Nonheme-iron absorption from a phytate-rich meal is increased by the addition of small amounts of pork meat

Abstract

Muscle tissue from various sources is known to promote nonheme-iron absorption. However, systematic studies of the dose dependency of this effect of meat on iron absorption from an inhibitory meal with low amounts of meat are lacking. We investigated the dose-response effect of small amounts of meat on nonheme-iron absorption from a meal presumed to have low iron bioavailability. Forty-five healthy women with a mean (+/-SD) age of 24 +/- 3 y were randomly assigned to 1 of 3 groups, each of which was served (A) a basic meal (rice, tomato sauce, pea purée, and a wheat roll) and (B) the basic meal with either 25, 50, or 75 g pork (longissimus muscle). Meal A contained 2.3 mg nonheme iron, 7.4 mg vitamin C, and 220 mg (358 micro mol) phytate. Each meal was served twice, and the order of the meals was ABBA or BAAB. The meals were extrinsically labeled with (55)Fe or (59)Fe. Iron absorption was determined from measurements of (59)Fe whole-body retention and the activity of (55)Fe and (59)Fe in blood samples. Twenty-five grams meat did not increase nonheme-iron absorption significantly (P = 0.13), whereas absorption increased 44% (P < 0.001) and 57% (P < 0.001), respectively, when 50 and 75 g meat were added to the basic meal. In absolute values, this corresponds to an absorption that was 2.6% and 3.4% higher, respectively, than that with the basic meal after adjustment of the data to a level of 40% absorption from a reference dose. Small amounts of meat (>or=50 g) significantly increase nonheme-iron absorption from a phytate-rich meal low in vitamin C.