Fiber, dietary types

Liu, S., Whole-grain foods, dietary fiber, and type 2 diabetes searching for a kernel of truth. Am. J. Clin. Nutr. 77, 527, 2003. 

CHANDALIA M, GARG A, LUTJOHANN D, VON BURGMANN K, GRUNDY S M, BRINKLEY L J (2000) Beneficial effects ofhigh dietary fiber intake in patients with Type 2 Diabetes Mellitus. N Eng J Med, Ml 1392-8. 

Aldoori WH, Giovannucci EL, Rockett HRH, Sampson L, Rimm EB, Willet WC A prospective study of dietary fiber types and symptomatic diverticular disease in men. J Nutr 1998 128 717-719. 

Some types of mushrooms contain moderate quantities of good-quality protein and are good sources of dietary fiber, vitamins C and B, and minerals (Breene 1990). Extensive clinical studies have demonstrated that some species have medicinal and therapeutic value, by injection or oral administration, in the prevention/treatment of... 

Antidiabetic activity. Dietary psyllium fiber, administered to patients with type 2 diabetes at three doses of 5 g each daily be-... 

High in pectin and other types of soluble dietary fiber... 

Dietary fiber has been suggested to play a protective role against chemically-induced toxicity (1) and against colon cancer (2). However, the mechanism(s) by which dietary fiber modulates chemical toxicity or colon cancer has not been well studied. The fiber fraction of the diet is resistant to mammalian digestive enzymes and consequently dietary fiber is not absorbed from the small intestine (3). However, certain types of dietary fiber specifically fermentable fibers, including the pectic substances and hemicelluloses, are readily digested by the intestinal microflora (4,5). Pectic... 

Animal feeds as well as human diets vary considerably in the type and quantity of dietary fiber. Wise and Gilbert (9) using modified detergent methods analyzed fourteen commercial rodent diets and found that the total dietary fiber content varied from 8.3 to 22.4%. In fact, it is not unusual for commercially available cereal-based rodent diets to contain 20% dietary fiber on a dry weight basis (10). In general, the fermentable fibers constitute more than half of the total dietary fiber the remainder composed of the fibers more resistant to fermentation, such as cellulose and lignin (9). Thus, a significant portion of rodent diets has the potential to be fermented in the intestinal tract. 

Our first indication that fermentable fiber could alter microfloral metabolism was based on studies assessing the influence of dietary fiber types on the disposition of model xenobiotics using pharmacokinetic analysis (14). Amaranth was selected as a model xenobiotic for these studies because it was absorbed only after reduction by gut microflora (15). 

The foregoing indicates that much remains to be learned concerning the effects of fiber on the metablic influences of xenobiotics. Very little has been done to elucidate influences of types of fiber and to relate them to fiber structure. The sex differences observed have not been exploited to learn what there is about the male-female difference (hormones, blood chemistries) which could be used to make dietary fiber a more effective protective agent in males. 

Dietary Fat and Fiber and Bile Acid Excretion. In order to understand the specifics of the mechanisms whereby dietary fat influences colon cancer, the effect of type and amount of dietary fat on biliary and fecal bile acids was studied in rats (40,47,48). These... 

Studies of the incidence of and mortality from colon cancer at the international level suggest an association of this neoplasm with total dietary fat (33,34). Lui et al (35), studying the disappearance rate of food and mortality from colon cancer between the years 1967-1973 in 20 industrialized countries, concluded that there was a direct correlation of this tumor type and the per capita intake of total fat, saturated and monounsaturated fat and cholesterol. Furthermore, fiber intake was inversely correlated with colon cancer in these studies. 

The data on absorption efficiency of Mn are by no means consistent, but efficiency is probably in the range of one to three percent depending on the type of diet and on the presence or absence of dietary Mn antagonists (eg., ash or fiber). This range of absorption efficiencies in the chick is not greatly different from estimates of one to four percent made in mammals (28-29). Thus, the chick s high Mn requirement relative to mammals is probably not totally a result of inefficient Mn absorption. Instead, avians may experience a more rapid turnover of stored Mn than mammals, although more definitive data are needed to verify this hypothesis. 

Since almost nothing is known about the effect of isolated fibers on the absorption of manganese and constituents of dietary fiber vary both in chemical and physical properties, the effects of two major types of fiber — cellulose and pectin — were examined using our protocol. The effect of phytate was also measured since it is associated with high fiber foods and has been reported to increase requirements for manganese (40). 

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