Absorption of Co60-labeled vitamin B12 in man and uptake by parasites, including Diphyllobothrium latum.

Abstract

Abstract Intestinal absorption of vitamin B 12 labeled with radiocobalt (Co 60 ), using the urinary excretion method of Schilling, was determined in six nonanemic patients infected with Diphyllobothrium latum, four with Tacnia saginata, twelve with Ascaris lumbricoides, one with Necator americanus, one with Trichuris trichiura, and eight with Giardia lamblia. Normal urinary excretion ranging from 8 to 22 per cent of the oral dose was found in all instances, except that one patient with both giardiasis and sprue excreted only 1 per cent of the dose; this was thought to be caused by the sprue and not the giardiasis. Seven fish tapeworms (D. latum) showed significant uptake of Co 60 -tagged vitamin B 12 varying from 2.6 to 13.7 per cent of the oral dose given to the host, whereas none of the other helminths showed any appreciable uptake. The relationship of these findings to the development of pernicious anemia caused by tapeworms and the geographic differences in the ability of D. latum to interfere with absorption of vitamin B 12 and produce macrocytic anemia in the host are discussed.