Mineral contents of brans passed through the human GI tract.

Concentrations of Cu, Fe, Zn, Ca, and phytate were measured in dry-milled corn bran, wheat brans, and soybean hulls prior to being baked in bread and after passage through the human GI tract. Significant changes in mineral concentrations in the retrieved remnants compared to the starting materials were as follows: Cu, Fe, and Zn increased by factors of from two to four and Ca increased at least ten-fold in dry milled corn bran; Ca increased and phytate decreased in wheat brans; Zn increased and Fe decreased in soy hulls. These studies show that indigestible remnants of wheat brans in the human colon associate preferentially with calcium and that dry milled corn bran remnants can be loaded with increased concentrations of all four minerals, and especially with calcium. Concentrations of minerals and phytate were significantly greater in whole fecal samples from wheat bran diets than in the corresponding retrieved bran remnants.