AVAILABILITY OF CALCIUM, MAGNESIUM, PHOSPHORUS, IRON, AND ZINC IN RATS FED OAT BRAN CONTAINING DIETS

Rats were used to study the effects of nonheated oat bran (NHOB) and baked oat bran (BOB) on apparent absorption and retention of Ca, Mg, P, Fe, and Zn. Four isonitrogenous and isoenergetic diets consisting of a control, 15% NHOB, 30% NHOB, and 30% BOB were fed for 28 days. Oat bran was baked under moisture and heat conditions simulating dough preparation and bread-making. BOB had higher insoluble fiber (mainly beta-glucans and Klason lignin), lower total phytate, and diminished levels of highly phosphorylated inositols. NHOB feeding reduced Ca availability and impaired absorption of mineral Ca. Magnesium absorption and retention (percent of intake) were lower in the NHOB groups; due to compensation of Mg output by NHOB intake, daily Mg absorption and retention increased. Fe, Zn, and P showed higher daily absorption and retention in the NHOB groups. As compared with NHOB, ingestion of BOB resulted in lower Ca and Fe availability and had no effect on Zn and P; daily Mg absorption and retention were not affected.