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.
Key Words: Hemoglobin, anaemia, indigenous health, inflammation, nutrition
Résumé
OBJECTIF: Déterminer les corrélats de l’hémoglobine (Hb) et de l’anémie non expliquée par une carence en fer (anémie inexpliquée) chez les Inuits adultes du Canada.
MÉTHODE: Une enquête transversale a permis d’évaluer le régime, le profil démographique, l’anthropométrie, l’Hb à jeun, la ferritine, le récepteur soluble de la transferrine (sur un sous-ensemble), la protéine C-réactive ultrasensible (hsCRP) sérique, la composition des acides gras érythrocytaires, le taux de plomb dans le sang, et les anticorps à Helicobacter pylori chez les Inuits adultes à l’exception des femmes enceintes (n = 2 550), âgés de ≥18 ans provenant de ménages sélectionnés au hasard dans 36 communautés inuites dans la région désignée des Inuvialuits, au Nunavut et au Nunatsiavut dans le Nordlabrador, au Canada.
RÉSULTATS: Les concentrations en Hb étaient inférieures et la prévalence de l’anémie inexpliquée était supérieure chez les hommes inuits après l’âge de 50 ans. Le taux d’anémie était constant chez les femmes inuites, mais alors qu’avant la ménopause il s’agissait principalement d’anémie ferriprive, après la ménopause, il s’agissait principalement d’anémie inexpliquée. Les faibles niveaux d’instruction et l’hsCRP étaient associés à un risque accru d’anémie inexpliquée. Chez les hommes inuits, les taux élevés d’acide eicosapentanoïque (AEP) érythrocytaire et de plomb dans le sang étaient également associés à un risque accru d’anémie inexpliquée. La fréquence de l’alimentation traditionnelle présentait une association positive avec l’Hb
CONCLUSION: La répartition par âge et les écarts régionaux de l’anémie indiquent que les différences physiologiques liées à l’ethnicité ne peuvent expliquer la prévalence de l’anémie chez les Inuits. L’AEP érythrocytaire, l’inflammation et les infections élevés, ainsi que les faibles niveaux d’instruction, peuvent contribuer à la prévalence de l’anémie dans cette population, prévalence qui n’est pas liée au bilan en fer. Ainsi, le mode de vie traditionnel peut protéger les Inuits contre l’anémie nutritionnelle, mais contribuer à réduire l’Hb par les expositions environnementales. La signification clinique de l’anémie inexpliquée chez les Inuits adultes plus âgés exige une enquête plus poussée, car sa prévalence représente un problème de santé publique modéré.
Mots Clés: hémoglobine, anémie, santé autochtone, inflammation, nutrition
Footnotes
Acknowledgements: Sources of funding included: Canadian Federal Program for International Polar Year, Health Canada, Canadian Institutes of Health Research, Indian and Northern Affairs Canada, Government of Nunavut Health and Social Services, ArcticNet. JJ was supported by a CIHR Doctoral Research Award. GE and HW were both in receipt of Canada Research Chair salary awards. We acknowledge the guidance throughout this project of the regional steering committees of Inuvialuit Settlement Region, Nunavut and Nunatsiavut for the Inuit Health Survey, and the entire survey team, especially CINE and McGill University support staff and our many collaborators. Finally, all participating communities and participants are warmly acknowledged and thanked.
Conflict of Interest: None to declare.
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