Dietary fiber consumption, effect

Later it was observed that butyric acid is a naturally occurring dietary HD AC inhibitor. It is formed upon dietary fiber fermentation within our digestive system. Although butyrate does not normally reach high enough levels for cancer treatment, it has been proposed that daily consumption over an individual s lifetime may provide chemoprevenfive effects. ... 

Bile-acid metabolism explains the ability of certain kinds of dietary fiber to help lower serum cholesterol. A molecule of bile acid circulates through the liver and intestine five or more times before finally being eliminated. Soluble fiber (such as that found in oat bran) binds bile acids, but itself cannot be absorbed. Therefore, fiber-bound bile acids are eliminated in the stool. Because bile acids derive from cholesterol, synthesizing more bile acid drains the body s stores of cholesterol, which leads to a reduction in serum cholesterol, and therefore, to a lower risk of coronary artery disease. Eating oat fiber cannot overcome an excessive dietary cholesterol consumption, of course. In other words, consuming excessive amounts of well-marbled steak and expecting to overcome the effects by eating a bran muffin would be foolish. 

Although there is sufficient data to indicate causal relationships between diet and cancer, drastic changes in dietary guidelines are premature at this time. Since many vitamins and trace elements are anti-carcinogens or anti-promoters, more research should be done on understanding their mechanisms of action. Further research on the role of dietary fiber intake on the inhibition of tumor development is warranted since the mechanism is unknown and there may be adverse effects on nutritional status in high fiber diets. As more information becomes available, it may be possible to modify dietary patterns slightly to reflect decreased consumption of deleterious compounds and increased consumption of beneficial components such that an overall decrease in the risk of diet and cancer could result. 

An obvious factor for the inconsistent results of the effect of different intakes of dietary fiber on colorectal cancer is the variation in the analytical methodology used in different studies. There is also increasing evidence that total dietary complex carbohydrates may be as important as fiber. Analysis of stool weight from 20 populations in 12 countries showed that larger stools were correlated with a lower incidence of colon cancer. Intakes of starch and dietary fiber (rather than fiber alone) were the best dietary correlates with stool weight. A subsequent meta-analysis showed that greater consumption of starch (but not of NSPs) was associated with low risk of colorectal cancer in 12 populations. The examination also showed that fat and protein intakes correlated positively with risk. This meta-analysis is probably the first of its kind to... 

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