nutrients Article Multiple Micronutrients, Including Zinc, Selenium and Iron, Are Positively Associated with Anemia in New Zealand Aged Care Residents Sue O. MacDonell 1, * , Jody C. Miller 2 , Michelle J. Harper 2 , Malcolm R. Reid 3 , Jillian J. Haszard 2 , Rosalind S. Gibson 2 and Lisa A. Houghton 2   Citation: MacDonell, S.O.; Miller, J.C.; Harper, M.J.; Reid, M.R.; Haszard, J.J.; Gibson, R.S.; Houghton, L.A. Multiple Micronutrients, Including Zinc, Selenium and Iron, Are Positively Associated with Anemia in New Zealand Aged Care Residents. Nutrients 2021, 13, 1072. https://doi.org/10.3390/nu13041072 Academic Editor: Jose Lara Received: 24 February 2021 Accepted: 23 March 2021 Published: 25 March 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Department of General Practice and Primary Care, School of Population Health, University of Auckland, Auckland 1072, New Zealand 2 Department of Human Nutrition, University of Otago, Dunedin 9054, New Zealand; jodym409@gmail.com (J.C.M.); michelle.harper@otago.ac.nz (M.J.H.); jill.haszard@otago.ac.nz (J.J.H.); Rosalind.gibson@otago.ac.nz (R.S.G.); lisa.houghton@otago.ac.nz (L.A.H.) 3 Trace Element Centre, Department of Chemistry, University of Otago, Dunedin 9054, New Zealand; malcolm.reid@otago.ac.nz * Correspondence: sue.macdonell@auckland.ac.nz Abstract: Anemia is a significant comorbidity for older adults not fully attributable to iron deficiency. Low-grade inflammation and other micronutrient deficiencies also contribute. This cross-sectional study examined the relationships between nutrient and non-nutrient factors with hemoglobin and anemia in 285 residents (>65 years) of 16 New Zealand aged-care facilities. Blood samples were analyzed for hemoglobin, ferritin, sTfR, hepcidin, zinc, selenium, and interleukin-6 (IL-6), (with ferritin, sTfR, zinc and selenium adjusted for inflammation). Linear regression models examined the relationships between micronutrient biomarkers (iron, zinc, selenium, vitamin B-12 and D), age, sex, and health factors with hemoglobin. Thirty-two percent of participants exhibited anemia, although <2% had either depleted iron stores or iron deficiency. Plasma zinc and selenium deficiencies were present in 72% and 38% of participants, respectively. Plasma zinc and total body iron (TBI) were positively associated (p < 0.05) with hemoglobin, while gastric acid suppressing medications, hepcidin, and interleukin-6 were inversely associated. These relationships were maintained after the application of anemia cut-offs. These findings emphasize the importance of considering multiple micronutrient deficiencies as risk factors for anemia. Keywords: anemia; inflammation; nursing home; anti-secretory medications; proton pump inhibitors; interleukin-6; soluble transferrin receptor; total body iron 1. Introduction Anemia in older adults is a significant comorbidity that increases with age and frailty [1]. Approximately 12% of community dwelling older adults over 65 years have hemoglobin concentrations indicative of anemia, and this proportion doubles for those aged over 80 years [2–5]. In aged-care facilities (nursing homes), the prevalence can be even higher, ranging from 25 to 60% [6–12]. Despite being frequently classified as mild and asymptomatic [8], anemia in older adults is associated with detrimental consequences that contribute to a reduced quality of life and include impairments in cognition, muscle strength and physical function as well as a greater incidence of frailty, admission to hospital and overall mortality [1,9,11,13,14]. The etiology of anemia in older adults is complex and attributed to multiple factors including age-associated physiological changes and chronic inflammation [1,15], medica- tions [16,17] and micronutrient deficiencies, most commonly of iron and vitamin B-12 [1,18]. However, low hemoglobin concentrations have also been associated with deficiencies of Nutrients 2021, 13, 1072. https://doi.org/10.3390/nu13041072 https://www.mdpi.com/journal/nutrients