Oat or bean products, rich in water-soluble fiber, have distinct hypocholesterolemic effects in humans. After a control diet, 20 hypercholesterolemic men were randomly allocated to oat-bran or bean supplemented diets for 21 days on a metabolic ward. Control and test diets provided equivalent energy, fat, and cholesterol but test diets had twice more total and 3-fold more soluble fiber. Oat-bran diets decreased serum cholesterol concentrations by 19% (p less than 0.0005) and calculated low-density lipoprotein cholesterol by 23% (p less than 0.0025). Bean diets decreased serum cholesterol concentrations by 19% (p less than 0.0005) and low-density lipoprotein cholesterol by 24% (p less than 0.0005). Oat-bran increased fecal weight by 43% but beans did not. While oat-bran increased fecal bile acid excretion, beans had the opposite effect. Oat-bran or bean supplements may have an important role in nutritional management of selected hypercholesterolemic patients.

SCF, a nondigestible carbohydrate, increased calcium absorption in free-living adolescent females. Two groups of bacteria may be involved, one directly fermenting SCF and the second fermenting SCF metabolites further, thereby promoting increased calcium absorption. This trial was registered at clinicaltrials.gov as NCT01660503.

The binding in vitro of the sodium salts of cholic acid, chenodeoxycholic acid, deoxycholic acid, taurocholic acid, taurochenodeoxycholic acid, taurodeoxycholic acid, glycocholic acid, glycochenodeoxycholic acid, and glycodeoxycholic acid by alfalfa, bran, cellulose, lignin, and cholestyramine was measured. Cholestyramine bound an average of 81.3% of all the bile acids and salts tested whereas cellulose bound only negligible amounts (1.4%). Of the other substances tested, lignin bound 29.2%, alfalfa, 15.9% and bran, 9.0%. No distinct pattern of binding was discerned. It is therefore apparent that the validity of statements concerning the effect of fiber on bile salf metabolism rests upon the specificity of the composition of the fiber involved and the bile acids or salts tested.

Dietary fibers are thought to benefit bone health through increasing mineral absorption and retention following fermentation in the lower gut and solubilization of minerals. This study compared eight fibers to cellulose following a 12 week intervention for production of short-chain fatty acids (SCFA), calcium absorption, mineral retention and bone content, and bone density and strength in a weanling rat model. Benefits to bone were poorly to modestly related to SCFA production, calcium absorption, or mineral retention, but some parameters were better predicted by cecal content weight, suggesting other mechanisms may be important. Nevertheless, two resistant starches, a soluble fiber dextrin and Polydextrose, increased bone calcium content. Soluble corn fiber and soluble fiber dextrin had the greatest benefit to bone properties including whole body bone mineral content and density and greater volumetric bone mineral density, cortical thickness and area, and peak breaking strength of the distal femur.

Nine normolipidemic young men consumed a constant diet for 2 mo into which oat bran was incorporated during the second month so that we might test the hypotheses that oats lower serum cholesterol concentrations by decreasing bile acid and fat absorption and increasing bile acid synthesis. Bile acid kinetics were determined by measuring the 13C enrichment of serum cholic and chenodeoxycholic acids. Oat bran consumption decreased serum cholesterol levels (p < 0.01) and cholic acid pool size (p < 0.05). Deoxycholic acid pool size (p < 0.01) and the synthesis and fractional turnover rates of both primary bile acids (p < 0.05) increased. Total bile acid pool size did not change. Fecal excretion of total bile acids, the two secondary bile acids and fat increased significantly. The results demonstrate that oat bran lowers serum cholesterol levels in part by altering bile acid metabolism. In addition, the substantial increase in the proportion of the total bile acid pool that was deoxycholic acid is consistent with the hypothesis that oat bran also decreases cholesterol synthesis.