakes for EPA (20:5n3) and DHA (22:6n3) met suggested dietary targets, and estimated selenium (Se) intake fell within the Acceptable Range of Oral Intake. Estimated intakes of Hg (rs = 0.41, P < 0.001), Se (rs = 0.44, P < 0.001), EPA (rs = 0.32, P < 0.001), and DHA (rs = 0.28, P < 0.001) were correlated with their respective blood concentrations. Mean estimated Hg intake (7.9 μg · kg(-1) · wk(-1)) exceeded the TRV of 5.0 μg · kg(-1) · wk(-1), with 35% of the population above this guideline. Because the estimated intakes of each of the nutrients were strongly correlated (Se: rs = 0.92, P < 0.001; EPA: rs = 0.82, P < 0.001; DHA: rs = 0.81, P < 0.001) with estimated Hg intake, efforts to decrease Hg exposure must emphasize the overall healthfulness of traditional foods and be designed to prevent concomitant harm to the nutrient intakes of Inuit.