Abstract: Epidemiological studies indicate that cereal dietary fiber (DF) has physiological effects by reducing the risk of many chronic metabolic diseases such as cardiovascular diseases, obesity, type Ⅱ diabetes and some gastrointestinal cancers. Pentosans, also known as arabinoxylans (AX), are the major part of dietary fiber in many cereals. They can be degraded in the colon by specific intestinal bacteria possessing AX-degrading enzymes, and promote the growth of bifidobacteria and lactobacilli in the gut. The prebiotic properties of pentosans are mainly affected by various degrees of polymerization, substitution, and cross-linking as well as side chain distribution. The beneficial effects of pentosans are attributed to bound ferulic acid besides their own molecular structures, which has a slow and continuous release and absorption through the colon to provide important antioxidant protection.

Key words: dietary fiber, cereal, pentosans, ferulic acid, gut microflora