Abstract: Dietary fiber is one of the essential nutrients to the human body. The fiber itself can not be directly absorbed and utilized by the body, but it has some effects on gastrointestinal tract function and absorption of many nutrients. The nutrients include macronutrients - protein, lipids and carbohydrates; micronutrients - vitamins, minerals and microelements. Dietary fiber does not have significant effect on protein metabolism and nitrogen balance, but some fiber can decrease the absorption and availability of lipids and carbohydrates. Some experiments show that dietary fiber does not affect absorption and availability of minerals and microelements, but some other experiment reports indicate that dietary fiber can prompt the absorption. Experi-mental results show that dietary fiber may affect the absorption of vitamin A, vitamin E and vitamin B12 but it has no obvious impact on the bioavailability of any other vitamins.

Key words: dietary fiber, nutrients, digestion and absorption