Comparative Effects of Iron Deficiency Induced by Bleeding and a Low-Iron Diet on the Intestinal Absorptive Interactions of Iron, Cobalt, Manganese, Zinc, Lead and Cadmium1 PETER R. FLANAGAN,2 JAMES HAIST AND LESLIE S. VALBERG Department of Medicine, University Hospital and The University of Western Ontario, London, Ontario, Canada N6A 5A5 ABSTRACT Dietary iron deficiency enhances the absorption of iron, cobalt, manganese, zinc, cadmium and lead, whereas, iron deficiency due to bleeding in creases the absorption of iron, cobalt and perhaps manganese. To determine whether the response to bleeding is qualitatively different from that induced by dietary iron deficiency, metal absorption was studied in mice fed either a high- iron diet (120 ppm Fe) and bled (0.5 ml) or fed a low-iron diet (<3 ppm Fe). Iron absorption from an intragastric dose was increased by the loss of 0.5 ml of blood; smaller losses of blood had no effect. Also, iron absorption was increased more by dietary iron deficiency than by bleeding. In perfusion experiments, bleeding in creased the duodenal absorption of only iron and cobalt, whereas dietary iron deficiency enhanced the absorption of all the metals except cadmium. The pat terns of absorptive inhibition of the metals by each other were similar in bled mice and in mice with dietary iron deficiency except that interactions among metals with lower affinities for the iron absorption mechanism —manganese, zinc, cadmium and lead —were more obvious in mice fed the low-iron diet. We concluded that bleeding only partially activates the iron absorptive mechanism and that the lack of a bleeding effect on the absorption of manganese, zinc, cad mium and lead results from the weaker interactions of these metals with a partly- activated absorption process. J. Nutr. 110: 1754-1763, 1980. INDEXING KEY WORDS iron deficiency •heavy metals •interactions Iron deficiency induced by feeding animals fed an iron-supplemented diet animals a low-iron diet has been widely has been used as well in studies of metal used in studies of intestinal absorption of absorption. However, this technique ap- iron and closely related metals. The pears to enhance the absorption of iron, results have revealed that the intestinal cobalt and manganese (1) but not that of transport system is not exclusive for iron, zinc (1, 4), lead (9) and cadmium.3 This When dietary iron is low, the absorption difference may be either a qualitative or of trace elements such as iron, cobalt, a quantitative effect. On the one hand, manganese and zinc (1-4) and certain bleeding may activate transport mech- toxic metals such as lead and cadmium (5-9) is increased. These metals appear to Received forpublication s February isso. Share at least part of the Same absorptive ' This research was supported by the Medical Research Council of pathway and to compete for analogous ^Ä^^ transport Sites (10) of Medicine, University Hospital, Box .5339, Terminal A, London, - i.,, Ontario, Canada, N6A 5A5. Iron deficiency induced by bleeding ' Hamilton, D.L.&vaiberg, L.s. unpublishedata. 17,54 by guest on June 24, 2013 jn.nutrition.org Downloaded from