American Journal of Clinical Nutrition, Vol 27, 152-162, Copyright © 1974 by The American Society for Clinical Nutrition, Inc.

Measurement of the total daily dietary iron absorption by the extrinsic tag model

¹ From the Instituto Venezolano de Investigaciones Cientificas, Apartado 1827 Caracas, Venezuela

Measurement of the daily non-heme iron absorption from diets consumed in several areas of Venezuela was determined by the extrinsic tag method. Diets were selected from three regions (Central region, Andes and Coast) with different environment and food habits. Breakfast and lunch extrinsically tagged with ⁵⁹Fe and ⁵⁵Fe, respectively, were administered on the first 2 days of each study. Fifteen days later, blood was drawn to determine hematological characteristics and radioactivity and subjects were fed again with supper tagged with ⁵⁹Fe. Finally a standard dose of iron ascorbate tagged with ⁵⁵Fe was administered on the 16th day and blood was taken 2 weeks later to determine the increase of blood radioactivity. Neither milk nor cheese and butter improved the poor absorption of vegetal iron administered at breakfast. Absorption of 3 to 4 mg of vegetal iron was increased about twice by the effect of 50 mg of meat, about thrice by 100 g of fish and about five times by 150 g of papaya containing 66 mg of ascorbic acid. The absorption from heme iron in meat accounts for 62 and 42% of the total iron absorbed from Central Andes diets, respectively, whereas fish iron absorption accounts for about 10% of the total iron absorbed. The data presented indicate that the amount of dietary iron does not reflect the net amount of iron absorbed by the individuals and that ingredients of a meal such as beef, fish and fruits are paramount to obtain a reasonable utilization of the non-heme iron.