Fiber hypothesis

Adlercreutz H.Does Fiber-rich food containing animal lignan precursors protect against both colon and breast cancer An extension of the Fiber Hypothesis . Gastroenterology >6 6 -66. 1984. 

Experiments with chemically induced colon cancer in the rat have partially, but not consistently, supported the dietary fiber hypothesis (12). Thus, Bauer et al. (13,14) recently reported that both high- and low-methoxylated pectin (6.5 or 5% in a diet containing 20% casein, 20% fat and no other dietary fiber) given during induction of colon cancer with subcutaneous 1.2-dimethyl— hydrazine, enhanced the yield of tumors. Guar gum, 5%, also tended to increase the tumor yield, although not significantly compared with controls on a virtually fiber-free diet. Others(15) however reported a protective effect of 15% pectin. 

The beneficial effects of dietary fiber on the alimentary tract were emphasized by another of the founders of the dietary fiber hypothesis, Denis Bur-kitt, who based his arguments largely on the concept of fecal bulk, developed as a result of field... 

Dunnigan, J. (1984). Biological effects of fibers Stanton s hypothesis revisited. Environ. Health Perspect. 57, 333-337. 

This hypothesis would seem testable in a number of ways, one of which I am working on currently. Basically, since epithelial tissue and muscle fibers are present in Placozoa and in the epithelial component of Cnidaria, the specific proteins of epithelia and muscle should show more similarities to each other than to nerve which is absent in Placozoa and derived from amoeboid cells in Cnidaria. My students and I are attempting to test this hypothesis on a broad scale (not confined to Cnidaria) by looking at similarities among tissue-specific proteins in general. The question is Do sequences in proteins identified with epithelia and muscle show more similarities with each other than they do with sequences of specific proteins for other tissues . 

There are several reports on the coating of bone-like hydroxyapatite onto natural polymer substrates. Kawashita et at. [57] reported that carboxymethylated chitin and gellan gum gels, which have carboxyl groups, can form hydroxyapatite on their surfaces in SBF if they are treated with a saturated Ca(OH)2 solution in advance, while curdlan gel, which has no carboxyl group, does not form hydroxyapatite in SBF, even if it is treated with Ca(OH)2 solution. These results support the hypothesis that carboxyl groups induce hydroxyapatite nucleation. Kokubo et at. [58,59] reported that non-woven fabrics of carboxymethylated chitin and alginate fibers also form hydroxyapatite on their surfaces in SBF if they are treated with Ca(OH)2 solution. 

There is some evidence that long-term cyclic administration of rifaximin combined with fiber supplementation is effective for inducing symptomatic relief in patients with uncomplicated diverticular disease of the colon. A therapeutic gain of approximately 30% compared to fiber supplementation only can be expected. The drug is well tolerated and no relevant side effects have been reported. Symptoms attributed to diverticula (abdominal pain or discomfort, bloating, disturbance of bowel habits) are nonspecific symptoms and are also features of irritable bowel syndrome. It has been suggested that irritable bowel syndrome and diverticular disease of the colon may coexist in many people and when bowel symptoms occur with diverticulosis coli, they may be due to a coexistent irritable bowel rather to the diverticula themselves [47, 48]. This hypothesis is supported by the fact that many patients with symptomatic diverticular disease show co-... 

The chiral-bilayer-effect hypothesis has been evoked for the rationalization of the helical fibers formed from enantiomeric or diastereomeric surfactants (Fig. 54) [373], Different packing of the chiral surfactants in the crystals (head-to-tail) and in bilayer or micellar aggregates (tail-to-tail) is the basis for this postulate. Crystallization from aggregates requires an energetically costly, 180°... 

---