Effects of Soluble Corn Bran Arabinoxylans on Cecal Digestion, Lipid Metabolism, and Mineral Balance (Ca, Mg) in Rats

J Nutr Biochem. 1999 Sep;10(9):500-9. doi: 10.1016/s0955-2863(99)00036-4.

Abstract

The effects of soluble corn bran arabinoxylans on cecal digestion, lipid metabolism, and mineral utilization [calcium (Ca) and magnesium (Mg)] were investigated in rats adapted to semipurified diets. The diets provided either 710 g/kg wheat starch alone (control) or 610 g/kg wheat starch plus 100 g/kg corn soluble fiber (arabinoxylans) and either 0 or 2 g/kg cholesterol (control + cholesterol and arabinoxylans + cholesterol, respectively). Compared with rats fed the control diets, rats fed the arabinoxylan diets had significant cecal hypertrophy (+50% after 3 days of the fiber adaptation) and an accumulation of short-chain fatty acids, especially propionic acid (up to 45% in molar percentage). Arabinoxylans enhanced the cecal absorption of Ca and Mg (from 0.07 to 0.19 micromol/min for Ca and from 0.05 to 0.23 micromol/min for Mg). Mg balance was enhanced by arabinoxylans (+25%). The arabinoxylan diet markedly reduced the cholesterol absorption from 50% of ingested cholesterol in controls up to approximately 15% in rats adapted to the arabinoxylans diet. Arabinoxylans were effective in lowering plasma cholesterol (approximately -20%). There was practically no effect of the diets on cholesterol in d > 1.040 lipoproteins (high density lipoproteins) whereas arabinoxylans were very effective in depressing cholesterol in d < 1.040 lipoproteins (especially in triglyceride-rich lipoproteins). Corn fermentable fiber decreased the accumulation of cholesterol in the liver. In parallel, the arabinoxylan diet counteracted the downregulation of 3-hydroxy-3-methylglutaryl-CoA by cholesterol. These data suggest that arabinoxylans may have a great impact on intestinal fermentation, mineral utilization, and cholesterol metabolism.