Prevalence of unexplained anaemia in Inuit men and Inuit post-menopausal women in Northern Labrador: International Polar Year Inuit Health Survey

Abstract

OBJECTIVE: To identify correlates of hemoglobin (Hb) and anaemia unexplained by iron deficiency (UA) in Canadian Inuit adults. METHODS:A cross-sectional survey assessed diet, demographic information, anthropometry, fasting Hb, ferritin, soluble transferrin receptor (on a subset), high-sensitivity C-reactive protein (hs-CRP) in serum, red blood cell (RBC) fatty acid composition, blood lead, and antibodies to Helicobacter pylori in non-pregnant, Inuit adults (n = 2550), ≥18 years of age from randomly selected households in 36 Inuit communities in Inuvialuit Settlement Region, Nunavut Territory and Nunatsiavut of Northern Labrador, Canada.RESULTS: Hb concentrations were lower and UA prevalence higher in Inuit men after 50 years of age. Rate of anaemia was constant among Inuit women but changed from primarily iron deficiency anaemia pre-menopause, to primarily UA in post-menopause. Low education levels and hs-CRP were associated with increased risk of UA. For Inuit men, % RBC eicosapentaenoic acid (EPA) and elevated blood lead were also associated with increased risk of UA. Frequency of traditional food intake was positively associated with Hb.CONCLUSION: Age patterns and regional variation of anaemia suggest that ethnicity-related physiological differences cannot explain anaemia prevalence for Inuit. High RBC EPA status, inflammation and infections, and lower education levels may contribute to the prevalence of anaemia in this population, which is not related to iron status. Thus, traditional lifestyle may protect Inuit from nutritional anaemia but contribute to lower Hb through environmental exposures. The clinical significance of UA for older Inuit adults requires further investigation, as the prevalence represents a moderate public health problem. 14 Education level was assessed by number of school grades completed and dichotomized into ≤ elementary school (grade 6) or > elementary school. Dietary assessment was conducted with a single 24-hour recall using a four-stage, multipass approach and a semi-quantitative food frequency questionnaire (FFQ) with 37 traditional food (TF) items and 5 market foods. The FFQ assessed frequency of intake over the past year according to seasonal availability, as previously described. 2,14TF was defined as animal and plant species culturally identified as food and harvested from the local environment, whereas market food was that shipped from the South and purchased in stores 12 .Recall data were entered into CANDAT software (Godin London) and nutrient analyses obtained from the 2007b Canadian Nutrient File and supplemental databases, as previously described. 2,3,14 Statistical analysisSmoking-adjusted (# cigarettes/day) mean Hb concentrations by age decile were analyzed by one-way ANOVA and reported in Figure 1. Weighted prevalence estimates of IDWA (iron deficiency without anaemia), IDA and UA are presented in Figure 2. Sampling weights reflected the proportion of participating adults using Statistics Canada's Census data of age-appropriate Inuit by community. Independe...

Anemia, iron status, and associated protective and risk factors among children and adolescents aged 3 to 19 years old from four First Nations communities in Quebec

“…Conversely, among boys, inflammation was associated with lower Hb, and traditional meat intake was associated with higher SF and Hb concentrations. Comparable results were reported in adult Inuit men and women, for whom anemia was mainly iron-dependent in premenopausal women but inflammatory-related in men (Jamieson et al 2016). Inflammation is known to antagonize the absorption of iron mediated by vitamin C as it enhances hepcidin release and down regulates feroportin1, an iron transporter in the small intestine (Jamieson et al 2012;Sears 1992).…”

“…In these communities, dietary shifting from traditional foods, largely composed of wild animal, fish, birds, fruits, and plants, to poor-quality market foods lower in iron often results in iron deficiency (ID) (INSPQ 2015) and if severe enough to impair erythropoiesis, to iron deficiency anemia (IDA) (Christofides et al 2005). Furthermore, inflammation secondary to infection and obesity disturbs Hb and red blood cell synthesis, and results in anemia of chronic inflammation (ACI) (Jamieson et al 2016;Cash and Sears 1989). Other vitamin deficiencies, along with lead (Pb) intoxication (at exposure levels above 100 μg/L), are also known causes of anemia that some researchers in population studies regroup as unexplained anemia (UA) (Christofides et al 2005;Jamieson et al 2012;Plante et al 2011;Hegazy et al 2010).…”

Potential impact of restricted caribou (Rangifer tarandus) consumption on anemia prevalence among Inuit adults in northern Canada

“…As described in greater detail elsewhere [6,24,25], blood biomarkers of nutrient status and contaminant exposure were quantified from fasting (8-16 h preceding the interview) venous blood samples. Blood samples were collected by certified nurses in vacutainer tubes with clot activator and polymer gel for serum separation (Becton Dickinson), or EDTA-coated vacutainers for whole blood hematology.…”

“…Hb from venous blood samples (morning participants) and blood drops from a finger prick (afternoon participants) was determined using the azide methemoglobin method with a HemoCue 201+ portable photometer (HemoCue; Lake Forest, California). Serum ferritin (SF) and high-sensitivity C-reactive protein (hs-CRP) were quantified by automated chemiluminescence assay (Liaison Ferritin; Diasorin, Italy) and by auto-analyzer (Beckman Coulter; Brea, California), respectively [6]. Soluble transferrin receptor (sTfR) levels were determined by ELISA (R&D Systems; Minneapolis, Minnesota) for a subsample of the population (n = 1039).…”

“…Moreover, anemia is disproportionately represented in people of lower socioeconomic strata [2], and Indigenous Peoples in various global regions [3]. Among Inuit (Arctic Indigenous People) in northern Canada, the prevalence of anemia is several times higher than the average prevalence documented in many developed countries (approximately 8%) [4], and corresponds to a moderate (25-30% prevalence) to severe (40-43% prevalence) public health problem [5][6][7].…”