Date of Award:

1987

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Nutrition and Food Sciences

Advisor/Chair:

Arthur W. Mahoney

Abstract

To study the effect of meat (beef) on dietary iron bioavailability from enriched white bread (EWB) or whole wheat bread (WWB), diets were prepared in which the ratios of beef iron to bread iron were 100:0, 75:25, 50:50, 25:75 or 0:100. Hemoglobin regeneration efficiency (HRE), apparent iron absorption, and dry matter absorption were determined using weanling anemic and healthy male rats.

Meat iron was more available than EWB or WWB. Fortification iron in EWB was less available than the iron naturally present in WWB. At the iron dose given, HRE was similar for both anemic and healthy rats. Although healthy rats absorbed less dietary iron than the anemic ones, bread types did not affect percent iron absorbed. Iron status did not affect dry matter absorption from meat, bread or meat:bread mixtures. Meat did not enhance iron bioavailability from EWB or WWB diets.

To study the iron bioavailability of meat loaf prepared from meat and whole wheat flour (WWF) or whole wheat bread (WWB), diets were formulated with 30 ppm iron as cooked meat, WWF, WWB, meat loaf with 67% of the iron from meat and 33% from flour (or bread), or meat loaf with 33% of the iron as meat and 67% from flour (or bread). HRE, apparent iron absorption, dry matter absorption, total body iron gain (iron retention), iron59 retention and absorption and heme iron absorption were determined using anemic and healthy male rats.

HRE•s for healthy rats were similar for both meat:flour or meat:bread loaves. Anemic rats absorbed more iron than healthy rats. Baking increased slightly the percent iron absorbed by anemic rats. Iron status did not affect dry matter absorption from t he diets. The total iron bioavailability of the whole wheat flour or bread diets was not enhanced by dietary meat.

Anemic rats retained and absorbed more iron59 than healthy rats and this difference increased with the ratio of iron from flour or bread in the meat loaves. The absorption of iron 59 (nonheme iron) was influenced by source of iron in the diet (meat, flour, bread or FeS04) and also nutritional status (anemic or healthy rats). Healthy rats had almost one-half the specific activity in their bodies and hemoglobin iron as the anemic ones had. Baking the flour into bread did not affect the specific activity of liver, body or hemoglobin iron. It was concluded that meat did not enhance nonheme iron absorption in this study.

Heme iron absorption, determined by indirect means, was about 50% of the total heme iron in the diets for both anemic and healthy rats.

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