Effects of soluble corn bran arabinoxylans on cecal digestion, lipid metabolism, and mineral balance (Ca, Mg) in rats

The effects of soluble corn bran arabinoxylans on cecal digestion, lipid me tabolism, and mineral utilization [calcium (Ca) and magnesium (Mg)] were in vestigated 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 (c ontrol + cholesterol and arabinoxylans + cholesterol, respectively). Compar ed with rats fed the control diets, rats fed the arabinoxylan diets had sig nificant cecal hypertrophy (+50% after 3 days of the fiber adaptation) and an accumulation of short-chain fatty acids, especially propionic acid (up t o 45% in molar percentage). Arabinoxylans enhanced the cecal absorption of Ca an Mg (from 0.07 to 0.19 mu mol/min for Ca and from 0.05 to 0.23 mu mol/ min for Mg) Mg balance was enhanced by arabinoxylans (+25%). The arabinoxyl an diet markedly reduced the cholesterol absorption from 50% of ingested ch olesterol in controls up to approximately 15% in mts adapted to the arabino xylans diet. Arabinoxylans were effective in lowering plasma cholesterol (a pproximately -20%). There was practically no effect of the diets on cholest erol in d > 1.040 lipoproteins (high density lipoproteins) whereas arabinox ylans were very effective in depressing cholesterol in d > 1.040 lipoprotei ns (especially in triglyceride-rich lipoproteins). Corn fermentable fiber d ecreased the accumulation of cholesterol in the liver. In parallel, the ara binoxylan diet counteracted the downregulation of 3-hydroxy-3-methylglutary l-CoA by cholesterol. These data suggest that arabinoxylans may have a grea t impact on intestinal fermentation, mineral utilization, and cholesterol m etabolism. (J. Nutr. Biochem. 10:500-509, 1999) (C) Elsevier Science Inc. 1 999. All rights reserved.