Dietary fiber extracted from wheat bran pharmaceutical and dietary compositions containing same

A dietary fiber which is obtained by a process comprising the steps of:

• (i) extracting, at least once, wheat bran with water at a temperature of 180.degree. to 200.degree. C., (ii) filtering and removing insoluble substances from the extracted solution, (iii) purifying the extracted solution by salting-out, dialysis, ultrafiltration, reverse osmosis, gel filtration or precipitation to remove substances having molecular weight not higher than 400, and (iv) freeze-drying the purified solution to obtain a solid dietary fiber, the resulting dietary fiber having the following properties:
• (a) an average molecular weight of 5.times.10.sup.2 to 1.times.10.sup.5 measured by a GPC-Lalls method;
• (b) a sugar content, determined by a color reaction of the phenol-sulfuric acid method, of 95.3 to 99.0% by weight and a protein content, determined by a color reaction of the Lowry-Folin method, of 0.1 to 3.0% by weight;
• (c) contains 88.2 to 95.4 mol % glucose, 3.7 to 7.7 mol % xylose, 0.1 to 1.2 mol % galactose, 1.0 mol % or less fructose and 1.1 mol % or less arabinose;
• (d) contains at least one amino acid selected from the group consisting of aspartic acid, threonine, serine, glutamic acid, proline, glycine, alanine, cysteine, valine, isoleucine, leucine, tyrosine, phenylalanine, hydroxylsine, lysine, histidine, and arginine;
• (e) a molecular ratio between .alpha.-bound glucose and .beta.-bound glucose in a glucose component of 1:40 to 1:80;
• (f) a molar concentration of 1,4-glucose bond is 85 to 90% and a molar concentration of 1,3-glucose bond is 4 to 10%;
• and
• (g) an analytical result of a sugar component thereof by the Southgate method is:
• ______________________________________ % by weight ______________________________________ water soluble and hardly digestible polysaccharides 78 to 96 cellulose 1.0 to 5.7 hemicellulose 1.7 to 15 lignin 1.3 to 3.3. ______________________________________