![Figure 1. Determinants of iron deficiency anemia. In the public health context, IDA can be considered to have immediate and upstream determinants. Immediate determinants: Intestinal iron absorption is influenced by food factors (type of iron [heme or nonheme] and coconsumption of inhibitors or enhancers of absorption) and host factors (iron stores and genotype for hemoglobinopathy/iron regulation [eg, TMPRSS6]). Inhibitors of nonheme iron absorption include phytates, polyphenols (tannins), zinc, and calcium. Hookworms cause chronic gastrointestinal blood loss, and some schistosomes produce intestinal and genitourinary bleeding. Helicobacter pylori causes peptic ulcers and may cause resistance to iron therapy. In a term baby, total hemoglobin mass must almost double during the first year; more in ex-preterm or low-birth-weight babies. Iron requirements escalate rapidly during adolescence because of an expansion in hemoglobin and muscle mass and, in girls, menarche. Iron absorption and incorporation into erythrocytes is impaired during malaria (and possibly other) infection and restored after treatment, predominantly mediated by hepcidin. In pregnancy, overall iron requirements exceed 1 g, and each pregnancy results in a net iron loss of 580 to 680 mg. Upstream determinants: Low dietary iron content, consumption of predominantly nonheme iron, and coconsumption of iron with inhibitors of absorption (cereals, grains) result in inadequate iron intake. People in low-income (especially rural) settings may not be able to access fortified foods. Poor sanitation and disposal of human waste promotes bacterial and parasitic (including hookworm) infection, and schistosomiasis follows exposure to freshwater containing infectious larvae. All these factors may be influenced by access to health care, anemia control policies, sanitation practices, agricultural practices, and ultimately, prevailing economic, political, and environmental conditions. (Based on model presented in: “Strategy for Improved Nutrition of Children and Women in Developing Countries”, a UNICEF Policy Review, UNICEF, New York, 1990, 36 pp)](https://ash.silverchair-cdn.com/ash/content_public/journal/blood/121/14/10.1182_blood-2012-09-453522/4/2607f1.jpeg?Expires=1724876106&Signature=cdhTAx~RtH~mAeAIB9qcLoX80SFLm6IXZnqWjtBKZuD6GQOCFL32Q48ieHP5gUu-I77yTKSK7IGp7HuKNxXf~wwPMdhQ2ZcxXAOQ0QIgu4Q~0C1iKGZkVGgtfwhmk3BEIPJNZCaKNF6PjgHwrgbFhW6F5FnzoRlSuOyTZKW6kfUBzF-PvpstVyu2kfUcHEb5Vb8GJU1YoucUjsFSu~HgalFiC5qke176u2JgoTGlfwxKs0uMAOekrEzznk0pQ~54RX3GE13oUZkYOVxDtDXUs7yTm-fQVpVA-tZRPIlwqmkyWEmfNxNeeeeyhvRbxiVhdgXHBDoekEpeYmTNL2iZGg__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Determinants of iron deficiency anemia. In the public health context, IDA can be considered to have immediate and upstream determinants. Immediate determinants: Intestinal iron absorption is influenced by food factors (type of iron [heme or nonheme] and coconsumption of inhibitors or enhancers of absorption) and host factors (iron stores and genotype for hemoglobinopathy/iron regulation [eg, TMPRSS6]). Inhibitors of nonheme iron absorption include phytates, polyphenols (tannins), zinc, and calcium. Hookworms cause chronic gastrointestinal blood loss, and some schistosomes produce intestinal and genitourinary bleeding. Helicobacter pylori causes peptic ulcers and may cause resistance to iron therapy. In a term baby, total hemoglobin mass must almost double during the first year; more in ex-preterm or low-birth-weight babies. Iron requirements escalate rapidly during adolescence because of an expansion in hemoglobin and muscle mass and, in girls, menarche. Iron absorption and incorporation into erythrocytes is impaired during malaria (and possibly other) infection and restored after treatment, predominantly mediated by hepcidin. In pregnancy, overall iron requirements exceed 1 g, and each pregnancy results in a net iron loss of 580 to 680 mg. Upstream determinants: Low dietary iron content, consumption of predominantly nonheme iron, and coconsumption of iron with inhibitors of absorption (cereals, grains) result in inadequate iron intake. People in low-income (especially rural) settings may not be able to access fortified foods. Poor sanitation and disposal of human waste promotes bacterial and parasitic (including hookworm) infection, and schistosomiasis follows exposure to freshwater containing infectious larvae. All these factors may be influenced by access to health care, anemia control policies, sanitation practices, agricultural practices, and ultimately, prevailing economic, political, and environmental conditions. (Based on model presented in: “Strategy for Improved Nutrition of Children and Women in Developing Countries”, a UNICEF Policy Review, UNICEF, New York, 1990, 36 pp)
