Dietary fi ber intake provides many health benefi ts. A generous intake of dietary fi ber reduces risk for developing the diseases including coronary heart disease [Liu et al. 1999], stroke [Steffen et al. 2003], hypertension [Whelton et al. 2005], diabetes [Montonen et al. 2003], obesity [Lairon et al. 2005] and certain gastrointestinal disorders [Petruzziello et al. 2006]. Furthermore, increased consumption of dietary fi ber improves serum lipid concentrations [Brown et al. 1999], lowers blood pressure [Keenan et al. 2002] [Watzl et al. 2005].Traditionally, dietary fi ber was defi ned as the portions of plant foods that were resistant to digestion by human digestive enzyme; this included polysaccharides and lignin. More recently, the defi nition has been expanded to include oligosaccharides, such as inulin, and resistant starches [Jones et al. 2006]. As simple, fi bers have been classifi ed as soluble, such as viscous or fermentable fi bers (such as pectin) that are fermented in the colon, and insoluble fi bers, such as wheat bran, that have bulking action but may only be HEALTH EFFECTS OF DIETARY FIBER ABSTRACTDietary fi bre is a group of food components which is resistant to digestive enzymes and found mainly in cereals, fruits and vegetables. Dietary fi ber and whole grains contain a unique blend of bioactive components including resistant starches, vitamins, minerals, phytochemicals and antioxidants. Dietary fi ber which indigestible in human small intestinal, on the other hand digested completely or partially fermented in the large intestine, is examined in two groups: water-soluble and water insoluble organic compounds. Dietary fi ber can be separated into many different fractions. These fractions include arabinoxylan, inulin, pectin, bran, cellulose, β-glucan and resistant starch. Dietary fi bres compose the major component of products with low energy value that have had an increasing importance in recent years. Dietary fi bres also have technological and functional properties that can be used in the formulation of foods, as well as numerous benefi cial effects on human health. Dietary fi bre components organise functions of large intestine and have important physiological effects on glucose, lipid metabolism and mineral bioavailability. Today, dietary fi bers are known to be protective effect against certain gastrointestinal diseases, constipation, hemorrhoids, colon cancer, gastroesophageal refl ux disease, duodenal ulcer, diverticulitis, obesity, diabetes, stroke, hypertension and cardiovascular diseases. In this review the physicochemical and biological properties of dietary fi bers and their important implications on human health will be investigated.

Arsenic is a very toxic element that must be removed efficiently from aqueous streams. Among the most promising techniques used for the removal of arsenic are separation methods using membranes. In this study, a regenerated cellulose ultrafiltration (UF) membrane and a poly(diallyl dimethyl ammonium chloride) P(DADMAC) were coupled and used in combination to remove As(V) from an aqueous solution. The influences of pH, the polymer:As(V) molar ratio, and the presence of interfering ions such as chloride and sulfate were investigated in arsenic removal via the washing method. The efficient retention of arsenic was observed at pH 7 with a 5:1 polymer:As molar ratio and with an efficiency of approximately 85 % at Z = 10 for P(DADMAC). The maximum retention capacity of As(V) was determined by the enrichment method, and the results indicated that 194 mg of As(V) was removed per gram of polymer. Finally, using enrichment and washing methods sequentially, the sorption-desorption process and regeneration of P(DADMAC) were performed successfully.