Healthy adults require 8 mg of iron per day from heme (meat and animal products) iron and/or non-heme (vegetables, nuts, fruit, and other sources) iron. Heme iron is absorbed more readily by the body than non-heme iron.1 This has implications for vegetarians. Even if their total dietary iron intake meets recommended levels, they might not be getting enough iron into their systems. Their diet may need almost twice as much dietary iron each day as the diets of nonvegetarians because of the lower intestinal absorption of non-heme iron in plant foods. Vegetarians should consider consuming non-heme iron sources together with a good source of vitamin C, such as citrus fruits, to improve the absorption of non-heme iron.
You could also be missing adequate iron because of the combination of foods you’re eating, such as tannins (found in tea), calcium, polyphenols, and phytates (found in legumes and whole grains).2
1 Barton JC. Iron deficiency. In: Rakel RE, Bope ET, eds. Conn’s Current Therapy. Amsterdam, the Netherlands: Saunders/Elsevier; 2008: 385-389.
2 Dietary supplement fact sheet: iron. National Institutes of Health Office of Dietary Supplements Web site. http://ods.od.nih.gov/factsheets/Iron-HealthProfessional/. Accessed April 3, 2013.